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Introduction :
pain is a stressor that can threaten homeostasis (a steady
physiological state). The adaptive response to such a stress involves
physiological changes that, in the initial stages, are useful and are also
potentially life-saving(Bultaci, 2007 ).
Unrelieved postoperative pain may result in clinical and psychological
changes that increase morbidity, mortality, costs as well as decrease
quality of life and potentially increase the incidence of chronic pain.
Negative clinical outcomes resulting from ineffective postoperative pain
management include deep vein thrombosis and pulmonary embolism,
coronary ischemia and myocardial infarction, pneumonia, poor wound
healing, insomnia and demoralization. Associated with these
complications are economic and humanistic implications such as
extended lengths of stay, readmissions, and patient dissatisfaction with
medical care. A recent study suggests that pain in ambulatory surgical
patients is still undermanaged and the incidence of moderate to severe
pain remains high (Apfel AL et al., 2003).
We all know that treatment of pain by getting rid of its causes is the
best way, but it is not always possible and especially it does not always
work fast enough. Half of the patients in US consultation rooms come for
the treatment of pain, and no part of pharmacology is better researched
than pain treatment (Barden et al, 2004).
Regional anesthesia and analgesia can be used to significantly
reduce postoperative pain scores and spare the use of systemic opioids.
Regional anesthesia can be performed at the neuraxis (epidural) or the
nerve root (paravertebral). Local anesthetic deposition at these sites will
1
selectively block nerve conduction and result in different analgesic and
side effect profiles . (Linda Le-Wendling, et al., 2015).
The paravertebral block is a selective block of the nerve roots at the
chosen levels. The resultant anesthesia or analgesia is conceptually
similar to a "unilateral" epidural anesthesia. Higher or lower levels can be
chosen to accomplish a band-like segmental blockade at the desired
levels. However, the paravertebral block does not result in
hemodynamically significant sympathetic blockade, therefore,
hypotension is not commonly seen with this block. The lumbar
paravertebral block is used most commonly in our practice for surgical
patients undergoing inguinal herniorrhaphy and lateral abdominal surgery
(Karmakar MK, 2001).
Epidural analgesia can be a useful method of pain management at
various situations. It facilitates early mobilization and also avoids
perioperative pulmonary complications (Sherwood ER et al., 2005).
Evidences for efficacy and safety of ultrasound guided regional
anaesthesia have made it a choice of regional anesthesia in comparison to
the conventional techniques. The use of ultrasound is set as a gold
standard in many institutions practicing regional blocks, and in the near
future, practicing regional anesthesia and intravascular access will need
an ultrasound as standard equipment (Shorten GD and O’Sullivan O,
2010)
Aim of the work2
This prospective randomized single blinded clinical study was
done to evaluate the efficacy of both continuous lumbar epidural
and ultrasound guided continuous paravertebral block on
perioperative analgesia and hemodynamic stability in patients
undergoing lower abdominal surgery.
Anatomy of epidural space:
3
It is an anatomic compartment between the dural sheath and
the spinal canal in some areas it is a real space and in others
only a potential space. It surrounds the spinal part of the dura
and extends from the foramen magnum of the skull above to the
sacral hiatus below. It can be categorized into cervical, thoracic,
lumbar and sacral epidural spaces (Mackintosh, RR.; & Lee,
JA. (1973).
Fig.1 Sagittal section of lumbar vertebrae showing epidural space (Mackintosh, RR.;
& Lee, JA. (1973).
Contents:
It contains the roots of the spinal nerves, the vertebral plexus of veins,
small arteries, lymphatics and the epidural fat. This fat is loose and allows
injected fluid to diffuse through it. The epidural contents are contained in
4
a series of circumferentially discontinuous compartments separated by
zones where the dura contacts the wall of the vertebral canal (Hogan,
1998).
Boundaries:
The space projects through each intervertebral canal to lie behind the
parietal pleura, whose negative pressure is transmitted to it. The epidural
space is bounded superiorly by the fusion of the spinal and periosteal
layers of the dura mater at the foramen magnum. Inferiorly, it is bound by
the sacrococcygeal membrane. The space is bounded anteriorly by the
posterior longitudinal ligament, vertebral bodies and discs while the
pedicles and intervertebral foraminae form the lateral boundary. The
ligamentum flavum, capsule of facet joints and the laminae form the
posterior boundary of the epidural space. (Bromage, 1978).
Measurement of the epidural space: The epidural space is most roomy at the upper thoracic levels. The
epidural space in the adult measures about 0.4 mm at C7-T1, 7.5 mm in
the upper thoracic region, 4.1 mm at T11-12 region and 4-7 mm in the
lumbar region.The space is far greater than that of the subarachnoid space
at the same level. (Nickallis & Kokri, 1986).
Shape and size of the epidural space: These are largely determined by the shape of the lumbar vertebral
canal and the position and size of the dural sac within it. It has been
5
suggested that though merely a potential space it could be up to 5 mm in
depth (Husemeyer & White, 1980).
Pressure of the epidural space: The epidural space with the exception of the sacral region is said to be
under negative pressure. It has been hypothesized that the initial or 'true'
negative pressure encountered when a needle first enters the epidural
space could be due to initial bulging of the ligamentum flavum in front of
the advancing needle followed by its rapid return to the resting position
once the needle has perforated the ligament. The bulging has been
confirmed to occur in fresh cadavers, and pressure studies carried out
during performance of epidural blocks in patients lend weight to this
hypothesis (Zarzur E, 1984).
Negative pressure can be magnified by increasing and reduced by
decreasing the flexion of the spine. The negative pressure appears to be
positive when the vertebral column is straightened. Depending on the
position of the needle, two different components of negative pressure
have been recognized. A basal value ranging from -1 to -7 cmH2O could
be observed when entering the epidural space. It remains stable providing
the patient is well relaxed. An artefactual component up to -30 cmH2O
could appear if needle is further advanced against the dural sac (Usubiaja
et al., 1967).
The epidural space identification is frequently dependent on the
negative pressure within this space. It has been demonstrated that the
epidural pressure is more negative in the sitting position than in the lateral
decubitus position especially in the thoracic region. It therefore suggests
6
that the space is better identified in the sitting position when the hanging
drop technique is used to identify the epidural space (Gil et al., 2008).
Anatomy of the Paravertebral space: The paravertebral space (Figure 2) is a wedge-shaped anatomical
compartment adjacent to the vertebral bodies.( Klein et al., 2004)
described an endoscopic technique that permits imaging of the contents
and boundaries of the paravertebral space in cadavers. The paravertebral
space is defined anterolaterally by iliopsoas muscle, posteriorly by the
superior costotransverse ligament, medially by the vertebrae and
intervertebral foramina. Within this space, the spinal root emerges from
the intervertebral foramen and divides into dorsal and ventral rami. The
sympathetic chain lies in the same fascial plane and communicates with it
via the rami communicantes. Hence, PVB produces unilateral sensory,
motor and sympathetic blockade.
Figure (2) : - A diagram showing anatomy of paravertebral space and needle insertion. (Mark and John, 2011)
7
Contents of the paravertebral space:
The PVS contains adipose tissue within which lie the spinal nerve, the
dorsal ramus, blood vessels, rami communicantes, and anteriorly the
sympathetic chain. The spinal nerves are segmented into small bundles
and lie freely in the adipose tissue of the PVS, which make them
accessible to local anesthetic solutions injected into the PVS.
Communication of paravertebral space:
The lumbar paravertebral space is continuous from L1 to L5 and
for descriptive purposes , the space is split into dermatomes . The PVS
may be divided into anterior and posterior segments by paravertebral
fascia which is a thin fibroelastic structure and may affect the pattern of
spread of local anesthetics during paravertebral block. (Deegan C.A et
al., 2009)
Superior it communicates with the thoracic PVS, there are
conflicting contrast studies in cadavers with regard a
communication between the thoracic and lumbar PVS. Clinically
lumbar plexus block is rarely seen following lower TPVB.
Inferior it communicates with the sacral PVS .
Medial it communicates with the epidural space via the
intervertebral foramina .
The prevertebral fascia lies anterior to the vertebral bodies and can
provide a conduit to the contralateral LPVS for local anesthetic but
this is unusual. (Deegan C.A et al., 2009)
Applied anatomy:
8
Dermatomal innervation :
The lumbar paravertebral block results in anesthesia of the skin of
the posterior, lateral and anterior aspects of the abdomen (L1-L5) .
Myotomal innervation :
The main muscles innervated by the lumbar nerves are the
transversus abdominis muscle, the internal and external oblique muscles
and the rectus abdominis muscle. (Attila et al., 2010) .
Nerves :-
The nerve root passes through its respective intervertebral foramen
to enter the medial aspect of the PVS. There is no fascial sheath covering
the nerve as it emerges as a loose bundle of neurons. This allows for
direct and quick action of local anesthetic on the neurons. Each root
projects a somatic dorsal ramus and a ramus communicantes within the
medial aspect of the PVS. The larger ventral portion passes through loose
areolar tissue and exits the PVS via the corresponding intercostal space.
(Barrett et al., 2004)
9
figure(3):-Relations of paravertebral space and nerves emerging through it (Lönnqvist
and Richardson ,1999)
Sono-anatomy (Ultrasound view of paravertebral space):
Using the traditional approach, locating the paravertebral space can be
technically difficult because it requires location of the transverse process
by blind needle placement and has a failure rate that varies from 8 to
10%. Failure to identify the transverse process results in several needle
redirections causing pain . (Lonnquist et al., 1995).
Sonographic Technique:
There are at least two described approaches to performing an
ultrasound guided PVB:
Classic approach: in which the probe positioned parallel to the
spinal process.
Proximal lateral approach: in which the probe positioned
perpendicular to the spinal process. (Riain et al., 2010).
10
Figure(4) :- Sonoanatomy of paravertebral space, US probe in sagittal
paramedian plane; ( Red line-transverse process). (Attila et al., 2010).
The ultrasound technique also offers the capability to visualize the
needle, the spread of local anesthetic solution and the placement of a
catheter in the paravertebral space under direct vision. (Ben-Ari et al.,
2009).
11
Pain is defined by the International Association for the Study of Pain
(IASP) as "an unpleasant sensory and emotional experience associated
with actual or potential tissue damage, or described in terms of such
damage". Pain is part of the body's defense system, triggering a reflex
reaction to retract from a painful stimulus, and helps adjust behavior to
increase avoidance of that particular harmful situation in the future.
Given its significance, physical pain is also linked to various cultural,
religious, philosophical, or social issues (Rey & Roselyne 2004).
Acute pain begins suddenly and is usually sharp in quality. It serves
as a warning of disease or a threat to the body. Acute pain may be mild
and last just a moment, or it may be severe and last for weeks or months.
In most cases, acute pain does not last longer than six months and it
disappears when the underlying cause of pain has been treated or has
healed. Unrelieved acute pain, however, may lead to chronic pain
(Blumenthal et al., 2005).
Classification of pain
Pain can be categorized according to several variables, including its
duration (acute or chronic), its pathophysiologic mechanisms (nociceptive
or neuropathic), and its clinical context (e.g., postsurgical, malignancy
related, neuropathic, degenerative). Acute pain follows traumatic tissue
injuries, is generally limited in duration, and is associated with temporal
reductions in intensity. Chronic pain may be defined as discomfort
persisting 3–6 months beyond the expected period of healing. In some
chronic pain conditions, symptomatology, underlying disease states, and
other factors may be of greater clinical importance than definitions based
on duration of discomfort. (Vadivelu et al., 2009)
Somatic pain can be further classified as superficial or deep.
Superficial somatic pain is due to nociceptive input arising from skin,
12
subcutaneous tissues, and mucous membranes. It is characteristically well
localized and described as a sharp, pricking, throbbing, or burning
sensation. Deep somatic pain arises from muscles, tendons, joints, or
bones. (Kaikman et al 2007).
The visceral form of acute pain is due to a disease process or
abnormal function of an internal organ or its covering (e.g., parietal
pleura, pericardium, or peritoneum). Four subtypes are described: (1) true
localized visceral pain, (2) localized parietal pain, (3) referred visceral
pain, and (4) referred parietal pain. True visceral pain is dull, diffuse, and
usually midline. It is frequently associated with abnormal sympathetic or
parasympathetic activity causing nausea, vomiting, sweating, and
changes in blood pressure and heart rate. Parietal pain is typically sharp
and often described as a stabbing sensation that is either localized to the
area around the organ or referred to a distant site (Table 1). The
phenomenon of visceral or parietal pain referred to cutaneous areas
results from patterns of embryological development and migration of
tissues, and the convergence of visceral and somatic afferent input into
the central nervous system. Thus, pain associated with disease processes
involving the peritoneum or pleura over the central diaphragm is
frequently referred to the neck and shoulder, whereas disease affecting
the parietal surfaces of the peripheral diaphragm is referred to the chest or
upper abdominal wall(Ready & Edwards 2006).
13
Table 1. Patterns of Referred Pain.
Location Cutaneous Dermatome
Central diaphragm C4
Lungs T2–T6
Heart T1–T4
Aorta T1–L2
Esophagus T3–T8
Pancreas and spleen T5–T10
Stomach, liver, and gallbladder
T6–T9
Adrenals T8–L1
Small intestine T9–T11
Colon T10–L1
Kidney, ovaries, and testes T10–L1
Ureters T10–T12
Uterus T11–L2
Bladder and prostate S2–S4
Urethra and rectum S2–S4
(Ready & Edwards 2006)
Pain pathway:
Nociception is a sequential process that includes transduction of
noxious stimuli into electrical signals by peripheral nociceptors,
conduction of encoded signals by afferent neurons to the dorsal horn of
the spinal cord, and subsequent transmission and modulation of the signals
at both spinal and supraspinal levels. In its simplest form, the nociceptive
pathway is a three neuron chain. (figure 1) The 1st neuron in the chain the
primary afferent neuron is responsible for transduction of noxious stimuli
14
and conduction of signals from the peripheral tissues to neurons in the
dorsal horn of the spinal cord. (Lemke et al., 2004)
Figure (1): Nociceptive pathway (Lemke et al., 2004)
Nociceptive fibers synapse with 2nd order nociceptive neurons in
the dorsal horn of the spinal cord. There are 2 main types of nociceptive
neurons in the dorsal horn (projection neurons and interneurons), and
these neurons are organized into layers or laminae. Neurons that mediate
nociception are located primarily in lamina I (substantia gelatinosa),
lamina II (marginal layer), and lamina V (Figure 2). Projection neurons
are located in laminae I and V and have axons that “project” to supraspinal
3rd-order neurons. Neurons located primarily in lamina I receive input
directly from nociceptive Aδ and C fibers and are called nociceptive-
specific neurons. (Lemke et al., 2004)
The 2nd neuron in the chain - the projection neuron - receives input
from the primary afferent neurons and projects to neurons in the medulla,
pons, midbrain, thalamus, and hypothalamus. Ascending nociceptive
15
tracts, including the spinothalamic, spinobulbar, and spinohypothalamic
tracts, convey nociceptive information from the dorsal horn of the spinal
cord to higher centers in the central nervous system. The spinothalamic
pathway is the major ascending nociceptive pathway; it is divided into
medial and lateral components. The medial component projects to medial
thalamic nuclei and then (via 3rd-order neurons) to the limbic system; it is
responsible for transmission of nociceptive input involved with the
affective-motivational aspect of pain. The lateral component projects to
lateral thalamic nuclei and then to the somatosensory cortex; it is
responsible for transmission of nociceptive input involved with the
sensory-discriminative aspect of pain. The 3rd order, supraspinal neurons
integrate signals from the spinal neurons and project to the subcortical and
cortical areas where pain is finally perceived. (Lemke et al., 2004)
Figure )2(: Dorsal horn neurons. Nociceptive (Aδ and C) and nonnociceptive (Aβ)
fibers(Lemke et al., 2004)
Types of nerve fibers:
Important fibres coming from the periphery into the dorsal horn include:
16
Tiny unmyelinated 'C' fibres that are important carriers of the long-
lasting burning pain that makes a surgical wound (for example)
such an unpleasant experience.
Thin myelinated 'A delta' fibres, concerned with more accurate
localisation of pain, and terminating mostly laterally in laminae I
and V.
Rather chunky 'A beta' fibres that carry information about vibration
and position sense from the periphery to the cord.
Unpleasant stimuli entering via the C fibres can be suppressed by
concurrent stimulation of A delta fibres (high amplitude low frequency
stimulation, for example by acupuncture) or by impulses passing through
A beta fibres. Examples of the latter include TENS (transcutaneous
electrical nerve stimulation) and the simple expedient of rubbing the skin,
which is well known by mothers to decrease perception of pain (Lemke et
al., 2004) .
Nociceptors:
Most nociceptors are free nerve endings that sense heat and
mechanical and chemical tissue damage. Types include (1)
mechanonociceptors, which respond to pinch and pinprick, (2) silent
nociceptors, which respond only in the presence of inflammation, and (3)
polymodal mechanoheat nociceptors. The last are most prevalent and
respond to excessive pressure, extremes of temperature (> 42°C and <
18°C), and alogens (pain-producing substances) (Westlund et al., 2007).
Nociceptors are present in both somatic and visceral tissues. Primary
afferent neurons reach tissues by traveling along spinal somatic,
sympathetic, or parasympathetic nerves. Somatic nociceptors include
17
those in skin (cutaneous) and deep tissues (muscle, tendons, fascia, and
bone), whereas visceral nociceptors include those in internal
organs(Westlund et al., 2007).
Chemical Mediators of Pain:
Neurotransmitters are chemicals that allow the movement of
information from one neuron across the gap between it and the adjacent
neuron. The release of neurotransmitters from one area of a neuron and
the recognition of the chemicals by a receptor site on the adjacent neuron
causes an electrical reaction that facilitates the release of the
neurotransmitter and its movement across the gap (Thomas et al., 2005).
Several neuropeptides and excitatory amino acids function as
neurotransmitters for afferent neurons subserving pain (Table 2). Many if
not most neurons contain more than one neurotransmitter, which is
simultaneously coreleased. The most important of these peptides are
substance P (sP) and calcitonin gene-related peptide (CGRP). Glutamate
is the most important excitatory amino acid (Schaefer et al., 2006).
Table 2. Major Neurotransmitters Mediating or Modulating Pain.
Neurotransmitter Receptor1
Effect on Nociception
Substance P NK–1 Excitatory
Calcitonin gene-related peptide Excitatory
Glutamate NMDA, AMPA, kainite, quisqualate Excitatory
Aspartate NMDA, AMPA, kainite, quisqualate Excitatory
Adenosine triphosphate (ATP) P1, P2 Excitatory
18
Somatostatin Inhibitory
Acetylcholine Muscarinic Inhibitory
Enkephalins , , Inhibitory
-Endorphin , , Inhibitory
Norepinephrine 2
Inhibitory
Adenosine A1
Inhibitory
Serotonin 5-HT1 (5-HT3)
Inhibitory
-Aminobutyric acid (GABA) A, B Inhibitory
Glycine Inhibitory
(Schaefer et al., 2006).
As important as the ascending pathways are fibres that descend from
brainstem to spinal cord to modulate the incoming signals. Notable
neurotransmitters mediating this anti-nociceptive effect include nor
adrenaline (nor epinephrine), especially in the locus coeruleus, and
serotonin in the raphe nuclei. Opioid receptors are prevalent here. Some
descending connections are:
19
Fig.3 Descending
connections that modulate incoming pain impulses. (Sutin & Carpenter 2004).
Incoming painful stimuli are transmitted (A) to the dorsal horn, and
from there (B) to the periaqueductal grey (PAG). Descending impulses
pass (C) to the raphe nuclei, especially the nucleus raphe magnus, in the
upper medulla, and thence back to the dorsal horn via reticulospinal fibres
(D). The above shows only the serotonergic descending fibres. Other
pain-suppressing impulses pass from the PAG to the locus coeruleus, and
from there to the dorsal horn. (Sutin & Carpenter 2004).
Assessment of Acute Pain
Based on the assumption that patient self-reporting is the "most reliable
indicator of the existence and intensity of pain” the ideal tool for pain will
identify the presence of pain and its evolution over time. In addition, tools
should be applicable to any person regardless of age, race, creed,
socioeconomic status, and psychological or emotional background
(Rowbotham & Macintyre 2003).
Assessment of pain in adults:
20
In the assessment of pain intensity, rating scale techniques are often
used. The most commonly used forms are:
• The Category Rating Scales: (e.g. none, mild, moderate, severe,
unbearable or 1-5).
• The Visual Analogue Scales (VAS): (e.g. 10 cm line with anchor points
at each end). The VAS has been shown to be more sensitive to change
and is therefore more widely used. These scales may also be incorporated
into pain diaries.
• McGill Pain Questionnaire (MPQ): (78 pain adjectives arranged into 20
groups further arranged into sets of words describing sensory aspects of
the quality of pain). Very widely used questionnaire.
(Svensson et al., 2007).
A Visual Analogue Scale (VAS) is a measurement instrument that tries
to measure a characteristic or attitude that is believed to range across a
continuum of values and cannot easily be directly measured.
Figure (4): Visual analogue scale (VAS) ,Verbal rating scale (VRS) and Numerical
rating scale (NRS), (Breivik et al., 2000)
Operationally a VAS is usually a horizontal line, 100 mm in length,
anchored by word descriptors at each end, as illustrated in Fig. 1. The
21
patient marks on the line the point that they feel represents their
perception of their current state. The VAS score is determined by
measuring in millimetres from the left hand end of the line to the point
that the patient marks. There are many other ways in which VAS have
been presented, including vertical lines and lines with extra descriptors.
(Niven & Dowens 2000).
Assessment of acute pain during movement (dynamic pain):
Assessment of the intensity of acute pain at rest after surgery is
important for making the patient comfortable in bed. However, adequate
relief of dynamic pain during mobilization, deep breathing, and coughing
is more important for reducing risks of cardiopulmonary and
thromboembolic complications after surgery. Immobilization is also a
known risk factor for chronic hyperalgesic pain after surgery, becoming a
significant health problem in about 1%, a bothersome but not negligible
problem in another 10%. Effective relief of dynamic pain facilitates
mobilization and therefore may improve long-term outcome after surgery.
(Jarzyna et al., 2011).
Management of acute postoperative pain:
Opioid Monotherapy:
Opioids have been used as analgesics for more than 2,000 years and
continue to be a key element in moderate to severe acute postoperative
pain management. However, opioid-only treatment plans can result in
intolerable and dangerous adverse effects, including constipation, nausea
and vomiting, excessive sedation, and respiratory depression. Concerns
are also being raised about a possible link between opioid-only treatment
plans and a paradoxic clinical situation in which increasing doses of
22
opioid result in increasing sensitivity to pain, a condition referred to as
opioid-induced hyperalgesia ( Pasero, 2011).
Adverse effects associated with opioids commonly occur and can
prevent patients from experiencing satisfactory analgesia. In a systematic
review analyzing opioid-induced adverse effects among postoperative
patients in 45 randomized-controlled studies, 31% of patients experienced
an adverse gastrointestinal (GI) event (ileus, nausea, vomiting,
constipation), 30.3% of patients reported an adverse central nervous
system (CNS) event (somnolence, sedation), 18.3% of patients reported
pruritus, 17.5% of patients experienced urinary retention, and 2.8% of
patients had respiratory depression (Wheeler et al., 2002).
Non-steroidal anti-inflammatory drugs (NSAIDs):
NSAIDs are considered to be appropriate for mild to some moderate-
intensity acute pain and as adjuncts to opioids for the relief of more severe
acute pain. They do not produce respiratory depression or impair GI
motility so are considered an important component with acetaminophen in
a multimodal treatment plan for acute pain. (Pasero et al., 2011).
The analgesia and anti-inflammatory effects induced by NSAIDs
are the result of cyclo-oxygenase 2 (COX-2) inhibition, while the adverse
effects of NSAIDs are generally the result of COX-1 inhibition. For
example, an adverse effect of COX-1 inhibition is reduced platelet
aggregation. The most common adverse effect of NSAIDs is gastric
complications, and patients with a history of peptic ulcer disease are
among the highest risk for this adverse effect. NSAIDs can also induce
acute renal failure, particularly in patients with acute or chronic volume
depletion, cardiac failure, liver cirrhosis, ascites, diabetes, or preexisting
hypertension. (Pasero et al., 2011)
23
Acetaminophen:
Because of its efficacy, safety, lack of clinically significant drug
interactions, and lack of the adverse effects associated with other
analgesics, IV acetaminophen is an attractive component of a multimodal
analgesic treatment plan. (Groudine et al., 2011)
Acetaminophen is not associated with the increased incidence of
nausea, vomiting, and respiratory depression that can occur with opioids,
or the platelet dysfunction, gastritis, and renal toxicity that are sometimes
associated with NSAIDs. (Silvanto et al., 2007)
Gabapentin and pregabalin:
Gabapentin first marketed in the nineties for its antiepileptic properties,
is known to be effective in treating chronic neuropathic pain, complex
regional pain syndromes, and restless legs syndrome. Gabapentin is
believed to act on a specific receptors, which are over expressed in the
dorsal horn of the spinal cord and in spinal ganglia in cases of
neurological injury. The advantages of gabapentin are that it does not
interact with haemostasis and does not induce respiratory depression.
Further, its anxiolytic properties can be useful preoperatively.
Recommended dosages are (300 to 3200 mg/day) in 2-3 doses.
Bioavailability of gabapentin is 36% to 60% and decreases with the
ingested dose because of good absorption at the small intestine level.
Gabapentin is not metabolized and is eliminated in the urine; therefore,
dosages should be modified in renal failure. Side effects are rare and
usually mild: dizziness,vertigo, headaches, nausea, vomiting, and
ataxia(Fassoulaki et al.,2006)
24
Regional Anesthesia and local anesthetics:
Regional anesthesia is used to desensitize a specific part of the body
to a painful stimulus. It is classified into six sites of placement of local
anesthetic: topical or surface anesthesia, local infiltration, peripheral nerve
block, intravenous regional anesthesia, epidural anesthesia, and spinal
(subarachnoid) anesthesia. (Stoelting et al., 2006).
Regional anesthesia techniques may include, but are not limited to,
spinal, epidural, peripheral nerve blocks, upper and lower extremity
blocks, airway blocks, and transversus abdominis plane (TAP) blocks.
Regional anesthesia techniques may be used alone, or in combination with
other anesthetic techniques, to provide anesthesia and analgesia for a
variety of surgical and obstetrical procedures as well as for chronic pain
management. Using regional anesthesia in combination with other
anesthetic techniques can minimize side effects of an individual anesthetic
technique, maximize benefits, and offer the patient options in the selection
of anesthesia and analgesia. (Olson et al., 2010)
Multimodal Pain Management
To address the under-treatment of postoperative pain and the
limitations of opioid monotherapy, a strategy known as multimodal pain
management was introduced in the early 1990s . This approach
simultaneously administers two or more analgesic agents with different
mechanisms of action. Combination therapy using drugs with distinct
mechanisms of action may add analgesia or have a synergistic effect and
allow for better analgesia with the use of lower doses of a given
medication than if the drug was used alone (Pasero, 2011). For example,
postoperative multimodal analgesia may consist of the use of opioid and
non-opioid pharmacologic agents, as well as regional anesthesia and
25
continuous peripheral nerve block. The multimodal approach has been
used by many professional organizations, including the American Society
of Anesthesiologists (ASA) and the American Pain Society (APS)
(Jarzyna et al., 2011).
Ultrasound guidance has greatly influenced the practice of regional
anaesthesia in the last 15 years. Between 1884, the year when Carl Koller
performed the first regional block for eye surgery in Vienna, and the late
1970s, the main developments were in new local anaesthetic drugs and
the introduction of mainly anatomical methods for nerve identification.
Unfortunately, anatomy is not exactly predictable and the natural
variability of human anatomy led to poor success rates for many
peripheral nerve blocks. (Kapral et al., 1994)
Current ultrasound equipment allows much easier identification of very
small neural structures than it was possible with machines introduced
only a few years ago. In addition, adjacent anatomical structures can be
identified. (Duggan et al., 2009)
Without any doubt, direct visualization of neural and adjacent
anatomical structures is the main advantage of the use of ultrasound for
regional block techniques. An important objective for ultrasound is
visualization of the spread of local anaesthetic during injection.
Confirmation of the correct disposition of local anaesthetic avoids any
maldistribution , such as epineural, perineural or intravascular injection.
In addition, an ability to perform blocks with small volume of local
26
anaesthetic is mainly based on an ability to observe the spread of the local
anaesthetic directly (Latzke et al., 2010).
Basic of ultrasound physics:-
Ultrasound is a form of mechanical sound energy that travels through a
conducting medium (e.g., body tissue) as a longitudinal wave producing
alternating compression (high pressure) and rarefaction (low pressure).
Sound propagation can be represented in a sinusoidal waveform with a
characteristic pressure (P),wavelength (λ), frequency (f), time (T) and
velocity (speed (c) + direction) (Figure-1). (Edler and Lindstrom, 2004)
)Figure -1 :(ultrasound waves, High-frequency probes produce shorter wavelength waves, and low-frequency probes produce longer wavelength waves(Edler and
Lindstrom, 2004)
Tissue appearance under ultrasound:
*Hyperechoic areas :- have a great amount of energy from returning
echoes and are seen as white.
*Hypoechoic areas: - have less energy from returning echoes and are
seen as gray.
27
*Anechoic areas without returning echoes are seen as black.
Ultrasound waves and tissue interaction:
The speed of ultrasound waves through biological tissue is based on
the density of tissues, and not the frequency of the ultrasound waves.
The greater the tissue density, the faster the ultrasound waves will
travel. The image processor in the ultrasound machine assumes that the
ultrasound waves are travelling through soft tissue at a velocity of
1,540 m/sec. Three things can happen to ultrasound waves as they
travel through tissue reflection, attenuation, and refraction. (Weyman,
1994)
1-Reflection:
The generation of ultrasound images is dependent on the energy of
the echoes that return to the probe. The amount of reflection of
ultrasound waves is dependent on the difference in acoustic impedance
at the interface between different tissues. Acoustic impedance is the
resistance of a material to the passage of ultrasound waves. (Figure -2).
The greater the difference in acoustic impedance at tissue interfaces,
the greater the percentage of ultrasound waves that is reflected back to
the probe to be processed into an image.(Middleton et al., 2004)
28
(Figure -2): Specular reflection vs. scattering reflection.(Middleton et al.,
2004)
2-Attenuation:
Attenuation of ultrasound waves is dependent on three factors:
Attenuation coefficient of the tissue.
Distance travelled.
Frequency of the ultrasound waves.
Attenuation is inversely related to frequency; the higher the frequency
of the ultrasound wave, the greater the attenuation. Therefore, high
frequency probes have less tissue penetration due to greater
attenuation, which makes imaging of deeper structures difficult with
high-frequency probes.(Jespersen,1998)
3-Refraction:
When the acoustic impedance between tissue inter faces is small,
the ultrasound wave’s direction is changed slightly at the tissue
interface, rather than being reflected directly back to the probe at the
inter face this is analogous to the bent appearance of a fork in water,
which is caused by refraction of light waves at the air/water inter face.
Refracted waves may not return to the probe in order to be processed
into an image. Therefore, refraction may contribute to image
degradation (Figure -3).(Otto, 2000)
29
(Figure-3): Refraction vs. reflection.(Otto, 2000)
Resolution: It is the ability to distinguish two close objects as separate, is very
important in ultrasound-guided regional anaesthesia. There are two
types of resolution:
Axial resolution.
Lateral resolution.
1-Axial resolution:
Axial resolution is the ability to distinguish two objects that lie
in a plane parallel to the direction of the ultrasound beam. Axial
resolution is equal to half of the pulse length. Higher frequency probes
have shorter pulse lengths, which allows for better axial resolution.
The ultrasound probe emits ultrasound waves impulses, not
continuously. These pulses of ultrasound waves are emitted
intermittently as the probe has to wait and listen for the returning
echoes.(Chan, 2009)
2-Lateral resolution:
Lateral resolution is the ability to distinguish two objects that lie
in a plane perpendicular to the direction of the ultrasound beam.
Lateral resolution is related to the ultrasound beam width, the more
narrow (focused) the ultrasound beam width, the greater the lateral
resolution. High frequency probes have narrower beam widths, which
allows for better lateral resolution. Poor lateral resolution means that
two objects lying side by side may be seen as one object. The position
30
of the narrowest part of the beam can be adjusted by changing the focal
zone.(Chan, 2009).
Ultrasound machine controls:
1-Depth:
The depth of tissue imaged can be adjusted on the machine and
relates to the type of probe being used. Low-frequency probes will be
able to image deeper tissue depths than high-frequency probes. With a
linear array probe, as the depth is increased, the image on the screen
will appear narrower and structures will appear smaller, but the width
of the field of view is relatively constant. Notice that the field of view
is constant from 3 cm to 6 cm but at 2 cm it has decreased. (Kossoff,
2000)
(Figure -4) :-General Electric (GE) ultrasound portable device control pannel
2-Frequency:
Variable-frequency probes allow changes in frequency within a
narrow range. An 8 to 13 MHz probe allows selection of frequency
between 8 and 13 MHz. The lower frequencies are used for deeper
31
structures and the higher frequencies are used for more superficial
structures. Select a frequency that balances penetration and resolution.
(Lawrence, 2007)
3-Gain:
Ultrasound probes transmit ultrasound waves 1% of the time and
spend the remaining 99% of the time listening for the returning echoes.
Increasing the gain increases signal amplification of the returning
ultrasound waves, in this way the gain function can be used to
compensate for loss of energy due to tissue attenuation. Returning
ultrasound waves are referred to as “signal” while background artifact
is referred to as “noise”. Increasing the gain increases the signal-to-
noise ratio. However, if the gain is increased too much, the screen will
have a “whiteout” appearance and all useful information is lost.
(Lawrence, 2007).
4-Color-flow Doppler:
Color-flow Doppler allows for detection of flow within vascular
structures. Moving objects, such as red blood cells (RBCs), affect
returning ultrasound waves differently than stationary objects. Color-
flow Doppler can differentiate between RBCs moving away from the
probe and RBCs moving towards the probe. Red blood cells moving
towards the probe will return ultrasound waves at a higher frequency
and are displayed as red; RBCs moving away from the probe will
return ultrasound waves at a lower frequency and are displayed as blue.
(Figure-5)(Otto,2000).
32
(Figure -5): Radial artery flow is seen as red when the probe is tilted towards the
direction of flow.(Otto, 2000).
5-Pulse-wave Doppler:
Pulse-wave Doppler provides flow data from a small area along
the ultrasound beam. The area to be sampled can be selected by the
operator. Once pulse-wave Doppler is selected, the image is frozen and
the operator selects the area to be sampled. The pulse-wave
information is displayed graphically at the bottom of the screen as well
as heard(figure -6).(Otto, 2000)
)Figure -6 :(Pulse-wave Doppler showing arterial flow in the femoral artery.(Otto, 2000)
33
Needle insertion:
1-In plane (IP)
The needle is inserted in the same plane as the ultrasound beam.
The goal is for the path of the needle to be entirely within the beam of
the ultrasound. The more parallel the needle is to the probe (shallower
angle of insertion) the easier the needle will be to visualize. When
inserting the needle, the goal is to be as close to parallel to the probe as
possible. Since with many blocks it will be impossible for the needle to
be parallel to the probe, the goal should be to have as shallow an angle
of insertion as possible. In order to achieve a shallow angle between
the needle and the probe, some blocks will require that the needle be
inserted a greater distance from the probe as opposed to right next to
the probe.(Chan, 2009)
2-Out of plane (OOP):
The needle is perpendicular to the beam of the ultrasound. The
needle is seen as a small hyperechoic dot on the screen. In an OOP
approach, the needle needs to travel a shorter distance to the target than
in-plane approach. For those making the transition from nerve
stimulation to ultrasound, the location of needle insertion in the OOP
approach is similar to the traditional nerve stimulator insertion points.
Finding the needle tip in an OOP approach can be challenging for the
beginner. The steeper the angle of insertion, the easier to see the needle
in an OOP approach.(Chan, 2009).
Advantages of ultrasound guided nerve block
Ultrasound guidance offers several potential advantages:
34
1- Direct visualization of nerves: This may replace other methods of
nerve localization, such as electrical stimulation or paraesthesia.
2- Direct visualization of anatomical structures: vessels, muscles,
bones, fascia tendons: This may help assess individual variations in
anatomy and facilitate identification of nerves.
3- Real-time control of needle advancement: This may reduce the
number of needle passes, shorten the block performance time and
lower the risk of complications caused by a needle e.g., vascular
puncture, neuropraxia or pneumothorax.
4- Assessment of LA spread around the nerves and immediate
supplementary injections in case of insufficient spread: This may
improve block effectiveness, shorten latency, prolong duration, allow
LA dose reduction and lower the risk of overdose.
5- Avoidance of muscle twitches: This may reduce block discomfort.
(Marhofer P., et al., 2005) .
35
Technique of epidural block:Patient position:
Epidural block can be performed in the lateral or sitting position. when
the spinous processes are not easily palpable, the sitting position is preferred.
In some patients, the sitting position may be associated with orthostatic
hypotension and syncope. For this reason, it is important for an assistant to
provide continuous support to the patient during the procedure. (Andrews et
al, 1993).
Methods of identification of the epidural space: Various methods have been used in identifying the epidural space.
Most of these traditional methods of locating the epidural space depend
on the negative pressure exhibited during the introduction of the epidural
needle into the space. Any techniques identifying the epidural space
should be simple and straightforward, effective, safe, and reliable to
minimize the number of complications associated with it (Nafiu &
Bullough, 2007).
36
1) loss of resistance (LOR) technique: It is One of the most reliable methods in identifying the space.it
depends on loss of resistance (LOR). This method of identification uses
either air or a liquid such as saline or a local anesthetic to achieve it. The
technique applies continuous or intermittent pressure on the piston of an
epidural glass or plastic syringe towards the barrel, and the loss of
resistance is where it becomes possible to inject through the syringe
attached to the epidural needle, so the piston can easily move into the
barrel. This technique works because the ligamentum flavum is extremely
dense, and injection into it is almost impossible. The syringe may contain
air or saline. The principles are the same, but the specifics of the
technique are different due to the greater compressibility of air with
respect to saline or lidocaine.
The identification of the epidural space with LOR to air has been found
to be more difficult and caused more dural punctures than with lidocaine
or air plus lidocaine techniques. Additionally, sequential use of air and
lidocaine had no advantage over lidocaine alone (Evron et al., 2004).
The techniques of LOR to air or saline are also associated with some
complications. While LOR to air has been linked to paraplegia and
pneumocephalus (Nay et al., 1993). LOR to saline is frequently
associated with dilution of the injected local anesthetic (Okutomi &
Hoka, 1998).
2) modified drip method:
In this method, a saline infusion was prepared, leaving the distal 40 cm
of infusion tubing full of air, and then attached to the hub of a Tuohy
needle. Accurate identification of the epidural space was accomplished in
less than one minute in 95% of cases. This technique showed some
37
advantages over the hanging drop and the manual loss of resistance
techniques. (Michel & Lawes,1991).
3) Membrane in Syringe technique: This is a modification of the loss of resistance technique for
identifying the epidural space during epidural anesthesia. A plastic
membrane is placed halfway inside a syringe dividing the syringe into
two compartments. The saline compartment encompasses the nozzle of
the syringe (the distal compartment). The plunger is installed in the
opposite half of the hallow cylinder. Air is trapped in the space between
the membrane and the rubber plunger (air compartment).(Lin et al.,
2002).
4) Macintosh epidural balloon: Though cost implication of the use of epidural balloon is more than the
LOR to air, it obviously offered better advantage over the traditional use
of air.
5) The use of epidrum:_ This device is designed to operate at a high enough pressure to
discharge into the epidural space but a low enough pressure to minimize
premature leaking into the patients' tissues. The optimal pressure is
generated by the extremely thin diaphragm on top of the device that acts
as the meniscus of a manometer, so allowing the operator to interpret the
diaphragm's signal to identify the position of the tip of the needle.
Epidrum has been known to offer the following benefits:
Relatively simple. The trainer can monitor the signal when the trainee
is performing the procedure.
It is safe, effective and reliable.
38
It allows the use of a smaller needle to: reduce post dural puncture
headache and reduce epidural haematoma formation.
It offers a visual endpoint
Optimised, low, constant pressure - minimizes false positive error.
Easily observed cerebral spinal fluid (CSF) in the event of a dural
tap(Samada et al .,2011).
Fig.1:midline vs. paramedian approach of epidural block(Balki et al, 2009)
Contraindications:
Absolute contraindications include patient refusal, lack of adequate
equipment, lack of expertise or supervisory staff, severe coagulopathy,
and infection at the site of puncture. Some patients may be technically
challenging because of previous back surgery, such as lumbar fusions and
Harrington rods.
39
Relative contraindications include low platelet count with no
coagulopathy, infection remote from the site of lumbar puncture,
progressive neurologic disease, increased intracranial pressure,
hypovolemia and low fixed cardiac output e.g. sever aortic stenosis(Silva
and Halpern, 2010).
Complications:
Complications of central neuraxial blockade, much depending on the
experience in patient management, as well as materials, equipment, and the
presence of risk factors, have been reported to occur at various frequencies
(Moen et al, 2004).
Neurological complications resulting from accidental penetration of the
dura are similar to those that occur with spinal anesthesia. Inadvertent dural
puncture and postdural puncture headache, direct neural injury, total spinal
anesthesia, and subdural block have been commonly reported.
1) Inadvertent dural puncture and postdural puncture
headache:
The incidence of inadvertent dural puncture ranges between 0.19–0.5%
of epidural catheter placements. Postdural puncture headache (PDPH),
described as a positional, bilateral frontal-occipital, nonthrobbing pain, may
develop in as much as 75% of patients (Van de Velde et al, 2008).
2) Direct neural injury:
Direct neural injury has a reported incidence of 0.006%, and has been
associated with paresthesias during needle placement and pain on injection
(Ruppen et al, 2006).
40
3) Total spinal anesthesia:
Total spinal anesthesia may occur if the solution used for epidural
anesthesia is inadvertently administered into the intrathecal space in large
volumes. Symptoms are of a rapidly arising subarachnoid block, potentially
resulting in cardiovascular collapse and apnea requiring prompt
resuscitation. Provided that immediate, skilled resuscitative efforts are made,
complete recovery should be expected (Hara and Sata, 2006).
4) Epidural Hematoma:
Hemorrhagic complications are serious adverse outcomes that may
arise from neuraxial anesthesia. Epidural hematoma is a rare, but potentially
devastating, complication that requires emergency decompression in case of
clinical deterioration. It is rarely attributed to an arterial source, and can
develop spontaneously (Horlocker, 2004).The risk is reported to increase
15-fold when there is a concomitant use of anticoagulants, and appropriate
precautions are not taken. Appropriate timing of anticoagulant
administration is important in decreasing the risk of bleeding (Horlocker et
al, 2010).
5) Epidural catheter related infections:
Epidural abscess and meningitis has been reported to occur in 1: 1000
and 1: 50,000 catheter placements, respectively.The classic presentation
signs and symptoms are severe midline back pain, fever, and leukocytosis,
with or without neurological symptoms (worsening lower limb weakness and
paraplegia, incontinence, irradiating pain, nuchal rigidity, and headache).
Symptoms commonly appear after removal of the epidural catheter (Christie
and McCabe, 2007).
6) Pruritis:
41
Pruritis is the most common side effect of neuraxial analgesia. The
incidence and severity is dependent on the opioid dose, and is more frequent
with intrathecal opioids than with epidural opioids (58% versus 30%). The
cause of pruritus is not well understood, but it is unlikely to be related to
histamine release. Antihistamines, often prescribed to treat pruritus after
neuraxial opioids, are usually ineffective. There is increasing evidence that
neuraxial opioid-induced pruritus is mediated through central μ-opioid
receptors. Opioid antagonists (e.g. naloxone) or partial agonist-antagonists
(e.g. nalbuphine) are effective in relieving pruritus (Herman et al, 1999).
7) Nausea and Vomiting:
With an estimated incidence of 17% to 35%, nausea and vomiting may
occur as the opioid diffuses from the site of the epidural injection to the
chemoreceptor trigger zone for vomiting located in the 4th ventricle (Bragg,
1998). This side effect usually occurs 4 to 6 hours after administration and
may be associated with activity, such as turning and coughing (Naber et al,
2009).
8) Urinary Retention:
It usually occur in the first 24 to 48 hours and then resolves
spontaneously. Signs and symptoms include a lack of urge to void and
bladder distention. The underlying mechanism may be the action of the
narcotic on the spinal nerves innervating the detrusor muscle, thereby
altering bladder tone (atonia) and predisposing to bladder over distension
and increased residual volumes. For unknown reasons, urinary retention
occurs more often in elderly men, patients with pre-existing bladder
disorders, and during pregnancy and the postoperative period.Many centers
insert an indwelling Foley catheter for the duration that the epidural catheter
remains in place. If a Foley catheter is not used, intermittent catheterization
42
may be necessary. However, catheterization in some populations may in fact
further increase the risk of infection (Lingaraj et al, 2007).
9)Hypotension:
Hypotension is a second potential narcotic-related side effect of
epidural analgesia. However, as epidural narcotics have a localized action
and do not produce sympathetic nervous system blockade, they generally
have little effect on blood pressure. The hypotensive state may be a result of
fluid volume changes or immobility postoperatively, in which case IV fluids
are indicated.Local anesthetics are not specific to sensory afferent fibers, and
they do block autonomic and motor efferent fibers. This sympathetic
blockade can lead to hypotension and exacerbate or intensify postural
hypotension due to hypovolemia. As a result, postural hypotension may
restrict early ambulation and potentially increase morbidity. Therefore,
assessment of the patient's motor strength prior to ambulation is
critical (Roffey et al, 2001).
10) Respiratory Depression:
The most serious narcotic-related side effect associated with epidural
analgesia is respiratory depression. It is manifested by a decrease in the
depth of respirations or tidal volume, followed later by a decrease in
respiratory rate. Initially, the patient may be able to maintain an adequate
respiratory rate but the hyperventilation that occurs does not allow adequate
oxygen CO2 exchange. This impaired gas exchange leads to mental status
43
changes indicative of increasing CO2 levels. Therefore, a decrease in the
patient's level of consciousness or arousability is considered the first and the
best indicator of respiratory depression (Wild, 1990).
Technique of paravertebral block:
Manoj K. Karmakar, MD; Anthony M-H. Ho, MD lumbar
paravertebral block (lPVB) is the technique of injecting local anesthetic
alongside the lumbar vertebra close to where the spinal nerves emerge
from the intervertebral foramen. This produces unilateral, segmental,
somatic, and sympathetic nerve blockade, which is effective for
anesthesia and in treating acute and chronic pain of unilateral origin from
the abdomen. Hugo Sellheim of Leipzig (1871–1936) is believed to
have pioneered lPVB in 1905. Kappis, in 1919, developed the technique
of paravertebral injection, which is comparable to the one in present-day
use. Although paravertebral block was fairly popular in the early 1900s, it
seemed to have fallen into disfavor during the mid and later part of the
century, the reason for which is not known. In 1979 Eason and Wyatt
rekindled interest by describing a technique of paravertebral catheter
placement. Our understanding of the safety and efficacy of lPVB has
improved significantly in the last 25 years, and there has been a gradual
renewal of interest in this technique. Currently it is used not only for
analgesia but also for surgical anesthesia, and its application has been
extended to children(Kirchmair et al., 2001)
Classic method:
44
The classic insertion technique for PVB is percutaneous and has been
described by Eason and Wyatt. Similar to epidural insertion, loss of
resistance is felt immediately after puncturing the superior
costotransverse ligament, which represents the posterior border to the
paravertebral space. Approximately 2.5 cm lateral to the midline of the
spine, the transverse process is touched and a needle is directed over
(commonly) or under the boney landmark no more than 1 cm and local
anesthetic with or without a catheter is inserted. The skin to paravertebral
distance is, on average, 5.5 cm. The technique is also perfectly described
by Hounsell. Percutaneous insertion has a failure rate of 10%.
Ultrasound guided technique:a)Transverse scan :
With this scanning technique,the transducer is positioned 4 to 5 cm
lateral to lumbar spinous processes at the L3-L4 level and directed
slightly medially to assume a transverse oblique orientation.This
approach allows imaging of lumbar paravertbral region with the erector
spinae muscle, psoas major muscle, quadratous lumborum muscle,
transverse process and the anterolateral surface of vertebral body.In the
transverse oblique view,the inferior vena cava(IVC) On right sided scan,
or the aorta, on the left-sided scan, also can be seen and provide
additional information on the location of the psoas muscle, which is
positioned superficial to these vessels. In this view, the psoas muscle
appears slightly hypoechoic with multiple hyperechogenic striations
within. The lower pole of the kidney can often be seen, when scanning at
the L2-L4 level, as an oval structure that ascends and descends with
respirations(Gadsden JC et al., 2008). The key to obtaining adequate
images of the psoas muscle and lumbar paravertebral space with the
45
transverse oblique scan is to insonate between two adjacent transverse
processes. This scanning method avoids acoustic shadow of the
transverse processes, which obscures the underlying psoas muscle and the
intervertebral foramen (angle between the transverse process and
vertebral body) and allows visualization of the articular process of the
facet joint (APFJ) as well. Because the intervertebral foramen is located
at the angle between the APFJ and vertebral body, lumbar nerve roots
often can be depicted.(Farny j et al., 1994)
A
B C
Figure 2: (A) Ultrasound anatomy of the lumbar paravertebral space using transverse oblique view. SP, spinal process; ESM, erectors spinae muscle; QLM,
46
quadratus lumborum muscle; PsMM, psoas major muscle; VB, vertebral body. The lumbar plexus root is seen just below the lamina as it exits the interlaminar space and enters into the posterior medial aspect of the PsMM. (B) Needle path in ultrasound-guided lumbar paravertebral block using transverse oblique view. LP, lumbar plexus; PsMM, psoas major muscle; VB, vertebral body. (C) Spread of the local anesthetic solution . Due to the deep location of the space, spread of the local anesthetic may not always be well seen. Color Doppler imaging can be used to help determine the location of the injectate.(Cowie B et al., 2010)
b)Paramedial sagittal scan:
Kirchmair and colleagues suggested a paramedial sagittal scan
technique with transverse scan to delineate the psoas major muscle at the
L3-L5 level with the patient in the lateral position. Once a satisfactory
image is obtained, the needle is inserted in-plane medial to the transducer
approximately 4 cm lateral to the midline. Then the needle is advanced
until the correct position is confirmed by obtaining a quadriceps motor
response to nerve stimulation (1.5-2.0 mA). Needle-nerve contact and
distribution of the local anesthetic is not always well seen, although nerve
roots may be better visualized after the injection. Injection, dosing, and
monitoring principles are the same as with the nerve stimulator-guided
technique(Doi et al., 2010).
47
Figure 3: Ultrasound image of the lumbar
paravertebral space demonstrating the
complex anatomy of the region. LP,
lumbar plexus; VB, vertebral body. Power
Doppler ultrasound is capturing the flow
in the inferior vena cava (IVC). The right
kidney is also visualized.
Figure 4: Transverse image of lumbar
paravertebral space demonstrating
sacrum and transverse process (TP) of L5.
Starting the scanning process from the
sacral area and progressing cephalad
allows the identity of the individual
transverse processes (levels). As the
transducer is moved cephalad and the
surface of the sacrum disappears, the next
osseous structure that appears is the
transverse process (TP) of L5.
48
Figure 5: Transducer position (curved,
phased array) and the needle insertion
plane to accomplish ultrasound- guided
lumbar paravertebral block in the
longitudinal view and an out-of-plane
needle insertion.
Figure 6: Simulated needle insertion
paths (1,2) to inject local anesthetics at
two different levels to accomplish a
lumbar paravertebral (LP) block. Needles
(1 and 2) are seen lodged about 2 cm
deeper and between the transverse
processes (TPs) using an out-of-plane
technique.
More recently, Karmakar and colleagues described the "trident sign
technique," which uses an easily recognizable ultrasonographic landmark,
transverse processes, and an out-of-plane needle insertion. The trident
sign technique derives its name from the characteristic ultrasonographic
appearance of the transverse processes (trident) to estimate the depth and
location of lumbar paravertebral space . After application of ultrasound
gel to the skin over the lumbar paravertebral region, the ultrasound
transducer is positioned approximately 3 to 4 cm lateral and parallel to
the lumbar spine to produce a longitudinal scan of the lumbar
49
paravertebral region (Figure 7). Then the transducer is moved caudally,
while still maintaining the same orientation, until the sacrum and the L5
transverse process become visible (Figure 8). The lumbar transverse
processes are identified by their hyperechoic reflections and acoustic
shadowing beneath which is typical of bone. Once the L5 transverse
process is visible, the transducer is moved cephalad gradually, to identify
the L3-L4 level. The goal of the technique is to guide the needle through
the acoustic window between the transverse processes (between the "teeth
of the trident") of L3-L4 or L2-L3 into the posterior part of the psoas
major muscle (Figure 2B). After obtaining ipsilateral quadriceps muscle
contractions, the block is carried out using the previously described
injection and pharmacology considerations (Figures 6 and 7).
Figure 7: Local anesthetic (LA) disposition during injection of local anesthetic into
the psoas muscle and the L2-L3 level. The spread of LA is often not well seen using
two-dimensional imaging. LP, lumbar plexus; TP, transverse process.
A paramedial scan also can be used with an in-plane needle approach.
In this technique, an insulated needle is inserted in-plane from the caudal
end (Figure 4) of the transducer while maintaining the view of the
transverse processes. Again, the goal is to pass the needle and inject local
50
anesthetic with a real-time visualization of the needle path and injection
into the posterior part of the psoas muscle (Figure 5).
In summary, ultrasound-guided PVB is a technically advanced
procedure. Experience with ultrasound anatomy and less technically
challenging nerve regional anesthesia techniques are useful to ensure
success and safety. Although the use of ultrasound in PVB is not widely
accepted, in expert hands, ultrasound guidance can increase the accuracy
and possibly safety, by providing information on the location,
arrangement, and depth of the osseous and muscular tissues of
importance in lumbar PVB. It should be kept in mind that the dorsal
branch of the lumbar artery is closely related to the trans-verse processes
and the posterior part of the psoas muscle.
Limitations of paravertebral block:
a) Considering the rich vascularity of the lumbar paravertebral area,
the use of smaller gauge needles and avoidance of this block in
patients on anticoagulants is prudent.
b) Injections into this area should be carried out without excessive
force because high-injection pressure can lead to unwanted
epidural spread and/or rapid intravascular injection.
c) In patients with obesity or advanced age, it can can be more
challenging. Aging is associated with a reduction in skeletal
muscle mass (sarcopenia) and replacement of the muscle mass by
adipose tissue, leading to changes in ultrasound absorption and
scattering.
51
Patients and methods
After local ethical committee approval and patient informed written
consent, this prospective randomized blinded clinical study was
conducted on 38 patients above 18 years old ASA I-III undergoing
elective inguinal herniorraphy and appendectomy under general
anesthesia. These patients will be randomly allocated by closed envelope
into two equal groups :-
Group PVB : Will receive in-plane ultrasound guided continuous
lumbar paravertebral block with 0.5% bupivacaine bolus dose followed
by continuous infusion of bupivacaine 0.125% with fentanyl 1mcg/ml.
Group EPB: Will receive continuous lumbar epidural analgesia with
0.5% bupivacaine bolus dose followed by continuous infusion of
bupivacaine 0.125% with fentanyl 1mcg/ml
Exclusion criteria:
1) Age < 18 years.
2) Coagulopathy.
3 (Patient uncooperation.
4 (Local sepsis
5 (anatomical deformity of the back.
6 (Allergy to local anaesthetic agent.
7 (Morbid obesity (BMI >35 kg m2).
8 (Neurologic disorders.
Preoperative visit :-
One day before surgery, a meeting was done with the patients to explain
visual analogue scale (VAS), ( a rating scale in which the patients mark
52
the location on the 10-centimeter line corresponding to the amount of
pain they experienced). This gives them the freedom to choose their
pain's exact intensity. Also routine investigations in the form of twelve
leads electrocardiography (ECG), complete blood count (CBC),
coagulation profile (bleeding time, prothrombine time, international
normalized ratio and partial thromboplastine time), liver functions, and
kidney functions were fulfilled.
)Figure 1:(Visual analogue scale (VAS)Verbal rating scale (VRS) and Numerical
rating scale (NRS)
General anaesthesia:-
Before the induction of general anaesthesia:
Intravenous access was established and IV fluids started, Monitoring of
the patients in the form of5-Lead ECG, Arterial Blood Pressure (Non
Invasive Blood pressure monitoring) and Pulse oximeter were conducted.
Prior to the regional block, IV access and arterial cannulation with local
anesthetic infiltration will be established and patients will be monitored
with electrocardiography, blood pressure monitoring (noninvasive), pulse
oximetry and capnogram.
53
Insertion of lumbar paravertebral catheter / lumbar epidural catheter
was done before induction of general anesthesia.
Induction of general anaesthesia:
After insertion of epidural/paravertebral catheters patients will be
turned supine. General anesthesia will be induced with IV fentanyl 1–2
mcg/kg, propofol 2–3 mg/kg followed by rocuronium 0.5–0.8 mg/kg to
facilitate endotracheal intubation.
Maintainance of general anaesthesia:
Anesthesia was maintained with Isoflurane 1.5% and rocuronium
0.15mg/kg as a maintainance dose every 30 minutes till the end of the
procedure. Ventilation parameters was adjusted as follows: TV = 7
ml/kg, respiratory rate = 12/min. and peak inspiratory pressure 30- 35 cm
H2O. End tidal CO2 was maintained between 35-40 mmHg.
Heart rate and mean arterial blood pressure (MAP) were monitored
throughout the operation and maintained within ± 20% of the
preoperative baseline by giving IV bolus doses of fentanyl approximately
1 mcg/kg if the MAP or heart rate increased more than 20% from the
baseline.
Recovery from general anaesthesia:
After the end of operation, reversal of neuromuscular blockade was
done by neostigmine 0.04-0.07 mg/kg and atropine 0.02 mg/kg. When
sufficient spontaneous breathing was established and the patient
responded adequately to instructions, the trachea was extubated after
gentle oropharyngeal suction. After emerging from anesthesia, the
patients was transferred to the post anesthesia care unit (PACU) for a 2
hours observation period .
54
Techniques of lumbar paravertebral block (PVB) :
A standard regional anesthesia tray was prepared with the following
equipment:
Sterile towels and 4"x4" gauze packs
20-mL syringes with local anesthetic .
Sterile gloves and marking pen.
One 1½" 25-gauge needle for skin infiltration
An 18 gauge 8 cm needle epidural set(Perifix.B.BRAUNMelsungen
AG).
Syringe pump(Fresenius Kabi) ,
GE LOGIQ P5 ultrasound machine
The lumbar paravertebral block (PVB) will be performed in the
preoperative area while the patient in the sitting position and leaning
forwards. After surgical disinfection of lumbar paravertebral areas with
protection of the ultrasound probe and cable with a sterile ultrasound
probe cover, the lumbar paravertebral space (LPVS) was identified with
ultrasound , using a5-8 MHz curved array ultrasound transducer
probe placed over a spinous process in the mid-line in a longitudinal
fashion . Once the best image of the interspace structures appeared,
Under sterile conditions,4-6 mL of local anesthetic (Lidocaine1 %) was
infiltrated subcutaneously alongside the line where the injections was
made . an 18 gauge 8 cm epidural needle(Perifix.B.BRAUNMelsungen
AG) was utilized for locating the paravertebral space
55
, The tip of the needle will be advanced under direct vision to
paravertebral space which is present at 6-8cm depth from skin surface in
lumbar region. Saline (3 mL) will then injected to:
a- demonstrate the position of injectate.
b- allow easier passage of the catheter, to a distance of 2-3 cm beyond
the needle tip.
An initial test dose of 3 mL of 2% lidocaine mixed with 1:200,000
epinephrine was injected followed by 0.5% bupivacaine(15-20ml) (0.3
mL/kg), administered over 10 minutes after recording arterial blood
pressure.
Technique of lumbar epidural block :
Epidural block will be performed in all patients in the sitting position
with binding forward and the legs are allowed to hang over the edge of
the bed with the feet supported by a stool. The shoulders are hunched
forward and the patient is encouraged to hug a pillow in towards the
abdomen to provide anterior flexion of the spine.Then anatomical land
mark will be identified by palpating the iliac crests that lie opposite the
disc between L4&L5. The skin surrounding this area will be sterilized by
povidone iodine solution and skin wheal will be infiltrated with local
anesthetic (Lidocaine 2%). using 22 gauge needle then the epidural
catheter 20 gauge will be placed at selected interspaced using midline
approach and saline loss of resistance technique through an 18-G touhy
epidural needle under complete sterile technique and directed
perpendicular to skin. Only 5 cm of the catheter will be left in the space
and the test dose (3ml Lidocaine 2%+1:200,000 adrenaline) will be
injected through the catheter to exclude subarachnoid and intravascular
56
catheter position. Epidural analgesia was done by using 0.5% bupivacaine
(5-8ml)( 0.1ml/kg) as loading dose.
In both groups continous infusion of bupivacaine 0.125% was started
at a rate of (0.1 ml/kg/hr) with fentanyl 1mcg/ml and maintained
throughout the period of the study(24 hours).
Hypotension was treated with intravenous ringer’s solution 15 ml/kg and
ephedrine 10 mg as needed to keep MAP more than 65 mm Hg.
Bradycardia ( HR < 60/ min.) was treated with atropine 0.01-0.02 mg/kg.
The following parameters were measured:
1-Demographic characteristics: Age in years, body mass index and ASA physical status.
2-Operative details: duration of surgery (time started from surgical incision till removal of surgical drapes).
3-Mean arterial blood pressure, heart rate at 0, 30 min, 1, 2, 6, 12, 24hr after the block.
4- respiratory rate and arterial oxygen saturation(Sao2) at 0,30 min, 1,2,6,12,24hr after surgery.
5-Postoperative pain level by 10-cm visual analogue scale(VAS) from 0 ( no pain) to 10 (unbearable pain) at 1, 2,6, 12, 24 hours after surgery. If VAS will be higher than 4, the infusion will be increased up to (10 ml/hr).
6- Pain rescue-analgesia consumption after 24 hours. If pain score exceed
4 despite the maximum infusion rate of bupivacaine, rescue analgesia
5mg bolus of morphine will be administered intravenous to achieve
satisfactory pain control, can be repeated every 4-6 hours.
57
Complications:
Postoperative nausea and vomiting, rescue antiemetics were offered to
any patient who complained of nausea or vomiting.
Sedation was measured by using Ramsay sedation scale (If Awake;
Ramsey 1: Anxious, agitated, restless, Ramsey2: Cooperative,
oriented, tranquil, Ramsey 3: Responsive to commands only. If
Asleep; Ramsey 4: Brisk response to light glabellar tap or loud
auditory stimulus, Ramsey 5: Sluggish response to light glabellar tap
or loud auditory stimulus) the presence of sedation was defined as a
sedation scale >2 at any postoperative time point.
Pruritus.
Complications related to the block technique.
The study ended 24 hours after the operation.
Statistical analysis: Analysis of data will be done by using SPSS (statistical program for
social science version 16) as follows:
Description of quantitative variables as mean and standard deviation.
Description of qualitative variables as number and percentage.
Unpaired student t-test will be used to compere the quantitative
variables between groups.
45Chi-square test will be used to compare qualitative variables
between groups.
P < 0.05 will be considered significant.
P < 0.01 will be considered highly significant.
Sample size calculation:
Considering pain rescue-analgesia consumption as the primary
outcome, and taking α error = 0.05 (confidence interval = 95%)
58
and the power of test (1-β) as 80%. Sample size was calculated
from previous study was done by Wardhan et al, (2014). We
considered that a reduction more than 25 % in morphine
consumption will be satisfactory (The effect size was 0.96).
Thus, we recruited 38 patients for randomization (19 patients in
each group).
59
Results
This study was conducted on 38 patients underwent unilateral lower
abdominal surgery (inguinal herniorraphy and appendectomy). Patients
were divided into two equal groups:
Group I ( PVB ): received in-plane ultrasound guided continuous
lumbar paravertebral block with 0.5% bupivacaine bolus dose followed
by continuous infusion of bupivacaine 0.125% with fentanyl 1mcg/ml.
Group II (EPB): received continuous lumbar epidural analgesia with
0.5% bupivacaine bolus dose followed by continuous infusion of
bupivacaine 0.125% with fentanyl 1mcg/ml.
As regards age, weight, height, BMI and ASA status, there was no
significant differences between both groups (P>0.05).
Average age was 41.21y in group (PVB) and 43.84y in group (EPB) and
p- value=0.29
Average weight was 49.95kg in group (PVB) and 49.42kg in group
(EPB) and p- value = 0.91
Average height was 160.4cm in group (PVB) and 159.93cm in group
(EPB) and p- value = 0.76,
Average BMI was 27 kg/m2 in group (PVB) and 27.63kg/m2 in group
(EPB) and p- value = 0.47,
Average duration of surgery was 74.37min in group (PVB) and 77.84min
in group (EPB) and p-value = 0.27
60
Table (1 (:- Demographic data and duration of surgery
Group I (PVB) Group II (EPB)
Test of significance
p- value
Age(years) 41.21±7.68 43.84±7.29 t=1.08 0.29Weight(Kg) 49.95±15 49.4
2±13.96t=0.11 0.91
Height(Cm) 160.4± 5.66 159.93 ± 6.12
t=0.31 0.76
BMI(kg/m2) 27.01±2.2 27.63±2.96 t=0.73 0.47Duration of
surgery(min)74.37±15.24 7.84±18.24 t=1.2 0.24
ASA Status I 8 6X2 =0.5 0.7II 8 10
III 3 3
Data were presented as mean ± SDASA status data were presented as numbers and percentageP – Value < 0.05 was considered statistically significant
Type of surgery:
As regards comparison of type of surgery between both groups, there was
no significant difference in the type of surgery between both groups.
(Table 2): type of surgery in both groups
Type of surgery Group I (PVB) Group II (EPB)
Test of significance
p- value
Inguinal hernia 15 16x2=0.18 p=0.9 appendectomy 4 3
Data were presented as numbers and percentage
Visual Analogue Scale (VAS)
VAS was measured at rest and on patient's movement (knee flexion), at1,2,6,12 and 24 hours postoperative (table3)
61
Table (3):-visual analogue score (VAS) of both groups
Post-operative Group I (PVB)
Group II (EPB)
Test of significance
p-value
1hr At rest 4 ±3 3 ±1.62 t= 1.607 0.114On
movement4.37 ± 1.88 4.1 ± 1.81 t= 0.567 0.573
2hr At rest 2.73 ±1.68 2.06 ±1.20 t= 1.778 0.081On
movement3.7 ± 1.95 3 ± 1.41 t=1.593 0.117
6hr At rest 2.4 ±1.40 2 ±1.08 t= 1.201 0.235On
movement3.4 ± 1.57 3.07 ± 1.36 t=0.870 0.388
12hr At rest 2.2 ±1.21 2 ±1.17 t= 0.651 0.518On
movement2.4 ± 1.25 2.03 ± 0.99 t=1.271 0.209
24hr At rest 1.43 ±1.28 1 ±0.91 t= 1.499 0.139On
movement2.33 ± 1.18 2 ± 0.98 t=1.178 0.244
Data were presented as mean ± SD
Current study showed insignificant differences between both groups as regards VAS either at rest or on patient's movement as shown in fig.(1) and fig.(2)
At 1hr post-operative, there was insignificant difference between both groups as regards VAS both at rest(p=0.114) and on patient's movement (p=0.573).
At 2hrs post-operative, there was also insignificant difference between both groups as regards VAS both at rest (p=0.081) and on patient's movement (p=0.117).
62
At 6hrs post-operative, there was insignificant difference between PVB and EPB groups as regards VAS both at rest (P=0.235) and on patient's movement (p=0.388).
At 12hrs post-operative, there was also insignificant difference between both groups as regards VAS both at rest (p=0.518) and on patient's movement (p=0.209).
At 24hrs post-operative, there was also insignificant difference between both groups as regards VAS both at rest (p=0.139) and on patient's movement (p=0.244).
VAS R 1 VAS R 2 VAS R 6 VAS R 12 VAS R 240
0.5
1
1.5
2
2.5
3VAS at rest
PE
Fig. (1) :- VAS values at rest
63
VAS M 1 VAS M 2 VAS M 6 VAS M 12 VAS M 241
1.5
2
2.5
3
3.5VAS at movement
PE
Fig.(2):VAS values on patient's movement
Total pain rescue-analgesia consumption during 24 hours:
As regards total morphine consumption in the first post-operative 24
hours (5 mg morphine were given as bolus dose when VAS exceeds 4
despite the maximum infusion rate of bupivacaine),the current study
showed no statistically significant difference (p>0.05) between PVB and
EPB groups.
Table (4) :- Total pain rescue-analgesia consumption during 24 hours (mg/24h)
Groups Group PVB Group EPB Test of of
significance
P - value
Total-analgesia
consumption (mg morphine/24 h)
6.84 ± 2.48 6.58 ±2.91 0.30=t0.77
64
Group P Group E6
8
Fig.(3): Total analgesic consumption during 24 hours (mg morphine/24 h)
Mean arterial blood pressure (MAP) -:
As regards comparing mean arterial blood pressure (MAP) between
both groups ;Current study showed statistically highly significant change
in MAP in EPB group as compared with PVB group at1,2,6,12 and 24hr
postoperative as shown in table(5)
(Table 5):mean arterial blood pressure (MAP) of both groups in mmHg
MAP (mmHg)
Group I (PVB)
Group II (EPB)
Test of significant
p- value
Base line 78.95±5.31 80.84±3.25 t=1.33 0.191 hrs. 77.11±4.46 70.05±4.45 t=4.88 0.001** >2 hrs. 76.26±4.78 69.16±3.95 t=4.99 0.001** >6 hrs. 78±3.94 71.42±4.46 t=4.81 0.001** >
12 hrs. 79.11±2.16 75.32±2.79 t=4.68 0.001** >24 hrs. 880.4
2±2.4173.25±2.41 t=8.75 0.001** >
Data were presented as mean ± SD*significant **highly significant
65
MAP at 1hr showed highly significant difference between both groups (p<0.001),Also at 2hrs, there is high significant difference in MAP between PVB and EPB groups (p<0.001),At 6hrs, there is high significant difference in MAP between both groups as p<0.001At 12hrs, MAP showed high significant difference in PVB and EPB groups (p<0.001).Also there was high significant difference in MAP at 24hrs post-operative between PVB and EPB groups.
MAP0 MAP1 MAP1 MAP2 MAP6 MAP12 MAP2460
65
70
75
80
85
MAP
Group PGroup E
Fig.(4): MAP values in all groups (mm Hg)
Heart rate (HR) -:As regards heart rate(HR) in both groups ,current study showed
insignificant decrease in heart rate in EPB group as compared with PVB
group at 1,2,6 and 12hrs post-operative.
Table (6):-Heart rate (HR) of both groups
HR (beat/min)
Group I (PVB)
Group II (EPB)
Test of significant
p- value
66
Base line 79.84±3.27 80.26±2.68 t= 0.43 0.671 hrs. 79.64±2.67 78.61±2.59 t= 1.79 0.062 hrs. 78.53 ±
2.0176.68 ± 2.21
t= 3.63 0.01*
6 hrs. 79.32 ± 2.77
77.47 ± 2.95
t= 1.98 0.05*
12 hrs. 79.32 ± 2.77
77.47 ± 2.95
t= 1.98 0.055
24 hrs. 78.74 ± 3.03
79.79 ± 2.49
t= 1.17 0.25
Data were presented as mean ± SD*significant **highly significant
0 1 2 6 12 2476
76.5
77
77.5
78
78.5
79
79.5
80
80.5
81
Group EGroup P
Fig.(5):-heart rate(bpm)
At 1hr post-operative, there was insignificant decrease in heart rate in
EPB group (p>0.05).
Also at 2hrs, there was significant decrease in heart rate in EPB group as
compared toPVB group (p=0.01).
At 6hrs, there was significant decrease in heart rate in EPB group
(p<0.05).
Heart rate showed insignificant decrease in EPB group as compared to
PVB at 12hrs post-operative (p>0.05).
67
At 24hrs, there was insignificant increase in heart rate in EPB group
(P=0.25).
Respiratory rate:- As regards respiratory rate (RR) in the two groups, current study showed
no statistically significant differences in RR between both groups as
shown in fig.(6)
Table (7):-Respiratory rate values\min
RR Group I (PVB)
Group II (EPB)
Test of significant
p- value
Base line 18.05±1.51 17.84±1.26 0.467 0.6431 hrs. 18.32±0.95 18.37±1.01 0.165 0.8692 hrs. 18.26±1.51 18.21±1.01 0.145 0.8856 hrs. 18.42±1.02 18.26±1.05 0. 274 0.640
12 hrs. 18.32±0.95 18.47±1.02 0.494 0.62324 hrs. 18.42±0.96 18.11±1.10 0.942 0.352
68
0RR 1RR 2RR 6RR 21RR 42RR71
81
91
RR
1seireS2seireS
Fig.(6): - Respiratory rate values in both groups during 24 hours
At 1hr post-operative, mean RR was 18.32 in PVB group and 18.37 in EPB
group i.e. no significant difference between the two groups.
At 2hr, mean RR was 18.26 in PVB group and 18.21 in EPB group .
At 6hr, mean RR was 18.42 in PVB group and 18.26 in EPB group.
At 12hr, mean RR was 18.32 in PVB group and 18.47 in EPB group.
At 24hr, mean RR was 18.42 in PVB group and 18.11 in EPB group.
Complications
As regarding complications during the study in all groups,
complications as nausea , vomiting , pruritis and drowsiness were recorded ,
table(9).
Nausea: - Regarding nausea in both groups, there were 4 patients (21.05%)
in group EPB and 1 patient (5.3%) in group PVB. These results are
statistically non significant (p=1)
69
Vomiting: - As regards incidence of vomiting in both groups , there were 3
patients ( 15.8%) in group EPB and 0 patient (0 %) in group PVB .p=1 this
means that results are statistically insignificant.
Pruritis :- The incidence of pruritis was 2 patients (10.5%) in group P , and 1
patient (5.3 %) in group E. these results are statistically insignificant as p=1.
Drowsiness :- Regarding drowsiness in both groups , number of patients
complaining in group PVB was 2 patients (10.5%) and in group EPB there
was one patient ( 5.3%) . p=1 so the results are insignificant.
Urine retention:-There were 6 patients (31.05%) complaining of urine
retention in group EPB and 0 patients(0%) in group PVB .p-value <0.05 i.e.
there was significant difference between the two groups as regards urine
retention.
Table (8): complications in both groups
Complications Group P Group E P Value
Nausea 1 (5.3%) 4 (21.05% ) 0.15
Vomiting 0 ) 0(% 3 ) 15.8( % 0.07
Pruritis 2 ) 10.5(% 1 ) 5.3(% 0.55
Drowsiness 2) 10.5(% 1 ) 5.3(% 0.55
Urine retention 0(0%) 6( 31.05%) 0.04
70
Data were presented as numbers and percentage
*significant
pain is a stressor that can threaten homeostasis (a steady physiological
state). The adaptive response to such a stress involves physiology
changes that, in the initial stages, are useful and are also potentially life-
saving (Bultaci, 2007 ).
Unrelieved postoperative pain may result in clinical and psychological
changes that increase morbidity, mortality, costs as well as decrease
quality of life and potentially increase the incidence of chronic pain.
Negative clinical outcomes resulting from ineffective postoperative pain
management include deep vein thrombosis and pulmonary embolism,
coronary ischemia and myocardial infarction, pneumonia, poor wound
healing, insomnia and demoralization. Associated with these
complications are economic and humanistic implications such as
extended lengths of stay, readmissions, and patient dissatisfaction with
medical care. A recent study suggests that pain in ambulatory surgical
patients is still undermanaged and the incidence of moderate to severe
pain remains high (Apfel AL et al., 2003).
71
As regarding our study, it was held at Benha university hospital to
compare the efficacy of continuous lumbar epidural block versus
ultrasound guided continuous lumbar paravertebral block on
perioperative analgesia and haemodynamic stability in patients
undergoing lower abdominal surgery in a prospective, randomized study.
38 patients were included in this study (19 patients in each group).there
were no differences between them as regarding demographic
characteristics (age, weight, height, BMI), type and duration of surgery.
The primary outcome measure: is the mean morphine consumption in
the first 24 hours postoperative and visual analogue scale ( VAS).
The secondry measures include: age, weight, height, BMI, ASA, vital
signs (MAP, HR, RR), type and duration of surgery and complications
(nausea, vomiting, pruritis, drowsiness and urine retention).
As regards visual analogue scale (VAS) that was measured both at rest
and on patient's movement at 1,2,6,12 and 24 hours post-operative, there
was insignificant difference between both groups although it was slightly
lower in EPB group.
Also there was insignificant difference in total morphine consumption in
the first post-operative 24 hours.
These results goes with( Pankaj N Surange and Brig Chadalavada
Venkata Rama Mohan 2012 )who compared Continuous Lumbar
Paravertebral Versus Continuous Epidural Block in patients undergoing
hip Surgery where 60 patients were randomly allocated into two groups
of 30 subjects:
72
1. Group I: 5 mL/h, 0.125% bupivacaine, continuous paravertebral
group.
2. Group II: 5 mL /h, 0.125% bupivacaine, continuous epidural
group.
Then 2.5-3ml of 0.5%bubivacaine injected intrathecal. the patients were
observed for 48hours after surgery and no statistical significant
differences were found between the two groups in VAS either at rest or
on exercise (active and assisted hip flexion and extension against
gravity). Other study done by (Hazem Ebrahem Moawad et al., 2013)
who performed a prospective randomized study to compare between
paravertebral and epidural block after open renal surgery. Mean
postoperative VAS scores demonstrated no significant difference between
both groups throughout the duration of monitoring(24 hours) .The total
analgesic consumption (meperidine) at 24 h postoperatively also showed
no significant difference between the two groups. After 24 h, all patients
had the worst pain with VAS score 4 mm in the EP group, versus 5 mm
in the PVB group. ( G. Türker et al., 2003) performed a study for
Comparison of the catheter-technique psoas compartment
(paravertebral)block where 30 ml of 0.5%bupivacaine was injected in the
paravertebral space and the epidural block by injection of 15ml of
0.5%bupivacaine in the epidural space for analgesia in partial hip
replacement surgery. Ten minutes before the end of the operation, each
patient was connected to a patient-controlled analgesia device set to
deliver an infusion of 0.125% bupivacaine and 2 µg/ ml fentanyl at a rate
of 10 ml/ h, in addition to 5-ml boluses for post-operative analgesia. The
groups were similar regarding pain scores (at rest and on movement) and
patient satisfaction. An updated metaanalysis was done by (Xibing Ding
et al., 2014) to compare analgesic efficacy and side effects of
73
Paravertebral Compared with Epidural Blockade for Thoracotomy. There
was no statistically significant difference in pain scores between the PVB
and EPI groups at postoperative 4–8 h, at 24h or at 48h ). There was also
no significant difference in morphine consumption between the two
groups at postoperative 24 h .Another study for comparing between
epidural and paravertebral blocks in patients undergoing thoracotomy
was done by( O Cucu et al.,2004). All patients received a bolus
dose of %0.25 bupivacaine 10 ml before wound closure and a infusion of
%0.25bupivacaine 0.1ml/kg/ hr was started immediately upon arrival to
surgical intensive care unit and continued for 24 hours. There were no
significant differences between the groups with respect to VAS scores at
any point of observation. The mean pain scores were 52.40±21.50 and
44.40±19.40 in epidural and paravertebral groups respectively in the
immediate postoperative period at rest and whereas at 4 th hour they were
decreased to 30±14.10 and 27.20±13.40. In both groups pain scores were
significantly lower compared to immediate postoperative period on all
occasions of measurement. There were no statistically significant
differences between the groups in morphine consumption, 37.56±25.93
mg and 36.78±18.58 mg (p = 0.903) for epidural and paravertebral groups
respectively.
Debreceni et al., 2003 who studied the comparison between
Continuous epidural and paravertebral analgesia following thoracotomy .
They founded that pain management with continuous epidural analgesia
was superior to continuous paravertebral analgesia, in the early
postoperative period. The statistically significant difference in the VAS
scores between the two groups (up to 12hr postoperative only), in favor
of the epidural technique, this can be explained by; the large volume
injected into the epidural space (0.2 ml/kg).
74
Our study does not go with( Antipin, E et al., 2014) who compared
between lumbar paravertebral and lumbar epidural blocks as methods of
analgesia in the first stage of labour : A prospective randomized study of
nulliparous women included three groups of patients: the group of 30
patients with EA (0.15% ropivacaine + fentanyl 2 µg/ml); the PVB group
of 30 patients (0.75% ropivacaine 10 ml bilaterally); the control group of
30 patients . The severity of pain at the opening of the cervix was
completely alleviated from the maddening group EA (VAS 82,6 ± 1,9
mm) and PVB (VAS 83,2 ± 1,7 mm) to a small (5,2 ± 0,9) and ( 14,5 ±
1,8), respectively. this is most probably due to higher concentration of
ropivacaine used in PVB group(0.75) versus (0.15)in EPB group.
As regards mean arterial pressure (MAP) in our study, there was slight
decrease in MAP AT 1,2,6 and 12 hours from base line in PVB group
while in EPB group there is marked decrease in MAP at 1,2,6,12 and 24
hours from baseline and statistical analysis between both groups was
highly significant(p<0.001).
As regards heart rate (HR) change in our study, there was insignificant
decrease in (HR) in PVB group and significant decrease in EPB group.
statistical analysis showed significant difference in HR between both
groups at 2 hr postoperative (p=0.01).
These results goes with a prospective randomized study done by
(Hazem Ebrahem Moawad et al., 2013) who compared paravertebral
block versus epidural block in open renal surgery. They found a
significant decrease in MAP in EPB group compared with PVB group 15
min, 30 min, 1 h, 1½, and 2 h from the start of surgery (P<0.001).
similarly , there was a significant decrease in HR in EPB group compared
75
with PVB group at 2, 2½, 3, and 3½ h and at 30 min, 12 h,16 h, and 24 h
postoperatively (Pranged from <0.01 to <0.001).
Regarding Pankaj N Surange and Brig Chadalavada Venkata
Rama Mohan ,they performed a study ion 2012 named Comparative
Evaluation of Continuous Lumbar Paravertebral Versus Continuous
Epidural Block for Post-Operative Pain Relief in Hip Surgeries. The
preoperative heart rate (HR) and MAP of all patients were recorded
before the procedure was performed. Subsequent readings were taken
every 5 minutes. Intraoperatively after spinal anesthesia and thereafter
recorded at 2, 4, 8, 12, 18, 24, 32, 40 and 48 hours.
There mean arterial pressure was significantly lower in the epidural
group compared with the paravertebral group from 2 hours after the
infusion was begun to 48 hours. Regarding the heart rate,it was not like in
our study as it was higher in the epidural group throughout the study
period, albeit insignificantly. In a study done by( G. Tu'rker., et al
2003)involving thirty patients undergoing total hip replacement surgery
where psoas compartment block was done in fifteen patients (group P)
and epidural block in the other fifteen(group E).Hemodynamic
parameters(MAP and HR) were recorded every 10 minutes
intraoperative. . Group E showed significantly greater drops in mean
arterial blood pressure from baseline at 30, 40 and 50 min after the start
of general anesthesia. Significantly more Group E patients required
epinephrine supplementation. In an updated meta-analysis done
by( Xibing Ding et al., 2014) to compare analgesic efficacy and side
effects of paravertebral compared with epidural blockade in thoracotomy
patients , PVB was associated with less hypotension.In another study
done by (O Cucu et al., 2005) in thoracotomy patients to compare
epidural anaesthesia and paravertebral block, heart rate and MAP were
76
significantly lower in epidural group at postoperative 6 th,12th and 24
hours as compared to paraverteral group (p<0.01). Intragroup
comparisons showed that, in epidural group MAP decreased significantly
at all points of measurements compared to preinduction values (p<0.01).
Also MAP at 6 h hours was found to be lower than the one measured
after 20 minutes of bolus dose. Parallel to that, heart rate also was also
found to be lower at all points of observations compared to preinduction
and postbolus values in epidural group, In paravertebral group, although
not as much as epidural group, heart rate was also found to be lower at all
occasions as compared to prenduction values (p<0.05) .
As regards complications in our study, they include nausea, vomiting,
pruritis, drowsiness and urine retention .there were 1 patient(5.3%)in
group PVB and 4 patients(21.05%)in group EPB complaining of nausea,
0(0%) in PVB and 3(15.8%)patients in EPB complaining of vomiting ,
2(10.5%)patients in PVB group and 1(5.3%)patients in EPB group
complaining of pruritis and drowsiness, 0(0%)patient in PVB group and
4(21.05%)patients in group EPB suffering from urine retention. These
results are statistically insignificant.
Our study goes with (Pankaj N Surange and Brig Chadalavada
Venkata Rama Mohan 2012) who concluded that paravertebral block is
technically simple and easy to learn with few contraindications, provides
hemodynamic stability, and has a low complication rate and is therefore a
safe and effective technique in controlling postoperative pain after
unilateral hip surgery.
In a prospective randomized study done by (Hazem Ebrahem
Moawad et al., 2013), Postoperative shivering developed in 2 patients in
each group. Whereas 3 patients in EP group suffered from nausea
77
postoperatively compared with 2 patients in the PVB group. In a study
performed by (G. Turker et al., 2003) There were no differences
between the two groups regarding catheter-related problems. Orthostatic
hypotension, urinary retention, and nausea-vomiting were also
significantly more frequent in Group E (P<0.05, P<0.01 and P<0.05,
respectively).In the study done by( Xibing Ding .,et al 2014) to compare
analgesia and side effects of paravertebral versus epidural blockade in
thoracotomy patients, PVB resulted in significantly less incidence rates of
urinary retention (OR 0.21, 95%CI: 0.10 to 0.44; I2 = 0%; p<0.0001),
nausea and vomiting (OR 0.49, 95% CI: 0.28 to 0.87; I2 = 27%, p = 0.01),
and hypotension (OR 0.11, 95% CI: 0.05 to 0.25; I2 =
0%, p<0.00001)compared to EPB. Rates of failed technique were lower
in the PVB group (OR 0.51, 95%CI: 0.30 to 0.86; I2 = 29%; p = 0.01).
However, there was no significant difference in pulmonary complications
(OR 0.51, 95% CI: 0.23 to 1.11); I2 = 0%; p = 0.09. In another study done
by (O Cucu et al., 2005) in patients with thoracotomy, 3 patients in
epidural and 2 patients in paravertebral group experienced at least one
nausea and vomiting episode graded as severe and they were given
ondansetron (p=1). Two patients in each group reported nausea episode
graded as mild and they were not given any medication. urine retention
could not be assessed as Foley catheters had been routinely inserted at the
time of surgery.
Limitations of the study:
One of the possible shortcomings of our study; the study did
not include a placebo control group.
The study limited assessment of postoperative analgesia to
the first 24 postoperative hours.
78
However, the blocks demonstrated to produce satisfactory levels of
analgesia for at least 48 hours.
Conclusion
Our study showed that both continuous epidural and continuous
paravertebral blocks are effective in controlling postoperative pain after
lower abdominal surgeries with lower rate of complications (hypotension,
bradycardia, nausea, vomiting and urine retention) in paravertebral group.
79
pain is a stressor that can threaten homeostasis (a steady physiological
state). The adaptive response to such a stress involves physiology
changes that, in the initial stages, are useful and are also potentially life-
saving.
Unrelieved postoperative pain may result in clinical and psychological
changes that increase morbidity, mortality, costs as well as decrease
quality of life and potentially increase the incidence of chronic pain.
Negative clinical outcomes resulting from ineffective postoperative pain
management include deep vein thrombosis and pulmonary embolism,
coronary ischemia and myocardial infarction, pneumonia, poor wound
healing, insomnia and demoralization. Associated with these
complications are economic and humanistic implications such as
extended lengths of stay, readmissions, and patient dissatisfaction with
medical care. A recent study suggests that pain in ambulatory surgical
patients is still undermanaged and the incidence of moderate to severe
pain remains high.
80
Aim of the study: This study was done to evaluate efficacy of both
continuous lumbar epidural and ultrasound guided continuous
paravertebral block on perioperative analgesia and hemodynamic stability
in patients undergoing lower abdominal surgery.
Patients and methods: this prospective randomized blinded clinical
study was done on 38 patients above 18 years who were randomized into
two equal groups:
-group PVB:(19 patients received in-plane ultrasound guided continous
lumbar paravertebral block with 15-20 ml(0.3ml/kg) of 0.5% bupivacaine
bolus dose followed by continuous infusion of bupivacaine 0.125% with
fentanyl 1mcg/ml.
-group EPB:(19 patients received continuous lumbar epidural analgesia
with 5-8 ml(0.1ml/kg) of 0.5% bupivacaine bolus dose followed by
continuous infusion of bupivacaine 0.125% with fentanyl 1mcg/ml.
After insertion of epidural/paravertebral catheters patients were turned
supine. General anesthesia was induced with IV fentanyl 1–2 mcg/kg,
propofol 2–3 mg/kg followed by rocuronium 0.5–0.8 mg/kg . Anesthesia
was maintained with Isoflurane 1.5% and rocuronium 0.15mg/kg as a
maintainance dose every 30 minutes till the end of the procedure.
Ventilation parameters was adjusted as follows: TV = 7 ml/kg,
respiratory rate = 12/min. and peak inspiratory pressure 30- 35 cm H2O.
End tidal CO2 will be maintained between 35-40 mmHg.heart rate and
MAP were monitored.
The primary outcome measure: is the mean morphine consumption in
the first 24 hours postoperative and visual analogue scale ( VAS).
81
The secondry measures include: age, weight, height, BMI, ASA, vital
signs (MAP, HR, RR), type and duration of surgery and complications
(nausea, vomiting, pruritis, drowsiness and urine retention).
Results: there was insignificant differences between epidural and
paravertebral groups as regarding VAS and total morphine consumption
in the first post-operative 24 hours.
As regarding MAP and HR, they were lower in epidural group.
complications including nausea, vomiting and urine retention were higher
in epidural group.
Conclusion: both continous epidural and continous paravertebral blocks
are effective in controlling postoperative pain after lower abdominal
surgeries with lower rate of complications (hypotension, bradycardia,
nausea, vomiting and urine retention) in paravertebral group.
82
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العربى الملخص
للألم الجسم بدايتها يستجيب فى تعد فسيولوجية بطريقةنافعةومفيدة.
اكلينيكيا يؤثر الجراحية العمليات مابعد معالجةآلام عدم كماأنمعدلات وزيادة زيادةالتكلفة إلى ممايؤدى المرضى على ونفسيا
. إلى أيضا كمايؤدى المزمنة الآلام حدوث نسبة وازدياد الوفاة , ذبحة حدوث بالأوردة الدم تخثر مثل السلبية الآثار من العديد
, , القلب, بعضلة الدم تجلط الرئوى بالشريان الدم تجلط صدرية. الأرق و الجروح التئام عدم و رئوى التهاب حدوث
مدة إطالة إلى يؤدى إذ الاقتصادية الناحية من سلبيا يؤثر أنه كماخروجه بعد المستشفى إلى المريض عودة أو بالمستشفى الإقامة
. له المقدمة الطبية الرعاية عن المريض رضاء عدم و منها
89
مع التعامل فى قصور وجود إلى حديثا أجريت دراسة أشارت وقدبين ما شدتها تتراوح التى و الجراحية العمليات مابعد آلام
. شديدة إلى متوسطة
: الدراسة من الهدفطريق عن التخدير فاعلية بين المقارنة إلى الدراسة هذه تهدفبجانب المستمر الحقن و الجافية الأم فوق المستمر الحقنتخفيف فى الصوتية فوق الموجات باستخدام القطنية الفقراتالحيوية العلامات استقرار و السفلى البطن عمليات بعد الألم
للمرضى.: البحث وطريقة المرضى
على الدراسة هذه فوق 38أجريت أعمارهم تم, 18مريض عامامنهما كل تحتوى متساويتين مجموعتين إلى عشوائيا تقسيمهم
مريضا :19على : الفقرات بجانب المستمر للحقن خضعت الأولى المجموعة) , إعطاؤها تم الصوتية فوق الموجات باستخدام مل)20-15القطنية
البيوبيفاكين عقار .0.5من أولية% كجرعة , : وتم الجافية الأم فوق المستمر للحقن خضعت الثانية المجموعة
البيوبيفاكين) 8-5إعطاؤها ( ر غقا من .0.5مل أولية% كجرعةعيار ( قسطرة وضع تم المجموعتين كلتا المستمر) 20في للحقن
/ 0.1بمعدل البيوبيفاكين/ عقار من ساعة كجم عقار% 0.125مل معبمعدل للتخدير/ 1الفنتانيل المريض إخضاع تم ثم مل ميكروجم
الكلى .ثم الكلى التخدير من المريض إفاقة تم الجراحية إنهاءالعملية بعد
العلامات لمتابعة الجراحية عمليات بعد ما الرعاية لوحدة نقل. المستمر الحقن استمرار مع لمدةساعتين الحيوية
عند الآتية المعايير قياس تم :24,12,6,2,1ثم الإفاقة بعد ساعة
90
1) لايوجد) صفر من تتراوح والتى البصرى بالمقياس الألم شدة( محتمل) ( غير ألم عشرة إلى ألم
خلال) 2 المسكنة المواد استهلاك ساعة24معدلالقلب) 3 ضربات ومعدل الدم ضغط متوسطالتنفس) 4 معدل
: البحث نتائجبالنسبة الدراسة مجموعتى بين واضح فرق وجود ملاحظة يتم لم
المسكنة المواد استهلاك أومعدل البصرى بالمقياس الألم لشدةساعة.24خلال
كانوا فقد القلب ضربات ومعدل الدم ضغط لمتوسط أمابالنسبة. الجافية الأم فوق حقنها تم التى المجموعة فى أقل
( , , ) كانت فقد البول احتباس القئ الغثيان للمضاعفات وبالنسبة. الجافية الأم فوق حقنها تم التى المجموعة فى أكثر أيضا
الجافية الأم فوق المستمر الحقن من كلا أن ذلك من ونستنتجمابعد لآلام فعال علاج القطنية الفقرات بجانب المستمر والحقن
. الجراحية العمليات
91
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