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ANESTHESIA FOR OPHTHALMIC SURGERY
Dr Md Ferdous IslamCMH,Dhaka
INTRODUCTION
Anesthesia for EYE surgery presents many unique challenges.
In addition to possessing technical expertise, the anesthesiologist must have detailed knowledge of ocular anatomy, physiology, and pharmacology.
Ocular anatomy Physiology of intraocular pressure and
effect of anesthetic drug on it, Systemic effects of ophthalmic drugs Technique of anaesthesia: advantage
and limitations Pre op evaluation General anaesthesia Complications Specific considerations for eye
surgeries
Challenges for the anaesthesiologist are
Akinesia Analgesia Minimal Bleeding Awareness of drug interactions Regulation of intraocular pressure Prevention of the oculocardiac
reflex Management of oculocardiac reflex Control of intraocular gas
expansion Smooth emergence
TECHNIQUES OF ANAESTHESIA GENERAL ANESTHESIA
LOCAL ANESTHESIA
a. Topical anesthesia
b. Infiltration anesthesia
Retrobulbar block
Peribulbar block
Sub Tenon block
Sub conjunctival block
c. Nerve block
d. Intra cameral
AGENTS
Adjuvants:Inj.Adrenaline( 1 in 100000) It reduces systemic absorption by local
vasoconstriction.It also reduces chance of bleeding, prolongs the duration of action. It is contraindicated in HTN and Heart diseases.
Inj Hyaluronidase It enhances diffusion of agents through tissue by
breaking down extracellular matrix. It is used 15 unints/ ml of anesthetic solution
GA Vs LA The choice is made on the basis of
the duration of the surgery, the relative risks and benefits of
each technique for the patient, patient preference.
Indication of GA In children EUA Probbing of NLD Surgeries Cataract Glaucoma Enucleation in Retinoblastoma Injury Repair Squint DCR
In adults Repair of perforating injury Mentally retarded pt Non co operative Pt Too nervous and apprehensive pt Eneucleation, evisceration,
Exenteratin surgery Major Occuloplastic surgery Surgeon’s preference
General versus Local AnesthesiaGeneral
Anesthesia:
Patient refusal
Children / movemen
t disorders
Major / lengthy
procedures
Inability to lie still /
flat
Local Anesthesi
a:
No Physio-logical distur-bance , PONV
Economic, Day care
Regional Anesthesi
a:
Good akinesia
and anaesth
esia
Minimal effect on IOP
Minimal equipm
ent require
d
Topical Anesthesi
a:
no risk of hemorrhag
e, brainstem
anesthesia, optic nerve damage or
globe perforation
LIMITATIONS…General Anesthesia:
Eye surgery necessitates
positioning the anesthesiologist away from the
patient’s airway
Patients at extremes of age
Pediatric patients : associated congenital
disorders (eg: rubella syndrome, Down syndrome).Co-morbidity in
elderly: esp. Diabetes,
hypertension and coronary artery
diseaseOphthalmic
drugs
Local Anesthesia:
Complications , Allergy to drug
Skill of anaesthetist
Shortness of breath on
lying down, chronic cough
Parkinson’s disease
Eye Trauma
Topical Anesthesia:
lack of eye
akinesis
treatment of
uncomplicated
cataracts only
PREOPERATIVE EVALUATION Eye surgery patients are a high-risk
group Age diabetes, hypertension, and
atherosclerosis informed consent of the patient.
HISTORY
Allergies and drug sensitivities A current list of medications Patient factors incl dementia,
deafness, language difficulty, restless legs syndrome, obstructive sleep apnea, tremors, dizziness, and claustrophobia.
PHYSICAL EXAMINATIONS Check for signs of major cardiac or
pulmonary decompensation.
Particular attention should be paid to positioning issues, such as severe scoliosis or orthopnea, Tremor.
CARDIOVASCULAR EVALUATION The AHA and American College of
Cardiology published guidelines for perioperative cardiovascular evaluation for noncardiac surgery.
Ophthalmic procedures such as cataract extraction are specifically identified as low-risk procedures.
HYPERTENSION
Severe hypertension may lead to perioperative complications.
It would be prudent to reschedule elective procedures in patients with sustained stage 3 hypertension until after 2 weeks of antihypertensive therapy.
PULMONARY CONSIDERATIONS
Preoperative risk reduction strategies
incl cessation of cigarette smoking, treatment of airflow obstruction administration of antibiotics for
respiratory infections. Patients should be assessed for sleep
apnea. Intravenous sedation is often contraindicated in these patients.
ENDOCRINE CONSIDERATIONS Severe hyperglycemia and
hypoglycemia should be avoided. A FBS should be checked
preoperatively. Insulin therapy should be used, if
needed, to maintain blood glucose at 150 to 250 mg/dL.
ANTICOAGULATION Perioperative management of
anticoagulants against possible hemorrhagic complications. That depends on the following: The degree of anticoagulation. The hemorrhagic potential of the surgical
procedure as in orbital and oculoplastic surgery; of intermediate probability in vitreoretinal, glaucoma, and corneal transplant surgery; least likely in cataract surgery.
INVESTIGATIONS
ECG: New chest pain, decreased exercise tolerance, palpitations, near-syncope, fatigue, or dyspnea. Tachycardia, bradycardia, or irregular pulse on examination.
Serum electrolytes: H/O severe vomiting or diarrhea, poor oral intake, changes in diuretic management, or arrhythmia.
Critical results: Na less than 120 mEq/L or greater than 158 mEq/L.
K less than 2.8 mEq/L or greater than 6.2 mEq/L.
INVESTIGATIONS Urea nitrogen: renal decompensation.
Critical result: Greater than 104 mg/dL. RBS: Polydipsia, polyuria, or weight loss.
Critical results: Less than 46 mg/dL or greater than 484 mg/dL.
Hematocrit/hemoglobin: History of bleeding, poor oral intake, fatigue, decreased exercise tolerance, or tachycardia. Critical results: Hematocrit less than 18% or greater than 61%. Hemoglobin less than 6.6 mg/dL or greater than 19.9 mg/dL
GENERAL ANESTHESIA
PREMEDICATION
An effective antiemetic should be used
to decrease PONV. eg- Ondansetron
Opioids are avoided as they contribute
to PONV.
Benzodiazepines are given.
GENERAL ANESTHESIA
Intravenous agents: Propofol , Thiopental and Etomidate.
Coughing during intubation: avoided by a deep level of anesthesia and profound paralysis.
The IOP response: to laryngoscopy and endotracheal intubation can be blunted.
LMA: can also be used. Less changes in IOP.
AIRWAY MANAGEMENT maintenance of spontaneous
respiration via a facemask should be used, as intubation will raise the intraocular pressure.
Examination under anaesthesia (EUA)-spontaneous respiration through a reinforced laryngeal mask airway (LMA)
GENERAL ANESTHESIA
RELAXATION- A nondepolarising muscle relaxant is
used instead of succinylcholine because the latter increases intraocular pressure.
However, the rise in IOP is small by succinylcholine than the fall caused by intravenous induction agent, and also considering risk of aspiration succinylcholine can be used in an emergency case.
USE OF NITROUS OXIDE The use of nitrous oxide in eye surgery
is limited by two factors. Increase the risk of PONV, and in
ophthalmic procedures there is a high incidence of PONV
Secondly, nitrous oxide diffuses from the blood into gas filled spaces in the body.
It should be avoided in vitreoretinal detachment surgery where intraocular gas bubbles of sulphur hexachloride or perfluropropane are introduced into the eye to tamponade detached surfaces.
GENERAL ANESTHESIA
EXTUBATION & EMERGENCE A smooth emergence from general
anesthesia Deep level of anesthesia. Intravenous lidocaine (1.5 mg/kg)
prior to extubation. Severe postoperative pain is
unusual.
The effect of anesthetic agents on intraocular pressure (lOP).
Topical anesthesia
Relieve pain and itching caused by conditions such as sunburn or other minor burns, insect bites, minor cuts and scratches.
Fluorescence dye examination for corneal ulcer.
Gonioscopy Corneal scrapping for bacteriological study Paracentesis Perform a contact /applanation tonometry. Cataract, pterygium and glaucoma surgery Removal of small foreign objects from the
uppermost layer of the cornea or conjunctiva.
Retrobulbar Block A long needle is introduced at junction
of middle third and lateral third of inferior orbital margin and then directed backwards and medially towards the apex of the orbit.
Effects are Anaesthesia, akinesia, Hypotony
proptosis
65
Peribulbar Blocks• At superior and inferior parts of
peripheral space of orbit.• The superior injection.• The Inferior Inj• An Intermittent Pr. • Advantages
66
Sub-Tenon’s Block
• Sensory block• Short-ciliary nerves
pass through Tenon’s capsule to globe
• Akinesia• Direct blockade of ant.
nerve fibres as they enter extra-ocular muscles 68
FACIAL NERVE BLOCK
Blocked at several points after exiting from the base of the skull from the stylomastoid foram
Van Lint block A needle is introduced about 1 cm below and behind the lareral canthus. About 4ml sol along the supero lateral and inferolateral orbital margin in a V shape manner.
O'Brien’s procedure About 4 ml sol is infiltrated at the neck of the mandible just infront of the tragus.
Other Nerve Block Intratrochlear nerve block Supraorbital nerve block Lacrimal nerve block Infraorbital and Zygomatic nerve
block
Intra Cameral Anaesthesia
Injecting 1% Lidocaine inj into ant chamber by side port incision or paracentsis.
Anaesthetises Iris and the Ciliary Body
Reduces pain and IOP The drug must be washed
properly
COMPLICATIONS
COMPLICATIONS OF REGIONAL ANAESTHESIA
Retrobulbar hemorrhage
CRAO
Stimulation of OC reflex
Puncture of posterior globe
IV injection of LA brainstem anesthesia - (delayed
onset LOC and resp. depression)
Optic nerve trauma.
RETROBULBAR HAEMORRHAGE
Venous hemorrhages - spread slower
Arterial hemorrhages - rapid and taut orbital swelling with marked proptosis.
incidence-1% to 3%. Clinical suspicion: stained
conjunctiva and a proptotic globe
RETROBULBAR HAEMORRHAGEMANAGEMENT Determine IOP OphthalmoscopyTREATMENT reduce orbital compartment
pressure, thereby IOP Osmotic diuretics Lateral canthotomy Orbital decompression
OCULOCARDIAC REFLEX
The Oculocardiac Reflex(OCR) is manifested by Bradycardia Ectopics Nodal rhythm Atrioventricular block Cardiac arrest
OCULOCARDIAC REFLEX
Caused By: Traction on the extraocular muscles
(medial rectus) Ocular manipulation Manual pressure on the globe
The OCR is seen during: Eye muscle surgery Detached retina repair Enucleation
OCULOCARDIAC REFLEX Factors contributing to the
incidence of the oculocardiac reflex: Preoperative anxiety
Hypoxia
Increased vagal tone owing to age
OCULOCARDIAC REFLEX
Management stop stimulation by the surgeon
before the arrhythmia progresses to sinus arrest
Atropine (0.01 mg/kg IV) local injection of lidocaine near the
eye muscleEnsure depth of general anesthesia normocapnia surgical manipulation is gentle.
OCULORESPIRATORY REFLEX may cause shallow breathing,
reduced respiratory rate and even full respiratory arrest.
Trigemino vagal reflex- connection exists between the trigeminal sensory nucleus and the pneumotactic centre in the pons and medullary respiratory centre.
Commonly seen in strabismus surgery
OCULOEMETIC REFLEX
It is likely responsible for the high
incidence of vomiting after squint surgery (60-90%).
Trigemino-vagal reflex with traction on the extraocular muscles stimulating the afferent arc.
Antiemetics may reduce the incidence, a regional block technique provides the best prophylaxis
Disturbances of swallowing and respiratory difficulties
Horner's syndrome permanent facial nerve paralysis-
longer needles and hyaluronidase use of a single injection of a large
volume of LA
BRAINSTEM ANAESTHESIA Amaurosis
Gaze Palsy (Ductional Defects),
Apnea Shivering Tachycardia and
Hypertension Dysphagia Loss Of
Consciousness Cardiac Arrest
BRAINSTEM ANAESTHESIA The onset of symptoms -delayed 2
to 40 minutes after injection.
Management: Early and prompt treatment 100% oxygen maintenance of vital signs tracheal intubation and controlled
ventilation
OCULAR PENETRATION AND PERFORATION most common in the myopic,
elongated globes. Myopics with staphyloma. associated with the use of large,
dull needles. a sensation of "poking through
”during the placement of the needle.
sudden appearance of hypotony, vitreous hemorrhage or a diminished red reflex
OCULAR PENETRATION AND PERFORATION Diagnosis -Indirect fundoscopy
The most common sequelae- Retinal detachment
Appropriate retinal surgery-to prevent the loss of vision.
COMPLICATIONS ASSOCIATED WITH GENERAL ANAESTHESIA
PONV
Increase in IOP-extrusion of intraocular contents
Intraocular gas expansion
Pulmonary embolism
POST OPERATIVE NAUSEA AND VOMITING Most common complication
associated with outpatiet The incidence in patients
undergoing strabismus surgery -85%.
MANAGEMENT Metoclopromide i.v (10 mg) 5HT3 antagonists Dexamethasone i.v
Pulmonary Embolus
chief cause of postoperative ophthalmic surgery death
particularly a problem with long procedures (retinal and oculoplastic surgery) in the elderly.
from a leg deep venous thrombosis
Pneumatic leg compression devices
INTRAOCULAR GAS EXPANSION Intravitreal air/SF6 injection: to
flatten a detached retina and allow anatomically correct healing
Nitrous oxide:expansion of air bubble and rise in IOP
Prevention: discontinue nitrous 15-20 mins prior to injection
Ref
American Academy of Ophthalmology Alexander J.E. Foss,Essential Ophthalmic Surgery