Case 1 - The Stabbing

8/3/2019 Case 1 - The Stabbing

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Case 2.01 The Stabbing

1. Anatomy of the thorax

Thorax consists of:

1. Chest wall ribs, sternum and vertebralcolumn (T1 T12) (provide most of the

structural support)

2. 2 pleural cavities surrounding the lungs3. The area between theses cavities the

mediastinium, in which are found the heart,

great vessels, trachea, oesophagus, vagus

and phrenic nerves, thymus gland and the

thoracic duct.

4. The mammary glands are also found on theexternolateral chest wall.

The thorax is separated from the abdomen

by the diaphragm. It is continuous with the

neck at the thoracic inlet between the

sternum and T1. Structures pass between

the thorax and the neck through this inlet.


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(aka outlet as the subclavian artery passes OUT of the thoracic inlet)

The ribs articulate with the vertebral column behind and the sternum, in front. These articulations permit the

movement of breathing.

Intercostal spaces between the ribs are occupied by muscle and a neurovascular bundle that supplies the

muscles, the skin over them and the lining of the pleural cavity deep to then.

The repeating pattern of the ribs, vertebrae and neuromuscular bundles is an example of segmentation.

Vertebral levels and surface markings

The suprasternal or jugular notch is at T2

The sternal angle of Louis is at T4 (if you palpate this angle and then move laterally you can palpate rib 2. From

here you can count downwards through the intercostal spaces and ribs.)

The xiphisternum or xiphoid process is at T9

Bones and Joints of the chest wall

The chest wall is made up of 12 pairs of ribs., the sternum and intercostal muscles. The ribs are numbers 1-12

superiorly inferiorly and articulate with the vertebral column posteriorly and the sternum(mostly) anteriorly.

The sternal end of the ribs is lower than the vertebral end. Ribs are united at the anterior end by costal cartilage

with primary cartilaginous joints.

Vertebrae A thoracic vertebral is identifiable because of its facets(flat areas) for articulation with ribs.

Vertebrae T2-T9 have 2 demifacets on each side whereas the rest only have one.


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Ribs each rib has a head a neck a tubercle and a shaft.

There are typical and atypical ribs (1.11 and 12). You only need to know about the 1st of the atypical ribs. It has a

scalene tubercle in the upper surface to which the scalenus anterior muscle attaches. There is a groove for the

subclavian vein anterior to this tubercle and a groove for the subclavian artey posterior.

Sternum has 3 parts, from superior to inferior. The manubrium, body and xiphoid process. There may be a

hole in the centre of the body as it is formed by any number of individual

sternebrae that should fuse but may fail to do so.

Joints between vertebrae and ribs typical ribs have 3 synovial articulations with

the vertebrae.

- The head has upper and lower articular facets set almost at a right angle to eachother, the lower articulating with the vertebrae corresponding in number to the

rib and the upper with the vertebrae above. Ribs 1, 10, 11 and 12 have only one

facet and only articulate with the numerically corresponding vertebrae.- The tubercle of most ribs (not 11 or 12) articulates with the transverse processes

of the corresponding vertebrae.

- These joints allow the ribs to move white breathing.

-Ligaments these are not of great importance. They include:

Triradiate ligament from the head of the rib to the vertebrae above, the intervertebral disc and the vertebrae

below.

Costotransverse ligaments between the vertebral transverse process and the tubercle of the rib.

Joints between the ribs , sternum and vertebral column the first costal cartilage is continuous with the

manubrium (primary cartilaginous joint) and remains so throughout life until it ossifies completely. Costal

cartilages 2-7 have synovial articulations with the sternum. The second costal cartilage articulates at the sterna

angle with the manubrium AND the body of the sternum. Costal cartilages 8-10 have synovial articulations with


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the costal cartilage immediately above. Costal cartilages 11-12 are free of any anterior articulation but provide

attachments for muscles.

Ribs 1-7 are vertebrosternal or true ribs

Ribs 8-10 are vertebrochondral or false ribs

Ribs 11-12 are floating ribs

Muscles of the chest wall

Intercostal muscles and spaces

There are three layers of tissue between ribs, partly muscle and partly

membrane external, internal and innermost intercostals, with the

intercostals neurovascular bundle running between the internal and

innermost. The area between the ribs occupied by these intercostals

muscles is the intercostal space.

External intercostal muscle. Muscle at the back and sides. Membrane

anteriorly. Fibres pass from the upper rib downwards and forwards to

the upper border of the rib below.

Internal intercostal muscle. Muscle at the front and sides, membrane

posteriorly. Fibres pass upwards and forwards, more or less at right

angles to those of the external intercostals.

Innermost intercostal muscle. As Internal intercostal.

Inside the chest wall there are usually muscle fibres that fan out from the sternum to the internal aspect of ribs

3-6. This is transverse thoracis and is equivalent to transverse abdominis in the abdomen (it is not important)

Neurovascular bundle costal groove

These muscles are supplied by the segmental intercostal nerve corresponding in number to the intercostals

space. The rib has a groove underneath most of its length on the internal aspect. The intercostals groove

provides some shelter for the intercostal neurovascular bundle. Within the groove the bundle is arranged from

top to bottom, VAN vein, artery, nerve. In each intercostals space there are also smaller branches of the

intercostals nerve and atery (collateral branches) which run on the top of the rib below.

Muscles of the pectoral girdle

Overlying the ribs and intercostals are muscles which attach the upper limb (humerus, clavicle and scapula) to

the trunk: Pectoralis major and minor, latissimus dorsi, levator scapulae, rhomboids and trapezius.


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Blood Supply of Chest Wall

Posterior intercostal arteries

Are branches of the aorta and are called segmental arteries, apart from the first and second which come from

the costocervical trunk, a branch of the subclavian artery(not from the aorta because it does not pass high

enough in the thorax)

Anterior Intercostal arteries

Arise from the right and left internal thoracic arteries, branches of the subclavian which run internally down the

chest wall 1-2cm lateral to the sterna border. They are important in supplying the breast.

Lateral thoracic artery - Important for the breast

Other branches of the subclavian/axillary arteries thoracoacromial, superior thoracic.


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Veins

Anterior intercostals veins drain to the internal thoracic veins, then to the subclavian braciocephalic superior

vena cava.

Posterior intercostals veins drain to the azygos system and the superior vena cava. As the first one or two

posterior intercostals arteries arise differently to the rest the first posterior intercostals veins drain differently to

the rest, to the brachiocephalic veins.

Intercostal nerves

These are ventral rami of the thoracic segmental nerves. The run in the costal groove of each of each rib and

supply the intercostals muscles, a strip of skin overlying the intercostals muscles and a similar strip of parietal

pleura on the internal aspect of the chest wall. Anteriorly when the ribs turn upwards, the neurovascular bundle

parts company with the ribs and continues in the direction already established. Lower intercostal nerves will also

supply skin of most of the anterior abdominal wall. And the parietal peritoneum deep to it.

Intercostal nerves contain both motor and sensory fibres. Cell bodies of motor fibres to skeletal muscle are in

the ventral horn of the grey matter of the correspondingly numbered spinal cord segment. Cell bodies of sensory

fibers in an intercostals nerve are in the dorsal root ganglion of the parent segmental nerve.

This arrangement gives rise to the concept of segmental innerveration, and allows autonomic reflex in one area

a physiological phenomenon particularly important clinically in the limbs

2. Anatomy of the Respiratory OrgansPrinciple organs of the respiratory system are the nose,

pharynx, larynx , trachea, bronchi, and lungs.

Nose

Warms, cleanses and humidifies air. The external nose is

supported and shaped by bone and cartilage. Superiorly it

is supported by nasal bones medially and maxillae laterally.

The inferior half is supported by lateral and alar cartilages.

Dense connective tissue shapes the flared portion called

the ala nasi which forms the lateral wall of the nostrils. The

nasal cavity extends from the anterior nares/nostrils to the

posterior nares/choanae. The dilated chamber inside the

ala nasi is called the vestibule. This has stiff nasal hairs

called vibrissae. The nasal septum divides the nasal cavity

into right and left chambers called the nasal fossae. These

fossae have folds called conchae that increase the surface


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area so the air is warmed and humidified. The nasal cavity is separated from the oral cavity by the palate.

Pharynx

A muscular funnel that is about 13cm long. Air turns 90 degrees to head downwards when it meets the

nasopharynx. The oropharynx is the part of the pharynx that starts at the back of the tongue. The

laryngopharynx connects the oro and nasopharynges.

Larynx

This is also known as the voicebox. It is a cartilaginous chamber about 4cm long. Its primary role is to keep food

out of the airway but it has also evolved to produce sound. The superior opening is called the glottis; it is

guarded by a flap called the epiglottis. The framework of the larynx consists if 9 cartiages. The epiglottic

cartilage, which is superior is made of elastic cartilage but the rest are hyaline cartilage. The walls of the larynx

are muscular.

Trachea

Aka windpipe, is a rigid tube about 12cm in length and 2.5cm in diameter. It is anterior to the oesophagus and is

supported by 16-20 C-shaped rings of hyaline cartilage. These rings reinforce the cartilage and prevent it from

collapsing during inhalation. The open part of the C faces posteriorly where it is spanned by smooth trachealis

muscle. The gap in the C allows the oesophagus to expand as food passes through. The trachealis muscle can

contract and relax to adjust tracheal airflow. The larynx and trachea are mostly lined by ciliated pseudostratified

columnar epithelium which function as a mucociliary escalator where the mucus traps debris and the cilia beat

and drive it up to the pharynx so it can be swallowed.

Lungs

Each lung is conical and has a concave base resting on the diaphragm and an apex that projects slightly superior

of the clavicle. The broad costal surface presses against the ribcage and the smaller concave mediastinal surface

faces medially. The lung receives the bronchus, blood vessels, lymphatic vessels and nerves through the hilum,

which is on the mediastinal surface. These structures entering the hilum constitute the root of the lung. The left

lung is smaller than the right and has an indentation called the cardiac notch to accommodate the heart. The left

lung has a superior lobe and an inferior lobe with a deep fissure between them called the oblique fissure. The

right lung has 3 lobs the superior, inferior and middle which are divided by the oblique and horizontal fissures.

The lung has spongy parenchyma containing the bronchial tree, a highly branched system from the primary

bronchus to about 65000 terminal bronchioles. The two primary bronchi arise from the trachea at the level of

the angle of Louis. Each bronchi continues for 2-3cm and enters the hilum of its respective lung. The right

bronchus is slightly wider and more vertical than the left. The bronchi are supported by C-shaped hyaline

cartilage as well. All divisions of the bronchial tree have a substantial amount of elastic connective tissue, which

helps to expel air from the lungs by recoiling. After entering the hilum the bronchus separates into lobar

bronchus for each pulmonary lobe. Thus there are 2 secondary bronchi in the left lung and 3 in the right. Each

secondary bronchus separates into tertiary or segmental bronchi (10 in the right lung and 8 in the left). The

portion of lung supplied by each tertiary bronchus is called a bronchopulmonary segment. Secondary and


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tertiary bronchi are supported by overlapping plates of cartilage. Branches of the pulmonary artery closely

follow the bronchial tree on the way to the alveoli. The bronchial tree itself is nourished by the bronchial artery

which arises from the aorta and contains systemic blood. Bronchioles are continuations of the airway that are

1mm or less in diameter and lack cartilage. A well developed layer of smooth muscle in their walls enables them

to dilate and constrict. The portion of the lung ventilated by one bronchiole is called a pulmonary lobule. Each

bronchiole divides into 50-80 terminal bronchioles, these measure less that 0.5mm in diameter and have no

mucous glands or goblet cells. They do, however contain cilia, so mucous can be beaten away from the terminal

bronchioles and alveoli. Each terminal bronchiole gives off 2 respiratory bronchioles that have scant smooth

muscle and divide into thin walled passages called alveolar ducts that end in irregularly shaped spaces called

alveolar sacs.

Alveoli bud from the walls of respiratory bronchioles, alveolar ducts and alveolar sacs. The presence of alveoli

indicates where gas exchange with the blood occurs. There are about 150 million alveoli in the lungs. An alveolus

is a pouch about 0.2-0.5mm wide. It consists of:

- (Predominantly) squamous (type I) alveolar calls thin cells that allow rapid diffusion of gas between thealveolus and the bloodstream

- (5%) round cuboidal great (type II) alveolar cells secrete a detergent like lipoprotein called pulmonarysurfactant which forms a thin film inside the alveoli and the bronchioles

- Alveolar macrophages (dust cells) patrol the lumens of the alveoli and the connective tissue betweenthem.

Scanning e.m. showing some of the Capillary Alevolus Type II pneumocyte300 million alveoli in the human lung.

Each alveolus is surrounded by a basket of blood capillaries supplied by the pulmonary artery. The barrier

between alveolar air and blood (respiratory membrane) consists only of squamous (type I) alveolar cells, the

squamous endothelial cell of the capillary and their fused basement membranes. These have a total thickness of

0.5micrometres. Pulmonary circulation has very low blood pressure.


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Pleurae

The surface of the lung is covered by a moist serous membrane called the visceral pleura which extends into the

fissures. At the hilum the visceral pleura folds back on itself and forms the parietal pleura, which adheres to the

mediastinum, the superior surface of the diaphragm and the inner surface of the rib cage. The space between

the visceral and parietal pleurae is called the pleural cavity. The two membranes are separated by a film of

slippery pleural fluid.

The pleurae and pleural fluid have 3 functions:

1. Reduction of friction pleural fluid acts as a lubricant thatenables the lungs to expand and contract with minimal

friction.

2. Creation of pressure gradient pressure in the pleural cavityis lower than atmospheric pressure and this assists in inflation

of the lungs

3. Compartmentalisation the pleurae, mediastinum and pericardium compartmentalise the thoraciccavity and prevent infections of one organ spreading easily to another organ.

Lung surfactant: dipalmitoylphosphatidylcholine (DPPC) + lipids and proteins


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Reduces alveolar surface tension, during inspiration promotes inflation of all rather than some alveoli, increases

lung compliance, prevents alveolar collapse at and of expiration

Law of Laplace P=2T/r surfactant ensures this balance is maintained.

Lung surfactant ensures that if two alveoli have equal radii but different tensions that the tension is reduced so

they both expand to take in equal amounts of air.

If there are two alveoli of equal tensions but different radii the lung surfactant reduces the tension more in the

smaller alveolus.

Lack of surfactant can result in alveolar collapse (atelectasis). This is more likely to occur at the end of expiration

when the radius is minimal.

Surface Markings of the lungs

The pleura extends above the clavicle in the neck (vulnerable to stab wounds)

Pleura also descends below the costal margin in the right costosternal margin and between the 12th

rib and the

vertebral column on the left and right.

Lung tissue is the same as the pleura except it doesnt extend much below T1

These structures do, however, move during breathing and change with posture. Everything is lower when you

are standing erect than when you are lying down.

Diaphragm

The diaphragm accounts for 75% of the change in intrathoracic volume during quiet inspiration. It is attached

around the bottom of the thoracic cage. It arches over the liver and moves downwards when it contracts. The

distance it moves ranges from 1.5cm to 7cm with deep inspiration.

The diaphragm has 3 parts:

Costal portion made up of muscle fibres that are attached to the ribs around the bottom of the thoracic cage.

Crural portion made up of fibres that are attached to the ligaments along the vertebrae. Pass either side of the

oesophagus and can compress it when they contract.

Central tendon the crural and costal portions insert into this. This is also the inferior portion of the

pericardium.

The costal and crural portions are innervated by different parts of the phrenic nerve and can contract separately.


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Xiphoid sternum

Domes

Abdominal organs

3. Physics of respirationThe respiratory system is made up of as gas-exchanging organ (the lungs) and a pump that ventilates the lungs.

The pump consists of the chest wall, respiratory muscles and the areas of the brain that control these and the

nerves that connect the muscles to the brain.

At rest a normal human being takes about 12-16 breaths per minute. About 500ml of air is taken in per breath.

Partial pressures

Gases expand to fill the volume available to them (unlike liquids). The volume occupied by a given number of

gas particles is the same regardless of the composition of gas at a given temperature and pressure. Thereforethe pressure of any one gas(the PARTIAL PRESSURE) in a mixture of gases is equal to the total pressure

multiplied by the fraction of the total amount of gas it represents.

Gases diffuse from areas of high pressure to areas of low pressure. The rate of diffusion depends on the

concentration gradient and the nature of the barrier between the 2 areas.


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Inspiration

This is an active process. The contraction of inspiratory muscles increases intrathoracic volume. When the

diaphragm is stimulated by phrenic nerves it flattens. The external intercostals also contract as do the scalenes

so the ribs swing upward and out. As the ribcage expands and the diaphragm drops the parietal pleura clings to

them. Because of surface tension in the pleural fluid, the visceral pleura clings to the parietal pleura and so thelungs are also pulled out and expand and the pressure in the airways becomes slightly negative. Therefore air

flows into the lungs from an area of higher pressure to an area of lower pressure. Inhaled air is also warmed as it

enters the lungs and this causes its volume to increase so this inhaled air also causes the lungs to inflate.

Expiration

At the end of inspiration the lung recoil begins to pull the lungs back into the expiratory position where recoil

pressures of the chest wall balance. The air pressure in the lungs becomes slightly positive and the air flows out

of the lungs as there is lower atmospheric pressure. Expiration is passive as no muscles which decrease

intrathoracic volume contract. However, there is some contraction of inspiratory muscles in early expiration

which act as a braking force to slow expiration.

To exhale more completely than usual the internal intercostal muscles must be contracted, which depress the

ribs. Abdominal muscles can also be contracted. This causes the intrapulmonary pressure to rise much higher

than normal (20-30 mmHg) causing faster and deeper evacuation of the lungs. This is useful for singing and

public speaking.

Lung Volumes

The amount of air that moves into the lungs with inspiration is called TIDAL VOLUME

Air inspired with maximal inspiratory effort is called INSPIRATORY RESERVE VOLUME (expiratory reserve volumeis with maximal expiratory effort air left in the lungs after maximal expiratory effort id called RESIDUAL

VOLUME)

VITAL CAPACITY is the largest amount of air that can be expired after maximal inspiratory effort.


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4. Physiology of gas exchangeNeural control of ventilation

The heartbeat and breathing are the most evident rhythmic processes of the body. The heart has an internal

pacemaker and continues to beat even if all nerves are severed, but breathing depends on constant stimulationfrom the brain. The reasons for this are that skeletal muscle requires nervous stimulation to contract and

breathing requires coordination of multiple muscles that require a mechanism to make sure they contract at the

right time.

Neurons in the medulla oblongata and pons provide automatic control for automatic control of unconscious

breathing. Neurons in the motor cortex of the cerebrum provide voluntary control.

Medulla oblongata

Contains inspiratory neurons and expiratory neurons(fire during forced expiration). Fibres from these neurons

pass down the spinal cord and synapse with lower motor neurones in the cervical and thoracic regions. Then thefibres travel in the phrenic (diaphragm) and intercostal (intercostal muscles) nerves. The exact method for the

rhythm of respiration is unknown. The medulla has 2 nuclei. The inspiratory centre or dorsal respiratory group

(DRG) which contains inspiratory neurons. When these fire the muscles of inhalation contract. The more they

fire for the deeper inhalation is, the longer they fire for the lower respiratory rate is as each breath is prolonged.

The expiratory centre or dorsal respiratory group has inspiratory neurons in the middle and expiratory neurons


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at the anterior and posterior ends. The expiratory neurons inhibit the inspiratory centre when deeper expiration

is required.

Pons

Regulates ventilation by means of a pnemotaxic centre in the upper pons (and maybe an apneustic centre in the

lower pons). The pnemotaxic centre sends a constant stream of inhibitory impulses to the inspiratory centre in

the medulla oblongata. The impulse frequency controls how last inspiration lasts. High frequency = short

breaths.

Voluntary control

With conscious attention it is possible to do things such as hold our breath, take a deep breath etc. This control

originates from the motor cortex of the frontal lobe of the cerebrum that can bypass the brainstem respiratory

centres by sending impulses down corticospinal tracts. There are limits to voluntary control as when CO2 levels

get too high the automatic control overrides will.

Air-water interface

When air and water are in contact gases diffuse down their concentration gradient until the partial pressure of

each gas is equal to its partial pressure in the water. If gas is more abundant in air than in water then in diffuses

into the water. Therefore the greater the PO2 in the alveolar air than the more O2 the blood picks up. And since

blood arriving at the alveolus has a higher PCO2 than air the blood releases its CO2 into the air. It is said to

UNLOAD the CO2 and LOAD O2.

Alveolar gas exchange

Both the loading of oxygen and the unloading of carbon dioxide are dependant on erythrocytes (RBCs). The

efficiency of these processes depends on how long the RBC spends in the capillary compared to how long it

takes for O2 and CO2 to reach equilibrium concentrations in the capillary blood. It takes only 0.25 seconds for

the gases to equilibrate and the RBCs spend at least 0.3 seconds in the alveolar capillary at highest blood flow.

This process is so efficient for the following reasons:

1. High concentration gradients of both gases (O2s is higher)2. Solubility of gases (O2 is more soluble that nitrogen and CO2 is more soluble than O2 so evens out the

difference in concentration gradient.

3. Membrane thickness (very thin so little obstacle to diffusion)4. Large membrane area (70m2)5. Good perfusion of capillaries


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5. Histology of the lungsUpper Respiratory Tract

Ciliated, mucin-secreting cells line the upper airways

The architecture of the nasal cavity and the paranasal sinuses provide a large surface area for warming and

moistening inspired air and for trapping inhaled particles. Air enters the repiratory system through the nostrils.

Skin extends a short distance into the vestibule of the nostril but then becomes non-keratinized squamous

epithelium, although occasional patches of stratified squamous

epithelium persist, most of the nasal and paranasal sinus

cavities are lined by pseudostratified squamous epithelium.

Many of the columnar cells bear numerous cilia. Scattered

among these cells are mucus secreting or goblet cells with

microvilli on their luminal surface. This pattern continues

throughout most of the air conducting part of the respiratory

tract and is known as RESPIRATORY-TYPE EPITHELIUM.

The nasal and sinus mucosa is highly vascular and contains

mucous and serous glands. Beneath the nasal epithelium the

lamina propria contains many glands. 3 main glands can be

distinguished.

1. Mucous glands which secrete mucous to supplement thegoblet cells in the epithelium.

2. Serous glands containing basophilic granules which mayproduce small amounts of amylase

3. Serous glands contain eosinophilic granules which producelysosome

Inspired air is moistened by the secretions of the serous

components of the glands and a sheet of mucus lies on the

mucosal surface and traps inhaled particles. The mucus is then

wafted by the cilia toward the pharynx where it is swallowed or

expectorated. The lamina propria also contains immune cells

such as plasma cells, macrophages and a few neutrophils and

eosinophils. Eosinophils are numerous in those who suffer with

allergic rhinitis. The highly vascular aspect of the lamina propria

is also a major contributant to warming the air.

Paranasal cavities are useful because they provide a large surface area for warming and moistening air and

because they play a role in the nature of sounds in speech.


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The nasopharynx is a posterior continuation of the nasal cavities and becomes the oropharynx at the level of the

soft palate. It is lined by columnar ciliated epithelium containing the occasional goblet cell and has frequent

patches of squamous epithelium. The patches of squamous epithelium arise by metaplasia and increase as you

near the oropharynx and also with age. In the nasopharynx there is also abundant mucosa associated lymphoid

tissue in the submucosa. This tissues samples inhaled antigenic materials and enables defence mechanisms

against it. Larger nodule aggregates of this tissue make up the tonsils. Olfactory mucosa is located in the roof of

the nasal cavity.

The laryngeal region has a complex architecture which:

. Prevents inspired air entering the oesophagus

. Prevents ingested food entering the trachea

. Permits the production of complex soundsIt therefore contains the epiglottis, the true vocal cords and the ventricular vocal cords. Laryngeal architecture is

maintained by a series of cartilaginous plates, these are joined by collagenous ligaments and mobilised by

striated muscle.

The trachea is lined with

respiratory mucosa and is

braced with cartilage. One

narrow strip of the tracheal wall

is deficient in cartilage. Here the

gap is bridged by dense

fibrocollagenous ligament thatis rich in elastic fibres and

bundles of smooth muscle. This

allows some constriction of the

tracheal lumen. The ligament

connecting the two cartilage

ends prevents dilation. The

internal lining is

pseudostratified ciliated

columnar epithelium containing

scatted goblet cells.Subepithelial seromucous

glands are particularly

numerous in the posterior band

devoid of cartilage.


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The main bronchi are extrapulmonary and enter each lung at the hilum. They then divide into lobar bronchi

and then segmental bronchi they further subdivide for a variable number of generations.

Throughout their course the bronchi have a similar structure to the trachea but there are variations. The basic

structure is:

Pseudostratified columnar epithelium

Subepithelial fibrocollagenous tissue containing variable quantities of seromucous glands

Variable amounts of smooth muscle, with elastic fibres arranged in longitudinal bands

Variable amounts of partial cartilaginous ring

The bronchial tree is lined by pseudostratified columnar epithelium which is pseudostratified in larger bronchi

and becomes less complex in smaller peripheral branches. The epithelium contains ciliated columnar cells,

mucus-secreting goblet cells and neuroendocrine cells

Ciliated cells are columnar in most of the bronchial tree but are shorter and almost cuboidal in most of the

peripheral branches they have a basal nucleus, and lysosomes and numerous mitochondria in their supranuclearcytoplasm. The luminal surface bears about 200 cilia and microvilli.

Basal cells lie on the basement membrane and are small cells that are not in contact with the lumen. They form

a stem cell population from which other cells develop.

Intermediate cells are stem cells that are mid transformation into ciliated or mucous secreting goblet cells.

Goblet cells are scattered between goblet cells and are most numerous in the main and lobar bronchi, becoming

less common in the smaller branches.

Neuroendocrine cells are small round cells with dark staining nuclei and clear cytoplasm. They are located in the

basement membrane. They are most numerous in the smaller bronchi. They possess cytoplasmic processes that

contain neuroendocrine granules. They secrete hormones and active peptides. They may be scattered or

congregate in clumps.

Smooth muscle, lymphoid tissue and seromucous glands are present in the walls of the bronchi. There are also

elastic fibres of fibrocollagenous stroma arranged in longitudinal bands.

In the main bronchi the smooth muscle is mainly confined posteriorly due to the cartilaginous rings, it persists in

the smallest branches long after the cartilage ceases to be present.

The submucosal bronchial glands are seromucous glands that empty into the lumen via short ducts. The serouscomponent is thought to secrete lysozomes and glycoproteins. The mucus is thin and traps inhaled matter and

microorganisms. The ciliated columnaer epithelium waft this matter upwards

Myoepithelial cells lie between the secretory and duct lining cells and their basement membrane and some

neuroendocrine cells are also present.


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The bronchial wall contain MALT (mucosa associated lymphoid tissue). Lymphocytes and IgA are closely

associated with the bronchial glands and lymphoid aggregations are common, being most evident at

bifurcations.

Bronchi of all sizes contain some cartilage main extrapulmonary bronchi have regular incomplete rings of

cartilage but the intrapulmonary bronchi have an irregular roughly circumferential arrangement of cartilageplates connected by dense fibrocollagenous bands. As the bronchi get smaller and more peripheral the cartilage

plates decrease in size and number and are mainly concentrated at bifurcations.

Bronchioles are distal airways that branch repeatedly. As they do so they reduce their luminal size. Smooth

muscle becomes the main component of their walls. Bronchioles are lined with ciliated columnar epithelium

without pseudostratification. The cells become lower and more cuboidal in the small peripheral branches.

Occasional goblet cells persist, as do small numbers of neuroendocrine cells but there are no seromucous cells

and a new cell called CLARA CELL is found. The Clara cell is neither ciliated nor mucus producing and is most

numerous in the terminal bronchioles.

Distal respiratory tract

Bronchioles are lined with cuboidal ciliated

epithelium which merges with flattened epithelium

lining the entrances to the alveolar ducts which are

lined with alveoli.

Alveoli have a polygonal air space of about 250

micrometers in diameter each when inflated, with a

thin wall that contains pulmonary capillaries and

forms the air-blood barrier. They also contain pores

called the pores of Kohn which connect each alveolus

to those adjacent to it. They provide direct

communication from alveolus to alveolus which

permits rapid and even distribution of air throughout

the lobe of the lung during inspiration. However, a

disadvantage is that pathogens can also use these pores

to quickly spread through the lungs.

Alveoli contain type I and type II pneumocytes, which lie

on the alveolar basement membrane, and alveolar

macrophages. Type I pneumocytes are very thin cells

that allow gaseous diffusion. They represent about 40%

of the alveolar cell population but form 90% of the surface lining of the alveolar sacs and alveoli. They are flat

cells with flattened nuclei and are joined by tight junctions. They contain scanty mitochondria and the cytoplasm

gives only a thin cover to the basement membrane which contributes to the thinness of the air-blood barrier.


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Type II pneumocytes represent 60% of the alveolar call population numerically but only 5-10% of the surface

area. These are rounded cells which are located at angles and bifurcations. Their nuclei are round and dark and

their cytoplasm are rich in mitochondria and rER and sER. They also contain electron dense vesicles and

spherical bodies of material which is rich in phospholipids, proteins and glycosaminoglycans which forms the

basis of surfactant.

Alveolar macrophages phagocytose inhaled bacteria and particulate matter. Normally they lie on top of the

alveolar lining cells and can be seen free in the alveolar space. They patrol airspaces and the interalveolar septa

passing freely between the two. Apart from engulfing foreign particles and pathogens they remove extra

surfactant and secrete enzymes. After phagocytosis they either pass to the terminal bronchioles and into thelymphatic system or they adhere to the mucus coated cilia and are carried out to be swallowed. They can also

remain in the interstitium (septa).

The alveolar wall also contains elastic tissue and this allows the lungs to stretch and accommodate air, recoil to

expel air and also tethers the bronchioles to the lung parenchyma and therefore the pleura.

Pulmonary vasculature

Lungs have dual blood supply and venous drainage. Blood is provided by the pulmonary and bronchial arteries

and veins. The bronchial system provides oxygenated blood to the larger components of the bronchial tree. The

pulmonary vascular system is more important as this is the capillary component and therefore the site of gasexchange. They provide the lungs with deoxygenated blood from the right side of the heart. The proximal

pulmonary artery branches are elastic arteries. They have a narrow intima which is single layer of endothelium

lying on scanty collagen fibres and myofibroblasts, a media composed of layers of elastic fibres, smooth muscle

cells and collagen and laminae that are formed of longitudinally running elastic fibres. The distal pulmonary

arteries are muscular and the media of them is mainly circularly orientated smooth muscle. Continuous

branching results in arterioles and the muscular layer becomes discontinuous and eventually disappears. The


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oxygenated blood from the alveolar capillaries enters the venules which have a thin intima that lies on a narrow

zone of collagen and elastic fibres. As they form larger and larger venules the numbers of myofibroblasts and

smooth muscle cells increase in the media. The larger veins have distinct media with internal elastic lamina.

Pleura

The visceral pleura is composed of 5 ill-defined layers:

- Outer layer of flat mesothelial cells- A narrow zone of loose, fibrocollagenous tissue with no basement membrane between it and the

mesothelium

- An irregular elastic external layer- An interstitial layer of loose fibrocollagenous stroma containing lymphatics, blood vessels and nerves

and some smooth muscle fibres

- An internal elastic layer with short lengths of elastic fibre some of which merge with the interaveolarsepta.

The parietal pleura is similar but more simple with only one layer of elastic fibres. It sits on a layer of adipose

tissue, beneath which is a layer of dense collagenous tissue which is continuous with the periosteum of the ribs

and the perimysium of the intercostals muscles.


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6. Reaction/effect of trauma sympathetic nervous systemAcute stress reaction (also called acute stress disorder or simply shock) is a psychological condition arising in

response to a terrifying event.

"Acute Stress Response", was first described by Walter Cannon in the 1920s as a theory that animals react tothreats with a general discharge of the sympathetic nervous system. The response was later recognized as the

first stage of a general adaptation syndrome that regulates stress responses among vertebrates and other

organisms.

The onset of a stress response is associated with specific physiological actions in the sympathetic nervous

system, both directly and indirectly through the release ofepinephrine and to a lesser extent norepinephrine

from the medulla of the adrenal glands. The release is triggered by acetylcholine released from pre-ganglionic

sympathetic nerves. These catecholamine hormones facilitate immediate physical reactions by triggering

increases in heart rate and breathing, constricting blood vessels in many parts of the body - but not in muscles

(vasodilation), brain, lungs and heart - and tightening muscles. An abundance of catecholamines at

neuroreceptor sites facilitates reliance on spontaneous or intuitive behaviors often related to combat or escape.

Normally, when a person is in a serene, unstimulated state, the "firing" of neurons in the locus ceruleus is

minimal. A novel stimulus, once perceived, is relayed from the sensory cortex of the brain through the thalamus

to the brain stem. That route of signaling increases the rate of noradrenergic activity in the locus ceruleus, and

the person becomes alert and attentive to the environment.

If a stimulus is perceived as a threat, a more intense and prolonged discharge of the locus ceruleus activates the

sympathetic division of the autonomic nervous system (Thase & Howland, 1995). The activation of the

sympathetic nervous system leads to the release of norepinephrine from nerve endings acting on the heart,

blood vessels, respiratory centers, and other sites. The ensuing physiological changes constitute a major part of

the acute stress response. The other major player in the acute stress response is the hypothalamic-pituitary-

adrenal axis.

These catecholamine hormones facilitate immediate physical reactions associated with a preparation for violent

muscular action. These include the following:

Acceleration of heart and lung action

Inhibition of stomach and intestinal action

General effect on the sphincters of the body

Constriction of blood vessels in many parts of the body

Liberation of nutrients for muscular actionDilation of blood vessels for muscles

Inhibition ofLacrimal gland (responsible for tear production) and salivation

Dilation of pupil

Relaxation of bladder

Inhibition of erection
http://en.wikipedia.org/wiki/Psychologyhttp://en.wikipedia.org/wiki/Walter_Cannonhttp://en.wikipedia.org/wiki/Sympathetic_nervous_systemhttp://en.wikipedia.org/wiki/Epinephrinehttp://en.wikipedia.org/wiki/Norepinephrinehttp://en.wikipedia.org/wiki/Medullahttp://en.wikipedia.org/wiki/Adrenal_glandhttp://en.wikipedia.org/wiki/Acetylcholinehttp://en.wikipedia.org/wiki/Ganglionhttp://en.wikipedia.org/wiki/Hormonehttp://en.wikipedia.org/wiki/Thalamushttp://en.wikipedia.org/wiki/Brain_stemhttp://en.wikipedia.org/wiki/Inhibitionhttp://en.wikipedia.org/wiki/Sphinctershttp://en.wikipedia.org/wiki/Lacrimal_glandhttp://en.wikipedia.org/wiki/Lacrimal_glandhttp://en.wikipedia.org/wiki/Sphinctershttp://en.wikipedia.org/wiki/Inhibitionhttp://en.wikipedia.org/wiki/Brain_stemhttp://en.wikipedia.org/wiki/Thalamushttp://en.wikipedia.org/wiki/Hormonehttp://en.wikipedia.org/wiki/Ganglionhttp://en.wikipedia.org/wiki/Acetylcholinehttp://en.wikipedia.org/wiki/Adrenal_glandhttp://en.wikipedia.org/wiki/Medullahttp://en.wikipedia.org/wiki/Norepinephrinehttp://en.wikipedia.org/wiki/Epinephrinehttp://en.wikipedia.org/wiki/Sympathetic_nervous_systemhttp://en.wikipedia.org/wiki/Walter_Cannonhttp://en.wikipedia.org/wiki/Psychology


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7. Emergency services ATLSAdvanced trauma life support is the standard method for the

initial management of severely injured patients.

The principleis simpletreat the greatest threat to life first. Lossof airway will kill before inability to breathe,

and inabilityto breathe will kill before bleeding and loss of circulation.

A definitive diagnosis is not necessary to

treat the patient

initially. The most important point to remember is that no harm

should be done to the patientduring treatment. The management

of severely injured patients is divided into the primary and

secondary

survey.

ABCDE of trauma

Airway and cervical spine control

Breathing and ventilation

Circulation and haemorrhage control

Disability and neurological status

Exposure and environment

Primary survey

The primary survey comprises a rapid evaluation of the patient,resuscitation, and institution of life preserving

treatment.This process is called the ABCDE of trauma. Adjuncts to the

primary survey include relevant imaging

during resuscitationand re-evaluation.

In practice, most of the steps of the ABCDE are carried outsimultaneously by a trauma team. Anaesthetists will

usuallydeal with the airway and intravenous access while the surgeonevaluates the chest, abdomen, and pelvisfor potential life

threatening injuries.

Supine radiograph showing endotracheal tube 5 cm above carina (arrow)

Imaging is requested as part of the primary survey while thepatient is

assessed, life threatening injuries are dealt with, and resuscitation

procedures instituted. Imaging should notbe performed if it interferes with

the rest of the primary surveyor definitive care, and only investigations that

may have a

direct effect on the patient's initial problems should be done.

Examples of imaging done as part of the primary survey includeradiographs of the supine anteroposterior chest,

supine pelvis,and lateral cervical spine (although this can be delayed if

necessary); and limited ultrasonography

(also known as FAST,focused assessment with sonography for trauma)

Airways and cervical spine control


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The airway should be assessed for patency. Foreign bodies andvomit should be removed and facial, mandibular,

tracheal, andlaryngeal injuries should be excluded clinically.

Radiograph of supine pelvis may be requested for the primary survey. This

radiograph shows no abnormality.

If the patient is conscious and talking, there is usually noimmediate need for

airway intervention. If the patient is unconsciousand breathing

spontaneously, an oropharyngeal airway may sufficeas a temporary

measure. Any patient who has a head injury anda score on the Glasgow

coma scale of 8 or less should be intubated.However, intubation may be required for optimal control of airways

in patients with higher scores.

Glasgow coma scale score

Eye opening (graded 1-4)

Spontaneous4

To speech3

To pain2

None1

Best motor response (graded 1-6)

Obeys command6

Localises pain5

Normal flexion4

Abnormal flexion3

Extension (decerebrate)2

None1

Verbal response (graded 1-5)

Orientated5

Confused conversation4

Inappropriate words3

Incomprehensible sounds2

None1

Maximum score 15, minimum score 3


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Mild injury 14-15

Moderate injury 9-13

Severe injury 3-8

Coma 8

If the patient has been intubated, a chest radiograph shouldbe taken to check the position of the endotracheal

tube. Thetip of the tube should not lie below the level of the aorticarch in a supine chest radiograph and a

minimum of 3.5 cm (andpreferably 5 cm) above the carina.

Care should be taken to avoid worsening a potential cervicalspine injury while establishing and safeguarding an

airway.If the airway has been secured and the neck immobilised the

cervical spine radiograph can be delayed.

The cervical spineshould be immobilised with a cervical collar, sandbag, and tape.

Should the collar need to be

removed, an experienced memberof the trauma team should carry out in-line manual immobilisationof the

head and neck.

Breathing and ventilation

A patent airway does not guarantee adequate ventilation. Thelungs, chest wall, and diaphragm must be

assessed for potentialinjuries that could compromise ventilation acutely. These injuriesinclude tension

pneumothorax, tension haemothorax, flail chest,and open pneumothorax. It can be difficult to exclude these

injuries in a patient with multiple trauma. A chest radiographmust be taken as soon as possible. If the patient is

subsequentlyintubated or ventilated, a second radiograph should be taken

to confirm that the endotracheal

tube is in a satisfactory positionand that life threatening injuries have not been made worse.

Ventilation can

cause a simple pneumothorax to become a tensionpneumothorax.

Opaque left haemothorax with evidence of contralateral shift of the

mediastinum.

Circulation and haemorrhage control

The patient's haemodynamic state must be assessed quickly andaccurately because bleeding is a major cause of

preventabledeath. Clinical evaluation is essential, in particular, the

level of consciousness, skin colour, and pulse.

Any externalsource of bleeding should be identified and dealt with immediately

using manual pressure. When

the examination or history suggestsinternal injury, a pelvic radiograph should be taken and limited

ultrasonography (FAST) done to exclude hidden blood loss.


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Main causes of hidden blood loss

Chest, abdomen, and retroperitoneal injuries

Pelvic fractures

Multiple long bone fractures

FAST can be performed by a physician, surgeon, or radiologistand has been shown to be valuable in the

assessment of blunttrauma patients in the emergency room, especially in unstablepatients with multiple

injuries. Ultrasonography should be performedin five areas. These areas are the 5 Psperihepatic, perisplenic,

and pelvis in the abdomen, and pericardial (to exclude a pericardialtamponade) and pleural (to detect fluid or a

pneumothorax orconsolidated lung) in the chest. The presence of a pelvic fracture

or free fluid on

ultrasonography mandates a specialist opinion.

Disability (neurological examination)

The patient's neurological state is assessed with the Glasgowcoma scale. It is easy and quick to use and is a

determinantof patient outcome and possible further management.

All patients with a head injury should have computed tomographyof the head, especially if they have lost

consciousness, haveamnesia, or severe headaches. Up to 18% of patients with mild

head injuries (Glasgow coma

scale 14-15) have abnormalitieson computed tomography, and 5% of these patients may require

surgery.

Extradural haematoma and a subtle subdural haematoma (left), subdural

haematoma (middle left), diffuse axonal injury (middle right), and

combination injuries (right).

If the patient has a head, scan itmissing a serious headinjury may have

catastrophic consequences

Computed tomography should be done as soon as possible becausemorbidity and mortality rises substantially if

surgery is delayed.The intracranial findings of computed tomography may include

no abnormality, extradural

haematoma, subdural haematoma, contusionsand intracerebral haematomas, subarachnoid blood, diffuse

axonalinjury, and combination injuries.

Supine anteroposeterior radiograph of normal chest with ABCDEs

interpretation

The National Institute of Clinical Excellence (NICE) introducedUK guidelines

for management of head injury in 2003 that support the advanced trauma life

support guidelines. They emphasisethat computed tomography must be done within an hour of thepatient

arriving at the hospital.


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Exposure and environment

The patient should be fully exposed (by cutting off all clothes)to allow a full examination. It is, however, critical

to keepthe patient warm with blankets and a heated emergency room.

Large volumes of fluids may be infused,

and these intravenousfluids should be warmed.

Adjuncts to primary survey and resuscitation

As a minimum, patients should have electrocardiography, theirblood pressure monitored, pulse oximetry, a

nasogastric tube,and a urinary catheter. Blood gases should also be monitored.

If a fracture at the base of the

skull is suspected, the nasogastrictube can be inserted after computed tomography of the head or

an orogastric

tube placed. ABCs interpretation of pelvic radiographs

Alignment

Check the pubic symphysis is symmetrical and not widened

Carefully check that the sacroiliac joints are intact

Bones

Check that all three pelvic rings are intact

Use a bright light to check iliac crests and hips

Look at the lumbar spine and hip joints separately

Cartilage

Check the distance of the pubic symphysis

Again check the sacroiliac joints

Check both hips

Soft tissues

Check the soft tissue planes are symmetrical

Look for obturator internus

Carefully delineate the perivesical fat plane

Make sure the gluteus medius and psoas fat planes are intact

Interpreting primary survey images

All imaging must be supervised and done without fuss or undue

delay and with meticulous technique. Attentionto detail isessential. In particular, the film must be labelled (includingthe patient's name and a side marker).

Interpretation of the supine chest radiograph (ABCDEs)

Airways

Check trachea is clear and central


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Is airway patent?

Check position of endotracheal tube

Are there any teeth or foreign bodies?

Check all lines and tubesBreathing

Exclude tension pneumothorax and haemothorax

Check there is no radiological flail segment

Exclude rib fractures

Check lungs are clear

Circulation

Check heart size and mediastinal contours are normal

Make sure that the aortic arch is clearly seen

Check the hila and vascular markings are normal

Diaphragm

Check that diaphragms appear normal (size, shape, and position)

Can both diaphragms be clearly seen?

Check under each diaphragm

Edges

Check the pleura and costophrenic recesses

Exclude a subtle pneumothorax or effusion

Soft tissues and skeleton

Look for surgical emphysema

Check clavicles and shoulders and exclude rib fractures

Look at the paraspinal lines and check the spine

The supine chest radiograph should be taken as soon as possibleafter the patient has been exposed and centred

correctly. Attentionmust be paid to stop patients being rotated and keeping themin the middle of the trolley.

Radiograph of supine pelvis showing ABCDEs interpretation

8. Examination of the lungs


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Palpation

Palpation is the method of "feeling" with the hands during a physical examination.

Percussion

Percussion is a method of tapping body parts with fingers, hands, or small instruments as part of a physical

examination. The purpose is to evaluate the size, consistency, borders, and presence or absence of fluid in body

organs.

Percussion of a body part produces a sound like playing a drum - that indicates the type of tissue within the

organ:

Lungs sound hollow on percussion because they are filled with air.

Bones and joints sound solid.

The abdomen sounds like a hollow organ filled with air, fluid, or solids.

Auscultation

The doctor will use a stethoscope to listen to the lungs and breath sounds.

From a clinical point of view the following should be noted:

- When you place a stethoscope on a patients back you are listening mainly to the lower lobe. There is a small

area of upper lobe, but no middle lobe at all.

- When you place a stethoscope on a patients anterior chest wall, you are listening mainly to the upper and

middle lobes

- You will listen to the middle lobe by placing the stethoscope at the side and in the axilla.

- You cannot listen to individual pulmonary segments or even individual lobes.

- When a patient is lying in bed on his back, the most dependant bronchopulmonary segments are the apical and

posterior segments of the lower lobe. These segments are most often affected by lung infections in ill bedridden

patients.

- In normal breathing, lung tissue does not occupy the lower extremities of the costodiaphragmatic recesses, but

it may in deep inspiration. This means in this region surface markings on the lungs is different from the surfacemarkings of the pleural cavities.

Abnormal Breath Sounds

- Rales: hissing, whistling, scrapping or rattling sounds are associated with increased airway resistance.These sounds are created by turbulent airflow past pus or mucus or past airways narrowed by
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inflammation. Moist rales are gurgling sounds and are heard over fluids in conditions such as bronchitis,

tuberculosis and pneumonia. Dry rales are heard in asthma and pulmonary oedema.

- Stridor: loud high pitched sound that can be heard without a stethoscope. Indicates acute airwayobstruction such as partial blockage of the glottis by a foreign object.

- Wheezing: whistling sound that can occur I inspiration and expiration. Indicates airway obstruction sueto mucus build up or bronchospasms.

- Coughing: familiar sign of several respiratory disorders. It is primarily a reflex action that clears theairway but can also indicate irritation of the lining of the respiratory passageways. A productive cough

ejects sputum, which can be ejected and analysed.

- Friction rub: distinctive crackling sound produced by abrasion between abnormal serous membranes.You also may have the following tests:

Chest X-rays

The posteroanterior radiograph is taken with the anterior

of the patients chest touching the cassette holder and

with the x-rays traversing the thorax form the posterior to

the anterior aspect. It must not be even slightly oblique. If

it is not the sternal ends of both clavicles should be

equidistant from the vertebral spines.

The following should be examined in systematic order:


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1. Superficial soft tissues the nipples/breasts may be superimposed on the lung fields. Thepectoralis major may also cast a soft shadow.

2. Bones the thoracic vertebrae are imperfectly seen. The cotransverse joints of the ribs shouldbe examined from above downward and compared with the other side. Costal cartilages are not

normally seen, but if they are calcified they will be visible. Theclavicles should be clearly seencrossing the upper part of each lung field. The medial borders of the scaplulae may be seen

overlapping the periphery of each lung field.

3. Diaphragm should cast dome shaped shadows on each side. The right is slightly higher thanthe left. Beneath the right dome is the shadow of the liver. And beneath the left dome a bubble

may be seen in the fundus of the stomach.

4. Trachea it will be a superimposed radiotranslucent air filled shadow.5. Lungs dense shadows at the lung roots caused by blood vessels, large bronchi and lymph

nodes. The lung fields due to the air content readily permit the passage of x-rays. The lungs aretherefore more translucent on full inspiration than expiration. Pulmonary blood vessels are seen

as shadows radiating from the lung root.

6. Mediastinum shadow is produced by various structures in the mediastinum, superimposedone on the other. The outline of the heart and great vessels are visible. The transverse diameter

of the heart should not exceed half the width of the thoracic cage. On deep inspiration the

vertical length of the heart increases as the diaphragm extends and the transverse diameter is

narrowed.

ALSO:

- Arterial blood gases

- electrocardiogram

Tension Pnemothorax: Unilateral absence of breath sounds suggests pneumothorax; resonance to percussion

and dilated neck veins suggest tension pneumothorax. When heard through a stethoscope, the breath sounds

are decreased. Structures in the center of the chest (mediastinum) may appear to have moved. There may be air

trapped in the tissue of the chest wall (subcutaneous emphysema), causing a spongy feeling when the chest is

felt with the hands (palpation).

- Hamman's Sign (or 'Crunch') is a crunching systolic sound heard over the sternal edge in mediastinalemphysema or left apical pneumothoraces.

- Crepitus (crackling in the soft tissues beneath the skin) indicating surgical emphysema.- The engorged veins in the neck suggest the patient has hypovolaemia and is a potential sign of tension

pneumothorax.
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- An increase in negative intrathoracic inspiratory pressure increases venous return (the tensionpneumothorax sends feedback that a deep inspiration is occurring because the intrathoracic pressure is

so high and causes more deoxygenated to return to the heart to be oxygenated at the lungs (I THINK).

Also pressure on the side of the heart where the pneumothorax is will cause increased output on that

side of the heart.

Collapsed lung: Listening to the chest with a stethoscope may reveal decreased breath sounds on one side of the

chest. There may be a bluish coloration of the skin caused by lack of oxygen. The affected person may have a

rapid heart rate.

Diagnosis of tension pneumothorax using a needle and a cannula

12G intraveneous cannula with supporting needle inside and

50ml syringe

Right mid-clavicular

line

Once the chest wall has

been penetrated,the

needle is withdrawn

leaving the catheter in

place. In the presence

of a tension

pneumothorax air

would rush out of the

catheter under

pressure.

9. Pneumothorax
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Aortic rupture (a tear in the aorta, which is the major

artery coming from the heart) can be seen on a chest x-

ray. In this case, it was caused by a traumatic perforation

of the thoracic aorta. This is how the x-ray appears when

the chest is full of blood (right-sided hemothorax) seen

here as cloudiness on the left side of the picture- Blunt or penetrating trauma- Requires rapid decompression and

fluid resuscitation

- May require surgical intervention- Clinically: hypovolaemia absence of

breath sounds dullness to percussion

- CXR may be confused with collapse

Pneumothoraxoccurs when air leaks from inside of the

lung to the space between the lung and the chest wall. Thelung then collapses. The dark side of the chest (right side of

the picture) is filled with air that is outside of the lung

tissue.

If fluid, such as blood, or air, gets into the pleural space, the lung can collapse, preventing adequate air

exchange. Chest tubes are used to treat conditions that can cause the lung to collapse, such as:

- air leaks from the lung into the chest (pneumothorax)- bleeding into the chest (hemothorax)- after surgery or trauma in the chest (pneumothorax or hemothorax)- lung abscesses or pus in the chest (empyema).

If air enters the pleural space, the lung will collapse. This is called a pneumothorax. If the chest wall is

penetrated, which may occur as a result of an injury, air can enter the pleural space from the outside. Air can

also enter from the inside, from the lung itself, if the lung is torn or ruptured. One of the most common causes

of spontaneous non-traumatic pneumothorax is a pulmonary bleb. This is a weakness and out-pouching of the

lung tissue, which can rupture. This introduces air into the pleural space.


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Pneumothorax may result from chest trauma, excess pressure on the lungs, or a lung disease such as COPD,

asthma, cystic fibrosis, tuberculosis, or whooping cough. In some cases, the cause is unclear.

Symptoms

- Chest pain (stabbing).- Decreased venous return- Decreased cardiac output- Low blood pressure- Desaturation, not always- Hypercarbia (too much carbon dioxide in the blood)- Dyspnoea (shortness of breath)

Spontaneous pneumothorax

Aeitiology

- Can be inherited by the autosomal dominant route with variable penetrance.- Penetrance 21% in the Females.- 50 % in the males.- Marfans syndrome- Ehlers Danlos syndrome.

There are two types of spontaneous pneumothorax:

Primary spontaneous pneumothorax Secondary spontaneous pneumothorax
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Spontaneous means there is no traumatic injury to the chest or lung. Primary spontaneous pneumothorax

occurs in people without lung disease. It occurs most often in tall, thin, young people.

Sometimes people have a family history of this problem. People who have had one spontaneous pneumothorax

are at higher risk of the same thing (on the same side or the other side) occurring again.

Secondary spontaneous pneumothorax occurs in people who have underlying lung disease. The most common

lung disease that causes spontaneous pneumothorax is chronic obstructive pulmonary disease (COPD).

Other lung diseases associated with spontaneous pneumothorax include:

Asthma Cystic fibrosis Interstitial lung disease Lung cancer Pneumonia Tuberculosis

Symptoms often begin suddenly, and may occur during rest or sleep. They can include:

Abnormal breathing movemento Restricting chest wall motion when breathing to protect against paino Splinting -- bending over or holding the chest to protect against pain

Cough Rapid respiratory rate Shortness of breath Sudden chest pain or chest tightness

o Breathing or coughing makes pain worseo Chest pain may be dull, sharp, or stabbing
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Tension pneumothorax

A tension pneumothorax is a complete collapse of the lung. It occurs when air enters, but does not leave, the

space around the lung (pleural space).

Any condition that leads to pneumothorax can cause a tension pneumothorax. In uncomplicated pneumothorax,

air can enter and leave the pleural space easily. In tension pneumothorax, however, air enters the pleural space

with each breath and gets trapped there.

As the amount of trapped air increases, pressure builds up in the chest. The lung collapses on that side and can

push the important structures in the center of the chest (such as the heart, major blood vessels, and airways)

toward the other side of the chest. The shift can cause the other lung to become compressed, and can affect the

flow of blood returning to the heart.

This situation can lead to low blood pressure, shock, and death.

Symptoms

Sudden chest pain Shortness of breath Chest tightness Easy fatigue Bluish color of the skin due to lack of oxygen Rapid heart rate
http://www.nlm.nih.gov/medlineplus/ency/article/003079.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003075.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003088.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003215.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003077.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003077.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003215.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003088.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003075.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003079.htm


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Low blood pressure Decreased mental alertness Decreased consciousness Rapid breathing Bulging (distended) veins in the neck

Possible Complications

Acute respiratory failure Air in the mediastinal space, which can interfere with heart and lung function (pneumomediastinum) Very low blood pressure (shock) Death

Traumatic pneumothorax

A traumatic pneumothorax is a collection of air inside the chest, between the lung and inner chest wall,

which causes the lung to collapse.

Traumatic pneumothorax occurs when a physical injury causes the lung to collapse. It can be caused

by chest injury from a gunshot or knife wounds. It may also be caused by automobile accidents, or can

happen after certain medical procedures.

High-risk medical procedures include transbronchial biopsy, pleural biopsy, thoracentesis, central

venous catheter placement, intercostal needle anesthesia, and esophagoscopy.

Hemothorax, a collection of blood between the lung and chest wall, often happens with traumatic

pneumothorax.

Symptoms

History of recent chest injury or high-risk procedure, plus:

Chest pain Shortness of breath Breathing, rapid Chest tightness Hypoxemia (low oxygen level in blood)
http://www.nlm.nih.gov/medlineplus/ency/article/003202.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003071.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/000084.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/000039.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003416.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003862.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003420.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/000126.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003079.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003075.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003071.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003071.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003075.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003079.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/000126.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003420.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003862.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003416.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/000039.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/000084.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003071.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003202.htm


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10.Dressings for pneumothorax

Dressing sealed on

three sides only.Acts as flap valve,

allowing air flow

through chest wall

outwards but not

inwards.

Following

application of the

dressing sealed on

three sides, thepatient is

positioned with the

injured side down:

The optimal treatment is the application of an Asherman chest seal. The skin may need to be shaved or wiped

dry of sweat or blood to enable adequate adhesion.

11.Treatment of pneumothoraxIn general, if a health care provider suspects tension pneumothorax, treatment should start before tests are

done.

In an emergency, a small needle (such as a standard intravenous needle) may be placed into the chest cavity

through the ribs to relieve pressure.

Needle decompression


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- Tension pneumothorax is a rare prehospital event, particularly in blunt trauma. It is difficult toassess the exact numbers accurately as thoracocentesis is often performed in the absence of a true

tension pneumothorax, but recent studies show a prevalence of 6%. Tension pneumothorax is more

likely to occur in positive pressure ventilation. If the patient with multiple trauma is deteriorating,

with an unknown cause, specifically look for tension pneumothorax. If localising features are not

found consider the presence of bilateral pneumothoraces. Common features in patients who are

awake include universal symptoms of chest pain and respiratory distress, with tachycardia and

ipsilateral decreased air entry found in 5075% of cases. In ventilated patients, the universal findings

are rapid onset deterioration with a decrease in oxygen saturations and blood pressure. High

ventilation pressures, reduced chest wall movement and air entry are found in about 33% of cases.

Technique of needle decompression.

- Avoid thick muscle, breast tissue or areas with surgical emphysema.- The first choice of site is the 2nd intercostal space in the midclavicular line. Studies have shown that

there is a low accuracy in correct anatomical placement and therefore practitioners should be

familiar with the landmarks.

- The standard 14G cannula is 4.5 cm long, and depending on the body mass index of the patient thismay not be long enough to decompress all tension pneumothoraces.

- The cannula may also fail to decompress the tension pneumothorax due to obstruction by blood,tissue or kinking. Therefore, the cannula should be inserted into the chest attached to a syringe and

flushed with 2 ml of air, if there is no obvious air release on insertion.

- Other causes of failure include a localised tension pneumothorax in the patient with pre-existinglung disease, or the presence of a large air leak in which the air will collect in the pleural spacequicker than can be drained by the narrow bore of the cannula.

- If the anterior approach fails due to suspected depth of chest wall, then the lateral approach shouldbe attempted in the 5th intercostal space, anterior axillary line if the chest wall appears thinner at

this site.

- Consider using a longer needle or a commercial device designed for this purpose.If needledecompression fails at both sites, the practitioner is certain of the diagnosis and is appropriately

trained and competent: thoracostomy may be performed. After this an intercostal chest drain

should be inserted or an Asherman chest seal over the open chest wound.

- Needle decompression should not be used for simple pneumothorax or haemothorax.- There is considerable risk of iatrogenic pneumothorax if misdiagnosis and decompression is

performed. Needle decompression in the absence of a pneumothorax may even create an iatrogenic

tension pneumothorax. There is increasing concern regarding the number of needle decompressions

being performed without the appropriate clinical indications, leading to significant morbidity and

unnecessary interventions for the patient.


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- Continuing observation and reassessment is essential by a person who can repeat decompression ifnecessary: this includes during transfer. If the cannula fails to work and the patient is beginning to

retension, repeat needle decompression should be performed adjacent to the initial successful site.

Surgical emergency

- Rx: emergency decompression before CXR- Either large bore cannula in 2nd ICS, MCL or insert chest tube- CXR to confirm site of insertion

Pneumothorax can be life-threatening. The immediate treatment for pneumothorax is tube thoracostomy, or

the insertion of a chest tube.

Explanation 1. Chest tubes are inserted to drain blood, fluid,

or air and allow full expansion of the lungs. The tube is

placed in the pleural space. The area where the tube will be

inserted is numbed (local anesthesia). The patient may also

be sedated. The chest tube is inserted between the ribs into

the chest and is connected to a bottle or canister that

contains sterile water. Suction is attached to the system to

encourage drainage. A stitch (suture) and adhesive tape is

used to keep the tube in place. The chest tube usually

remains in place until the X-rays show that all the blood,

fluid, or air has drained from the chest and the lung has fully

re-expanded. When the chest tube is no longer needed, it

can be easily removed, usually without the need for medications to sedate or numb the patient. Medications

may be used to prevent or treat infection (antibiotics).

Explanation 2. A long, flexible, hollow, narrow tube is inserted through the ribs into the pleural splace, and the

tube is attached to a suction device. This allows the air to be evacuated from the pleural space, and allows the

lung to re-expand. Chest tubes are generally inserted using local anesthesia. The chest tube is left in place until

the lung leak seals on its own; this usually occurs within two to five days.

Recovery from the chest tube insertion and removal is usually complete, with only a small scar.

The patient will stay in the hospital until the chest tube is removed. While the chest tube is in place, the nursing

staff will carefully check for possible air leaks, breathing difficulties, and need for additional oxygen. Frequent

deep breathing and coughing is necessary to help re-expand the lung, assist with drainage, and prevent normal

fluids from collecting in the lungs.

Pulmonary blebs can be resected, preventing future pneumothorax. This is frequently done using a

thoracoscopic surgical procedure. The patient is put to sleep using general anesthesia. Long, narrow


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instruments, including one with a camera on the end to allow for visualization of the interior of the thorax, are

introduced through small incisions in the chest wall

Pulmonary bleb

Explanation 3. An incision is made in the chest wall below the

diagnostic cannula and distant from the wound (e.g. for Stephen - in 5th right interspace and in the mid-

axillary line).Blunt dissection (use of a large pair of scissors) is used to achieve full penetration of the chestwall.Insertion of a finger through the incision is useful to check that the pleural cavity has been penetrated.Having created access (for the chest drain) to the pleural cavity, two sutures are inserted - one at each end of

the incision.These are initially left untied - they will subsequently be used to close the incision after the drain

has been withdrawn.

The chest drain (a plastic tube) is inserted through the incision and into the pleural cavity.

Insertion of the drain is sometimes aided by the use of a rod (trochar) within the lumen of the drain. The use

of a trochar is not without risk and it is now considered preferable to manage without it. In the picture the

drain has been inserted and the trochar is being withdrawn.


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The

chest drain is connected to its under water seal and fluid collection vessel.This must be positioned below the

level of the patient or fluid will siphoninto the pleural cavity.


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A further suture (positioned close to the incision) is used to anchor the drain:

Explanation 4. The standard treatment is a chest tube, a large plastic tube that is inserted through the chest wall

between the ribs to remove the air. The chest tube is attached to a vacuum bottle that slowly removes air from

the chest cavity. This allows the lung to re-expand. As the lung heals and stops leaking air, the vacuum is turned

down and then the chest tube is removed. Some people might need to stay in the hospital to have the chest

tube checked, and because it can take several days for the affected lung to fully re-expand.

Surgery may be needed if the problem happens again, or if the lung does not re-expand after 5 days with a chest

tube in place.

A stapling device is inserted into the chest during thoracoscopic surgery, and the segment of lung with blebs is

stapled across and then removed. Most patients respond quite well to this procedure, and usually require one to

three days in the hospital after surgery to recover. A chest tube is frequently left in place for one to two days

after surgery to evacuate any residual air in the pleural space. ONLY REQUIRED FOR SPONTANEOUS

PNEUMOTHORAX

Complications of chest drains

Insertional

- Direct trauma.Positional

- Blockage.- Kinking.- Extra thoracic placement.

Infective


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- Entry site.- Empyema.

12. Anaesthetics and Analgesics

Anaesthetics

General anaesthesia is the loss of awareness of general sensory inputs to the CNS and includes varying degrees

of analgesia, amnesia and loss of consciousness. It may be accompanied by muscle relaxation

and loss of homeostatic control of respiration and cardiovascular function.

An adequate level of general anaesthesia is essential for major surgical procedures.

Modern general anaesthetics allow rapid and smooth induction of surgical anaesthesia with a short recovery

phase. Anaesthesia is usually rapidly induced in adults as an intravenous bolus dose and is subsequently

maintained by an inhalation anaesthetic.

General anaesthetics act on cell membranes. The stages of anaesthesia can be explained by the accessibility of

the different neurones to the anaesthetic agent.

Side effects: depress myocardial contractility, depress response of the respiratory centre, decrease liver blood

flow. Reduce renal blood flow and renal vascular resistance, relax uterus, cause muscle relaxation, can produce

post operative nausea and vomiting.


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Local anaesthetics block the transmission of pain by reducing the ion fluxes that are responsible for the

depolarisation of excitable calls, particularly the rapid influx of Na+

as well as the slower efflux of K+

. Local

anaesthetics inhibit both afferent and efferent pathways as

well as neuromuscular junctions. Pain pathways are more

effectively inhibited than those involved in touch and

pressure.

A variety of mechanisms inhibit nerve transmission. Non

specific membrane effects, specific intraneuronal receptor

activity (therefore must be lipid soluble).

Side effects: irritation and inflammation at the site of

administration, can affect excitable membranes e.g. the

heart.

Techniques of administration affect the extent of local

anaesthesia. Surface administration (slowly penetrate the

skin), infiltration anaesthesia (a local injection of an

aqueous solution of the salt of the base (e.g. hydrochloride),

nerve trunk block (injected around a nerve trunk to produce

anaesthesia distal to the site of injection), epidural

(injection into spinal column but outside dura mata to

produce anaesthesia above and below site of injection),

spinal (injection into the lumbar subarachnoid space causes

anaesthetic to flow in the direction of the posture of the

patient )

Sympathetic fibres are particularly sensitive to local

anaesthetics and this can result in cardiovascular

complications particularly hypotension.

From CALNet: Local anaesthetics produce a reversible blockade of action potential conduction in sensory and

some other nerves when applied locally in effective concentration.

The nervous system consists of a network of myelinated and unmyelinated nerves which collect sensory

information from all parts of the body and relay it to the CNS where the information is processed for cognitive,

mechanical and emotional responses.

Sensory information travels along sensory nerves in the form of ACTION POTENTIALS (A.P.s) the cell

membrane of each axon in the resting state is electrically polarised, being positively charged on the outside of

the membrane and negatively charged on the inside. When a stimulus is applied the charges reverse which

causes this reverse of charges to be conveyed along the neurone and to the CNS.

Methods of achieving Local anaesthesia


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Physical cooling when nerves are cooled sufficiently they fail to produce action potentials

The maintenance of the nerve membrane is dependant on the Na+/K+/ATPase pump which slows down and

stops as the temperature is reduced. This is why ice packs can give some pain relief in damaged extremities and

why hands go numb in winter. When liquid ethyl chloride is sprayed on skin, the rapid evaporation of it removes

heat from the skin, cooling the sensory nerves and producing a local anaesthetic effect. Physical pressure thisreduces the ability of nerve fibres to conduct action potentials.

However, there is risk of applying to much pressure and crushing which is why this is not used in medicine.

Physical axonia the membrane potential is dependant on the Na+/K+/ATPase pump which is dependant on

oxygen but this a

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Case 1 - The Stabbing