Respiratory Flashcards

Question

What are the Lung Capacities, define them

Answer 1

Lung Capacities Lung volumes change with breathing pattern. Capacities do not, as they are measured from fixed points in the breathing cycle. Vital Capacity The biggest breath that can be taken in, measured from the max inspiration to max expiration. It often changes in disease, and is about 5L in a typical adult. Functional Residual Capacity The volume of air in the lungs at resting expiratory level (Expiratory reserve volume + residual volume). It is typically about 2L. Inspiratory Capacity The biggest breath that can be taken from resting expiratory level (lung volume at the end of quiet expiration). It is typically about 3L.

Answer 2

Blood flowing through alveolar capillaries picks up oxygen and loses carbon dioxide by diffusion of those gases across the alveolar wall. The rate at which gases exchange is determined by three factors: Area The area of the alveolar surface is large because there are a huge number of alveoli, generating in a normal lung an exchange area of around 80m2. In normal lungs, the area available is not a limiting factor on gas exchange. ``` Resistance to diffusion The diffusion pathway from alveolar gas to alveolar capillary blood is short, but there are several structures between the two. First gas must diffuse through the gas in the alveoli, then through: o The alveolar epithelial cell o Interstitial fluid o Capillary endothelial cell o Plasma o RBC membrane This means gases have to diffuse through 5 cell membranes, 3 layers of intra cellular fluid and 2 layers of extra cellular fluid. Despite this the overall barrier is less than 1 micron. ``` Two gases have to diffuse, oxygen into the blood and carbon dioxide out of it. The resistance is not the same for the two gases. For most of the barrier (the cells, membranes and fluid) the rate of diffusion is affected by the solubility of the gas in water, and carbon dioxide diffuses much faster, because it is more soluble. Overall, Carbon Dioxide diffuses 21 times as fast as oxygen for a given gradient. This means that anything affecting diffusion will only change oxygen transport, as that is limiting (If there is a problem affecting the exchange of gases, O2 will be affected first) Partial Pressure The partial pressure of oxygen and carbon dioxide in the alveolar gas must therefore be kept very close to their normal values (O2 – 13.3kPa/CO2 – 5.3kPa) if the tissues of the body are to be properly supplied with oxygen and lose their carbon dioxide. This is achieved by exchange of gas between alveolar gas and atmospheric air brought close to it through the airways of the lung by the process of ventilation. Air is driven through the airways of the lungs by the pressure changes produced by increases and decreases in the volume of the air spaces next to the alveoli. The movement of breathing lowers pressure in the terminal and respiratory bronchioles during inspiration, so air flows down the airways to them and then increased pressure during expiration so air flows back out again. Fresh atmospheric air does not enter the alveoli, and exchange of oxygen and carbon dioxide occurs by diffusion between alveolar gas and atmospheric air in the terminal and respiratory bronchioles.

Answer 3

Serial (Anatomical) Dead Space Air enters and leaves the lungs by the same airways. So the last air in is the first air out, does not reach the alveoli and is therefore unavailable for gas exchange. The volume of the conducting airways is known as the Anatomical or Serial Dead Space and is normally about 150ml. Physiological Dead Space The air contained in the conducting airways is not the only air that fails to equilibrate with alveolar capillary blood. Some alveoli receive an insufficient blood supply; others are damaged by accident or disease, so that even in the air that reaches the alveolar boundary, there is a proportion that fails to exchange. The volume of air in alveoli not taking part in gas exchange is known as the Alveolar (or Distributive) Dead Space. Anatomical Dead Space + Alveolar Dead Space = Physiological Dead Space

Answer 4

Nitrogen Washout Test o The patient takes a maximum inspiration of 100% oxygen. o The oxygen that reaches the alveoli will mix with alveolar air, and the resulting mix will contain Nitrogen (there is 79% Nitrogen in air) o However, the air in the conducting airways (dead space) will still be filed with pure oxygen. o The person exhales through a one way vale that measures the percentage of Nitrogen in and volume of air expired o Nitrogen concentration is initially zero as the patient exhales the dead space oxygen. o As alveolar air begins to move out and mix with dead space air, nitrogen concentration gradually climbs, until it reaches a plateau where only alveolar gas is being expired o A graph can be drawn to determine the dead space, plotting Nitrogen % against Expired Volume.

Answer 5

Physiological Dead space is determined by measuring pCO2 (or pO2) of expired alveolar air. The alveolar air is diluted by dead space air to form the expired air, and the degree of dilution is a measurement of a physiological dead space.

Answer 6

Alveolar Ventilation Rate The amount of air that actually reaches the alveoli Alveolar Ventilation Rate = Pulmonary Ventilation Rate – Dead Space Ventilation Rate or = (Tidal Volume x RR) – (Dead Space Volume x RR)

Answer 7

Air is drawn into the lungs by expanding the volume of the thoracic cavity. Work is done during breathing to move the structures of the lungs and thorax and to overcome the resistance to flow of air through the airways. The space between the lungs and thoracic wall, the pleural space, is normally filled with a few millilitres of fluid, the surface tension of which forms a pleural seal holding the outer surface of the lungs to the inner surface of the thoracic wall. Therefore the volume of the lungs changes with the volume of the thoracic cage. Pneumothorax If the integrity of the pleural seal is broken, the lungs will tend to collapse. E.g. If air gets in between the two layers of the pleura, fluid surface tension is lost and the lungs collapse.

Answer 8

Lung Compliance The ‘stretchiness’ of the lungs is known as compliance. It is defined as volume change per unit pressure change. High Compliance means that the Lungs are Easy to Stretch. Compliance is measured by measuring the change in lung volume for a given pressure. The greater the lung volume the greater the compliance and vice versa. However, even with the constant elasticity of lung structures, compliance will also depend on the starting volume from which it is measured, so it is more usual to calculate Specific Compliance, which is: Volume Change Per Unit Pressure Change / Starting Volume of Lungs

Answer 9

The elastic properties of the lungs arise from two sources, Elastic Tissues in the lungs and Surface Tension forces of the fluid lining the alveoli. Surface Tension Surface tension is interactions between molecules at the surface of a liquid, making the surface resist stretching. The higher the surface tension, the harder the lungs are to stretch (lowers compliance). Surfactant At low lung volumes, the surface tension of the lungs is much lower than expected. This is due to the disruption of interactions between surface molecules by Surfactant, produced by Type 2 Alveolar Cells. Surfactant is a complex mixture of phospholipids and proteins, with detergent properties. The hydrophilic ends of these molecules lies in the alveolar fluid and the hydrophobic end projects into the alveolar gas. As a result they float on the surface of the lining fluid, disrupting interaction between surface molecules. Surfactant reduces surface tension when the lungs are deflated, but not when fully inflated. So little breaths are easy, and big breaths are hard, and it takes less force to expand small alveoli than it does large ones. Bubbles in the Lung Alveoli form an interconnecting set of bubbles. If Laplace’s law is applied (Pressure is inversely related to the radius of a bubble), large alveoli would ‘eat’ small ones. As alveoli get bigger, the surface tension in their walls increases, as surfactant is less effective. So pressure stays high and stops them from ‘eating’ the smaller alveoli.

Answer 10

Overall, work is done against: o The elastic recoil of the lungs and thorax o Elastic properties of the lungs o Surface tension forces in the alveoli o Resistance to flow through airways o Of little significance in health, but often affected by disease

Answer 11

Spirometry The patient fills their lungs from the atmosphere, and breathes out as far and fast as possible through a Spirometer. Simple Spirometry allows measurement of many lung volumes and capacities. Vital capacity is particularly significant. Tables can be used to predict the vital capacity of an individual of known age, sex and height. Vital Capacity may be less than normal because the lungs are not: 1. Filled normally in inspiration 2. Emptied normally in expiration 3. Or Both

Answer 12

Forced Vital Capacity (FVC) FVC is the maximum volume that can be expired from full lungs. Forced Expiratory Volume in One Second (FEV1) FEV1 is the volume expired in the first second of expiration from full lungs. It is affected by how quickly air flow slows down, so is low if the airwards are narrowed (Obstructive deficit, see below).

Answer 13

Vitalograph Restrictive and obstructive deficits can be separated by asking patients to breathe out rapidly from maximal inspiration through a single breath spirometer, which plots volume expired against time. Maximal filling of the lungs is determined by the balance between the maximum inspiratory effort and the force of recoil of the lungs. If the lungs are unusually stiff, or inspiratory effort is compromised by muscle weakness, injury or deformity, then a Restrictive Deficit is produced. FVC Reduced FEV1 >70% FVC During expiration, particularly when forced, the small airways are compressed. This increases flow resistance, eventually to the point where no more air can be driven out of the alveoli. If the airways are narrowed, then expiratory flow is compromised much earlier in expiration, producing an Obstructive Deficit. FEV1 Reduced FVC Relatively Normal

Answer 14

Flow Volume Curves Flow volume curves are a graph of Volume Expired against Flow Rate, derived from a Vitalograph trace. A – When the lungs are full, the airways are stretched so resistance is at a minimum. Flow is therefore at maximum (Peak Expiratory Flow Rate PEFR) B-D – As the lungs are compressed, more air is expired and the airways begin to narrow, so resistance increases and flow rate decreases. In normal individuals, peak flow is affected most by the resistance of the large airways, but will also be affected by severe obstruction of the smaller airways (e.g. Asthma). Mild obstruction of the airways produces a ‘scooped out’ expiratory curve. More severe obstruction will also reduce PEFR.

Answer 15

Helium Dilution Test The Helium Dilution Test is used to measure Functional Residual Capacity (FRC), which is used to calculate the residual volume. Helium is an inert, colourless, odourless, tasteless gas that is not toxic. It cannot transfer across the alveolar-capillary membrane and is therefore contained within the lungs. o At the end of a normal tidal expiration the patient is connected to a circuit, which is connected to a contained containing a gas mixture with a known Helium Concentration (C1) and Volume (V1) - End of Tidal Expiration: - Lung Volume = FRC = ERV +RV o The patient continues to rebreathe into the container until equilibrium occurs - Usually takes 4 – 7 minutes o The new concentration of Helium = C2 o C1 x V1 = C2 x V2 - V2 = V1 + FRC o Since C1, V1 and C2 are all known, FRC can be calculated. o Residual Volume = FRC – ERV - ERV measured by Spirometry

Answer 16

Transfer Factor The Carbon Monoxide Transfer Factor measures the rate of transfer of CO from the alveoli to the blood in ml per minute per kPa (ml/min/kPa). It is a way of measuring the diffusion capacity of the lung, because the amount transferred will depend on how well gas diffusion takes place. Inhaled CO is used because of its very high affinity for Hb. Since almost all the CO entering the blood binds to Hb, very little remains in plasma so we can assume plasma ppCO is zero. Therefore, the concentration gradient between alveolar ppCO and capillary ppCO is maintained. As a result the amount of CO transferred from alveoli to the blood is limited only by the diffusion capacity of the lung. o The patient performs a full expiration, followed by a rapid maximum inspiration of a gas mixture composed of air, a tiny fraction of CO and a fraction of an inert gas such as helium.  Tiny fraction of CO as it is toxic  Fraction of inert gas to make an estimate of total lung volume o The breath is held for 10 seconds. o The patient exhales, and gas is collected mid-expiration, to gain an alveolar sample o Concentration of CO and inert gas o From these measurements, the Carbon Monoxide Transfer Factor is calculated

Answer 17

Nitrogen Washout Test Serial (Anatomical) Dead Space is measured by the Nitrogen Washout Test. o The patient takes a maximum inspiration of 100% oxygen. o The oxygen that reaches the alveoli will mix with alveolar air, and the resulting mix will contain Nitrogen (there is 79% Nitrogen in air) o However, the air in the conducting airways (dead space) will still be filled with pure oxygen. o The person exhales through a one way vale that measures the percentage of Nitrogen in and volume of air expired o Nitrogen concentration is initially zero as the patient exhales the dead space oxygen. o As alveolar air begins to move out and mix with dead space air, nitrogen concentration gradually climbs, until it reaches a plateau where only alveolar gas is being expired o A graph can be drawn to determine the dead space, plotting Nitrogen % against Expired Volume.

Answer 18

Oxygen is not very soluble in water. At a partial pressure of 13.3kPa and a temperature of 370C, plasma contains 0.13mmol/L of dissolved oxygen. At rest we need 12mmol of Oxygen per minute. The volume that would contain this amount is 92 Litres.

Answer 19

Typical ppO2 in the lungs is 13.3kPa Typical ppO2 in tissues is ~5kPa

Answer 20

Haemoglobin (Hb) reversibly binds to oxygen over a very narrow range of ppO2. It is a tetrameric protein (2xA, 2xB subunits) containing four Haem groups, allowing it to bind four molecules of oxygen. Hb can exist in two states - a low affinity T-state (tense) and a high affinity R-state (relaxed). Transition between these two states gives Hb its sigmoidal binding curve, so Hb’s affinity to O2 increases as more O2 binds.

Answer 21

H+, Increasing Temperature and CO2 and decrease the affinity of Hb for O2. At sites of low pH (high [H+]), and increased CO2, for example muscle tissue during exercise, more oxygen is required and will be released. This is called the Bohr effect. The oxygen dissociation curve shifts to the RIGHT.

Answer 22

If the pO2 in the capillaries of tissues falls, pH falls and temperature rises so that Hb will give up more oxygen. Therefore the saturation of Hb leaving the capillaries will be greatly reduced. If venous pO2 is known, a dissociation curve can be used to calculate the percentage of oxygen that has been given up to that tissue.

Answer 23

Blood flowing through alveolar capillaries picks up oxygen and loses carbon dioxide by diffusion of those gases across the alveolar wall. The rate at which gases exchange is determined by three factors: o Area available for the exchange o Resistance to diffusion o Gradient of partial pressure

Answer 24

o Dissolves in water More soluble than O2 o Reacts with water Forms H+ and HCO3- Reversible reaction depending on concentrations of reactants o Binds directly to proteins Forms Carbamino compounds

Answer 25

pHG = 6.1 + log (HCO3/[pCO2*0.23])

Answer 26

o In Plasma CO2 dissolves in plasma and undergoes a slow reaction (little carbonic anhydrase) with water, creating HCO3- o In RBCs CO2 also reacts with water, rapidly (carbonic anhydrase is present) to form H+ and HCO3-. H+ ions bind to Hb, drawing the reaction towards HCO3- production The amount produced depends primarily upon the buffering effects of Hb

Answer 27

H+ ions bind to Haemoglobin, so it acts as a buffer by ‘mopping up’ H+ ions. This drives the reaction of CO2 with Water, producing more H+ ions and HCO3-.

Answer 28

Carbamino Compounds Carbamino compounds bind directly to proteins, contributing to CO2 transport, but not acid base balance. There is slightly more formed in venous blood, as pCO2 is higher.

Answer 29

Arterial Blood CO2 – 21.5 mmol/Litre | Venous Blood CO2 – 23.5 mmol/Litre

Answer 30

Venous Blood CO2 – Arterial Blood CO2 = Amount transported from tissues  lungs = 23.5 – 21.5 = 2mmol/Lire o 80% travels as HCO3- Depending on how much O2 Hb has lost, allowing it to bind H+ o 11% travels as carbamino compounds o 8% travels as dissolved CO2

Answer 31

Hypoxia – A fall in alveolar, thus arterial pO2 Hypercapnia – A rise in alveolar, thus arterial, CO2 Hypocapnia – A fall in alveolar, thus arterial CO2 Hyperventilation – Ventilation increases with no change in metabolism (Breathing more than you actually have to) Hypoventilation – Ventilation decreases with no change in metabolism (Breathing less than you actually have to)

Answer 32

pCO2 affects plasma pH (Henderson-Hasselbach) o Hyperventilation pCO2 down pH up o Hypoventilation pCO2 up pH down

Answer 33

Hypoventilation o Hypercapnia and Respiratory Acidosis o pH falls bellows 7.0 o Enzymes become lethally denatured Hyperventilation o Hypocapnia and Respiratory Alkalosis o pH rises above 7.6 o Free calcium concentration falls enough to produce fatal tetany Ca2+ is only soluble in acid, so when pH rises, Ca2+ cannot stay in the blood. Nerves become hyper-excitable.

Answer 34

Respiratory Acidosis CO2 is produced more rapidly than it is removed by the lungs (hypoventilation). Alveolar pCO2 rises, so [Dissolved CO2] rises more than [HCO3-], producing a fall in plasma pH. Compensated Respiratory Acidosis Respiratory Acidosis persists, and the kidneys respond to low pH by reducing the excretion of HCO3-, thus restoring to ratio of [Dissolved CO2] to [HCO3-], and therefore the pH. Respiratory Alkalosis CO2 is removed from alveoli more rapidly than it is produced (hyperventilation). Alveolar pCO2 falls, disturbing the ratio of [Dissolved CO2] to [HCO3-], producing a rise in plasma pH. Compensated Respiratory Alkalosis Respiratory Alkalosis persists, and the kidneys respond to the high pH by excreting HCO3-, thus restoring the ratio of [Dissolved CO2] to [HCO3-], and therefore the pH.

Answer 35

Metabolic Acidosis Metabolic production of acid displaces HCO3- from plasma as the acid is buffered; therefore the pH of blood falls. Compensated Metabolic Acidosis The ratio of [Dissolved CO2] to [HCO3-] may be restored to near normal by lowering pCO2. The lungs increase ventilation to correct pH. Metabolic Alkalosis Plasma [HCO3-] rises, causing the pH of blood to rise (e.g. after vomiting). Compensated Metabolic Alkalosis The ratio of [Dissolved CO2] to [HCO3-] may be restored to near normal by raising pCO2. The lungs decrease ventilation to correct pH.

Answer 36

Falling Inspired pO2 The falling arterial pO2 is detected by Peripheral Chemoreceptors located in the Carotid and Aortic bodies. The carotid and aortic bodies are stimulated by a decrease in oxygen supply relative to their own oxygen usage, which is small. They only respond to large drops in O2. Stimulation of the receptors: o Increases the tidal volume and rate of respiration o Changes in circulation directing more blood to the brain and kidneys o Increased pumping of blood by the heart Increase in Inspired pCO2 The Peripheral Chemoreceptors in the Carotid and Aortic bodies also detect changes in pCO2, but are insensitive. Central Chemoreceptors in the Medulla of the brain are much more sensitive, altering breathing on a second to second basis. Central chemoreceptors detect changes in Arterial pCO2. o Small rise in pCO2 -> Increase Ventilation o Small falls in pCO2 -> Decrease Ventilation o Are the basis of negative feedback control of breathing

Answer 37

The arterial pO2 is detected by Peripheral Chemoreceptors located in the Carotid and Aortic bodies. The carotid and aortic bodies are stimulated by a decrease in oxygen supply relative to their own oxygen usage, which is small. They only respond to large drops in O2. Stimulation of the receptors: o Increases the tidal volume and rate of respiration o Changes in circulation directing more blood to the brain and kidneys o Increased pumping of blood by the heart

Answer 38

Central Chemoreceptors in the Medulla of the brain are much more sensitive, altering breathing on a second to second basis. Central chemoreceptors detect changes in Arterial pCO2. o Small rise in pCO2  Increase Ventilation o Small falls in pCO2  Decrease Ventilation o Are the basis of negative feedback control of breathing - If pCO2 rises, central chemoreceptors stimulate ventilation - Which blows off CO2, returning pCO2 to normal - Vice-versa The central chemoreceptors actually respond to changes in the pH of cerebro-spinal fluid (CSF). The CSF is separated from the blood by the blood-brain barrier. The pCO2 of the CSF is determined by arterial pCO2, but HCO3- and H+ cannot cross. CSF [HCO3-] is controlled by Choroid Plexus Cells. The pH of CSF is determined by the ratio of [HCO3-] to pCO2. In the short term, [HCO3-] is fixed (cannot cross BBB), so falls in pCO2 -> Inc. pH and rises in pCO2 -> Lower pH. Persisting changes compensated for via the Choroid Plexus Cells altering CSF [HCO3-].

Answer 39

Hypoxia – A fall in alveolar, thus arterial pO2

Answer 40

There are five factors necessary to maintain arterial pO2 in the normal range, and problems with any of them may result in hypoxia 1. Low pO2 in inspired air Everything is normal, the air breathed in just has low pO2 People living at high altitudes 2. Hypoventilation o Always associated with increased pCO2 (Type 2 Respiratory Failure) o Neuromuscular Problems Respiratory depression due to opiate overdose Head injury Muscle weakness (NMJ/Nerve/Muscle diseases) o Chest wall problems (Mechanical) Scoliosis/kyphosis Morbid obesity Trauma Pneumothorax o Hard to Ventilate lungs Airway obstruction COPD & Asthma when the airway narrowing is severe and widespread Severe fibrosis 3. Diffusion Impairment o O2 diffuses much less readily than CO2, so is always affected first o pCO2 is therefore low/normal – Always Type 1 Respiratory Failure o Structural Changes Lung fibrosis causing thickening of alveolar capillary membrane o Increased Path Length Pulmonary Oedema o Total area for diffusion reduced Emphysema 4. Ventilation Perfusion Mismatch o O2 diffuses much less readily than CO2, so is always affected first o pCO2 is therefore low/normal – Always Type 1 Respiratory Failure o Reduced Ventilation of some Alveoli Lobar Pneumonia o Reduced Perfusion of Some Alveoli Pulmonary Embolism 5. Abnormal Right to Left Cardiac Shunts o E.g. Cyanotic Heart Disease such as Tetralogy of Fallot (See CVS)

Answer 41

Type 1 Respiratory Failure o Respiratory Rate increased o pO2 down o CO2 nomral or down Type 2 Respiratory Failure o Respiratory Rate increased o pO2 decreased o CO2 increased

Answer 42

Asthma is a chronic disorder characterised by Airway Wall Inflammation and Re-modelling. It is a Reversible Airflow Obstruction. Airways in asthma have thickened smooth muscle and basement membranes. Triggers cause the airway smooth muscle to contract, reducing airway radius, increasing resistance and reducing airflow

Answer 43

Asthma is: o Increasing in prevalence o More common in the developed world o Increasing in populations who move from developing -> developed countries o 5.4 million people in the UK current receive treatment o 1.1 million children o 4.3 million adults ``` o Genetic risk o Sensitisation to airborne allergens - House Dust Mite - Pollens - Air pollution - Tobacco smoke (Pre-/post natal exposure, active) o Hygiene hypothesis ```

Answer 44

The diagnosis of asthma is a clinical one. There is no standard definition of the type, severity or frequency of symptoms, nor of the findings on investigation. Asthma is defined as more than one of the following recurring symptoms: o Wheeze High pitched, expiratory sound Wheeze originates in airways which have been narrowed by compression or obstruction In asthma the wheeze is of variable intensity and tone (Polyphonic) o Cough Often worse at night (Lack of sleep, poor performance at school) Exercise induced (Decreased participation in activities) Dry cough o Breathlessness With exercise o Chest Tightness o Variable Airflow Obstruction ``` Examination Inspection o Chest Scars, deformities Hyper-expansion (Barrel Chest) o General health Eczema, hay-fever Lethargy Can they speak? o Room Meds Charts Percussion o Hyper-resonant Auscultation o Polyphonic wheeze ```

Answer 45

Spirometry – Flow Volume Loop o Low PEFR o Low FEV1/FVC Ratio o >12% increase in FEV1 following salbutamol Allergy Testing o Skin prick to aero-allergens, e.g. cat, dog, HDM o Blood IgE levels to specific aero-allergens Chest X-Rays o Performed to exclude other diseases/inhalation of foreign body/pneumothorax

Answer 46

Inflammation o Mast Cells Increased in asthma Release prostaglandins, histamine etc o Eosinophils Large numbers in the bronchial wall and secretions of asthmatics o Dendritc Cells and Lymphocytes Dedritic cells have a role in the initial uptake and presentation of allergens to lymphocytes T-Helper lymphocytes (CD4) release cytokines that play a key part in the activation of mast cells Th2 phenotype favour the production of antibody production by B lymphocytes to IgE. Remodelling o Epithelium Stressed and damaged with a loss of ciliated columnar cells o Basement membrane Deposition of collagens, causing it to thicken o Smooth Muscle Hyperplasia causing thickening of the muscle

Answer 47

Although they may occur spontaneously, asthma exacerbations are most commonly caused by: o Lack of treatment adherence o Respiratory Virus Infections associated with the common cold o Exposure to allergen or triggering drug (e.g. NSAID)

Answer 48

Education Educate patients to correctly recognise their symptoms, to use their medication timely, use services appropriately and to develop their own Personal Asthma Action Plan. ``` Primary Prevention o Stop smoking o Fresh air o Reduce exposure to allergens/triggers o Weight Loss ``` ``` Pharmacological Management o B2-adrenoagonists o Muscarinic antagonists o Short term relief o E.g. Salbutamol o Anti-inflammatory agents o Corticosteroids o Preventer therapies ```

Answer 49

Chronic Obstructive Pulmonary Disease (COPD) is a chronic, slowly progressive disorder characterised by airflow obstruction, which does not changed markedly over several months. Airflow Obstruction o Reduced FEV1 o Reduced FEV1/FVC Ratio

Answer 50

``` COPD o 89% of the population is unaware o 3.7 million affected in the UK o 1 million symptomatic o 30,000 deaths o 1 million hospital inpatient days/year ``` Causes of COPD COPD is caused by the abnormal inflammatory response of the lung to noxious particles or gases, such as cigarette smoking and atmospheric pollutants. A much less common cause of emphysema is the inherited deficiency of A1-antitrypsin.

Answer 51

``` Symptoms o Productive Cough White or clear sputum o Wheeze o Breathlessness o Usually following many years of a smoker’s cough ``` Signs o May be no signs, or just quiet wheezes o Hyperventilation with prolonged expiration (prolonged disease) Expiratory airflow limitation o Accessory muscles of respiration are used o Hyperinflation of the lungs

Answer 52

o History Including MRC Dyspnoea scale o Chest X-Ray Not really to diagnose COPD, mainly to make sure they don’t have something else (e.g. cancer) o FEV1 Reduced FEV1 Reduced FEV1/FVC ratio o Other lung function tests Lung volumes, loop o High resolution CT scan Detect emphysema

Answer 53

Oxygen is given to patients to increase oxygen saturation and alleviate symptoms. It is a treatment for hypoxaemia, NOT breathlessness. ``` o Long term Patient uses a much during the day as possible o Portable o Intermittent When required ```

Answer 54

Smoking Cessation The single most useful measure in the management of COPD is persuading the patient to stop smoking (if they do). Even in advanced disease this may slow down the rate of deterioration. ``` Drug Therapy Used for both the short-term management of exacerbations and for the long-term relief of symptoms. Many of the drugs used are similar to those used in asthma. o Bronchodilators B2-adrenoagonists o Corticosteroids Immunosuppressive o Antibiotics Shortens exacerbations Given as soon as sputum turns yellow or green ``` Oxygen Therapy Increase blood oxygen saturation by administering oxygen (see above). Pulmonary rehabilitation Exercise training can modestly increase exercise capacity. Regular training periods can be used as home, e.g. walking fixed distances or climbing stairs. A1-antitrypsin Replacement If deficient ``` Treat co-morbid condition o Cardiac o Metabolic o Nutritional o Osteoporosis o Anxiety/depression ```

Answer 55

``` Common o Viridans streptococci o Neisseria spp o Anaerobes o Candida spp ``` Less Common o Streptococcus pneumonia o Streptococcus pyogenes o Haemophillus influenza Other o Pseudomonas o E. coli

Answer 56

o Cough and sneezing reflex o Muco-ciliary clearance mechanisms Ciliated columnar epithelium Nasal hairs o Respiratory mucosal immune system Lymphoid follicles of the pharynx and tonsils Alveolar macrophages Secretary IgA and IgG

Answer 57

``` Upper Respiratory Tract Infections o Rhinitis (common cold) o Pharyngitis o Epiglottitis o Laryngitis o Tracheitis o Sinusitis o Otitis media (Inflammation of middle/inner ear) ``` ``` URT Infections are most commonly caused by Viruses: o Rhinovirus o Coronavirus o Influenza/parainfluenza o Respiratory Syncytial Virus (RSV) ``` ``` May also be caused by Bacterial Super-Infection: o Common with sinusitis and otitis media o Can lead to Mastoiditis Meningitis Brain abscess ```

Answer 58

Pneumonia Pneumonia is a general term denoting inflammation of the gas-exchanging region of the lung, usually due to infection (bacterial or viral). Pneumonia is therefore an infection of the lung parenchyma. Inflammation due to other causes, such as physical or chemical damage is often called pneumonitis. Lobar Pneumonia Pneumonia localised to a particular lobe/s of the lung. Most often due to Streptococcus pneumoniae Broncho Pneumonia Pneumonia that is diffuse and patchy. Infection starts in the airways and spreads to adjacent alveoli and lung tissue. Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus, anaerobes, coliforms Aspiration Pneumonia Aspiration of food, drink, saliva or vomit can lead to pneumonia. This is more likely in individuals with an altered level of consciousness, e.g. due to anaesthesia, alcohol or drug abuse, or if there are problems swallowing due to nerve or oesophageal damage. Organisms include oral flora and anaerobes. Interstitial Pneumonia Inflammation of the Intersticium of the lung (Alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and perilymphatic tissues) Chronic Pneumonia Inflammation of the lungs that persists for an extended period of time

Answer 59

Community Acquired Common Bacteria o Streptococcus pneumoniae – 30% o Haemophilus influenza – 13% o Klebsiella pneumoniae Atypical Bacteria o Chlamydia pneumophilia - 10% o Mycoplasma pneumoniae o Legionella pneumophila ``` Hospital Acquired Bacteria o Gram –‘ve enteric bacteria - 10% o Pseudomonas o Staphylococcus aureus o MRSA ``` Aspiration Pneumonia o Anaerobes o Oral flora

Answer 60

Elderly, co-morbidities, acute onset, high fever, Pleuritic chest pain

Answer 61

Recent travel, younger patient, smokers, illness, multi-system involvement

Answer 62

Young, prior antibiotics, extra-pulmonary involvement (haemolysis, skin and joint)

Answer 63

Post-viral, Intra-Venous Drug User

Answer 64

Contact with birds

Answer 65

Animal contact (sheep)

Answer 66

Thrombocytopenia, leucopenia

Answer 67

Dental infections, abdominal source, aspiration

Answer 68

The presentation of pneumonia can be variable. There is almost always malaise, fever and a productive cough. The sputum may be purulent, or rusty coloured (little blood) or stained with lots of blood. There is commonly plueritic chest pain. Patients often feel breathless. Pneumonias may be of very rapid onset, particularly if pneumococcal or staphylococcal, with a fatal outcome in a short period of time. ``` Symptoms of Pneumonia o Fever, chills, sweats, rigors o Cough o Sputum Clear / purulent / ‘rust coloured / haemoptysis o Dyspnoea o Pleuritic chest pain o Malaise o Anorexia and vomiting o Headache o Myalgia o Diarrhoea ``` ``` o Chest Signs Bronchial breath sounds Crackles Wheeze Dullness to percussion Reduced vocal resonance ``` Hospital Acquired Pneumonia o Pneumonia occurring 48hrs after hospital admission o Makes up ~15% of all hospital acquired infections o Common in ventilated/post surgical patients

Answer 69

CURB 65 Score The severity of pneumonia can be assessed using the CURB 65 score, where the presence of two or more of the following features is an indication for hospital treatment, and patients with high scores may required ICU treatment. C – New mental Confusion U – Urea > 7mmol/L R – Respiratory rate > 30 per minute B – Blood pressure (Systolic < 90 or Diastolic < 60 mmHg)

Answer 70

Samples Collected to Investigate Pneumonia o Sputum o Nose and Throat swabs o Endotracheal aspirates o Broncho Alveolar Lavage fluid (BAL) o Open Lung Biopsy o Blood culture -Preferably before antibiotics o Urine -Detect the antigens of legionella/pneumococcus o Serum -= Antibody detection Microbiological Investigations of Pneumonia o Macroscopic - Sputum, purulent, blood stained o Microscopy - Gram staining, Acid fast o Culture - Bacteria and viruses o PCR - Respiratory viruses o Antigen detection - Legionella o Antibody detection - Serology

Answer 71

Pathogens infecting immunosuppressed hosts may be: o Virulent infection with common organism o Infection with opportunistic pathogen Viruses – Cytomegalovirus (CMV) Bacteria – Mycobacterium avium intracellulare Fungi – Aspergillus, candida, pneumocystis jiroveci Protozoa – Cryptosporidia, toxoplasma

Answer 72

Management of Pneumonias o Oral fluid/IV fluids if severe - Avoid dehydration o Anti-pyretic drugs - Reduce fever and malaise E.g. Paracetamol o Stronger analgesics - Deal with the pain (Pleuritic) o Oxygen - If there is cyanosis Antibiotics The infection is treated with antibiotics, which vary with the type of pneumonia. Community Acquired Pneumonia The target organism is normally Pneumococcus, which is usually sensitive to Penicillin or related antibiotics. Hospital Acquired pneumonia The target organism is more likely to be Gram –‘ve, making it necessary to use antibiotics that cover these organisms, e.g. IV Co-Amoxiclav.

Answer 73

o Resolution Organisation (Fibrous scarring) o Complications Lung abscess Bronchiectasis Empyema (pus in pleural cavity)

Answer 74

Immunization Flu vaccine – Given annually to high risk patients Pneumococcal vaccine – Two vaccines Chemoprophylaxis Oral penicillin / erythromycin to patients with higher risk of lower respiratory tract infections E.g. asplenia, dysfunctional spleen, immunodeficiency

Answer 75

Mycobacteria possess a lipid-rich cell wall that retains some dyes, even resisting decolourisation with acid (acid-fast).

Answer 76

Tuberculosis is spread from person to person by the aerosol route, making the lung the first site of infection. The Primary Complex Most infections resolve with local scarring (Primary Tuberculosis) Post-Primary Infection Post-Primary Infection refers to the development of tuberculosis beyond the first few weeks. The infection may progress throughout the body (Miliary Spread). This may resolve spontaneously, or develop into localised infection (E.g. meningitis). Pathology Mycobacterium Tuberculosis is ingested by macrophages, but escapes from the phagolysosome to multiply in the cytoplasm. The intense immune response causes local tissue destruction (Cavitation in the lung) and cytokine-mediated systemic effects (Fever and Weight loss). TB may affect every organ of the body, mimicking both inflammatory and malignant diseases. Pulmonary tuberculosis may present with a chronic cough, haemoptysis, fever and weight loss or as recurrent bacterial pneumonia. Untreated the infection follows a chronic, deteriorating course. Tuberculous meningitis presents with fever and slowly deteriorating level of consciousness. Kidney infection may lead to signs of local infection, fever and weight loss, complicated by ureteric fibrosis and hydronephropathy. The lumbosacral spine is a common site of bone infection – progression may cause vertebral collapse and nerve compression. Inflammation of large joints may lead to destructive arthritis.

Answer 77

Mycobacterium Tuberculosis is ingested by macrophages, but escapes from the phagolysosome to multiply in the cytoplasm. At the same time it provokes an immune response, stimulating the release of IL-12. IL-12 in turn drives the release of IFN-Y and TNF-A from NK and CD4 cells. These cytokines activate and recruit more macrophages to the site of infection, resulting in the formation of Granulomas.

Answer 78

Primary Changes o Few Symptoms o Lymph nodes may become enlarged in young people ``` Post-Primary Changes The Classical Presentation: o Cough (Not always productive) o Fevers towards the end of the day or at night o Weight loss and general debility ``` Chest X-Ray reveals pulmonary shadowing, which may be patchy solid lesions, cavitated solid lesions, streaky fibrosis or flecks of calcification.

Answer 79

``` Signs Non-specific Pallor Fever Weight Loss Clubbing Palpable lymph nodes ``` ``` Symptoms Primary usually asymptomatic Tiredness and malaise Weight loss and anorexia Fever Cough Breathlessness Haemoptysis occasionally ``` ``` X-Ray Changes Shadowing Cavities Consolidation Calcification Cardiomegaly Miliary seeds ```

Answer 80

Pleural Tuberculosis More common in males, there are two mechanisms of pleural involvement. There is almost always some pulmonary disease present: o Hypersensitivity response in primary infection o Tuberculous empyema with ruptured cavity. Tuberculosis empyema has a tendency to burrow through the chest wall.

Answer 81

TB is diagnosed by: o Clinical Features Cough, night fever, weight loss o Radiological Features Shadowing, cavities, consolidation, cardiomegaly, miliary seeds o Microbiology Identification of bacillus Direct smear and subsequent culture of the appropriate body fluid Important to isolate organism and determine its susceptibility to drugs

Answer 82

Initially patients are treated with four drugs for two months, after which two of them are dropped and the others are continued for another four months. Multiple drugs are used in an attempt to combat resistance (e.g. in 5-10% of patients TB is resistance to Isoniazid). As this is quite a long drug regime, with several different pills to take there can be problems with compliance. As such 15% of patients in the US receive Directly Observed Therapy (DOT), giving benefits including improved cure rates, reduction in rate, drug resistance and relapses. Initial Phase (2 months) Rifampicin - Hepatitis, rash, flu-like symptoms, shock, ARF, thrombocytopenic purpura Isoniazid - Rash, peripheral neuropathy, hepatitis Pyrazinamide - Rash, hepatitis, arthralgia Ethambutol - Optic neuritis Continuation Phase (4 months) Rifampicin Isoniazid

Answer 83

There is a rising trend of Multidrug-Resistant TB (MDRTB). About one in a million bacilli are spontaneously resistant. A case of MDRTB is suggested by a history of previous incomplete treatment, residence in a country with high incidence of MDRTB or failure to respond clinically to an adequate regimen. A regimen of several drugs at once (see above) is used in an attempt to combat resistance.

Answer 84

BCG Vaccine The BCG vaccine is a vaccination against tuberculosis that is prepared from a strain of the Attenuated Live Bovine Tuberculosis Bacillus. The bacteria retain a strong enough antigenicity to act as a vaccine for human tuberculosis. Issues The vaccine has a variable efficacy, depending on genetic variation of populations and BCG strains. Efficacy only lasts 15 years at most. UK Regulations In the UK up until 2005 all children ages 13 were immunised along with all neonates born into high-risk groups. Post 2005 the vaccination was only given to high-risk groups, as falling incidence of TB had reduced the vaccine’s cost effectiveness.

Answer 85

``` HIV Silicosis Malnutrition Overcrowding - Prison’s, homeless shelters IV Drug abusers Chronic Lung Disease (Smokers) Ethnicity - Asians more likely Diabetes Corticosteroids / anti A-TNF antibody (Infliximab) ```

Answer 86

HIV is a major risk factor for tuberculosis. The risk of developing TB is estimated to be between 20-37 times greater in HIV infected people than uninfected people. TB is a leading cause of morbidity and mortality among HIV patients.

Answer 87

If TB is suspected, contact is immediately made with TB radiology. The patient goes straight into a TB clinic, with no waiting times, and is given a questionnaire and sputum samples taken. Treatment begins within 7 days.

Answer 88

o Males Commonest male cancer Mortality rate is around 100 per 100,000 Incidence slowly falling due to reduction in smoking o Females Exceeds breast cancer as a cause of death in women Mortality rate is around 40 per 100,000 Incidence is steadily rising o Socio-economic groups Wide variation Rate three times higher in lowest compared with highest

Answer 89

Smoking Lung cancer is overwhelmingly related to smoking, with the risk being proportional to the duration of the habit and the number of cigarettes smoked. Around 90% of lung cancer in men and 80% in women are caused by smoking. ``` Other Aetiological Factors include: o Asbestos exposure o Radon exposure o Genetic factors o Dietary factors ```

Answer 90

``` Primary Tumour Cough Dyspnoea Wheezing Haemoptysis Chest pain Post-obstructive pneumonia Weight loss Lethargy / Malaise ``` ``` Regional Metastases Superior vena cava obstruction Hoarseness (Left recurrent Laryngeal nerve palsy) Dyspnoea (Phrenic nerve palsy) Dysphagia ``` Distant Metastases Bone pain / Fractures CNS symptoms (Headache, double vision, confusion etc.)

Answer 91

Paraneoplastic Syndrome Paraneoplastic syndrome is the presence of a symptom or disease due to the presence of cancer in the body, but not due to the local presence of cancer cells. They are mediated by humoral factors (cytokines and hormones) secreted by tumour cells, or the immune response against tumour cells. ``` o Endocrine Hypercalcaemia Cushing’s syndrome o Neurological Encephalopathy Peripheral neuropathy o Skeletal Finger clubbing oHaematological Anaemia Thrombocytopenia Disseminated Intravascular Coagulation (DIC) o Other Nephrotic syndrome Anorexia or cachexia ```

Answer 92

``` Imaging investigations of various types are central to both the diagnosis and assessment of the disease (staging). Staging is one of the most important determinants of treatment and prognosis. o First clinical suspicion Plain Chest X-Ray o Diagnosis and staging CT scan PET scan Isotope bone scan ``` There are two staging systems for Lung Cancer: Number and TMN

Answer 93

TNM Staging System T – Size and position of tumour o T1 – Cancer contained within lung (<3cm diameter) o T2 – Cancer has grown (3-7cm diameter) Into main bronchus <2cm from the carina Into the visceral pleura Made part of the lung collapse o T3 – Cancer has grown (> 7cm diameter) Invading chest wall, mediastinal pleura, diaphragm, pericardium Complete lung collapse > 1 cancer nodule in the same lobe of lung o T4 Cancer invading mediastinum, heart, major blood vessel, trachea, carina, oesophagus, spine, recurrent laryngeal nerve Cancer nodules in more than one lobe of the same lung N – Lymph node involvement o N0 – No cancer in lymph nodes o N1 – Cancer in lymph nodes nearest the affected lung o N2 – Cancer in lymph nodes in mediastinum, on the same side o N3 – Cancer in lymph nodes on the opposite side of the mediastinum / supraclavicular lymph nodes M – Metastases o M0 – No evidence of distal cancer spread o M1 – Lung cancer cells in distant parts of the body, such as pleura, opposite lung, liver or bones etc

Answer 94

Stage 1 – Small cancer, localised to one area of the lung Stage 2 and 3 – Larger Cancer, may have grown into surrounding tissues (lymph nodes) Stage 4 – Cancer has metastasised

Answer 95

Tissue for diagnostic purposes is usually obtained either by bronchoscopy, needle biopsy of the lung or Surgical biopsy. Making a histological diagnosis is important not only to confirm that the patient has lung cancer, but also to decided the cell type, which important both in terms of the prognosis and treatment.

Answer 96

Lung tumours are divided into two groups depending on the presence or absence of cells: o Non-Small Cell Lung Cancer o Small Cell Lung Cancer

Answer 97

Non-Small Cell o More than 2/3rds have inoperable disease at presentation Small Cell o ¾ have metastatic disease at presentation ``` Prognosis Depends On: o Cell type Small Cell worse than Non-Small Cell o Stage of disease o Performance status o Biochemical markers o Co-morbidities E.g. Cardiac or chronic respiratory disease ```

Answer 98

``` o Surgery Mostly Non-Small Cell (<20% operable) o Radiotherapy Radical – Curative Palliative – Symptom control o Chemotherapy Small cell – Potentially curative (Minority) Non small cell – Modest survival increase, symptom control o Combination therapy Combination of chemo and radiotherapy o Biological targeted therapies E.g. EGFR and VEGF o Palliative care ``` Management of Non-Small Cell Lung Cancer Usually involves multiple modality therapy: o Palliative Radiotherapy for local symptoms o Chemotherapy – 50 – 60% response rates. o Combination Therapy – Important in locally advanced disease o Targeted Agents – EGFR and VEGF ``` Management of Small Cell Cancer o Rarely operable o Combination Therapy – Responds well, adding ~1 year o Palliative Chemotherapy for symptoms o Death from cerebral metastases common ```

Answer 99

The widest part of the heart and ribcage are measured laterally. If the heart is over 50% of the width of the thorax, it is enlarged.

Answer 100

Lungs are normal on XRAY, but air is seen under the diaphragm. This is a sign of bowel perforation.

Answer 101

COPD can lead to hyperinflation of the lungs. This leads to blunting of both costophrenic angles, and flattened hemidiaphragms.

Answer 102

Calcified asbestos related pleural plaques have a characteristic appearance, and are generally considered to be benign. They are irregular, well defined and classically said to look like holly leaves.

Answer 103

If the trachea is genuinely displaced to one side (the patient is not rotated) try to establish if it has been pushed or pulled by a disease process. Anything that increases pressure or volume in one hemithorax will push the trachea and mediastinum away from that side. (E.g. Tension pneumothorax, pleural effusion, tumour) Any disease that causes volume loss in one hemithorax will pull the trachea over towards that side. (E.g. collapsed lung, fibrosis)

Answer 104

If there is tracheal or mediastinal shift away from the pneumothorax, the pneumothorax is said to be under tension. This is a medical emergency. Trachea is pushed away by air in the pleural cavity.

Answer 105

A pneumothorax forms when there is air trapped in the pleural space. This may occur spontaneously, or as a result of underlying lung disease. The most common cause is trauma, with laceration of the visceral pleura by a fractured rib.

Answer 106

A Pleural effusion is a collection of fluid in the pleural space. Fluid gathers in the lowest part of the chest, according to the patient’s position. If the patient is upright when the X-ray is taken, a pleural effusion will obscure the Costophrenic angle/Hemidiaphragm. If a patient is supine, a pleural effusion layers along the posterior aspect of the chest cavity, and is difficult to see on a chest X-Ray. Pleural effusions appear on X-rays as uniformly white, with a concave area at the top. This is called the Meniscus sign.

Answer 107

Displacement of the horizontal fissure is an indicator of lobar collapse. If there is volume loss of the right upper lobe (e.g. collapse), the horizontal fissure is displaced upwards. If there is volume loss of the right lower lobe (e.g. collapse), the horizontal fissure is displaced downwards.

Answer 108

The Interstitial space is a potential space between alveolar cells and the capillary basement membrane, which is only apparent in disease states, when it may contain fibrous tissue, cells or fluid.

Answer 109

o The development of fibrous tissue in the Intersticium, making lungs less compliant, producing a restrictive ventilatory defect. o Airway resistance is NOT increased. In fact, the FEV1/FVC ratio can be > 70%, due to the increased radial traction on the airway, which keeps the airway open. o Lengthening of the diffusion path between alveolar air and blood impairs gas exchange, with oxygen uptake being affected selectively, as CO2 diffuses much more readily.

Answer 110

Symptoms: o Shortness of breath, reduced exercise tolerance, dry cough Signs: o Tachypnoea, tachycardia, reduced chest movement (bilaterally) and coarse crackles. Cyanosis and signs of right heart failure may be present. Clubbing is seen in cryptogenic fibrosing alveolitis.

Answer 111

o Progressive inflammatory condition, unknown cause o Relatively rare, 3-5 cases per 100,000. Two times more common in males o Histologically there are increased activated Alveolar Macrophages Attract Neutrophils and Eosinophils Local lung damage due to ROS and proteases Tissue destruction and fibrosis o Patients report progressive shortness of breath on exercise, often with non-productive cough. o Most patients have finger clubbing o Chest X-Ray shows small lungs with micro-nodular shadowing predominating in the lower loves, with ragged heart borders o Can be restrained by treatment with high dose oral steroids in the early stages, less effective once fibrosis has developed Effectiveness of treatment is monitored by repeated lung function tests

Answer 112

o Inhalation of organic material triggers an allergic reaction in alveoli and bronchioles. o Condition may be Acute or Chronic: Acute o Sudden onset, rapidly progressing o Farmer’s Lung Antigen = Thermophillic actinomycetes found in mouldy hay Influenza like illness 4-9 hours later with a dry cough and breathlessness on exertion Fine mid and late inspiratory crackles May be a wheeze Chronic o Bird Fancier’s Lung Long Term Antigen Exposure = Pigeons / budgerigars Insidious malaise (feeling particularly unwell) Dry cough and breathlessness over months and years Inspiratory crackles o Finger clubbing does not occur in either Acute or Chronic. o Acute disease chest x-ray shows diffuse micro-nodular infiltrate denser towards the hila. o Chronic disease chest x-ray may be almost normal, progressing to fibrosis in late disease. o Lung function tests will show reduced compliance and reduced gas transfer.

Answer 113

o Inhalation of asbestos fibres, disease often develops long after the exposure. o Asbestosis inhalation is associated with three forms of disease (along with a marked increase in lung cancer): Benign pleural plaques Asbestosis (pulmonary fibrosis) Mesothelioma o Asbestos fibres that penetrate to the alveoli produce alveolitis Influx of macrophages produces characteristic asbestosis bodies Alveolitis progresses to fibrosis o History of asbestos exposure o Patient breathless on exertion and a dry cough. o Inspiratory crackles at the lung bases, which rise as the disease advances. o No treatment o Lung function tests show small lungs, reduced compliance and impaired gas transfer

Answer 114

o Disease of unknown cause, characterise by Non-Caseating Granulomas (Non-necrotising) in multiple organs and body sites o Most commonly in the lungs o Fluid is collected by lavage of the airways, and alveoli contain lots of cells, including macrophages and lymphocytes o Commoner in Afro-Caribbean and Asians than in Caucasians - Genetic predisposition o Highest incidence in 30’s and 40’s with more female cases o Often asymptomatic, but may have Cough, breathlessness o Grading system 0 – 4 o X-ray shows miliary and nodular shadowing and diffuse fibrosis o Stages 1 – 3 steroids are usually effective in suppressing the disease o Lung function tests show small lungs, reduced compliance and impaired gas transfer. May be evidence of air flow obstruction.

Answer 115

Asthma Lab Worker - Rat urine Diffuse fibrosis Boiler/Pipe Laggers - Asbestos Railway/Construction - Asbestos Nodular Fibrosis (E.g. pneumoconiosis) Coal Miner - Coal Dust Miner - Silican Demolition - Asbestos Alveolitis Farmer - Fungal spores from hay Pigeon Fancier - Avian antigens

Answer 116

Small lungs Micro-nodular shadowing (Lower lobes) Ragged heart borders

Answer 117

Micro-nodular infiltrate, denser towards the hila.

Answer 118

Almost normal, progressing to fibrosis in late disease

Answer 119

Miliary and Nodular shadowing | Diffuse fibrosis

Answer 120

Plaques – See above (Holly leaf) Fibrosis Mesothelioma

Answer 121

Pleura The pleura is a serous membrane consisting of a single layer of mesothelial cells with a thin layer of underlying connective tissue. The Parietal Pleura lines the inside of each hemi thorax (the bony thoracic cage, diaphragm and mediastinal surface) and becomes continuous at the hilum of the lung with the Visceral Pleura, which lines the outside of the lung. The visceral pleura extend between lobes of the lung into the depths of the oblique and horizontal fissures. Pleural Cavity The pleural cavity, or space, is a potential space between the two layers of pleura that are continuous at the hilum. Both layers of pleura are covered with a common film of fluid produced from the parietal surface and absorbed by the parietal lymphatic vessels. The pleural fluid allows the two layers to slide on one another, thus in health the pleura allows movement of the lung against the chest wall while breathing. The surface tension of the pleural fluid provides the cohesion that keeps the lung surface in contact with the thoracic wall. As a result, when the thorax expands in inspiration, the lung expands along with it and fills with air. The lungs do not occupy all the available space in the pleural cavity, even in deep inspiration.

Answer 122

Pleural Fluid o 15ml turnover per day (Can increase to 300ml) o Produced by Capillary Filtration at the Parietal Pleura (Starling Forces) Increased Lung interstitial fluid increase Increased Hydrostatic Pressure (E.g. heart failure) Increased Permeability (E.g. inflammation, spesis or malignancy) Decreased Oncotic Pressure (E.g. liver failure) o Absorbed via lymphatic drainage Decreased Lymphatic blockage Increased Systemic venous pressure

Answer 123

Pleural Effusion Any collection of extra fluid in the pleural space is known as a ‘Pleural Effusion’. Blood – Haemothorax Chyle (Lymph with fats in it) – Chylothorax Pus – Empyema Serous Fluid – Simple Effusion

Answer 124

Simple pleural effusions (Serous Fluid) is further characterised by protein content: Transudates have low protein content – < 30g/Litre Exudates have high protein content – > 30g/Litre ``` Transudates o Increased Hydrostatic Pressure Cardiac Failure o Decreased capillary Oncotic Pressure Hypoalbuminaemia Nephrotic Syndrome o Increased capillary Permeability Sepsis ``` ``` Exudates o Neoplasms Cancer involving pleural surface Secondary’s from breast, lung, ovarian, GI, lymphoma Primary tumour of pleura o Infection Pneumonia, TB o Immune Disease Connective tissue diseases (RA, SLE) o Abdominal Disease Pancreatitis (Diaphragmatic inflammation) Ascites (Transverse the diaphragm) Subphrenic abscess ```

Answer 125

Pleurisy, or pleuritis, is an inflammation of the pleura. o Sharp Pain on inspiration o Pain worse with coughing, sneezing, laughing etc. o Patients take small breaths, and hold affected side of chest o Involvement of diaphragmatic pleura causes pain in the shoulder on the same side (Referred pain) o Characteristic physical sign is Pleural Rub, a creaking noise heard through a stethoscope with respiratory movements ``` Causes of Pleurisy: o Infection is the most common cause TB Pneumonia o Autoimmune SLE RA o Lung Cancer o Pneumothorax o Pulmonary Embolism ``` Pleural Fibrosis Unabsorbed pleural effusion may lead to fibrosis of the pleura. A small degree of thickening has no effects, but wide spread fibrosis restricts expansion, with a measurable reduction in lung volumes and compliance. Pleural Tumours o Secondary deposits of tumours are not uncommon in the pleura. o The commonest primary tumour is a malignant mesothelioma. o Almost all victims exposed to asbestos 20 – 40 years before o Early symptoms are lose of pleural effusion, but with a duller pain o Signs are that or a large pleural effusion

Answer 126

Chest Wall Abnormalities Deformation of the ribs, sternum and thoracic spine o Sternal abnormalities (E.g. Pectus Carcinatum/excavatum) rarely produce functional impairment, just cosmetic o Scoliosis and kyphosis may produce significant function impairment of the thoracic cage Acquired abnormalities: o Trauma producing broken ribs, possible pneumothorax o Some old patients may have had surgery for TB, designed to collapse their lung Muscle and Neurological Disease The muscles involved in breathing may be affected by generalised muscular diseases, such as muscular dystrophy or by neurological disease such as motor neurone disease or polio. Muscle weakness produces respiratory failure with lower resistance to respiratory tract infections because of poor clearance of secretions.

Answer 127

``` CO2 retention o CSF acidic corrected by choroid plexus o Initial acidosis corrected by the kidney o Reduction of respiratory drive o Persisting hypoxia ``` Right Heart Failure (Cor pulmonare) o Effect of hypoxia on pulmonary arteries -> Pulmonary hypertension o Chronic respiratory failure is severely disabling

Answer 128

o Oxygen therapy o Removal of secretions o Assisted ventilation o Treat acute exacerbations

Answer 129

The paranasal sinuses are air-filled extensions of the respiratory part of the nasal cavity into cranial bones (Frontal, Ethmoid, Sphenoid and Maxilla). The sinuses are named according to the bones in which they are located.

Answer 130

The Right and Left Frontal Sinuses are between the outer and inner tables of the frontal bone, posterior to the superciliary arches and the root of the nose. They are usually detectable in children by 7 years of age. They each drain through a Frontonasal Duct into the ethmoidal infundibulum, which opens into the semilunar hiatus of the Middle Nasal Recess.

Answer 131

The Ethmoidal cells (Sinuses) are small invaginations of the mucous membrane of the middle and superior nasal recesses into the Ethmoid bone. The Ethmoidal cells usually are not visible in plain radiographs before 2 years of age. The Anterior Ethmoidal Cells drain directly or indirectly into the middle nasal recess through the ethmoidal infundibulum. The Middle Ethmoidal Cells open directly into the middle nasal recess. The Posterior Ethmoidal Cells open directly into the superior nasal recess.

Answer 132

The Sphenoidal Sinuses are located in the body of the sphenoid and may extend into the wings of the bone. The body of the sphenoid is fragile, and only thin plates of bone separate the sinuses from several important structures (Optic nerves and chiasm, the pituitary gland, internal carotid arteries). They drain directly into the Sphenoethmoidal Recess.

Answer 133

The Maxillary Sinuses are the largest of the paranasal sinuses. They occupy the bodies of the Maxillae. They drain by one or more openings, the Maxillary Ostium (ostia), into the middle nasal recess by way of the semilunar hiatus.

Answer 134

More common in children, women and Asians. It is often painless, and occurs most commonly in the neck. Osteo-articular TB TB burrows into bone. o Tuberculous Spondylitis Most common form of oesteoarticular TB Starts in sub-chondral bone and spread to vertebral bodies and joint space, before following the longitudinal ligaments, anterior and posterior to the spine. Mainly occurs in the lower thoracic and lumbar spine, but can be very high (Cervical tuberculosis) Parapledia and quadriplegia occurs in 25% of cases o Poncet’s Disease Aseptic polyarthritis Knees, ankles and elbows

Answer 135

Miliary Tuberculosis o Bacilli spreading through the blood stream o Either during primary infection or as reactivation o Lungs are always involved Even spread throughout both lungs, as it is in the blood Many visible through the lungs on an X-Ray o Headaches suggest meningeal involvement o Few respiratory symptoms o Ascites may be present o Retinal involvement in children