2010 First Sitting

2010A 01: 10 (100%) of candidates passed this question. A structured approach that included mentioning that 1000mls of blood was substantial – being approximately 20% of the blood volume of a 70 kg person was required for a good answer. Candidates were expected to also include changes in systolic and diastolic blood pressure, pulse pressure, heart rate, cardiac output and the neuronal (eg sympathetic nervous system response on the various circulations) and hormonal responses (eg rennin aldosterone, Anti-Diuretic Hormone, catecholamines, etc). Candidates were also expected to discuss differences in responses according to rate of blood loss. Flow diagram could have been used to illustrate some of these concepts. Syllabus: C1e References: Textbook of Medical Physiology, Guyton pg 278 – 282, Principles of Physiology for the Anaesthetist, Power & Kam pg 154

2010A 03: 8 (80%) of candidates passed this question This question was also best answered using a structured response and illustrations. Discussion and/or diagrams of the process of formation of temporary platelet plug and conversion to a definitive haemostatic plug after injury to the vessel wall, showing the Intrinsic, Extrinsic and Common Pathways with note of essential cofactors (tissue thromboplastin, Ca++) and fibrinolysis and clot resolution, inhibitors and controlers that prevent excessive coagulation. The latter would lead into outlining the mechanism of thrombolytics. It was expected candidates would mention such mechanisms as catalysing the formation of plasmin from plasmingoen, activation of endogenous plasminogen and direct conversion of plasminogen to plasmin. Syllabus: J2. 1, J2. 2e Reference: Pharmacology and Physiology in Anesthetic Practice, Stoelting pgs 510 - 511, Basic and Clinical Pharmacology, Katzung pg 380 - 383

2010A 04: 1 (10%) of candidates passed this question Candidates were expected to at least mention and describe the following points – absorption at the infrared spectrum; Beer-Lambert Law and it’s relevance to measurement of ETCO2; sources of error (effect of other gases, atmospheric pressure), sources of interference (gas sampling methods, heating), calibration, features of the sampling chamber that may cause error (glass construction, size), sampling rates, etc. Answers provided by candidates lacked breadth and depth, indicated that there was generally a poor understanding of this topic. The usual mistake was to discuss the clinical reasons behind the reading not reflecting the PaCO2 rather than sources of error of the end tidal CO2. Candidates should review this topic from the references from which the answer was sought and texts included as recommended reading. Syllabus: R2d, S2g

2010A 05: 5 (50%) of candidates passed this question Lactate is constantly produced from pyruvate via the enzyme lactate dehydrogenase (LDH). Lactate is produced during normal metabolism and in increased quantities during anaerobic metabolism. Candidates were expected to further describe this physiological processes. A good answered required quantification of lactate production during normal aerobic metabolism, during anaeorobic metabolism, the pathways involved (Glucose to Pyruvate, Pyruvate to Citric Acid cycle in presence of Oxygen, Pyruvate + NADH to Lactate + NAD+ without Oxygen) associated ATP production, site of intracellular production, why red blood cells differ and lactate metabolism (eg oxidation to pyruvate by well-oxygenated muscle cells which is then directly used to fuel the citric acid cycle conversion to glucose via the Cori cycle in the liver through the process of gluconeogenesis). Good answers illustrated the loss of energy potential with the production of lactate and discussed the situations that would lead to an inbalance between production and metabolism of lactate. Candidates who did poorly in this question did so due to a lack of depth and breadth for this topic. For example, even though the Cori Cycle was often mentioned, it was poorly described in relation to lactate metabolism. Syllabus: K2g References: Textbook of Medical Physiology, Guyton Chp 67

2010A 06: 6 (60%) of candidates passed this question Good candidates had a structured approach to this questions. Submitted question structures took the form of key headings (eg, PaCO2, PaO2, pH, etc) with an accompanying explanation, which included diagrams, which were often underutilised. Candidate answers that lacked any structure were more likely to have omissions and lacked sufficient depth and as a result scored fewer marks. For a good answers candidates where expected to list and explain (preferably by including diagrams) physiological factors such as PaCO2, PaO2, pH, Exercise, temperature, pregnancy and the associated receptors for each mechanism. Syllabus: B1c 1 Reference: Nunn’s Applied Respiratory Physiology, Lumb, 6th edition 60-68 Principles of Physiology for the Anaesthetist, Power & Kam, 1st edition 92-98

2010A 07: 6 (60%) of candidates passed this question This question required a classification based on chemical structure and class action. Sympathomimetics, phosphodiesterase inhibitors, calcium sensitizers and cardiac glycosides should have been mentioned. Additional detail was expected, subdividing Sympathomimetics into catecholamines (naturally occurring and synthetic), and non-catecholamines (direct and indirect acting). Further classification based on peripheral vasomotor action demonstrated greater understanding. Better answers included diagrams illustrating the mechanism and point of action on the cardiac myocyte. Discussion of receptors, second messengers, and the role of calcium was essential. The question was aimed at “commonly used” agents, although some marks were awarded for discussion of calcium, glucagon and other rarely used drugs. Insufficient detail regarding mechanisms of action was a common observation. Syllabus: C2d 2 References: Pharmacology and Physiology in Anaesthetic Practice, Stoelting 4th Ed p293-320. Basic and Clinical Pharmacology Katzung 10th Ed p121-198. Pharmacology Rang & Dale 6th Ed p168-187, 290-291

2010A 08: 0 (0%) of candidates passed this question The preponderance of marks was allocated to a discussion of renal drug excretion and factors altering this function. Detail was expected including a definition of clearance, and the balance between filtration / secretion / reabsorption in the tubules. Specific mention of GFR, molecular weight of filterable compounds, protein binding, and charge effects determining filtration at the glomerular level was anticipated. Tubular transport mechanisms for secretion and reabsorption in the proximal and distal tubule should have been included in the discussion. Candidates needed to cover factors which alter GFR, competition for transport proteins, changes in pH on drug elimination, and disease states in answering the question. An understanding that drug dosing should be based on estimating creatinine clearance and plasma concentration monitoring was essential. Loading dose is usually unaltered. However, maintenance dose and dosing interval need to be adjusted owing to an increased half-life. Many candidates did not emphasise the need to increase dosing interval as well as reduce maintenance dose in renal impairment. Syllabus: II2d, D12h References: Goodman and Gilman's the Pharmacological Basis of Therapeutics p10-14. Foundations of Anaesthesia Basic and Clinical Science, Hemmings p107. Basic and Clinical Pharmacology, Katzung p35, 48-49.

2010A 09: 7 (70%) of candidates passed this question Answers to this question needed to address drugs that target the pathophysiology of asthma: bronchospasm, inflammation (oedema and hypersecretion), and hyperreactivity to inhaled stimuli. Not all drugs used to treat less severe forms of the disease are relevant in the critical care context. A discussion of efficacy versus toxicity was included in better answers. As a minimum, sympathomimetics, antimuscarinics, corticosteroids and methylxanthines should have been included. The role of inhaled Adrenaline as a B2-agonist mediating bronchodilatation and an alpha-agonist constricting the bronchial mucosa was relevant to the discussion. Ketamine and volatile anaesthetics could have been discussed as adjuncts to therapy in ventilated patients. More controversial therapies such as Magnesium and Heliox are less commonly prescribed, however marks were awarded for more comprehensive answers. Syllabus B2a 2a Reference: Goodman and Gilman's the Pharmacological Basis of Therapeutics 11th Ed p717-736

2010A 10: 6 (60%) of candidates passed this question For a good answer candidates were expected to mention the following key broad points, being there are drugs that act by decreasing acid production in the stomach, drugs that act as mucosal protectors and drugs that reduce intra gastric acidity. Based upon that candidates would be expected to mention and outline the mechanism of action of H2 receptor antagonists, H+K/=ATPase (proton pump) inhibitors, sucralfate’s mechanism of action and antacids. Candidates who structured their answer tended to provide more complete answers and score better. Candidates who failed did so because of a lack of sufficient knowledge of the mechanism of action of the drugs. Syllabus: Q2, 2a. b,c References: Basic and Clinical Pharmacology Katzung 10th Ed pg 1009. Pharmacology Rang & Dale 6th Ed p 526-7, 255, 497, 587

2010A 11: 2 (20%) of candidates passed this question For a good answer candidates were expected to describe the respiratory alkalosis and metabolic compensation associated with pregnancy. Candidates were expected to write a set of arterial blood gases showing a compensated respiratory alkalosis with a normal to slightly high P02. Values within +/- 5% of those expected, and found, in listed references would have scored candidates marks. Candidates were then expected to mention that the PaO2 is high despite a 20% increase in oxygen consumption (relate that to increase in alveolar ventilation, decrease in PaCO2, and alveolar gas equation; PaCO2 is low due to tidal volume increase by 35%, Although anatomical dead space increases VD/VT in unchanged, despite CO2 production increased by increased basal metabolic rate; HCO3 decreases because of increased renal excretion of HCO3 due to inhibition of renal secretion of hydrogen ions and ammonium; base deficit reflects the renal loss of HCO3. Some candidates described a low maternal P02, none commented on how the maternal P02 and PC02 enhance gas exchange to the foetus. While electrolyte values are often measured on arterial blood gas analysis they do not form part of an arterial blood gas and so comments on electrolytes gained no marks. The double Bohr and double Haldane effects were not required to answer this question. Once again, this question highlighted the importance of a structured approach to the answer, thus enhancing a candidates opportunity to cover all key areas and put their knowledge across. Syllabus: O1, 2a References: Nunn’s Applied Respiratory Physiology, Lumb, 6th edition, Chp 14

2010A 12: 1 (10%) of candidates passed this question Viruses are classified according to: a) genetic material b) mode replication c) structural proteins (capsids) d) presence of an envelope Thus DNA viruses, double or single stranded DNA usually replicate in the nucleus of the host cell via polymerase, not incorporated into the host genetic material. Examples being double stranded, herpes, adenovirus, poxvirus and single stranded, parvovirus. In comparison, RNA viruses, single strand and have 2 different reproduction strategies, being RNA sense(positive) and RNA antisense(negative), an example is paramyxovirus. For retroviruses, the single stranded RNA can’t act as mRNA and is transcribed into DNA by a reverse transcriptase. This DNA is incorporated into the host DNA, so the host makes the viral RNA, for example HIV. Candidates were also expected to briefly mention capsids and viral envelopes. In relation to the second part of the question, candidates were expected to mention that acyclovir inhibits DNA polymerase in the terminal nucleic acid chain and that oseltamivir is a neuraminidase inhibitor which prevents the budding of new viruses from the infected cells. Most candidates had very little knowledge of this area. Syllabus: M2 2a&d 8 Reference: Medical Microbiology and Infection at a Glance, Gillespie &, Bamford pgs 58,59, Basic and Clinical Pharmacology, Katzung pgs791,815

2010A 13: 7 (70%) of candidates passed this question. For a good answer candidates were expected to mention the role of serotonin (5 hydroxytryptamine) is an important neurotransmitter, a local hormone in the GIT and involved in platelet reactions. It is formed from tryptophan and metabolised by MAO (thus the potential effect of a combination SSRI with MAO inhibitor, or concurrent use of several serotonin affecting drugs). Typically the serotonin syndrome is a predictable effect of increased CNS levels of serotonin with a consequence of hyper reflexia, tremor, clonus, skeletal muscle contraction and hyperthermia (but in serotonin syndrome these effects are probably CNS mediated), hypertension, and diarrhoea. The expected list of drugs included the SSRI’s themselves, combination of SSRI’s and MAOI’s, antidepressants (2nd generation [e.g Venlafaxine]), Tramadol (blocks serotonin re-uptake), pethidine, fentanyl, ondansetron, sumatriptan (5-HT1 agonist). Syllabus: M3 References: Basic and Clinical Pharmacology, Katsung pg 264 – 269

2010A 14: 7 (70%) of candidates passed this question. It was expected candidates would outline the underlying principles of ultrasound imaging (reflection, scattering, refraction, and attenuation) and discuss that the basic image is the result of reflection of the transmitted ultrasound wave. Most candidates appreciated that the amplitude of the reflected echo is a function of the acoustic mismatch of the tissues and the angle of incidence and many candidates provided details mathematical descriptions concerning these principles. While high levels of technical details were not required the answer should include a mention of the use a piezoelectric transducer and that an ultrasound beam has 3 dimensions — Axial, Elevation and Lateral. Some comment of the modes of Display (A= Amplitude, M Time Motion, 21), etc) was expected. Extra credit was given for answers that included details regarding limits of depth of penetration (longer wavelength penetrate deeper, but loose image quality with longer wavelengths) and the varying properties of human tissue regarding refraction and attenuation (little refraction (path deviation) in human tissue and air attenuates). Specific comment on the Doppler Effect was required. It was expected candidates would described that it refers to the change in frequency of a sound wave reflected by a moving target and that the reflected frequency differs if moving toward or away. Correctly stating that the reflected Frequency is Higher Towards and Lower Away scored additional marks. Comments concerning obtaining the best Doppler images with lower frequencies (opposite to ultrasound) and colour Doppler attracted additional marks.

2010A 15: 4 (40%) of candidates passed this question Good answers were based around Fick’s Law, Starling forces and the Gibb’s Donnan effect. It was expected that candidates would give Fick’s equation and describe the components : Fick’s Law J = -DA dc/dx Candidates were also expected to describe Starlings equation and the equation for Osmotic Pressure. Starling Equation: Fluid movement = k[(Pc-Pi) – s(πp – πi)] Osmotic pressure : sRT(Ci-Co). Gibb’s Donnan effect and, other mechanisms of transport (filtration and pinocytosis) was also expected for a good answer. Syllabus: A combination C1c2.d, C21 2.e, C2b2.c, C2b2.e References: Pharmacology and Physiology in Anesthetic Practice, Stoelting pgs 294-300, 322- 325

2010A 16: 8 (80%) of candidates passed this question. For a good answer candidates were expected to make some mention of the link between myocardial O2 demand/heart rate/contractility/ This was often overlooked, and candidates who did tended to not respond to what the question was asking, that is “when used to manage myocardial ischaemia” Good answers had a structured response. For a good answer, candidates were expected to mention metoprolol effects of reducing left ventricular wall stress, decreased cAMP/mechanism, decreased heart rate, contractility, resultant decreased O2 demand as well as adverse effects include Bradycardia/ heart block/ hypotension/ bronchoconstriction, etc. In relation to GTN, to mention dilation via nitric oxide, predominantly venodilation, decreased venous return, LVEDP, wall stress, decreased O2 demand and increased supply via coronary vasodilation and adverse effects include hypotension/tachycardia/tolerance/headache. Candidates are reminded that if they are to use non-standard abbreviations, then those abbreviations must be defined somewhere within their answer.

6 (60%) of candidates passed this question For a good answer candidates were expected to define bioavailability and the factors that affected a drugs oral bioavailability. This was often overlooked by candidates. For example, factors affecting absorption (Metabolism by gut flora, drug / drug interactions with in the gut, lipophilicity and hydrophilicity of the drug (drug that are markedly lipophilic or hydrophilic cross the mucus layer or villous membrane poorly), First Pass clearance and sites and mechanism of possible metabolism, to define hepatic clearance, extraction ratio (providing a formula proved helpful to many candidates) and factors that affected hepatic drug clearance. Candidates often lacked an understanding of this area, or failed to mention it. In relation to the second part of the question, candidates were expected to mention the effects of reduced absorption and altered first pass metabolism resulting in uncertain bioavailability of oral drugs. Syllabus: Section II, 2a, b References: Pharmacology, Rang, Ritter and Dale, Chp 7. Goodman and Gilman's the Pharmacological Basis of Therapeutics, Chp 1

2010A 18: 7 (70%) of candidates passed this question Candidates who did well in this question used graphs to describe the various concepts, described normal physiology and covered the breadth of the topic. A good answer made mention of normal values of ICP, it’s variation with respiration and blood pressure and illustrated a trace of the ICP. An explanation of the Monroe Kelly doctrine was expected, CSF production and absorption and it’s relationship to raised ICP as well other compensatory mechanisms for a high ICP (eg displacement of CSF into spinal canal, displacement of venous blood into the jugular veins, rise in ICP leads to ischaemia if the brain. Critical ischaemia invokes the Cushing reflex. Major omissions by candidates was the use of diagrams, description of normal variation and only a superficial knowledge of compensatory mechanisms. Syllabus: G1, 2d,g References: Textbook of Medical Physiology, Guyton, Chp 61

2010A 19: (50%) of candidates passed this question A definition of dead space incorporating subtypes (anatomical, apparatus, alveolar, physiological) was expected. Explanation of measurement methods attracted additional marks. Changes to End-tidal CO2 relative to PaCO2 were relevant to the question. The Bohr equation was stated and variables defined in better answers. Causes of an increased dead space should have been described including hypoperfusion and increased alveolar pressure. Increased dead space primarily results in CO2 retention, unless minute ventilation is increased commensurately. The physiological effects of increased PaCO2, increased respiratory rate and work of breathing are central to the question. Many candidates predicted severe hypoxemia; however the alveolar gas equation was not stated to explain this observation. Hypoxemia is a relatively late effect of significant hypo-ventilation, especially if the patient is breathing supplemental O2. Syllabus: B1e 2c Reference: Nunn’s Applied Respiratory Physiology p310-311. Principles of Physiology for the Anaesthetist, Power & Kam p84-87 5

2010A: 1 (10%) of candidates passed this question This question invited candidates to describe the Urea Cycle in the liver. Urea is a waste product derived from deamination of amino acids and the detoxification of NH3. Many candidates did not outline the major steps in the biochemical process. The kidneys excrete up to 60% of the filtered urea load. The counter-current exchange mechanism in the renal medulla traps urea in the interstitium and generates a concentration gradient, essential for reabsorption of water. The handling of urea by the Loop of Henle and collecting duct, as well as the effect of ADH, should have been discussed. Many candidates did not include sufficient detail in their answers. Syllabus: D1 2c,g. I2a. References: Textbook of Medical Physiology, Guyton p 795, 319.

2010A 21: 1 (10%) of candidates passed this question. A definition based on stretch of the isolated myocyte prior to contraction, and extrapolation to the human heart, was expected. Surrogate measures of preload used in clinical practice needed to be explained and related to the definition (for example, end-diastolic volume and central venous pressure). The Frank-Starling Law was relevant to discussion of the significance of preload to cardiac performance. A diagram illustrating the interaction of important factors would have been helpful in answering this question. At a minimum, detail should have included atrial contractility, diastolic filling time, ventricular compliance, and the determinants of venous return. Better answers included discussion of the effects of afterload, arrhythmias, and valvular pathology. A distinction between the factors determining left and right ventricular preload would have demonstrated a more sophisticated understanding of the physiology. Syllabus: C1c, 2b,c. Reference: Cardiovascular Physiology, Berne and Levy, p64-65.

2010A 22: 8 (80%) of candidates passed this question For a good answer, candidates were expected to take the following approach and content of information. Triggers or initiators of vomiting include: Excessive distension or irritation of the upper GI tract, in particular the duodenum Stimulation of the chemoreceptor trigger zone (CTZ) Directly by certain drugs eg apomorphine, morphin Rhythmic motion of the body stimulating the vestibular labyrinth of the inner ear Cerebral excitation of vomiting by stimuli such as disquieting scenes, odors Neuronal pathways: Stimuli of the GI tract conveyed by vagal and sympathetic afferents to the bilateral vomiting centre within the medulla. Efferent arc from the vomiting centre via the 5th,7th,9th,10th and 12th cranial nerves, and spinal nerves to the abdominal wall muscles (and the diaphragm). Vomiting act: Antiperistalsis as the prelude to vomiting At the onset of vomiting, strong intrinsic contractions occur in both the duodenum and the stomach Partial relaxation of the lower oesophageal sphincter (LOS) Deep breath Raising of the hyoid/larynx to open the upper oesophageal sphincter14 Glottic closure Lifting of the soft palate to close the posterior nares Strong down ward contraction of diaphragm and simultaneous contraction of all the abdominal wall muscles Complete relaxation of the LOS Most candidates answered this question well. Antiemetic drugs and their mechanism of action gained no marks. Syllabus: Q1.2e Reference: Textbook of Medical Physiology, Guyton Pg 768

2010A 23: 3 (30%) of candidates passed this question The femoral artery lies in the femoral triangle. Candidates were expected to describe the content of the triangle. The upper medial and lateral borders of the triangle, the anterior and the posterior relationships of the femoral artery should also be described. The femoral artery is an extension of the external iliac artery and has an important branch, the profunda femoris artery which comes off on the lateral side. Diagrams gained marks as did mention of common anatomical landmarks to locate the artery. Candidates who failed did not have enough knowledge. Description of how to place an arterial line gained no marks. Syllabus: C1d2g References: Grays Anatomy pages 379,526-27,587,497

2010A 24: 3 (30%) of candidates passed this question This was a multi-part question, for which many candidates failed to apportion their time as indicated by the question. Most patients who enter Intensive Care receive opioid analgesia so candidates were expected to have detailed knowledge about the mechanics of action of opiates. For a good answer candidates were expected to mention that opiate agonists produce analgesia by binding to Mu receptors (which are G protein coupled) in the central and peripheral nervous system and spinal cord and their cellular mechanism of action eg presynaptic neurone - close voltage gated Ca channels and prevent neurotransmitter release and post synaptic neurone - hyperpolarise and inhibit post synaptic neurone. The fact that opiates also affect emotional side of pain and cause euphoria which may help with pain perception was often omitted. Mechanism of respiratory depression is mediated via mu receptor. It occurs at normal analgesic doses, and decreases the chemosensitivity of the respiratory centre to PaCO2 Mechanism of constipation results from increased tone and decreased motility of the GIT via action on visceral smooth muscle mediated by intramural nerve plexus and all three opioid receptors. Many candidates had poor organisation and poor knowledge of all aspects of this question. Syllabus: G2d 2b Reference: Pharmacology, Rang and Dale pgs 600-601, Basic and Clinical Pharmacology, Katzung pg 492 VIVAs A. Pharmaceutics B. Pharmacokinetics Dose response curve and basic pharm including ED50, Com & non Comp antagonists C. Pharmacodynamics D. Variability in Drug Response E. Cellular Physiology F. Respiratory ABG, H-H equation, Hypoxaemia, shunt, pulse oximetry G. CVS ABP trace, variation with resp, PPV, myocardial contractility, trnsducer H. Renal I. Body Fluids and Electrolytes J. Acid Base K. Neuro Conc-time cure for IV bolus fentanyl, Vd, t1/2, clearance spinal cord anatomy, LA, pain and meds, ketamine L. Musculoskeletal Sacromere, length-tension relationship, muscle relaxants, malignant hyperthermia, dantrolene M. ANS N. Liver Liver functions, blood supply, drug metabolism, cirrhosis on blood flow, Frusemide O. GIT P. Nutrition and Metabolism Q. Haematology R. Thermoregulation S. Immunology T. Microbiology U. Endocrine NS, mannitol, properties of fluids, pituitary, ADH V. Obstetrics W. Measurement and Monitoring X. Procedures