2010 Second Sitting

2010B 01: 5 (33%) of candidates passed this question. For a good mark it was expected that candidates define hypoxaemia and, in a structured manner, discuss the physiological causes of early postoperative hypoxaemia. Candidates should always try and begin their answer with a definition of the term that is to be discussed. Many candidates invoked clinical disease related causes and not physiological. This did not score marks. Similarly, factors leading to tissue hypoxia, such as anaemia or low 2,3-dpg were not given marks. Candidates may have done so because they confused “hypoxaemia” with “hypoxia”. Better answers addressed different physiological causes of hypoxaemia, including areas of low V/Q; hypoventilation; increased oxygen consumption; loss of hypoxic pulmonary vasoconstriction and closing capacity exceeding functional residual capacity. Syllabus: B1a2b, B1e,f,g References: Nunn’s respiratory physiology – various sections

2010B 02: 8 (53%) of candidates passed this question. There was a reasonable knowledge of the basics of ABO antigens and antibodies by most candidates. However, many answers seemed to lack perspective of the steps performed in the laboratory to improve immunological safety of transfusion. For a good answer it was expected that candidates also discuss the basis to serological testing and antibody screening. Syllabus: J2a, J2a2i References: Guyton Textbook of Physiology Chp 32 and 35, Australian Red cross Transfusion Medicine manual

2010B 04: 4 (27%) of candidates passed this question. A structured approach to answering this question was important. The principal topics to discuss included the increased cardiac output, increased blood volume, changes in red blood cell mass and protein concentrations, decrease in blood pressure and gravitational effects of the gravid uterus on major blood vessels. Answers benefited by specific details of percentage change and reference to timing of occurrence. Syllabus: O1,2a References: Hemmings Foundation of Anaesthesia: Basic and Clinical Science Pg 823 – 825, Miller Anaesthesia pgs2308-2309

2010B 05: 10 (67%) of candidates passed this question. Most candidates did reasonably well by including aspirin, ADP receptor blockade and glycoprotein 2b/3a blockade in their answers. The best approach to answer this type of question was to use a table with each anti-platelet agent within a column and headings for the rows such as mechanisms of action, adverse effects, mode of elimination and duration of action. Common omissions included the irreversibility of the blockade of the platelet function by many of these agents, renal toxicity and bronchospasm as side effects of aspirin, bone marrow toxicity of ADP receptor blockers, and dipyridamole as an anti-platelet agent. Some candidates classified clopidogrel as a glycoprotein 2b/3a blocker incorrectly and thought clopidogrel has a relative short duration of action on platelet function because of its half-life. Clopidogrel as a prodrug requiring activation by cytochrome P450 and hence significant potential drug interactions were not mentioned by any candidates. Syllabus: J2a,2d References: Goodman and Gillman, The Pharmacological basis of therapeutics Chp 55

2010B 06: 9 (60%) of candidates passed this question. The physiological consequences of tension pneumothorax were in general poorly described. Purely mentioning clinical features (eg distended neck veins) without an associated physiological explanation was not sufficient. Good answers described why tension pneumothorax causes hypoxaemia and hypotension. The cardiovascular mechanism for hypotension and the effect on pulmonary compliance, pulmonary vascular resistance, lung volumes, work of breathing, shunt fraction and carbon dioxide elimination should all have been described. Many candidates used valuable time making comments about tension pneumothorax being a medical emergency requiring prompt assessment and treatment. These comments attracted no marks, as they were not sought in the question asked. Often the clinical need for insertion of a needle/cannula for decompression was mentioned, but again this attracted no marks. Description of the anatomy relevant to the insertion of an intercostal catheter was very variable. Most candidates were able to detail the anatomical layers that the catheter had to traverse in order to gain access to the pleural space, and most explained why the catheter should enter the pleural space just above the rib. However, few accurately described where access to the pleural space should be sought and even fewer could explain why. The British Thoracic Society’s ‘safe triangle’ in the axilla and the anatomical boundaries of this were correctly described by very few candidates. No candidate described an anterior approach through the mid clavicular line, although anatomical details of this approach would have been acceptable. Syllabus: B1c 1 & B1b 2d References: Nunn’s respiratory physiology 4th Ed P423, Ganong Review of Medical Physiology 22nd Ed P688

2010B 07: 6 (30%) of candidates passed this question. This question was not well answered by many candidates. Candidates included advantages of these sedative / analgesic agents in their answers when they were not asked for in the question. The best approach to answer this question is to use a table listing their potential adverse properties in categories such as pharmaceutical and chemical properties, pharmacodynamic properties in different body systems, and pharmacokinetics. The common weaknesses observed included the side effects of ketamine, including its side effects on intracranial pressure, myocardial contractility and oxygen consumption, and hallucinations or delirium. Some adverse properties of propofol including bacterial contamination and pain on injection were also not well covered by many candidates. Syllabus: G2a,2a References: Goodman and Gilman The pharmacological basis of therapeutics 11th edition p350- 352

2010B 08: 7 (47%) of candidates passed this question. Most candidates were able to detail how insulin allowed influx of glucose into insulin dependent cells, in combination with potassium. Good candidates were able to explain how the inability to produce insulin allowed hypovolaemia and electrolyte loss, with the ensuing tachycardia and hypotension. Few candidates mentioned insulin’s action on hormone sensitive lipase (HSL), and that deficiency of insulin leads to increased activity of this enzyme. The fact that when insulin is not produced, the liver cells carry out β-oxidation of the fatty acid (released peripherally by the action of HSL) releasing acetyl CoA which is coalesced into acetoacetic acid was mentioned by only a few. However, the fact that ketone bodies in the form of acetoacetic acid, β-hydroxybutyric acid and acetone accumulate and cause a metabolic (anion gap) acidaemia, appeared to be well known. Few, went on to describe that a compensatory respiratory alkalosis will be generated and detail how and why this occurred. Syllabus: N2a&b, E2,F1, C1g 2b References: Guyton and Hall Textbook of Medical Physiology 10th Ed, pg 888

2010B 09: 8 (53%) of candidates passed this question. For a good answer candidates were expected to describe physical barriers, innate and acquired immunity. Physical barriers such as skin, mucous membranes, normal flora, secretions, etc were poorly covered. Aspects of immunity such as cellular and humoral were better covered but often lacked a sufficient depth of knowledge. Syllabus: M2a References: Guyton and Hall Textbook of Medical Physiology, Chp 33 and 34

2010B 12: 4 (27%) of candidates passed this question. This question sought knowledge of an important and basic area of physiology that applies to many circumstances encountered in daily intensive care practice. For a good answer candidates were expected to mention that bicarbonate is freely filtered, its fate along the nephron and that it is not normally found in the urine. Mechanisms by how it is reabsorbed and generated along the different segments of the nephron were expected to be described in some detail. The last part of this question relating to hypoventilation was poorly answered. For a good answer candidates were expected to mention that Hypoventilation results in an increase in arterial PCO2 that readily diffuses into tubular cells resulting in increased intracellular H2CO3 and subsequently bicarbonate, that is reabsorbed, and H+ that is secreted. Syllabus: D1 Renal Physiology, 2e, 2k References: Ganong, Review of Medical Physiology, Ch 39 and 40

2010B 13: 3 (20%) of candidates passed this question. This question was poorly answered by candidates. Basic aspects, which were critical for a good answer such as definitions were often inaccurate. Terms such as ‘amount’ or ‘content’ were commonly used without provision of units, when mass or pressure was required. The importance of temperature was often not mentioned. Most candidates identified the importance of the upper airway in humidification but did not describe details of this process and failed to discuss the events occurring during expiration. Syllabus: R2c, S2e, B1k,2d References: Davis, Basic Physics and Measurement in Anaesthesia, pgs 145-6, Nunn’s respiratory physiology pgs 12, 19, 166-7

2010B 14: 5 (33%) of candidates passed this question Most candidates correctly identified the diaphragm, intercostals, abdominals and accessory muscles as important. However, the majority of candidates omitted to mention the muscles of the larynx, pharynx and airway and thus failed to achieve a good score. Good answers included a detailed description of their function including differentiating between external and internal intercostals. Syllabus: B1b,1, 2a References: Nunn’s respiratory physiology P76 – 80 and West, Respiratory Physiology: the Essentials, pgs 93 - 95

2010B 15: 5 (33%) of candidates passed this question. This is core knowledge and it was expected candidates would describe physiological consequences accurately. Good answers included a definition of FRC and correct value. A number of candidates omitted this. It was also expected that candidates mention that as FRC falls, alveolar closure occurs, lung compliance decreases and airway resistance increases work of breathing increases, pulmonary vascular resistance, and thus right ventricular afterload increases. Many candidates described alveolar closure as causing increased dead space ventilation rather than altered V/Q. Syllabus: B1e References: Nunn’s respiratory physiology, pages 51-56

2010B 16: 4 (27%) of candidates passed this question A number of candidates discussed the distribution of potassium in the body and its role in membrane potentials. This was not asked for. Common omissions were a lack of comment on glomerular filtration, a lack of detail regards mechanisms of potassium transport in various parts of the glomeruli and failing to discuss control mechanisms other than aldosterone. Syllabus: E1,2b, D1,2f References: Guyton and Hall Textbook of Medical Physiology, Chp 29

2010B 17: 4 (27%) of candidates passed this question This question required candidates to provide an answer that integrates their knowledge of various aspects of cardiovascular physiology. Cardiac reflexes are fast-acting reflex loops between the heart and central nervous system that contribute to regulation of cardiac function and maintenance of physiologic homeostasis. This was often overlooked by many candidates. For a good answer it was expected that at least the chemo and baroreceptor, Bainbridge (elicited by stretch receptors located in the right atrial wall and the cavoatrial junction), Cushing (result of cerebral medullary vasomotor centre ischemia), oculocardic (provoked by pressure applied to the globe of the eye or traction on the surrounding structures), Bezold-Jarisch (responds to noxious ventricular stimuli sensed by chemoreceptors and mechanoreceptors within the LV wall) reflexes be mentioned and described.

2010B 18 : 1 (7%) of candidates passed this question. This is another very important, and not an infrequently seen, aspect of almost daily intensive care practice which was poorly understood by candidates. For a good answer candidates were expected to outline pharmacological (eg alteration in drug behaviour), physiological (eg shivering, vasoconstriction, impaired coagulation, etc) consequences. Additional points such as poor wound healing, discomfort also attracted a small number of marks. Candidates would have benefited by illustrating their answers with examples, eg prolonged recovery from anaesthesia and duration of neuromuscular blokade. Syllabus: L2e References: Hemmings, Foundation of Anaesthesia: Basic and Clinical Science pg 815

2010B 20: 8 (53%) of candidates passed this question. As the general population ages, and many elderly are admitted to intensive care units and/or encountered during intensive care ward consultations, this topic is highly relevant. Unfortunately candidate performance generally lacked sufficient depth and breadth in this area. Good answers were expected to mention changes in body compartments (eg total body water, lean body mass decrease, etc), consequences of changes in organ function (eg deteriorating glomerular filtration rate, reduced liver blood flow, etc), alterations in protein levels and binding, increased likelihood of drug interactions and the influence of disease states. Syllabus: Generic Pharmacology III2d. References: Millers’ Anaesthesia Chp 19

2010B 21: 8 (53%) of candidates passed this question. This was another important, relevant and essential aspect of basic physiology, for which candidates tended to lack sufficient breath and depth of the required knowledge. For a good answer candidates were expected to mention liquids empty much faster (and in an exponential fashion) than solids (which have a linear pattern), rate of emptying depends on the pressure gradient generated by the antrum against pyloric resistance. Antral pump activity is of most importance and that it is influenced by signals from both the stomach (eg distension) and the duodenum (volume, osmolarity, pH) and humoral factors (gastrin, cholecystikinin, secretin) and nervous stimulation (general parasympathetic nervous stimulation enhances gastric motility and sympathetic stimulation opposes it). Syllabus: Q2d References: Guyton and Hall Textbook of Medical Physiology, Chp 63, Power and Kam, Principles of Physiology for the Anaesthetists, pg 193

2010B 23: 4 (27%) of candidates passed this question. To achieve a good pass in this question, candidates needed to outline the ionic events associated with Phase 0 to phase 4 of the ventricular action potential followed by a description of excitation – contraction coupling. The second part of the question was best answered using a ventricular pressure-volume loop and overlaying the phases of the ventricular action potential. Description of the ionic events associated with the action potential phases was generally well done, but this was as far as many answers went in answering this question. Few candidates included a description of excitation-contraction coupling in there answer and few candidates considered an answer to the second part of the question. The use of illustrations helped answer this question. Syllabus: C1b References: Guyton and Hall Textbook of Medical Physiology, Chp 9

2010B 24: 10 (67%) of candidates passed this question. There are many valid lists that can be used as a template to answer this question. One such list might broadly classify antihypertensive agents into sympatholytic agents, vasodilators, calcium channel antagonists, renin-angiotensin inhibitors and diuretics. Within each of these categories are a variable number of sub classes, for example diuretics might include thiazides, loop diuretics and potassium sparing diuretics. A good answer would include such a listing with a brief description of the mechanism of action with respect to the antihypertensive effect and the name of a typical drug that acts in the manner described. Most candidates were able to generate such a list and populate it as required by the question, thus being rewarded with good marks. Poorer answers lacked any logical classification system and were merely a random list of antihypertensive drugs and their actions. Candidates are reminded that organisation within an answer helps in answering the question and achieving marks. Syllabus: C2b,2e References: Berne & Levy, Physiology, Ch 2-3 VIVAs A. Pharmaceutics B. Pharmacokinetics Basic pharm, opioid drugs C. Pharmacodynamics D. Variability in Drug Response E. Cellular Physiology F. Respiratory Arterial oxygen tension, resp physio and oxygen measurement G. CVS beta blockers, basic pharm, dose response curves Cardiovascular physiology, CO, SW, V loops,Rt heart pressures and function, BP measurement H. Renal Renal circulation, blood oxygen tension in kidney, autoregulation, GFR and determinants I. Body Fluids and Electrolytes J. Acid Base K. Neuro Basic pharm, opioid drugs Cerebral blood flow, relationship with PaCO2, Benzos L. Musculoskeletal M. ANS N. Liver O. GIT P. Nutrition and Metabolism Q. Haematology Coagulation cascade, Heparin pharm R. Thermoregulation S. Immunology T. Microbiology U. Endocrine V. Obstetrics W. Measurement and Monitoring X. Procedures IJV cannulation, basic statistics