2016 First Sitting

2016A 01: 61% of candidates passed this question. An opening statement such as oxygen delivery = cardiac output x oxygen content then allowed a more detailed description of the determinants of both oxygen content and cardiac output. It was expected candidates could detail the formula for Oxygen Content = Sat O2 % x 1.34 x Hb x 10 (depending on units) + PaO2 x .003, or x .03 (units) and accurately describe each element. Determinant of cardiac output completed the answer, often starting with CO = HR x SV while discussing the importance of preload, afterload and contractility. Many candidates spent little time on cardiac output which cost valuable marks. Some candidates provided a lot of detail on how oxygen is managed within the lung, the majority of which was not required as part of the answer. Some candidates answered the question describing the oxygen cascade only which was not sufficient to score well.

2016A 02: 29% of candidates passed this question. This topic has been asked previously. It was expected candidates could detail the impact of PEEP on a variety of respiratory parameters such as lung volume, dead space, arterial pO2 and intrapleural pressure. The cardiovascular consequences are well described including the effect on cardiac output, blood pressure and oxygen delivery. The physiological impact of lower levels PEEP in a young healthy person is different to that often seen in the critically ill and this was not appreciated by most candidates.

2016A 03: 33% of candidates passed this question. The majority of candidates gave extensive detail on West’s zones of the lungs and did not describe other parameters that vary from base to apex. Ventilation, resistance, compliance, alveolar and lung size all vary. Some candidates mixed up the changes at the apex versus the base.

2016A 04: 38% of candidates passed this question. It was expected this answer would involve discussion about membrane structure, the unique blood vessel structure (afferent and efferent arterioles allowing a high net pressure to be maintained) and Starlings forces all influencing ultrafiltation. Better answers included comment on mesangial cells contraction to decrease surface area ( caused by angiotensin 2). Details regarding molecular weight cut offs (> 7000 Da are not filtered freely) gained additional credit

2016A 05: 31% of candidates passed this question. Bile is produced by hepatocytes, excretion via cannaliculus and biliary tree. It is stored and concentrated in the gallbladder. Bile contains water, bile acids and bile salts, bile pigments and electrolytes. Some detail was expected regarding each of these and comment on “Primary bile acids”, conjugation with taurine and glycine and production of “bile salts”. It was often not appreciated bacteria in gut produce “secondary” bile acids such as deoxycholate and lithocholic acid. Additional credit was given for discussing “Unconjugated bilirubin” being derived from “heme” component of haemoglobin (85%) is carried via albumin to liver for conjugation via UDP-gluconuryl transferase to “conjugated bilirubin” and that gut bacteria generate water soluble urobilinogen, enterohepatic recycling and excretion in urine. The major role of bile is in lipid, cholesterol and lipid soluble vitamin absorption with a minor role in excretion of bile pigments. It was expected candidates would describe the emulsification of fat via bile salts and lipid micelle formation to facilitate absorption.

2016A 06: 50% of candidates passed this question. The structure of the question outlined exactly what was expected. Platelets are formed in the bone marrow from budding of megakaryocytes. Granulocyte colony stimulating factor and thrombopoeiten play a role in the process and they have a life span of about 10 days. It was expected candidates could describe or draw the structure detailing they have no nucleus, the presence of mitochondria and granules and provide some detail of the important external surface proteins (glycoproteins, ABO, human platelet antigens). Better answers also described the internal microtubule structure and related this to function (allows contraction and shape change). The description of function required detail around the importance of platelet plug formation and the role of adhesion, aggregation and activation in this process.

2016A 07: 62% of candidates passed this question. Significant CVS changes can occur by eight weeks and then progressively over the term of the pregnancy. Structured answers helped candidates avoid missing important areas of the answer. It was expected candidates could detail the major changes such as a 40 – 50% increase in blood volume, a 30 – 50% increase in cardiac output, a slight decrease in blood pressure, the heart size and position changes, the impact of aortocaval compression and alterations in colloid osmotic pressure. Some mention of the changes during labour and delivery was expected noting uterine contraction squeezes blood to maternal circulation (auto transfusion), cardiac output increases (immediately after delivery up by about 60 – 80%) and blood pressure increases (both systolic and diastolic) during labour. Hormones, particularly the effects of foetoplacental production or transformation of hormones, and their cardiovascular effects, especially on total body composition / filling pressures were under explained. The cardiovascular changes at parturition were not well explained.

2016A 08: 29% of candidates passed this question. Drug characteristics that might influence the renal excretion processes include charge, size, solubility, and binding to specific structures or protein. Whether the drug is unchanged versus metabolised can influence these factors. This question tests core knowledge of pharmacology principles and should be answered with equations, graphs or simple clear descriptions of physical and chemical principles. Extended examples and hedged statements about “influencing” without the direction, magnitude and necessary conditions for the influence did not score marks

2016A 09: 50% of candidates passed this question. The ECG device detects and amplifies the small electrical changes on the skin that are caused when the heart muscle depolarizes (0.5 – 2 mV). This is reflected as rises and falls in the voltage between two electrodes placed either side of the heart which is displayed either on a screen or on paper. Usually more than 2 electrodes are used and they can be combined into a number of pairs (For example: Left arm (LA), right arm (RA) and left leg (LL) electrodes form the three pairs LA+RA, LA+LL, and RA+LL). The output from each pair is known as a lead. Each lead is said to look at the heart from a different angle. Electrodes are commonly made of silver or silver chloride components that are attached to the main unit of the machine. Most ECG machines use 12 electrodes. Better answers made mention of the two lead types: unipolar and bipolar. Methods to reduce artefact include improving signal detection (conductive paste, skin preparation (dry, no hair, etc.)) and minimizing external electrostatic forces (common earthed environment, diathermy, etc.,) or patient environment (avoid shivering). The amplifier has three essential functions: High input impedance so as to minimize signal loss and reject interference (50 – 60 Hz), differential amplification, (to amplify the potential difference detected by the skin electrodes), and high common mode rejection (e.g. > 50Hz) to aid eliminating muscle artefact or electrical interference from the power grid.). Vector analysis is not a component of the ECG machine and so was not required to answer the question.

2016A 11: 26% of candidates passed this question. The question asked for a detailed account and the expected marks were spread across a range of systemic side effects, not just the cardiovascular and pulmonary side effects. Many candidates provided irrelevant and lengthy descriptions of the mechanisms of action of amiodarone which was not asked for in the question and gained no additional marks. Most successful answers used an organ systems approach to include the many side effects of amiodarone. Many candidates failed to mention skin side effects, neurological side effects, GI/hepatic side effects, pregnancy and breast feeding considerations, and interactions with other highly protein bound drugs. The predominant mechanism for hypotension with rapid IV administration of amiodarone was incorrectly given in a number of answers.

2016A 12: 38% of candidates passed this question. The question specifically asked for factors that influenced the speed of onset of neuromuscular block. This information is different to the factors that influence neuromuscular blockade in general which was what many candidates focussed on. It was expected candidates would address the main factors known to influence the speed of onset of neuromuscular block: - potency of the agent used (inverse relationship to speed of onset); rate of delivery of the agent to the NMJ (blood flow / muscle group); and mechanism of the neuromuscular block (nondepolarising vs depolarising).

2016A 13: 21% of candidates passed this question. It was expected the answer would start with a definition of afterload and then proceeded to indicate what effects this increase in afterload would have on ventricular end-systolic pressure, ventricular end-diastolic pressure, left atrial pressure, cardiac output, myocardial oxygen demand and myocardial work, coronary blood flow and systemic blood pressure. Most candidates who failed to pass this question submitted answers that were just too brief, only including a small subset of the material required. Very few candidates included any mention of myocardial oxygen demand or myocardial work or the impact upon the cardiac output. A number of candidates included a detailed description of the Sympathetic Nervous System and the Renin-Angiotensin system, material which was not asked for. There were quite a number of incorrect perceptions about what effect a sudden increase in afterload would have on the systemic blood pressure. Candidates who mentioned the baroreceptor response and the stretch receptor response where rewarded with additional credit.

2016A 14: 69% of candidates passed this question. A structure approached works well for “describe the factors …” questions. Better answers provided a definition of ICP, explained the Monro-Kellie doctrine and then detailed the factors which affect the volume of each of the components - cerebro spinal fluid (CSF), cerebral blood flow and brain parenchyma. Some candidates focused only on factors which cause intracranial hypertension and were thus unable to score full marks. Many candidates stated that CSF production was ICP dependant which is incorrect.

2016A 15: 52% of candidates passed this question. Better answers related structure to function. Many answers lacked key anatomical features (for example pores of Kohn, basement membrane, interconnecting walls / alveolar interdependence etc.). There was little understanding of the role and origin of the basement membrane of the alveolus. Some candidates went into detailed discussions of Work of Breathing, respiratory mechanics and the renin-angiotensin system which were not asked for. Answers not reaching a pass mark generally suffered from lacking detail and suggested only a superficial understanding of the area.

2016A 16: 38% of candidates passed this question. Answers to anatomy questions can be generally structured by considered the origin and ending of the structure, the surface landmarks and the relations (medial / lateral / anterior / posterior) and this would have worked well in this question. It was expected candidates could detail course (from origin to end) and relations of subclavian vein. This could then be used to highlight how these features may be relevant to central venous line insertion (proximity of subclavian artery or pleura creating the possibility of inadverant arterial puncture or pneumothorax. Many candidates failed to mention drainage of external jugular vein and thoracic duct and right lymphatic ducts into the subclavian veins. Candidates should ensure diagrams are accurate and well labelled and they use appropriate anatomical terminology rather than vague terms such as “in front”. Care should be taken ensuring accuracy (e.g. some mentioned dome of diaphragm instead of pleura or IVC instead of SVC)

2016A 17: 40% of candidates passed this question. Thyroid hormones consist of thyroxine (T4), tri-iodothyronine (T3) and reverse T3 (rT3). It was expected candidates would briefly describe each of these. T4 is a pro-hormone synthesized from tyrosine in follicular cells of the thyroid gland and represents 80% of body’s thyroid hormone production. It exists in free form, plasma protein bound (albumin and pre-albumin (TBPA) and tissue protein bound thyroid-binding globulin (TBG) and has a half-life around 7 days. Tri-iodothyronine (T3) is the most biologically active thyroid hormone (5 times T4), is produced directly from tyrosine (20%) or in the periphery by conversion of T4 (80%) with a half-life 1.5 days. Reverse T3 (rT3) is formed via peripheral conversion of T4 by de-iodination. A classic negative feedback loop exists to control thyroid hormone secretion. Thyroid Stimulating Hormone (TSH) from the anterior pituitary is controlled by Thyrotropin Releasing Hormone (TRH) from the Hypothalamus via hypothalamic-hypophyseal portal system. Both of these factors are inhibited by elevated levels of T4 and T3. The mechanism of action is by binding to nuclear receptors to effect protein synthesis. Thyroid hormone has a wide variety of physiological effects across many systems including respiratory, cardiovascular, metabolic and growth and sexual function. The answer required candidates to detail both the synthesis and control of thyroid hormones as well discussing the action of thyroid hormones. Few candidates could differentiate the roles and actions of T3 and T4.

2016A 18: 19% of candidates passed this question. Most candidates had at least a basic understanding of mitochondral function although some detail was required for a pass and many did not provide this. A well labelled diagram was used by many candidates and scored marks. Repetition of the same information illustrated on a labelled diagram in subsequent text was not required and did not score additional marks. It was expected answers would cover basic structure (double membrane structure with cristae and enzymes lining the membrane and within the matrix), details of the electron transport chain, the citric acid cycle and beta-oxidation of long chain fatty acids and mention the maternal origin of DNA. Better Answers provided some information on other functions such as production of reactive oxygen species, role in calcium homeostasis and apoptosis, urea cycle, haem synthesis and heat production

2016A 19: 36% of candidates passed this question. A good answer included a definition of temperature and a classification of the methods of measuring temperature such as electrical, non-electrical and infrared. There followed a brief description of the physical principles of thermistors, thermocouples and resistance thermometers; mercury and alcohol thermometers, bimetallic strips; and of infrared methods. Candidates who did well reproduced the content of the chapter on temperature measurement in the recommended text book. Candidates who were not familiar with this material attempted to answer the question by falling back on clinical experience of measuring temperature in different sites or occasionally referring to concepts of thermoregulation. Neither approach gained credit. Some candidates interpreted “methods” incorrectly as "site of measurement" so scored poorly.

2016A 20: 62% of candidates passed this question. Most candidates structured their answer to this question well – they were aware of first pass metabolism and the effect of protein synthesis upon volume of distribution of drugs. Knowledge concerning Phase I and Phase II reactions was frequently inadequate. Many candidates were aware that these processes as well as inactivating or activating drugs resulted in increased water solubility to aid excretion via bile or urine. Few candidates discussed the significance of the large blood flow to the liver or the implications of high and low extraction ratios especially in relation to liver blood flow.

2016A 23: 52% of candidates passed this question. Successful candidates were those who discussed the multiple locations in the vomiting pathway where a drug acts, the receptors involved and discussed 5 or more classes. Several approaches can be taken to this topic. Classification by drug group works well and then allows more detail to be provided about possible receptor activity. For example: Anithistamines: Promethazine H1 ++++ M ++ D2 ++ 5-HT3 Anitcholinergics: Scopalamine H1 + M ++++ D2 + 5-HT3 Benzamines: Metoclopromide H1 + M -- D2 +++ 5-HT3 ++, Neuroleptics: Droperidol H1 + M - D2 +++ 5-HT3 +, 5-HT3 Antagonists: Ondansetron H1 - M - D2 - 5-HT3 ++++, Granisetron H1 ++++ M ++ D2 ++ 5-HT3 ; Glucocorticoids: Dexamethasone H1 - M - D2 - 5-HT3 -, Propofol: GABBA Cannabinoids: direct on vomiting center. An alternative approach involves a discussion of the distribution of receptor sites: nucleus vestibularis H1 M, area postrema (chemoreceptor trigger zone) 5-HT3 D2 M1 H1, nucleus tractus solitarius 5-HT3 D2 M H2 and then discuss which drugs act where. This material has also been previously covered in the viva examination and knowledge of both drug properties and receptor distribution is often required. Few answers detailed relative activity at various receptors types – “+” scale illustrated above would be sufficient to convey an understanding to the examiners.

2016A 24: 60% of candidates passed this question. Candidates who had a structured approach (i.e. pharmaceutical, pharmacokinetic, pharmacodynamic) provided more content and scored higher. Candidates who also approached pharmacodynamic effects in an organ system based approach scored higher. Relating a pharmacokinetic property of midazolam (e.g. volume of distribution or half-life) to a un/desirable attribute e.g. offset of action and accumulation displayed a greater understanding of the question. For many candidates, the description of an ideal drug contained more detail and candidates were not able to adequately state how midazolam compares. VIVAs A. Pharmaceutics B. Pharmacokinetics C. Pharmacodynamics D. Variability in Drug Response E. Cellular Physiology F. Respiratory Resp physio, Abdominal pressure, splanchnic blood flow, terlipressin G. CVS Cardiac output, SV, myocardial contractility, calcium, catecholamines, digoxin Aging physio + pharm, oPioid pharmacology H. Renal I. Body Fluids and Electrolytes fluid flow and related physical principles around turbulent and laminar flow, invasive BP monitoring J. Acid Base buffer systems in the body and the renal handling of acid. Pharmacology, LA. K. Neuro Cerebral physio + pharm, propofol, ketamine Aging physio + pharm, oPioid pharmacology L. Musculoskeletal M. ANS N. Liver O. GIT P. Nutrition and Metabolism Q. Haematology R. Thermoregulation S. Immunology T. Microbiology Antibacterial agents, resistance, dosing rationale for aminoglycosides U. Endocrine blood glucose homeostasis and the pharmacology of insulin V. Obstetrics W. Measurement and Monitoring X. Procedures