2008 First Sitting VIVAs

of this drug. Candidates were expected to discuss administration, bioavailability, metabolism, excretion and half life of captopril. Candidates were then asked to compare it to the longer acting ACE inhibitors and discuss their advantages and/or disadvantages in ICU patients. The Viva then explored the candidate’s knowledge of dosing intervals, plasma concentration times curves and effect time curves in relation to ACE inhibitors. Candidates were expected to know why these curves differed, (avid enzyme binding), and thus why the dosing intervals for ACE inhibitors are so long in relation to their half lives. The concepts of Emax, EC50 and Therapeutic index were required. Candidates were then asked to discuss the mechanism of action of ACE inhibitors and their cardiovascular, endocrine, renal and CNS effects. Drug interactions and adverse effects were expected knowledge. Syllabus, General Pharmacology I and II, ACE inhibitors, C2b2f. References : Katzung B.G.'s'Basic and Clinical Pharmacology' Brunton L.L. Goodman and Gilman’s ' The pharmacological basis of Therapeutics'.

In order to pass this viva, candidates were expected to know the distribution of water in different body compartments, the difference in electrolytes composition in different compartments (E1), definition of osmosis and diffusion, and where osmosis and diffusion occurs in the body (B1f and D1), measurement and calculation of osmolality (E1), and how different intravenous fluids will be distributed in different body compartments (E2a). The common deficiency in the candidates’ answers included the difference in electrolytes composition between interstitial fluid and plasma and the reason behind it (F2a), how osmolality can be measured, the presence of an osmotic process in the medulla of the kidney where re-absorption of water occurs through the collecting tubules in the presence of anti- diuretic hormone (D1), and how the fluids will be distributed in the body when different intravenous fluids are administered. Syllabus : E1 2 References : Chapter 1 of Review of Medical Physiology by Ganong Vander’s Renal Physiology for details on this topic.

Candidates were expected to provide a definition for pain, discuss the pathways involved in the transmission of pain signals, and list the common mediators. Additional questions related to sensitisation (peripheral and central) and the Gate Control theory (G2c). Candidates were also asked to compare the pharmacology of local anaesthetics with particular reference to lignocaine and bupivacaine (G2b). As with any question related to pharmacology, candidates were expected to discuss factors listed under “General Pharmacology” in the syllabus: “An understanding of the pharmacology of a drug implies an understanding of the relevant pharmaceutics, pharmacokinetics (including dosage), and pharmacodynamics (including adverse effects and drug interactions).”

Classification of bacteria. Answers included shape, staining, atmosphere and presence and position of spores. Mechanism of antibiotic action. Answers included inhibition of cell wall synthesis and interruption of mRNA/DNA Mechanisms of antibiotic resistance. Answers included production of beta lactamase, impermeable cell wall and developing alternative metabolic pathways. Syllabus M2a Reference: Medical Microbiology and Infection at a Glance; Gillespie and Bamford, pp. 8- 21.

CH2 CH2 NH2 Candidates were expected to recognise ‘phenylethylamine’ and appreciate that it is the precursor molecule for the naturally occurring catecholamines. A brief overview of its structure activity relationships, particularly with respect to substitutions on the phenyl ring, β carbon and amine group (producing dopamine, adrenaline and noradrenaline) was expected. Questioning then progressed to discuss the pharmacology of noradrenaline in more detail. Changing questions,

a period of prolonged vomiting. An arterial blood gas analysis was performed on room air, revealing the following findings. pH 7.59 (7.35 – 7.45) PaCO2 58 mmHg (35 – 45) PaO2 72 mmHg (90 – 110) HCO3- 59 mmol/L (22 – 32) Interpret the findings. This viva tested the candidate’s knowledge of renal physiology related to the control of urinary pH, effects of acetazolamide and frusemide upon metabolic acid base state and respiratory response to metabolic acid base changes. The main points expected for a pass were knowledge of : • Respiratory response to changes in metabolic acid base. Use of correctly labelled graph or common formulae • Renal handling of H+ at the proximal and distal tubules. • Mechanism of HCO3- reabsorption and regeneration • Urinary buffers such as phosphate, ammonia and glutamine • Mechanism of frusemide associated metabolic alkalosis • Affect of acetazolamide on HCO3- The use of illustrations greatly assisted candidates to answer questions within this viva Syllabus : D1-2e, D2a and B1c-2a & b Reference : Textbook of Medical Physiology by A. C Guyton & J. E Hall.

Candidates were expected to identify the major features on a diagram of the foetal circulation. Additional questions concerned the changes to this that occur with birth (Syllabus section P and O1), the haemoglobin oxygen dissociation curve (B1 h), the factors that impact on this and the significance of these changes. Syllabus : P, O1, B1h

What equipment do you require to measure cardiac output via thermodilution techniques?