2017B

2017 (2nd sitting)

Question 1

Question

Compare and contrast the pharmacology of ibuprofen and paracetamol.

Example answer

Examiner comments

65% of candidates passed this question.
This was a standard compare and contrast question of common analgesic pharmacology and it
was generally well answered. The use of a table ensured all areas were covered including
class, indications, pharmaceutics, mode of action, pharmacodynamics, pharmacokinetics and
adverse effects. The uncertain nature (and possibilities) of the mechanism of action of
paracetamol was alluded to in better responses.
Details of the comparative pharmacokinetics were often lacking. Answers should have included
a comment on first-pass effect, the significance of the difference in protein binding and the
details of metabolism, particularly paracetamol. Metabolism limited to "hepatic metabolism and
renal excretionâ€ gained no marks as better responses were more detailed and clearer about the
differences between the two drugs. Knowledge of metabolism at therapeutic doses and the
effect of overdose were expected. Better answers included potential interactions with other
drugs (e.g. warfarin) and contraindications to the use of these drugs.

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Question 2

Question

Outline the daily nutritional requirements, including electrolytes, for a normal 70 kg adult.

Example answer

Examiner comments

21% of candidates passed this question
The provision of nutrition is a core skill in ICU. An understanding of its key elements enables prescription and modification. However, most answers lacked detailed information which is available in the standard texts. Better responses outlined the caloric requirements including each major element (water, carbohydrate, fat and protein) along with the caloric values and potential sources. Essential amino acids, fatty acids, fat and water-soluble vitamins were expected. A list of the requirements for major electrolytes and some of the trace elements were expected. Some candidates seemed to confuse calories, kilocalories and kilojoules.
Some answers did not provide the nutritional requirements, as asked, but instead discussed the
fate of the nutrients; hence did not score marks. Candidates are reminded to read the question
carefully.

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Question 3

Question

Describe the factors that determine the filtered load of a substance at the renal glomerulus.

Example answer

Examiner comments

67% of candidates passed this question
A good place to start was with the correct equation for a filtered load and a description of the
components. Better answers described the components and how they differ and change over
the glomerulus. Many candidates usefully based answers around the Starling forces.
A summary of factors including the role of plasma concentration, protein binding, molecular size
and charge was required to pass. Many answers gave examples for the effects of size and
charge and relate endocrine responses to specific alterations in arteriolar tone and how this
affected filtration. A detailed discussion of cardiovascular and endocrine responses to
hypovolaemia was not required.
Some candidates confused clearance with filtered load. Candidates are reminded to write
legibly - especially where subscripts and Greek letters are used. Directional arrows (if used)
should correlate with text.

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Question 4

Question

Describe how interstitial fluid recirculates to the vascular system.

Example answer

Examiner comments

10% of candidates passed this question
Candidates had a limited understanding of this area of the syllabus. It was expected that answers would describe important concepts including the anatomy of venous structures, valves and lymphatics, permeability and factors which influence permeability. A description of hydrostatic forces, other pressures involved, and the role of osmotic and electric forces were required.

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Question 5

Question

Compare and contrast unfractionated heparin with low molecular weight heparin.

Example answer

Name	HMWH (heparin)	LMWH (enoxaparin)
Class	Anticoagulant	Anticoagulant
Indications	Prophylactic and therapeutic anticoagulation (e.g. AF, DVT, PE, ACS etc)	Prophylactic and therapeutic anticoagulation (e.g. AF, DVT, PE, ACS etc)
Pharmaceutics	MW = 5,000-25,000 Da Clear solution for injection	MW = 5,000 Daltons Clear solution for injection
Routes of administration	IV, SC	SC (main), can also be given IV
Dose	Prophylactic: 5,000 IU BD-TDS Therapeutic: infusion (APTT target)	Therapeutic: 1mg/kg BD or 1.5mg/kg OD Prophylactic: 20-40mg OD
pKA
Pharmacodynamics
MOA	Heparin binds to antithrombin 3 > conformational change > increases affinity for inactivating thrombin (factor IIa) and Factor Xa	Enoxaparin binds to AT-3 > conformational change > increases affinity for inactivating factor Xa (and weakly factor IIa - 4x less activity)
Effects	Anticoagulation	Anticoagulation
Side effects	HAEM: increased risk of haemorrhage, bruising, HITTS (higher than LMWH)	HAEM: increased risk of haemorrhage, bruising, HITTS (lower than HMWH)
Pharmacokinetics
Onset	Immediate (IV), 30 mins (SC)	Peak effect 3-4 hrs post SC injection
Absorption	PO bioavailability - 0% Variable SC absorption - less predictable response	PO bioavailability - 0% >90% bioavailability post SC injection
Distribution	VOD = 0.1L/kg Lipid solubility: low Protein binding: high Does not cross BBB / placenta	VOD = 4.3L Protein binding: does not bind to heparin binding proteins
Metabolism	Reticuloendothelial system	Minimal hepatic metabolism
Elimination	Renal elimination (very minimal) - hence preferred in renal failure T 1/2 = 1 hrs	Renal elimination of active and inactive metabolites T 1/2 = 6-12 hours
Special points	Reversal: protamine (1mg = 100IU) - 100% Monitoring: APTT level	Reversal: protamine (<75% efficacy) Monitoring: Anti-Xa level

Examiner comments

68% of candidates passed this question.
This question was generally well answered and lent itself well to a tabular format. Expected information included an approximation of the molecular weights / significance of the differences in size and therefore its mechanism of action. Other pertinent areas to mention included pharmacokinetic differences and its use in renal failure, side effect profiles, monitoring, predictability of response and reversibility for the two agents.

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Question 6

Question

Describe the effects of Ventilation/Perfusion (V/Q) inequality on the partial pressure of oxygen (PaO2) in arterial blood.

Example answer

Examiner comments

48% of candidates passed this question
Overall answers lacked sufficient detail on a core area of respiratory physiology. Answers expected included a description of V/Q ratios throughout the lungs and an explanation of how V/Q inequality lowers PaO2.

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Question 7

Question

Compare and contrast the sympathetic and parasympathetic nervous systems.

Example answer

Examiner comments

75% of candidates passed this question
This question was generally well answered A table or diagram lent structure to the answer. More complete answers included details on the function, anatomy, a description of the pre- and post-ganglionic fibres, ganglia, receptors and neurotransmitters involved.
Whilst most commented on â€˜fight or flightâ€™ for the SNS and â€˜rest and digestâ€™ for the PNS, no candidate observed that the SNS is a diffuse physiological accelerator and that the PNS acts as a local brake. No candidate included the fact that the SNS supplies viscera and skin whilst the PNS only supplies the viscera. Many candidates failed to make reference to the fact that the postganglionic SNS receptor is G protein coupled and the PNS postganglionic receptor is Gcoupled on muscarinic receptors but operates an ion channel when nicotinic.
Candidates may have scored higher if they had provided a little more detail in their answers.

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Question 8

Question

Classify calcium channel antagonists and give one example of each class (30% of marks). Describe the pharmacology of Nimodipine including important drug interactions (70% of marks).

Example answer

Examiner comments

19% of candidates passed this question
The classification was done well. Most candidates demonstrated that they had a structure for a â€œdrugâ€ question, but were often challenged to fill in the detail of that structure and failed to deliver enough content to secure a pass. Many candidates wrote a generic answer for calcium channel blockers instead of the specifics of nimodipine.
Frequently the pharmacokinetic data recounted was incorrect. Candidates failed to distinguish between absorption and bioavailability. The difference between oral and intravenous dosing was often omitted. Few answered the section on important drug interactions.

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Question 9

Question

Briefly outline the formation, absorption, distribution, role and composition of cerebrospinal fluid

Example answer

Examiner comments

44% of candidates passed this question
The question spelt out very specific areas of CSF physiology to outline and the marks were evenly distributed among these areas. The candidates who did not pass this question usually did not provide enough detailed information. Details of the production and absorption of CSF were commonly lacking. The majority of candidates correctly described the composition of CSF; indicating whether a particular variable was higher or lower than in plasma, scored less marks than more specific information.

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Question 10

Question

Compare and contrast two methods of measuring cardiac output.

Example answer

Examiner comments

35% of candidates passed this question
Good answers began with a definition of cardiac output. For each method, it was expected that
candidates discuss the theoretical basis, equipment, advantages and disadvantages / sources
of error and limitations. Additional marks were awarded when an attempt was made to compare
and contrast the two methods (often helped by the use of a table).

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Question 11

Question

Describe the pharmacology of propofol

Example answer

Examiner comments

76% of candidates passed this question.
A structured approach proved a good basis to answer this question. It was expected candidates
would outline the uses such as anaesthesia, more prolonged sedation or possible additional roles in patients with seizures or head injuries. Discussion of the presentation and pharmaceutics, including a comment on antibacterial preservatives or lack thereof was expected. The mechanism of action should have been described. It was expected candidates could provide an indication of the usual dose (and how it differs in the more unwell / elderly patient population). A maximal rate and possible toxicity was expected.
A discussion on the pharmacodynamics by major organ systems was expected and credit was given for additional comments about hyperlipidaemia, urine colour changes or metabolic alterations. It was expected that candidates would mention propofol infusion syndrome at some point in their answer with some mention of clinical features or pathophysiology.
The important aspects of its pharmacokinetics should have been mentioned (high protein binding, large volume of distribution, termination of effect by redistribution, hepatic metabolism, context sensitive half life). A mention of adverse effects would complete the answer.

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Question 12

Question

Compare and contrast aspirin and clopidogrel

Example answer

Examiner comments

68% of candidates passed this question
Both of these commonly used agents are level A in the syllabus and thus a high level of detail was expected. Marks were awarded in the following areas - pharmaceutics, mechanism of action, pharmacokinetics (PK) and side effects. For the PK parameters a general description rather than exact values was sufficient (i.e. â€˜high protein bindingâ€™ rather than â€˜98% protein boundâ€™). It was expected that candidates would mention the fact that clopidogrel is a pro-drug and the factors which influence its conversion to the active form. Additional marks were awarded for well-structured answers which attempted a comparison between the two drugs (helped by the use of a table).

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Question 13

Question

Compare and contrast the pharmacology of intravenous fentanyl and morphine

Example answer

Examiner comments

68% of candidates passed this question
Good candidates produced a well-structured answer and highlighted the differences between the two drugs. It was important to include the dose, potency, time course of effect of both agents, and differences in pharmacokinetic and pharmacodynamic effects. Candidates should have specific knowledge of these important drugs. Many candidates failed to focus the question on intravenous fentanyl and intravenous morphine as asked. No marks were given for information about other routes of administration.

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Question 14

Question

Explain the mechanisms responsible for the cell resting membrane potential (60% of marks) and describe the Gibbs Donnan effect (40% of marks)

Example answer

Examiner comments

35% of candidates passed this question.
A good answer included a definition of the resting membrane potential and a clear description of
the factors that determine it. Explanation of these factors should have included a detailed description of the selective permeability of the membrane, electrochemical gradients and active transport mechanisms. Answers should demonstrate awareness of the Nernst equation and the Goldman-Hodgkin-Katz equation. These were often confused, sometimes with the GibbsDonnan effect. Descriptions of the Gibbs-Donnan effect generally lacked detail and understanding. The better answers included a definition and discussed in detail the influence of non-diffusible ions (intracellular proteins) on the distribution of diffusible ions

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Question 15

Question

List the properties of an ideal inotrope (50% of marks). How does adrenaline compare to these ideal properties (50% of marks)?

Example answer

Examiner comments

98% of candidates passed this question
Many candidates scored very highly on this core topic. It was expected information be included
on pharmaceutics, cost, availability and compatibilities. Relevant pharmacokinetics (onset/offset, titratability) and pharmacodynamics (including relevant receptors, nuances of haemodynamic effects e.g. effect on diastolic pressure and regional perfusion) should have been detailed. Adverse effects and safety profile (e.g. use in pregnancy, therapeutic index) should also have been included. Good answers were structured and highlighted differences with specific facts and data

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Question 16

Question

Classify and describe adverse drug reactions with examples of each.

Example answer

Adverse drug reaction

Noxious or unintended effect associated with drug administration at a normal dose
- This is different from an adverse drug event which is the occurrence of any untoward event following administration of a drug (thus all ADRs are ADEs)
Risk factors: extremes of age, polypharmacy, genetic variability (e.g. CYP enzymes), concurrent illness (renal, liver, cardiac impairment), pregnancy

Classification of adverse drug reactions

Reaction type	Mechanism	Features	Example/s	Management
Type A 'Augmented'	Related to the pharmacological action of the drug (dose related)	- Common - Predictable - Low mortality	- Bleeding related to administration of anticoagulants (e.g. heparin)	Reduce or withhold
Type B 'Bizarre'	Non-dose related (any exposure > reaction)	- Rare - Unpredictable - Not related to action of drug - High mortality	Anaphylaxis to penicillin's	Withhold and avoid future use
Type C 'Chronic'	Due to the cumulative dose received (dose and time related)	- Uncommon	Adrenal suppression with prolonged course of corticosteroids.	Reduce or withhold (may need to happen over time)
Type D 'Delayed'	Does not appear for a prolonged period after exposure (time related)	- Uncommon - Usually also dose related	Tardive dyskinesia from long term use of typical antipsychotics	Can be intractable
Type E 'End of treatment'	Withdrawal reactions from drug cessation	- Uncommon - Fast onset	Seizures from abrupt withdrawal of benzodiazepines or alcohol	Reintroduce + withdraw slowly
Type F 'Failure'	Unexpected failure or decrease in efficacy	- Common - Dose related	Ineffectiveness of clopidogrel (non metabolisers)	Increase dosage / alternative therapy

Examiner comments

44% of candidates passed this question.

Candidates should have provided a definition of adverse drug reactions and then a classification. There are at least two widely accepted systems for classification, either was acceptable; though candidates often switched between both which led to a less structured answer. The WHO classification is comprehensive and logical, though both Rang and Dale and Goodman and Gilman also have sections on this topic. Common errors were the citing of examples with the incorrect mechanism, describing only drug interactions rather than all adverse reactions and focussing the answer on the 4 hypersensitivity reactions which could only score a low mark. Some candidates confused drug errors with adverse reactions

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Question 17

Question

Define and explain damping, resonance, critical damping and optimum damping.

Example answer

Examiner comments

25% of candidates passed this question
Concise definitions were required with a clear explanation of the underlying physical principles.
The response time of the system, degree of overshoot, effect on amplitude, noise and ability to
faithfully reproduce frequencies relative to the natural resonant frequency were important considerations.
Many candidates interpreted the question as relating to arterial lines and a detailed discussion
of the components and characteristics of an intra-arterial catheter and transducer system did not
attract marks.

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Question 18

Question

Draw and numerically label, on a spirogram, the lung volumes and capacities of a 30 kg child.

Example answer

Examiner comments

87% of candidates passed this question.
This core respiratory physiology topic was well answered by most candidates. Candidates generally were able to draw a spirogram. A common omission was inspiratory capacity.

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Question 19

Question

Describe the physiology of a vasovagal syncope

Example answer

Examiner comments

41% of candidates passed this question
Generally, there was a lack of knowledge about this topic with many candidates confusing vasovagal syncope with a Valsalva or orthostatic hypotension. A â€œvasovagalâ€ is from excessive autonomic reflex activity in contrast to orthostatic hypotension which is a failure of the autonomic reflex response.
A good place to start was with a description of vasovagal syncope, also known as neurocardiogenic syncope. It is benign, self-limiting and caused by an abnormal or exaggerated autonomic response to various stimuli (which should have been listed). The mechanism should have been described including the various receptors involved

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Question 20

Question

Outline the functions of the liver

Example answer

Examiner comments

86% of candidates passed this question
This is a very straightforward question testing breadth of knowledge rather than depth. It was
well answered by the majority of candidates.

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Question 21

Question

Describe and compare the action potentials from cardiac ventricular muscle and the sinoatrial node.

Example answer

Examiner comments

95% of candidates passed this question
This topic was well understood and answered by most candidates. Some candidates had a good knowledge base but missed out on potential marks by failing to compare and contrast. A diagram outlining the various phases was a useful way to approach the question.

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Question 22

Question

Define bioavailability. Outline the factors which affect it.

Example answer

Examiner comments

33% of candidates passed this question
Many candidates did not specify that bioavailability describes the proportion/fraction of drug
reaching the systemic circulation (to differentiate from the portal circulation). Some candidates considered only factors impacting absorption from the GI tract or stated that bioavailability related only to orally administered drugs. Candidates failed to provide an equation, or got equations or graphs wrong. Nearly all candidates failed to provide a comprehensive list of factors affecting bioavailability.

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Question 23

Question

Outline the anatomy of the internal jugular vein relevant to central venous line cannulation (80% of marks). Include important anatomical variations (20% of marks).

Example answer

Internal jugular vein

Originates at the jugular bulb (confluence of the inferior petrosal and sigmoid sinus')
Exits skull via the jugular foramen with CN IX, X, XI
Descends inferolaterally in the carotid sheath (initially posterior > lateral to carotid artery with descent)
Terminates behind the sternal end of the clavicle where it joins with the subclavian vein to form the brachiocephalic vein
Tributaries: facial, thyroid, pharyngeal, lingual veins
Usually larger on the right

Relations

Anterior to IJV: SCM, lymph nodes, CN XI
Posterior to IJV: scalene muscles, lung pleura, lateral mass C1, vagus (poster-medial)
Inferior/at termination: pleura (which extends ~2cm above clavicle)
Medial: vagus, carotid artery

Variations

Stenosis, complete occlusion, aneurysms, absence
Variation in relation to carotid (e.g. anterior) in up to 1/4 cases

Ultrasound anatomy

Often lateral to carotid (not always) and often larger than carotid
Unlike carotid: Non pulsatile, thin walled, compressible
Doppler flows can also be helpful.

Surface anatomy

Identify triangle between the clavicle and two heads of SCM
Palpate carotid
Puncture lateral to carotid artery at 30 degree angle
Aim caudally towards ipsilateral nipple

Examiner comments

14% of candidates passed this question.
Good answers were structured including origin, termination, tributaries, relationships, surface
anatomy and common variations.
Factual inaccuracies were common and there was confusion about the relations of the internal
jugular vein. Many candidates did not mention the changing relationship between the internal
jugular and the carotid artery as they travel through the neck or the changes that result from
repositioning for insertion. Many candidates also forgot to mention surface anatomy and a
number talked about ultrasound and views used for insertion of central lines. Common
omissions included the origin, tributaries, relationship with the correct cranial nerves and the fact
that it is usually larger on the right. Almost nobody mentioned the relationship to the pleura.

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Question 24

Question

What is functional residual capacity (30% of marks)? Describe two methods of measuring functional residual capacity (70% of marks).

Example answer

Examiner comments

59% of candidates passed this question
Most candidates could state 2 methods of measuring FRC. Some candidates (especially for
nitrogen wash out) failed to provide enough information e.g. statements such as "if the amount
of nitrogen is measured then FRC can be derived" were insufficient to score many marks.

2017 (2nd sitting)

Question 1

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Question 2

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Question 3

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Question 11

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Question 12

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Question 13

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Question 14