SAQ 2017.2 Question 6

Describe the effects of morbid obesity on the respiratory system.

The material to answer this is scattered through the recommended texts and most of it can be deduced if you have a reasonable general understanding of respiratory physiology. It’s also nicely summarised in Foundations on Anesthesia : Basic Sciences for Clinical Practice by Hemmings and Hopkins Chapter 71 if you can find a copy.

It’s Friday so instead of making this a TRUE/FALSE post I’ll talk about answering an SAQ using this question as the base.

One of the examiners gives the advice :


This is great advice. Unfortunately a lot of exam answers have step 2 omitted. Step 2 is very important, and in the heat of the exam it is easy to forget it. I have had a sneak preview of the exam report and for this question the marking examiner commented that ‘Notably there were no marks achieved for describing the metabolic, endocrine or cardiovascular effects of morbid obesity’.

I would build on his advice and say an even better answer would be created by :


For example with this question you could write : (note use of point form, common abbreviations and clear arrows showing direction of change – all acceptable and even encouraged by examiners)

  •  FRC ↓ or FRC ↓ so oxygen store ↓ esp with pre-oxygenation (does this decrease in FRC have other implications too?)
  • ↑ pulmonary blood volume or  ↑ pulmonary blood volume → ↓ compliance → ↑WOB   (this change in blood volume is also relevant to gas exchange, why?)
  • diaphragm displaced cephalad → why is this relevant to the preload of this muscle?





SAQ 2017.2 Question 5

Outline the factors which influence the time taken for loss of consciousness with an inhalational induction of anaesthesia.

Loss of consciousness will be faster with a smaller FRC     TRUE/FALSE

Loss of consciousness will be faster in a patient who is anxious and struggling    TRUE/FALSE

Loss of consciousness will be faster with a more soluble anaesthetic agent    TRUE/FALSE

Loss of consciousness will be faster with an increased cardiac output    TRUE/FALSE

Benzodiazepine premedication may speed the process in some patients, and slow it in others    TRUE/FALSE



SAQ 2017.2 Question 4

Describe the generation and features of a normal awake EEG (15)

Briefly discuss the processing performed by EEG monitors (BIS/Entropy) to produce a single dimensionless number from the EEG (10)

This material is adequately covered in a couple of the books on the recommended reading list – Magee & Tooley, and Davis & Kenny. There are some better review articles around, and a mob of FANZCAs in Cairns paralysed each other sans anaesthesia using BIS monitoring and published it (British Journal of Anaesthesia, Volume 115, Issue suppl_1, 1 July 2015, Pages i95–i103).

The EEG measures action potentials     TRUE/FALSE

As a patient becomes more deeply anaesthetised their EEG drops in amplitude and frequency    TRUE/FALSE

Burst suppression becomes more pronounced with deeper levels of anaesthesia    TRUE/FALSE

Phase coherence becomes more pronounced with deeper levels of anaesthesia    TRUE/FALSE

Frowning will increase RE (response entropy) more than SE (state entropy)    TRUE/FALSE

SAQ 2017.2 Question 3

a) Describe the immediate cardiovascular responses to the sudden loss of 30% of the blood volume in a healthy awake person
b) How are these responses different if the patient is undergoing anaesthesia with sevoflurane?

The decrease in blood volume will be detected by the high pressure baroreceptors in the atria    TRUE/FALSE

The response will be mediated by the cardiovascular centre in the medulla    TRUE/FALSE

There will be arterial but not venous constriction    TRUE/FALSE

Sevoflurane will impair contractility    TRUE/FALSE

Sevoflurane will depress baroreceptor signalling    TRUE/FALSE


Evolution of an SAQ

A colleague wrote some evolution of a viva posts so I thought I’d give some insight on the development of an SAQ.

An SAQ is initially written by an individual and placed into a bank of questions. Once we decide to include that question in a paper a group of us will look at it and try to remove any ambiguity. An answer grid is then written (often not by the original author). An answer grid comprises the points we think address the question, with weighting to more important points and often with weighting towards answers which demonstrate understanding. Marks are allocated such that an excellent candidate could achieve full marks well within 8 minutes. Other examiners will then inspect and edit the grid – we are not expecting you to guess the thought processes of one individual. The grid is not set in stone, if a candidate writes correct and relevant points in their answer they will be given marks even if they are not in the final grid. The question is often re-edited at this stage to take out any more ambiguity or to to narrow or widen its breadth.



SAQ 2.17 Question 2

Using a labelled diagram, describe how a mechanical (non-cassette) variable bypass vaporiser achieves the concentration set on the dial. Describe the mechanisms that compensate for temperature and downstream pressure changes.

The vaporiser is encased in insulating material    TRUE/FALSE

The vaporiser’s heat sink has low thermal capacity   TRUE/FALSE

The maximal output of the vaporiser is dependent upon the saturated vapour pressure of the anaesthetic agent   TRUE/FALSE

As a liquid vaporises its temperature drops   TRUE/FALSE

A large vaporising chamber will assist in compensating for pressure changes due to the pumping effect   TRUE/FALSE

SAQ 2.17 Question 1

Time to look at the last written paper…

Q1.  Describe the visceral and somatic pain of labour with particular reference to the anatomy and pain pathways. 

Visceral pain predominates in the first stage of labour      TRUE/FALSE

Chemoreceptors are involved in pain modulation     TRUE/FALSE

Nociceptors detecting stretch are involved in the pain of second stage     TRUE/FALSE

Head descent can stimulate the lumbosacral plexus    TRUE/FALSE

Pain can be referred to the thighs in first stage only    TRUE/FALSE

Tips for performing well in vivas


The viva invite emails were sent out this week. My commiserations to those who did not receive an invite, it’s a tough email to get. Different coping strategies work for different people but at least part of the right answer for most people would be to take a break to recharge yourself for a new approach to study.

For those who were invited, congratulations. You’ll find your knowledge, understanding and verbal fluency leaping ahead in this period – verbalising your understanding and being challenged on it is an incredibly effective learning technique. I think this is where the value lies in viva practice, not in gaining ‘viva technique’. Behind the scenes examiners become expert at ‘examining techniques’, you should become expert on the subject matter covered by the primary examination.

An ex-examiner colleague directed me to this reference the other day – Twelve tips for performing well in vivas – which I have shown to some other examiners and we all pretty much agree that much of the material is not relevant to a science viva as opposed to a clinical viva. Some may find some comforting tips in there though, and it’s worth while reading through to tip 12 which I think is very useful.


BT_PO 1.38 : Define humidity and outline the importance of humidification

Nunn won’t be so much help today, it’s more application of some basic physics.

Turbulent flow in the upper airway is better than laminar flow for humidification TRUE/FALSE

High minute volumes will move the isothermic saturation boundary distally TRUE/FALSE

With an unchanged absolute humidity, relative humidity will decrease as temperature increases  TRUE/FALSE

Gas in an oxygen cylinder has a relative humidity of 50%  TRUE/FALSE

Physiological humidification of inhaled gas requires more energy than warming it  TRUE/FALSE



BT_PO 1.39 : Outline the non-ventilatory functions of the lungs

I was still reading Nunn’s Applied Respiratory Physiology today.

The lung is particularly poor at clearing thrombo-emboli  TRUE/FALSE

With quiet nasal breathing the isothermic saturation boundary is around the 1st to 2nd airway generation   TRUE/FALSE

Surfactant contains bactericidal proteins TRUE/FALSE

The optimal size for drug particle deposition in the lungs is 20 microns  TRUE/FALSE

There is an active cytochrome P-450 system in alveoli and airways  TRUE/FALSE