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Someone asked me to produce an answer for a question that gave an idea of how much needed to be written.

I’ve shown you examples of good and bad layout, but here is an answer that could be considered as having sufficient content to gain a pass.  It must have done, because I wouldn’t have passed the April 2008 SAQ paper otherwise!

The question I am answering is about pre-oxygenation and is question 5 in the April 2008 paper which you can find by clicking here.

A)    Method of Pre-Oxygenation

• Ask patient to breathe normally (normal tidal volume) for 3-5 minutes,
• Via face mask tightly applied to face,
• Connected to circle-absorber system,
• With fresh gas flow of 100% oxygen of >minute volume.

B)    Physiological basis

• O₂ consumption is approximately 250ml min^-1.
• FRC is ≈ 2500ml
• Preoxygenation replaces nitrogen containing air in the lungs with oxygen and generate reservoir of ≈ 2500ml oxygen.
• Oxygen saturation therefore maintained in apnoeic patient for 5-10 minutes.
• Also, small increase in oxygen reserves within body tissues.
• Duration required for preoxygenation is dependent on washin of oxygen and washout of nitrogen and can be decreased by patient increasing per breath volume (4-breath and 8-breath techniques).

C)    Assessment of adequacy

• Measure end-tidal oxygen concentration (>85% indicates good preoxygenation)
• Measure time for SpO2 to drop below 90% from onset of apnoea
• Measure arterial oxygen tension using arterial blood gases
• Mass spectrometry of expired gas

D)    Advantages of PreO₂

• Increases time to desaturation during securing an airway

Disadvantages

• Absorption atelectasis (airway closure followed by absorption of distal gas)
• Atelectasis due to airway narrowing (gas in alveolus absorbed faster than can be replaced through narrow airway)
• Patient anxiety heightened by tight fitting face mask (”I can’t breathe”) (increases oxygen demand)
• Potential to mask oesophageal intubation by delaying desaturation (offset by EtCO₂ monitoring in modern practice).

Now that’s my answer to the question.

It isn’t perfect, but I think it’s pretty good (and I want to hear from anyone who thinks it needs modifying: help-me@examintelligence.com).

I don’t think you need to write any more than that.

On another note:

James has written a Sexy Topics list over at Passing The Final, which I highly recommend you read.  It contains a lits of topics which are prime fodder for the SAQ.  Like him, though, I urge you not to underestimate the MCQ!

Good luck!