Ventilators in the operating theatre

You are ventilating a patient in theatre using a simple bag-in-bottle ventilator connected

to the common gas outlet. You are using a fresh gas flow of 1 L/min, a circle

breathing system and volume control ventilation mode. Using spirometry connected to

your anaesthetic machine you note a tidal volume of 500 mL, a respiratory rate of

12 breaths per minute and an I:E ratio of 1:2. You need to rapidly affect a change in

circuit concentration of volatile anaesthetic agent. You increase your fresh gas flow to

4 L/min. You leave all the ventilator settings unchanged. One minute later, what

delivered minute volume would you expect the spirometry to be registering?

a) 5 L/min

b) 6 L/min

c) 7 L/min

d) 8 L/min

e) 9 L/min

Altitude anaesthesia

While working abroad, at an altitude of 5000m, it becomes necessary to administer a

general anaesthetic with an FiO2 of 0.9, to a healthy patient who lives locally. The

operating theatre is heated and equipped with an anaesthetic machine that uses variable

orifice flowmeters and a Tec5 isoflurane vaporiser, out of circuit. Regarding your anaesthetic

management, the following statements are true EXCEPT for which one?

a) The delivered concentration of isoflurane will be more than that shown on the dial

of the vaporiser

b) The oxygen rotameter will accurately read the delivered flow of oxygen

c) The alveolar concentration of isoflurane will need to be higher than at sea level to

achieve the same degree of anaesthesia

d) The partial pressure of isoflurane in the vaporiser is the same as it would be if you

returned with the same vaporiser to sea level

e) The patient’s oxygen saturation is more likely to be 90% than 96%

Gas analysis

Which one of the following gases is paramagnetic?

a) Nitrogen

b) Nitrous oxide

c) Nitric oxide

d) Nitrogen dioxide

e) Dinitrogen tetroxide

Approaches to regional anaesthetic blockade of the brachial plexus

Which one of the following statements regarding approaches to the blocking of the

brachial plexus is TRUE?

a) The axillary approach alone is sufficient for all aspects of awake hand surgery

b) The interscalene approach blocks the plexus at the level of the trunks

c) The vertical infraclavicular approach has the highest rate of pneumothorax

d) An advantage of the supraclavicular approach is, being more distal, phrenic nerve

block is not a complication

e) The subclavian perivascular approach relies on the plexus being immediately

posterior to the subclavian artery as it crosses the first rib in between the scalenus

anterior and medius

Beta-adrenoreceptor antagonists

Which one of the following statements regarding β-blockers is TRUE?

a) When using esmolol, a loading dose of 0.1 mg/kg intravenously over one minute is

reasonable

b) Propranolol has high oral bioavailability

c) Atenolol has high β1 receptor selectivity

d) Metoprolol has low lipid solubility thus its absorption and bioavailability are

limited

e) Labetalol antagonises α1:β adrenoreceptorswith a ratio of 1:7 when administered orally

Herbal remedies

Which of the following DECREASES the anticoagulant effect of warfarin?

a) Garlic

b) Glucosamine

c) Echinacea

d) Evening primrose oil

e) St John’s wort

Prostaglandins in pregnancy

A 23-year-old severely asthmatic primigravida suffers a major post-partum haemorrhage

due to uterine atony following a vaginal delivery. As well as appropriate therapy

of major haemorrhage she receives syntometrine intramuscularly, syntocinon intravenously

as a bolus and then by infusion. Which one of the following would be the

MOST SUITABLE agent for further pharmacological management of her condition?

a) Carboprost

b) Mifepristone

c) Misoprostol

d) Alprostadil

e) Dinoprostone