Suggested Level of Knowlege: Detailed

LOs

BT_GS 1.24 Describe the uptake, distribution and elimination of inhalational anaesthetic agents and the factors which influence induction and recovery from inhalational anaesthesia including the:

· Concepts of partition coefficients, concentration effect and second gas effect

· Relationships between inhaled and alveolar concentration

· Significance of the distribution of cardiac output and tissue partition coefficients on uptake and distribution of volatile agents

Past SAQs

2016.2 Describe the effect of a pregnancy, at term, on wash-in of volatile anaesthetic agents.

2014.2, 2014.1 Describe the washout of desflurane from a patient following six hours of general anaesthesia. You may wish to use a graph to illustrate the description.

2012.2 Compare and contrast propofol and sevoflurane for maintenance of anaesthesia with respect to kinetics, cardiovascular and central nervous system effects.

2012.1 In relation to the pharmacokinetics of nitrous oxide, describe the significance of partition coefficients, increasing inspired concentration, the second gas effect and diffusion hypoxia.

2005.2 Describe how isoflurane is metabolised. In your answer give reasons why the overall extent of metabolism of isoflurane is so low.

2003.2 Draw and label, on the same X - Y axis, FA/FI curves for the following halothane concentrations in oxygen, showing a 30 minute period from starting administration.

(a) Halothane 1%, subject breathing spontaneously.

(b) Halothane 6%, subject breathing spontaneously.

(c) Halothane 6%, subject paralysed and ventilated.

With referene to the major factors determining the shape of FA/FI  curves explain the differences between A and B, and A and C.

2002.2 Draw a graph comparing the ratio of inspired to alveolar concentrations during the first half hour of administration for nitrous oxide, isoflurane, and halothane. Outline reasons for observed differences between the agents and indicate the effects of increases in alveolar ventilation and cardiac output.

Inhalational Pharmacokinetics