Anaesthetic agent of choice in renal failure is:

Anaesthetic agent of choice in renal failure is:

A. Methoxyflurane
B. Isoflurane
C. Enflurane
D. None

Answer is B. Isoflurane

The elimination of volatile anaesthetic agents is not dependent on renal function and their activity is unaffected by CRF. The hepatic metabolism of both enflurane and sevoflurane will theoretically produce nephrotoxic fluoride ions and their use should be discouraged for prolonged durations. Metabolism of halothane produces fluoride ions when the liver is hypoxic but has been used safely in patients with renal disease. It has a greater myocardial depressant effect and causes more arrhythmias than other inhalational agents and caution should be observed when used in CRF patients with cardiovascular impairment.  

Isoflurane, although more expensive, may be the agent of choice as it undergoes less metabolism to fluoride ions. Nitrous oxide has little effect on the kidney. Older agents such as cyclopropane, ether and tricloroethylene are not recommended as they cause renal vasoconstriction.

• Methoxyflurane is highly nephrotoxic
• Enflurane is best avoided as the nephrotoxic levels of fluoride ions are seen just after 3.5 MAC hours
• Isoflurane, Sevoflurane and Halothane result in little or no increase in fluoride ions and are preferred.