Background: Different anaesthetic agents have been shown to have different protective effects upon heart, brain and renal function under ischaemic conditions (oxygen starvation). Cardiopulmonary bypass takes over the work of the heart and the lungs during heart surgery, but oxygenation of vital organs such as the brain and heart may not be perfect, and can produce brain or heart damage as a consequence. Propofol and desflurane are commonly used anaesthetic agents, and there has been recent research to suggest that anaesthetic agents may provide some protection during periods where inadequate oxygenation occurs, with the potential to reduce the degree of organ damage. Both types of anaesthetics are used for cardiac surgery with anaesthetists choosing between them largely on the basis of personal preference.

Aim: To determine whether the use of either propofol or desflurane as the primary anaesthetic agent, can lead to differences in postoperative brain function, total morbidity or cost, following coronary artery surgery with cardiopulmonary bypass.

Methods: Patients will be recruited by professional research staff and will be randomised into one of two groups (90 in each group). They will receive a standardized technique for anaesthesia, cardiopulmonary bypass and postoperative ICU treatment. The only difference between the 2 groups will be as to which anaesthetic agent they receive during the surgical period, desflurane or propofol. Measurements will involve i) brain function testing before and 3 months after surgery ( a set of 10 verbal or manual tests), ii) incidence of delirium in the immediate postoperative period (a survey form), iii) incidence of total postoperative morbidity and iv) cost of hospital stay. Data collection will be by anaesthesia and research staff and a neuropsychologist will employed for performing the brain function testing.

Anticipated timeline: Initial recruitment completed by 15-18 months following trial commencement. Follow up completed 3 month after the last enrolment. Data validation, statistical analysis and manuscript preparation completed by 24 months.