Nitrous Oxide and Cerebrospinal Fluid Markers of Ischaemia following Cardiopulmonary Bypass

Abstract

Twenty patients with good ventricular function undergoing coronary artery bypass surgery were studied to determine whether the pre-bypass use of nitrous oxide resulted in any differences in cerebrospinal fluid markers indicative of cerebral ischaemia. All patients were anaesthetised with diazepam, fentanyl and pancuronium, after which ten patients received 50–60% nitrous oxide in oxygen until commencement of bypass, and the remaining patients 100% oxygen. Because of the known effect of nitrous oxide in expanding gaseous bubbles, any neurological dysfunction of gaseous microembolic origin may be worsened in the presence of nitrous oxide. Patients were lumbar punctured 24 hours after cardiopulmonary bypass and cerebrospinal fluid analysed for the following markers of central nervous system ischaemia: creatine kinase, lactate, total protein, noradrenaline, adrenaline and adenylate kinase. There was a statistically significant difference in cerebrospinal fluid lactate between the two groups. There were no statistically significant differences in the other cerebrospinal fluid markers of ischaemia.

Inhalational Anesthetics as Neuroprotectants or Chemical Preconditioning Agents in Ischemic Brain

“…However, one retrospective study of patients undergoing middle cerebral artery aneurysm surgery suggests that isoflurane was not as cerebroprotective as propofol, etomidate, or pentobarbital (Lavine et al , 1997). Interestingly, prebypass use of N 2 O in coronary artery bypass grafting patients did not affect most cerebral spinal fluid markers of central nervous system ischemia as measured 24 h post-coronary artery bypass grafting (Wells et al , 1987).…”