Effects of enflurane, isoflurane, sevoflurane and desflurane on reperfusion injury after regional myocardial ischaemia in the rabbit heart in vivo

It is known that volatile anaesthetics protect myocardial tissue against is chaemic and reperfusion injury in vitro. In this investigation, we have det ermined the effects of the inhalation anaesthetics, enflurane, isoflurane, sevoflurane and desflurane, administered only during early reperfusion, on myocardial reperfusion injury in vivo. Fifty chloralose-anaesthetized rabbi ts were subjected to 30 min of occlusion of a major coronary artery followe d by 120 min of reperfusion. Left ventricular pressure (LVP, tip-manometer) , cardiac output (CO, ultrasonic flow probe) and infarct size (triphenyltet razolium staining) were determined. During the first 15 min of reperfusion, five groups of 10 rabbits each received 1 MAC of enflurane (enflurane grou p), isoflurane (isoflurane group), sevoflurane (sevoflurane group) or desfl urane (desflurane group), and 10 rabbits served as untreated controls (cont rol group). Haemodynamic baseline values were similar between groups (mean LVP 106 (SEM 2) mm Hg; CO 281(7) mi min(-1)). During coronary occlusion, LV P and CO were reduced to the same extent in all groups (LVP 89% of baseline ; CO 89%). Administration of inhalation anaesthetics during early reperfusi on further reduced both variables, but they recovered after discontinuation of the anaesthetics to values not different from control animals. Infarct size was reduced from 49 (5)% of the area at risk in the control group to 3 2 (3)% in the desflurane group (P=0.021), and to 36 (2)% in the sevoflurane group (P=0.097). in the enflurane group, infarct size was 39 (5)% (P=0.272 ). Isoflurane had no effect on infarct size (48 (5)%, P=1.000). The results show that desflurane and sevoflurane markedly reduced infarct size and the refore can protect myocardium against reperfusion injury in vivo. Enflurane had only a marginal effect and isoflurane offered no protection against re perfusion injury in vivo. These different effects suggest different protect ive mechanisms at the cellular level.