It is known that volatile anaesthetics protect myocardial tissue against ischaemic and
reperfusion injury in vitro. In this investigation, we have determined 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 rabbits were subjected to 30 min of occlusion of a major coronary artery followed by 120 min of reperfusion. Left ventricular pressure (LVP, tip-manometer), cardiac output (CO, ultrasonic flow probe) and
infarct size (
triphenyltetrazolium staining) were determined. During the first 15 min of reperfusion, five groups of 10 rabbits each received 1 MAC of
enflurane (
enflurane group),
isoflurane (
isoflurane group),
sevoflurane (
sevoflurane group) or
desflurane (
desflurane group), and 10 rabbits served as untreated controls (control group). Haemodynamic baseline values were similar between groups (mean LVP 106 (SEM 2) mm Hg; CO 281(7) ml min-1). During
coronary occlusion, LVP and CO were reduced to the same extent in all groups (LVP 89% of baseline; CO 89%). Administration of inhalation anaesthetics during early reperfusion 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 32 (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 therefore can protect myocardium against
reperfusion injury in vivo.
Enflurane had only a marginal effect and
isoflurane offered no protection against
reperfusion injury in vivo. These different effects suggest different protective mechanisms at the cellular level.