Differential effects of intravenous anaesthetic agents on the response of rat mesenteric microcirculation in vivo after haemorrhage

Abstract

Background. The differential effects of i.v. anaesthesia on the response of the mesenteric microcirculation after haemorrhage in vivo are previously unexplored. Methods. Male Wistar rats (n=56) were anaesthetized intravenously either with propofol and fentanyl (propofol/fentanyl), ketamine or thiopental. A tracheostomy and carotid cannulation were performed and the mesentery surgically prepared for observation of the microcirculation using fluorescent in vivo microscopy. Animals were allocated to one of three groups: control, haemorrhage or haemorrhage re-infusion. Results. After haemorrhage, the response of the microcirculation differed during propofol/ fentanyl, ketamine and thiopental anaesthesia. During propofol/fentanyl anaesthesia there was constriction of arterioles (-16.7 (3.9)%), venules (-5.9 (1.7)) and capillaries (-16.3 (2.8)) (n=12). During ketamine and thiopental anaesthesia both constriction and dilation was observed. After haemorrhage and re-infusion, macromolecular leak occurred from venules during propofol/fentanyl and thiopental anaesthesia (P<0.05), but not during ketamine anaesthesia. Conclusion. In summary, i.v. anaesthetic agents differentially alter the response of the mesenteric microcirculation to haemorrhage.