Effects of halothane, enflurane and isoflurane on some systemic haemodynamics and coronary circulation in dogs

ABSTRACT

The effect of low and high concentrations of halothane, enflurane and isoflurane were studied in 30 dogs to assess and compare their effects on some haemodynamic parameters and coronary circulation. The dogs were divided into three grops [10 dogs in each], according to inhalational anaesthetic agent used. The first group received halothane in low and high concentrations 1% and 1.5% in oxygen. Enflurane was given in the second group in 1.5% and 3% in oxygen. The third group received isoflurane in 1.5% and 3% in oxygen. The parameters were recorded after induction of anaesthesia with thiopentone sodium [in a dose of 10-15 mg/Kg] before the start of inhalational anaesthetics [the control value], 30 minutes after administration of low and high concentrations of the inhalational anaesthetics. The results measured in this study compared to the control value with low and high concentrations, also comparing the two concentrations of inhalational anaesthetics together [low and high]. Femoral artery blood flow [FABF], arterial blood pressure [BP] and systemic vascular resistance [CVR] showed a significant decrease [P< 0.05]. On the other hand, a significant increase [P< 0.05] was observed in the central venous pressure [SVP] with the three inhalational anaesthetics. The coronary sinus blood flow [CSBF] revealed a significant decrease with halothane and enflurane, while a significant increase [P< 0.05] with isoflurane anaesthesia was reported. The coronary vascular resistance [CVR] revealed insignificant increase with halothane [P> 0.05], but a significant decrease was reported with enflurane and isoflurane anaesthesia. When comparing the effects of the three inhalational anaesthetics on the above mentioned parameters it denotes the following data FABF and CSBF decrease more with halothane than enflurane and isoflurane anaesthesia. On the other hand, BP, CVR and SVR decrease more with enflurane than halothane and isoflurane anaesthesia, contrary to this the CVP increase more with enflurane than halothane and isoflurane anaesthesia. So, we can conclude that enflurane is more myocardial depressant, halothane in between and the least was isoflurane. On the other hand, isoflurane is a powerful coronary vasodilator more than the other two inhalational anaesthetics