Atropine Effects in Anaesthesia With Sufentanil vs. Remifentanil

Induction of general anaesthesia with a combination of opiates and hypnotics often induces vasodilation resulting in several haemodynamic effects such as a decrease in blood pressure (MAP), heart rate (HR) and cardiac output (CO). This haemodynamic suppression may jeopardize tissue oxygenation, particularly cerebral oxygenation. Previous research of the investigators group has revealed that atropine has an exceptionally beneficial effect on the determinants of tissue oxygen delivery as well as on tissue oxygenation. The investigators have demonstrated a significant and clinically relevant increase in CO and cerebral tissue oxygenation (SctO2) for a desired increase in MAP. This is in steep contrast with the more usual clinical practice of administrating classical vasoactive medication such as phenylephrine or norepinephrine, since the two latter have an even negative effect on CO and SctO2. In previous research the investigators used standardized target controlled propofol/remifentanil infusions for induction and maintenance of anaesthesia. It is known that remifentanil has more intense haemodynamic side-effects compared to other opiates such as fentanyl, sufentanil or alfentanil. This raises the question whether the beneficial effect of atropine is restricted to propofol/remifentanil anaesthesia, or if this is equally valid during anaesthesia of propofol combined with other opiates such as sufentanil. Patients undergoing off-pump coronary artery bypass grafting (CABG) require a long and deep general anaesthesia, which is usually performed with the combination of drugs as mentioned above. Because these patients often experience severe haemodynamic fluctuations they need to be closely monitored.