Control of the haemodynamic response to surgical stimuli in semi-closed circuit or closed circuit anaesthesia using a multifunctional anaesthesia system

This study compared the ability of the Zeus® multifunctional anaesthesia system to control haemodynamic response to surgical stimulation in semi closed (SCA) or closed circuit anaesthesia (CCA) modes. Fifty patients undergoing gynaecological surgery were randomly assigned to SCA or CCA. Anaesthesia was induced with 2 mg propofol and 0.9 mg/kg rocuronium, intravenously, and maintained using sevoflurane (minimum alveolar concentration [MAC], 1.0) using 2 1/min oxygen plus 2 l/min nitrous oxide (SCA 4 l/min group) or 50% oxygen plus 50% nitrous oxide (CCA group). An increase in mean arterial pressure (MAP) > 20% above baseline in response to surgical stimulation provoked a stepwise increase in sevoflurane (1.3 MAC and then 1.6 MAC), followed by fentanyl 1 μg/kg intravenously (rescue drug). The time required for MAP to return to within 10% of baseline was significantly shorter in the CCA group (6.4 ± 3.6 min) compared with the SCA 4 l/min group (10.2 ± 6.0 min). The percentage of patients requiring fentanyl was significantly greater in the SCA 4 l/min group than in the CCA group. In conclusion, CCA controlled acute haemodynamic responses to surgical stimuli more successfully and rapidly than SCA 4 l/min, using a multifunctional anaesthesia machine.