Xenon or propofol anaesthesia for patients at cardiovascular risk in non-cardiac surgery.

BACKGROUND: The results of two European multi-centre trials on xenon anaesthesia led to the hypothesis that a xenon-based anaesthetic would keep left ventricular (LV) and circulatory function more stable than a propofol-based anaesthetic, in patients with coronary artery disease (CAD). METHODS: In a prospective, randomized design, 40 patients of ASA classes III and IV with known CAD were anaesthetized for elective non-cardiac surgery with either xenon (n=20) or propofol (n=20), each combined with remifentanil. Target criteria were intraoperative LV function as evaluated by transoesophageal echocardiography (TOE: Tei index, circumferential fibre shortening), arterial pressure, and heart rate (HR). RESULTS: Mean arterial pressure was decreased with propofol but was stable at pre-anaesthetic level with xenon (P<0.02) and HR was lower with xenon (P<0.01). The Tei index (also known as myocardial performance index) improved from 0.53 (0.14) to 0.45 (0.10) after 1 h with xenon and changed from 0.50 (0.14) to 0.55 (0.20) with propofol anaesthesia [means (SD); P=0.01 between the groups]. Deviation of circumferential fibre shortening from expected value after 1 h was -2 (14)% with xenon and -14 (18)% with propofol [means (SD); P=0.03]. There were no perioperative signs of acute myocardial ischaemia (TOE, ECG, and troponin T release). CONCLUSIONS: Xenon anaesthesia provided a higher arterial pressure level than propofol, with no signs of cardiovascular compromise, in patients with CAD. Echocardiographic indices showed better LV function with xenon.

Autonomic cardiac control with xenon anaesthesia in patients at cardiovascular risk.

BACKGROUND: The cardiovascular stability found with xenon anaesthesia may be caused by absence of circulatory depression. Xenon may also act directly on autonomic cardiovascular control. METHODS: In a prospective, randomized design, 26 patients (ASA class III and IV) with increased cardiac risk were anaesthetized for elective non-cardiac surgery with either xenon (n = 13) or propofol (n = 13), each combined with remifentanil. From intraoperative Holter ECG, 5-min intervals of stable sinus rhythm were analysed at baseline anaesthesia with etomidate/remifentanil, and after 30 and 60 min of propofol or xenon anaesthesia. Target criteria were total power and ratio of low to high frequency power of the heart rate (HR) power spectrum between 0.003 and 0.4 Hz, indicating global activity and sympatho-vagal balance of autonomic modulation of HR. RESULTS: When compared with baseline, total power decreased with propofol from 8.6 (1.6) to 7.1 (0.5) and to 7.8 (1.1) ms(2) at 30 and 60 min, respectively, [mean (sd) of logarithmic transform] and was unchanged with xenon (P = 0.02; anova). The low/high frequency power ratio changed from 3.0 (3.5) to 4.3 (4.3) and 4.1 (6.2), respectively, with xenon and from 3.9 (3.6) to 1.8 (1.5) and 1.8 (0.8) with propofol (P = 0.04; generalized linear model test). Mean arterial pressure was significantly higher with xenon throughout (P < 0.001; anova). CONCLUSIONS: Propofol caused a decrease in arterial pressure as well as autonomic HR modulation, but xenon did not. The higher arterial pressure with xenon anaesthesia may be explained by less suppression of sympatho-vagal balance.