Introduction: There is an increasing number of studies about the ischaemic preconditioning-like effects of volatile anaesthetic agents. In this study we compared the myocardial protective effects of TIVA, sevoflurane and isoflurane in clinical practice.
Method: 57 patients, scheduled for elective coronary artery bypass graft surgery (CABG), were enrolled. Patients were randomized into three groups: Group I (TIVA n = 17): fentanyl, midazolam iv. infusion and pancuronium were given for maintenance. Group II (sevoflurane n = 20): sevoflurane was administrated at 1 MAC for maintenance. Group III (isoflurane n = 20): isoflurane at 1 MAC. Fentanyl and pancuronium were given repeatedly as required in Groups II and III. In these two groups, the volatile anaesthetics were given until CPB was started. After unclamping the aortic cross clamp, sevoflurane and isoflurane were given in groups II and III until the end of the operation. In group I, the agents were infused during the same periods. ST segment changes were recorded electronically. Transthoracic echocardiography was done preoperatively and on the 3rd day postoperatively in order to assess left ventricular systolic functions and cardiac scores. Biochemical parameters, cardiac Troponin I (cTnI) and creatine kinase MB fraction (CKMB), were determined before and after CPB, 6 h after surgery, and 1st, 2nd and 3rd day postoperatively. Blood samples from arterial and retrograde coronary cannula were obtained simultaneously for lactate levels (before CPB and after unclamping the aorta).
Results: All demographic parameters were similar in the three groups. On the 1st day postoperatively, CK-MB levels were higher in group I than groups II & III (46.4 ± 8.8 vs. 31.5 ± 3.1 and 38.2 ± 3.1 U mL−1, P < 0.05). At 6 hours after surgery, cTnI levels in group I were significantly higher (41.3 ± 5.1 vs. 24.0 ± 3.2 and 28.1 ± 3.4ng ml−1, P < 0.05). ST segment analysis and echocardiographic evaluations showed no difference between the groups. After unclamping the aorta, lactate level of arterial blood sample was higher in group I than group III. Lactate level from the sample of retrograde cannula was significantly higher in group I than groups II & III (3.8 ± 0.3 vs. 3.1 ± 0.2 and 2.8 ± 0.8mg dL−1, P < 0.05).
Conclusion: Because of the higher biochemical parameters related with myocardial injury in TIVA group, it can be postulated that the volatile anaesthetic agents sevoflurane and isoflurane have a myocardial protective effect. In our study, sevoflurane showed no difference from isoflurane group and it has a similar ischaemic preconditioning-like effect as isoflurane in CABG operations.
1 Julier K, da Silva R, Garcia C, et al. Preconditioning by sevoflurane decreases biochemical markers for myocardial and renal dysfunction in coronary artery bypass graft surgery: a double-blinded, placebo-controlled, multicenter study. Anesthesiology