Protection by remote ischemic preconditioning during coronary artery bypass graft surgery with isoflurane but not propofol - a clinical trial

Background: Remote ischemic preconditioning (RIPC) of the myocardium by limb ischemia/reperfusion may mitigate cardiac damage, but its interaction with the anesthetic regimen is unknown. We tested whether RIPC is associated with differential effects depending on background anesthesia. Specifically, we hypothesized that RIPC during isoflurane anesthesia attenuates myocardial injury in patients undergoing coronary artery bypass graft (CABG) surgery, and that effects may be different during propofol anesthesia. Methods: In a randomized, single-blinded, placebo-controlled prospective study, serum troponin I concentration (cTnI) (baseline, and 1, 6, 12, 24, 48, and 72 h postoperatively) were measured during isoflurane/sufentanil or propofol/sufentanil anesthesia with or without RIPC (three 5-min periods of intermittent left upper arm ischemia with 5 min reperfusion each) in non-diabetic patients (n = 72) with three-vessel coronary artery disease (ClinicalTrials.gov NCT01406678). Results: RIPC during isoflurane anesthesia (n = 20) decreased the area under the cTnI time curve (cTnI AUC) (-50%, 190 +/- 105 ng/ml 72 h vs. 383 +/- 262 ng/ml 72 h, P = 0.004), and the peak (7.3 +/- 3.6 ng/ml vs. 11.8 +/- 5.5, P = 0.004) and serial (P < 0.041) postoperative cTnI when compared to isoflurane alone (n = 19). In contrast, RIPC during propofol anesthesia (n = 14) did not alter the cTnI AUC [263 +/- 157 ng/ml 72 h vs. 372 +/- 376 ng/ml 72 h (n = 19), P = 0.318] or peak postoperative cTnI (10.1 +/- 4.5 ng/ml vs. 12 +/- 8.2, P = 0.444). None of the patients experienced harm or side effects from the intermittent left arm ischemia. Conclusion: Thus, RIPC during isoflurane but not during propofol anesthesia decreased myocardial damage in patients undergoing CABG surgery. Accordingly, effects of RIPC evoked by upper limb ischemia/reperfusion depend on background anesthesia, with combined RIPC/isoflurane exerting greater beneficial effects under conditions studied.