Cardioprotective Properties of Humoral Factors Released after Remote Ischemic Preconditioning in CABG Patients with Propofol-Free Anesthesia-A Translational Approach from Bedside to Bench

The cardioprotective effect of remote ischemic preconditioning (RIPC) is well detectable in experimental studies but not in clinical trials. Propofol, a commonly used sedative, is discussed to negatively influence the release of humoral factors after RIPC. Further, results from experimental and clinical trials suggest various comorbidities interact with inducible cardioprotective properties of RIPC. In the present study, we went back from bedside to bench to investigate, in male patients undergoing CABG surgery, whether (1) humoral factors are released after RIPC during propofol-free anesthesia and/or (2) DM interacts with plasma factor release. Blood samples were taken from male patients with and without DM undergoing CABG surgery before (control) and after RIPC (RIPC). To investigate the release of cardioprotective humoral factors into the plasma, isolated perfused hearts of young rats (n = 5 per group) were used as a bioassay. The hearts were perfused with patients' plasma without (Con) and with RIPC (RIPC) for 10 min (1% of coronary flow) before global ischemia and reperfusion. In additional groups, the plasma of patients with DM was administered (Con DM, RIPC DM). Infarct size was determined by TTC staining. Propofol-free RIPC plasma of male patients without DM showed an infarct size of 59 +/- 5% compared to 61 +/- 13% with Con plasma (p = 0.973). Infarct sizes from patients with DM showed similar results (RIPC DM: 55 +/- 3% vs. Con DM: 56 +/- 4%; p = 0.995). The release of humoral factors into the blood after RIPC in patients receiving propofol-free anesthesia undergoing CABG surgery did not show any cardioprotective properties independent of a pre-existing diabetes mellitus.

Automated summary

The cardioprotective effect of remote ischemic preconditioning (RIPC) has been observed in experimental studies but not in clinical trials. Propofol is believed to have a negative impact on the release of humoral factors after RIPC. Furthermore, comorbidities may interact with the cardioprotective properties of RIPC. This study found that propofol-free RIPC did not lead to the release of cardioprotective humoral factors in male patients undergoing CABG surgery, regardless of the presence of diabetes mellitus.