The proposed mechanism through which RIPC induces its protection, addresses the release into the systemic circulation of substances that exert multi organ protective effects.
Although the safety and non-invasive nature of this method have made RIPC a theoretically brilliant protector of the myocardium, cardiac surgical literature includes conflicting results on this subject.
Although several other studies have emphasized that when using RIPC, postoperative troponin levels in adult patients following CABG surgery is decreased, (23,24) in this study, we found that RIPC induced by cycles of upper limb ischemia did not provide cardiac protection as represented by the values of cardiac biomarkers (troponin and CK-MB).
Moreover, a RCT investigating RIPC effects on myocardial function in children undergoing cardio-pulmonary bypass has shown that cardiac troponin I levels were significantly different between groups.
In Hong's study, although RIPC reduced the total amount of troponin I in off-pump CABG surgery patients by 26%, it did not reach statistical significance.
In discussing the results of our study, it should be mentioned that in 2009, Rahman described RIPC as the best hope for myocardial protection in cardiac surgery.
Finally, a recent systematic review and meta-analysis investigating 10 papers and 693 participants has shown that RIPC significantly decreases postoperative troponin concentration following open cardiac surgery.
In other words, there were mild treatment effects in blinded studies or even no statistically significant effect of RIPC on troponin concentrations.
In our study of patients who underwent CABG surgery, RIPC could not decrease myocardial injury.
Although, the extension of RIPC from the current method was never studied before, studies of whole body preconditioning with ether-derived volatile anesthetics show a decrease in the release of biomarkers associated with myocardial cell death and myocardial dysfunction in patients undergoing CABG surgery.
In other words, RIPC could not produce more additive effect in association with isoflurane.
The limitations of our study were, (i) we did not differentiate the effects of RIPC on high and low risk patients, (ii) we could not evaluate the clinical effect of RIPC on cardiac function and (iii) isoflurane was used as the sole anesthetic in our study that has cardioprotective effects and can affect the result of the study.