Effect of ischemic preconditioning with postconditioning on postoperative lung function in patients undergoing cardiac surgery involving cardiopulmonary bypass

Abstract

Background: Remote ischemic preconditioning is a protective mechanism in which transient ischemia to a distant organ protects the subsequent sustained ischemia-reperfusion injury of a target organ. We hypothesized that remote ischemic preconditioning with postconditioning (RIPC) might alleviate the pulmonary dysfunction after cardiac surgery involving cardiopulmonary bypass (CPB).

Methods: A total of 76 patients who underwent elective cardiac surgery involving CPB were randomized into the control group or RIPC group. In the RIPC group, four cycles of 5-min ischemia and 5-min reperfusion were administered two times to the upper limb: before CPB and after CPB. The primary endpoint was to compare the lung function evaluated by PaO2/FIO2 ratio and the secondary endpoint was to compare the other pulmonary variables between the two groups at postoperative 6, 12, 18, 24 hours.

Results: The mean PaO2/ FIO2 value was significantly higher in the RIPC group than in the control group at 24 hour after operation (290 ± 96 vs. 387 ± 137, p = 0.001) and the proportion of patients under mechanical ventilation longer than 48 hours was significantly higher in the control group (23 % vs. 3 % , p < 0.05). However, there were no significant differences on other parameters including oxygenation at other time points, systemic inflammatory markers, postoperative mechanical ventilation time and duration of ICU stay.

Conclusion: RIPC improved oxygenation at postoperative 24 hours and decreased the number of patients requiring ventilator care longer than 48 hours in patients undergoing elective cardiac surgery involving CPB. However, to determine the clinical significance of these protective effects, further studies would be required.