Pulmonary Protective Effects of Remote Ischaemic Preconditioning with Postconditioning in Patients Undergoing Cardiac Surgery Involving Cardiopulmonary Bypass: A Substudy of the Remote Ischaemic Preconditioning with Postconditioning Outcome trial.

BACKGROUND: The RISPO (Remote Ischemic Preconditioning with Postconditioning Outcome) trial evaluated whether remote ischaemic preconditioning (RIPC) combined with remote ischaemic postconditioning (RIPostC) improves the clinical outcomes of patients undergoing cardiac surgery. This substudy of the RISPO trial aimed to evaluate the effect of RIPC with RIPostC on pulmonary function in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

METHODS: Sixty-five patients were enrolled (32: control and 33: RIPC-RIPostC). In the RIPC-RIPostC group, four cycles of 5min ischaemia and 5min reperfusion were administered before and after CPB to the upper limb. Peri-operative PaO2/FIO2 ratio, intra-operative pulmonary shunt, and dynamic and static lung compliance were determined.

RESULTS: The mean PaO2/ FIO2 was significantly higher in the RIPC-RIPostC group at 24h after surgery [290 (96) vs. 387 (137), p=0.001]. The incidence of mechanical ventilation for longer than 48h was significantly higher in the control group (23% vs. 3%, p<0.05). However, there were no significant differences in other pulmonary profiles, post-operative mechanical ventilation time, and duration of intensive care unit stay.

CONCLUSIONS: In our study, RIPC-RIPostC improved the post-operative 24h PaO2/FIO2 ratio. Remote ischaemic preconditioning-Remote ischaemic postconditioning has limited and delayed pulmonary protective effects in cardiac surgery patients with CPB.