Limb Remote Ischemic Preconditioning Applied During Sevoflurane Anesthesia Does Not Protect the Lungs in Patients Undergoing Adult Heart Valve Surgery

Abstract

Background: Two consistent overall cell protective preconditioning treatments should provide more protection. We hypothesized that limb remote ischemic preconditioning (RIPC, second preconditioning stimulus) applied during sevoflurane inhalation (first preconditioning stimulus) would provide more protection to the lungs of patients undergoing adult heart valve surgery. Methods: In this randomized, placebo-controlled, double-blind trial, 50 patients were assigned to the RIPC group or the placebo group (1:1). Patients in the RIPC group received three 5-min cycles of 300 mmHg cuff inflation/deflation of the left-side lower limb before aortic cross-clamping. Anesthesia consisted of opioids and propofol for induction and sevoflurane for maintenance. The primary end point was comparison of the postoperative arterial–alveolar oxygen tension ratio (a/A ratio) between groups. Secondary end points included comparisons of pulmonary variables, postoperative morbidity and mortality and regional and systemic inflammatory cytokines between groups. Results: In the RIPC group, the a/A ratio and other pulmonary variables exhibited no significant differences throughout the study period compared with the placebo group. No significant differences in either plasma or bronchoalveolar lavage levels of TNF- α were noted between the groups at 10 min after anesthetic induction and 1 h after cross-clamp release. The percentage of neutrophils at 12 h postoperation was significantly increased in the RIPC group compared with the placebo group (91.34±0.00 vs. 89.42±0.10, P = 0.023). Conclusions: Limb RIPC applied during sevoflurane anesthesia did not provide additional significant pulmonary protection following adult valvular cardiac surgery.

Effect of remote ischemic preconditioning on lung function after surgery under general anesthesia: a systematic review and meta-analysis

“…Similarly to the P/F ratio and A-a DO 2 , RIPC was also associated with a lower respiratory index (MD − 0.17, 95% CI − 0.34 to − 0.01, I 2 = 94%) (Fig. 2 c) 7 , 9 , 13 , 14 , 18 , 29 , 41 .…”

“…A-a DO 2 and the respiratory index were also assessed. A-a DO 2 at 24 h after the operation was assessed in 10 trials with 884 patients 4 , 7 , 9 , 13 , 14 , 21 , 24 , 29 , 41 , 67 , which indicated that A-a DO 2 was significantly lower in the RIPC group, with significant heterogeneity (MD − 15.2 Torr, 95% CI − 29.7 to − 0.6, I 2 = 87%) (Fig. 2 b).…”

“…Regarding the anesthetic agents, 17 trials used propofol for the maintenance of general anesthesia 8 , 9 , 15 , 16 , 29 – 40 , whereas the other trials used volatile anesthesia or did not restrict/document the anesthetic agent. In most cases, RIPC was performed after the induction of general anesthesia or before the start of surgery 5 , 7 , 15 – 17 , 19 , 21 , 23 , 24 , 27 – 32 , 35 – 37 , 39 , 41 – 66 ; otherwise, it was performed before the start of cardiopulmonary bypass 4 , 8 , 13 , 20 , 67 or 12–48 h before surgery 18 , 22 , 25 , 26 , 34 . A tourniquet was placed almost equally on the upper or lower limb.…”