The first experience of the combined use of nitric oxide and molecular hydrogen for cardiac surgery in high-risk patients

Abstract

The purpose of the study was to evaluate the effectiveness of myocardial protection with a combined supply of nitric oxide (NO) (40 ppm) and hydrogen (1.2 ppm) into the gas-air mixture delivery line of the cardiopulmonary bypass (CPB) machine during the entire period of CPB.Methods. The study included patients (n = 91) who had cardiac surgery under cardiopulmonary bypass and pharmacological cold cardioplegia. Patients were randomized into 3 groups. The Group 1 (n = 30) was control. Groups 2 (n = 28) and 3 (n = 33) received an isolated supply of NO (40 ppm) and a combined supply of NO (40 ppm) and hydrogen (1.2 ppm) into the extracorporeal IR circuit, respectively. During the postoperative period, clinical and functional indicators were studied (dynamics of myocardial contractile function according to ultrasound data); duration of artificial pulmonary ventilation (ALV); stay in the intensive care unit; hospital stay; mortality; level of marker of myocardial injury – troponin I (cTnI). Myocardial injury index (MII) was calculated to assess the degree of injury.Results. It was found that the level of cTnI in the postoperative period increased statistically significantly in all groups but was statistically significantly lower in Groups 2 and 3 compared to Group 1 at the end of the surgery and 12 and 24 hours after the surgery. Also, level of cTnI was statistically significantly lower in Group 3 at all stages of the study compared to Group 1 and after 12, 24 and 48 hours compared to Group 2. Statistically significantly lower MII values were revealed at all stages of the postoperative period in Group 3 compared with Groups 1 and 2. Changes in indicators of myocardial contractile function suggest an earlier and more complete recovery in Groups 2 and 3 (the changes were statistically significantly higher than that in Group 1). In Groups 2 and 3, the incidence of acute heart failure was statistically significantly lower (p = 0.046) compared to Group 1, according to Fisher’s exact test. There were no statistically significant differences in the incidence of acute respiratory and multiple organ failure in Groups 2 and 3 compared to Group 1. Also, patients of Groups 2 and 3 did not experience any complications in the early postoperative period. In Group 3, there was a statistically significant decrease in the duration of mechanical ventilation and stay in the intensive care unit after surgery compared to Group 2.Conclusion. Isolated supply of NO into the IR circuit has an additional cardioprotective effect, which is confirmed by statistically lower levels of troponin I and smaller changes in the indicators of myocardial contractile function during the postoperative period compared to standard technology. A more pronounced protective effect on the myocardium was shown with the combined supply of NO and molecular hydrogen to the IR circuit as seen by statistically lower levels of troponin I and MII in the postoperative period compared with the isolated supply of NO.