The effect of nitric oxide supplied to the oxygenator of the cardiopulmonary bypass on the functions and morphology of internal organs: experimental animal study

Abstract

To evaluate the effect of NO added to the oxygenator during CPB on the liver and kidneys in pigs.Methods. The experiment was conducted on 10 pigs undergoing cardiac surgery using cardiopulmonary bypass (CPB). Animals of the experimental group (CPB-NO; n = 5) received NO with the gas mixture supplied to the oxygenator at 100 ppm. Animals of the control group (CPB-control; n = 5) did not receive NO via the oxygenator. The surgery lasted 4 hours and was followed by 12-hour postoperative monitoring. To assess the liver and kidney injury, the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, creatinine, neutrophil gelatinase-associated lipocalin (NGAL) were determined at baseline, at weaning from the CPB, 6 and 12 hours after weaning from the CPB. A pathomorphological study of the liver and kidneys was also performed.Results. A long period of CPB deliberately used in our experiment caused liver injury. In the CPB-control group, an increase in the ALT concentration was found: 43 (34; 44) U/l at baseline to 82 (53; 99) U/l 12 hours after CPB, p < 0.05. AST concentration in the CPB-control group increased from 25 (17; 26) U/l at baseline to 269 (164; 376) U/l 12 hours after CPB (p < 0.05). We found no significant increase in ALT and AST concentrations in the CPB-NO group. There were no significant differences in ALT and AST concentrations between CPB-NO and CPB-control groups at all study time points. In the CPB-control group, an increase in the creatinine level was found from 131 (129; 133) μmol/l at baseline to 273 (241; 306) μmol/l 12 hours after CPB (p < 0.05). We found no significant increase in creatinine levels in the CPB-NO group. Creatinine levels in the CPB-NO group were significantly lower than in the CPB-control group 12 h after weaning from CPB: 183 (168; 196) vs 273 (241; 306) μmol/l (p < 0.008). We found no significant differences between the study groups by the NGAL level. Morphology revealed characteristic alterative changes in tissues, circulatory disorders, and inflammatory infiltration of varying degrees of severity, which in combination is a manifestation of the acute damaging effect of CPB. In the CPB-NO group, the severity of pathological changes, measured in points, was lower than in the CPB-control group, but no statistically significant differences were found.Conclusion. NO added to the oxygenator gas mixture reduces liver and kidney injury during prolonged CPB. Further research is required.