Effect of nitric oxide supply on the morphofunctional state of the lungs during cardiopulmonary bypass modelling: an experimental study

Abstract

Perioperative management of cardiac surgery leads to significant morphofunctional impairment of the lungs, cardiopulmonary bypass (CPB) being the principal contributor. The pathophysiological mechanisms associated with cardiopulmonary bypass include ischaemic-reperfusion injury, oxidative stress and systemic inflammation. Nitric oxide is able to limit the associated damage.Aim of the study: to investigate the effect of nitric oxide supply on morphofunctional state of sheep lungs under simulated cardiopulmonary bypass. Methods. 12 sheep of Altai breed were divided into 2 equal groups. Classical techniques of pulmonary ventilation and cardiopulmonary bypass were simulated in the CPB group. The sheep of the CPB + NO group were supplied with 80 ppm nitric oxide (via respiratory circuit or extracorporeal circulation circuit) during mechanical ventilation and cardiopulmonary bypass. The gas supply started immediately after tracheal intubation and continued until the end of the experiment. In both groups, the cardiopulmonary bypass time was 90 min, after which the sheep were switched to spontaneous circulation and observed for 60 min. Subsequently, blood was sampled, and the animals were withdrawn from the experiment with subsequent collection of histologic specimens.Results. Statistically significant intergroup differences in P / F-index level before the end of the experiment were found (p = 0.041). Nitric oxide supply was associated with decreased infiltrate density in the lung parenchyma (p = 0.006) and increased alveolar area (p < 0.001).Conclusion. Supply of NO during modelling of cardiopulmonary bypass in experimental animals improves the morphological and functional state of the lungs by reducing inflammation, vascular changes and damage to the respiratory part of the lungs (structure of alveoli, alveolar passages and pneumocytes). Clinical studies are needed to investigate pulmonoprotective properties of NO in humans.