Does on-pump normothermic beating-heart valve surgery with low tidal volume ventilation protect the lungs?

Postoperative pulmonary dysfunction following cardiopulmonary bypass (CPB) usually develops secondary to the inflammatory process with contact activation, hypothermia, operative trauma, general anesthesia, atelectasis, pain, and pulmonary ischemia/reperfusion due to cross-clamping. The aim of the present study was to evaluate the effects of an on-pump, normothermic, and beating-heart technique and of low-volume ventilation on lung injury.

We compared the results for 20 patients who underwent operations with an on-pump, normothermic, and beating-heart technique of mitral valve surgery with low-volume ventilation (group 1) with the results for 23 patients who underwent their operations with an on-pump, hypothermic cardiac-arrest technique (group 2). In both groups, blood samples were collected from the right superior pulmonary vein, and inflammation and oxidative stress markers (malondialdehyde, lactic acid, platelet-activating factor, and myeloperoxidase) were studied.

Malondialdehyde, myeloperoxidase, and lactate values were significantly lower in group 1 than in group 2 just before the termination of CPB (P < .05). We observed no differences between the 2 groups with regard to values for platelet-activating factor.

Inflammation and oxidative stress markers were lower in the group of patients who underwent beating-heart valve surgery with low-volume ventilation. These results reflect less of an ischemic insult and lower inflammation compared with the results for the patients who underwent conventional operations.