Does cold blood cardioplegia solution cause deterioration in clinical pulmonary function following coronary artery bypass graft surgery?

Objective: Deterioration in pulmonary function is a common complication following coronary artery bypass graft surgery and there is still speculation to the precise causative factors thereof. Cardioplegia solution not drained by the atriocaval cannula enters the lung parenchyma unless removed by a pulmonary artery (PA) vent. The hypothesis of the present study was that cold blood cardioplegia solution damages the lung parenchyma, resulting in an observed deterioration of clinical lung function. Methods: A prospective, double-blind, randomised trial was conducted on 142 patients. The study group of 71 patients had a PA vent inserted at the time of cannulation, preventing cardioplegia from going through the lungs. In addition, positive end expiratory pressure (PEEP) was applied and low-volume lung ventilation carried out during cardiopulmonary bypass (CPB). The control group (n = 71) had cardioplegia enter the lung parenchyma during cardiopulmonary bypass. Clinical parameters of arterial blood gases, including estimated shunt fraction, spirometry tests and radiographic analysis was made preoperatively and at set times through the postoperative period. Results: Baseline demographics and intraoperative and postoperative management was the same in both groups, thus, yielding a homogenous sample for analysis. Significant changes were noted in arterial blood gases, spirometry, and radiographic analysis of effusion and atelectasis over the time periods studied (p < 0.001). There was, however, no significant difference between the study and control groups at any point (p > 0.05). Conclusions: The data, therefore, suggest that allowing cold blood cardioplegia solution to circulate the lungs during cardiopulmonary bypass does not have any (beneficial or detrimental) effect on clinical lung function postoperatively.