INFLUENCE OF RESPIRATORY SUPPORT STRATEGY DURING CARDIOPULMONARY BYPASS ON LUNGS OXYGENATING FUNCTION

Introduction There are high incidence of pulmonary complications and acute respiratory failure (3,2—28,6%)¹ after cardiac surgery with cardiopulmonary bypass. The study aimed to evaluate the effectiveness of various tactics of respiratory support during cardiopulmonary bypass (CPB) for the prevention of postoperative pulmonary complications. Methods This is a prospective, randomized, controlled clinical study in parallel groups. The study was approved by a local ethics committee. Informed consent was obligatory for all participants. Sixty patients were divided into two groups. In group 1 we provided a continuous positive airway pressure (CPAP) of +5 cm H2O during CPB. In group 2 patients underwent mechanical ventilation with reduced volume (volume control (VC) mode, tidal volume 3 ml / kg of ideal body weight) and respiratory rate of 6 breathes per minute with positive end-expiratory pressure + 5 cm H2O. The primary end-point of the study was the value of the partial pressure of oxygen in arterial blood to oxygen fraction in inhaled gas mixture ratio (paO2/FiO2) at different stages of perioperative management: T1 (after the beginning of mechanical ventilation, T2 (before the CPB), T3 (after CPB), T4 (at the end of the surgery), T5 (upon admission to the ICU), T6 and T7 (6 and 12 hours after surgery, respectively). Secondary end-points were the common lung complications rate (pneumonia, pleural effusion, atelectasis, pneumothorax), the frequency of recruitment maneuvers during the mechanical ventilation, the need for non-invasive ventilation after extubation, the frequency of re-intubation of the trachea. Statistical analysis was carried out in SPSS for Mac v19 (IBM, Inc, USA). Data were presented as mean (±standard deviation) or number (percent). A comparison of the quantitative characteristics was performed using the Mann Whitney U-test. Fisher's exact test was used for the incidence of complications between groups. A p value of less than 0.05 was considered statistically significant. Results The results are presented in Tables 1 and 2. The paO2/FiO2 in the VC group was higher than in the CPAP group at stages T3 and T5. The frequency of recruiting maneuvers in the VC group was lower than in the CPAP group. There was a lower incidence of atelectasis in the VC group than in the CPAP group (Table 2). The low-volume lung ventilation during the CPB is beneficial for oxygenating function of the lungs in comparison with CPAP respiratory support. Discussion The low-volume lung ventilation during the CPB is beneficial for oxygenating function of the lungs in comparison with CPAP respiratory support.