Perioperative oxygenation and pulmonary shunt during myocardial revascularization in function of duration of extracorporeal circulation

: Perioperative oxygenation is of great importance for the result of operative treatment, especially in patients undergoing open-heart surgery. We studied effect of the duration of extracorporeal circulation on value of pulmonary shunt in 27 patients undergoing coronary artery bypass grafting surgery. The patients were divided into one of two groups according to the duration of extracorporeal circulation: A1 group--extracorporeal circulation less than 90 minutes (9), and A2 group extracorporeal circulation over 90 minutes (18). Measurements of pulmonary shunt were performed at the following times: before (I) and after induction of anaesthesia (II), 5 minutes (III), 2 hours (IV) and 6 hours (V) after extracorporeal circulation, 30 minutes after extubation (VI), 24 hours after extracorporeal circulation (VII), on the second (VIII), third (IX), fifth (X), eighth (XI) and thirteenth (XII) postoperative day. Pulmonary shunt was calculated according to the standard shunt equation (Berggren 1942) in control times I-VII, and formula of estimated shunt in control times VIII-XII. The length of extracorporeal circulation had influence on pulmonary shunt and oxygenation in patients undergoing myocardial revascularization. Extracorporeal circulation lasting over 90 minutes significantly increased pulmonary shunt in the first 24 hours after extracorporeal circulation, excluding the period of artificial ventilation following operation. The recovery of pulmonary function occurred between the eighth and the thirteenth postoperative day, regardless of the duration of extracorporeal circulation.