Lysosomal enzyme activity influenced by various types of respiration during extracorporeal circulation.

The hypoxic damage of the lung as seen after extracorporeal circulation (ECC) is in correlation to lysosomal hydrolase and protease activation. In the recent study the effect of various types of respiration during ECC on lysosomal enzyme release were studied. 53 patients undergoing open heart surgery were divided into 4 groups: Apnoea, low frequency, continuous positive airway pressure, combination of low frequency and continuous positive airway pressure. Paired blood samples were withdrawn from the superior vena cava (SVC) and the left atrium (LA) throughout the cardiopulmonary bypass. A continuous increase of N-azetyl-beta-D-Glucosaminidase (NAG) in venous plasma and significant differences (SVC-LA) with higher activities in the LA in the apnoea group were detectable (p less than or equal to 0.05-p less than or equal to 0.01). In the other groups a time dependent course could also be evaluated, but the changes of the activities were not significant. The different types of respiration during ECC influenced the clinical course and outcome of the patients in correlation to the release of lysosomal enzymes from the lung. It is concluded that concentration gradients of lysosomal enzymes are an index for pulmonary damage due to the extracorporeal perfusion in open heart surgery. The activation of lysosomal enzymes in the lung circulation are positively influenced by "ventilation" during ECC.