Biochemical monitoring of the lung during and after extracorporeal circulation

The activity of NAG, lysozyme and PMN-elastase has been investigated in the superior vena caval and left atrium blood collected from patients who underwent open heart surgery. The effect of various types of respiration on the enzyme release has been also documented. Concentration gradients between v. cava sup. and left atrium has been used as an index for pulmonary damage post operatively. We found a time dependent increase of all enzymes during extracorporeal circulation. However, only the release of NAG and lysozyme is characteristic for pulmonary damage. We observed significant higher enzyme release from the lung after Apnea ventilation compared with the PEEP and low frequency ventilation group. Also significant higher NAG and lysozyme activity was found in patients who needed longer respiration post-operatively. PMN-elastase seems to be not suitable for diagnosis of post perfusion lung because the main amount of elastase released by mechanical destroy of the granulocytes.