[Pulmonary complications after extracorporeal circulation. ECC lung syndrome]

Pulmonary complications after cardiac surgery under extracorporeal circulation remain frequent and sometimes grave, in spite of the great progress which has been made over the past 20 years in the methods of cardiorespiratory assistance. The authors analyse the clinical and radiological repercussions of perfusion on the lung, in 40 patients operated under ECC for coronary revascularisation. The simutaneous study of the arterial, and mixed venous blood gasses and of the alveolar gases, in 20 of these patients showed the constant occurrence of a shunt syndrome, without alveolar hypoventilation or disorders in peripheral circulatory flow. Ventilatory alcalosis, hypocapnia, hypoxemia and the rise in the alveolar arterial oxygen gradient is increased during the second post-operative day. Among the variables studied (duration of ECC, degree of hypothermia, duration of the intervention, duration of anesthesia, pleurotomy) only the latter intervened in a statistically significant manner in this study, in the increase in hypoxemia. 46 pulmonary biopsies carried out before and after ECC in 23 coronary patients were examined with the electron microscope. The initial alveolar involvement affects the septal microcirculation with signs of an increase in capillary permeability leading to an interstitial and epithelial destruction. The use of a membrane oxygenator prevents some of the alveolar lesions, as has been proved by the study of five pulmonary biopsies carried out in dogs submitted to ECC of long duration. Catherterization of the pulmonary artery carried out in 35 patients by means of a SWAN-GANZ catheter, before the intervention enabled supervision of the degree of importance and speed of the hemodynamic variations in the pulmonary circulation during the different phases of ECC (during the phase of ventricular fibrillation). The rise in the flow of left output can lead to the occurrence of negative pulmonary intravascular pressures which can be prejudicial for capillary trophicity. The syndrome of "ECC lung", a veritable "induced post-agressive lung" must be placed in the group of refractory hypoxemia of which it represents one of the most typical pictures.