Respiratory mechanics during and after anaesthesia for major vascular surgery

To evaluate the effects of major vascular surgery on respiratory mechanics, eleven patients undergoing general anaesthesia for abdominal aortic surgery were studied. Till aortic cross-clamping, the only respiratory variables that significantly increased were the elastance (EW, +126%) and resistance of the chest wall. After aortic cross clamping, lung elastance (EL) increased consistently (from 12.1 to 17.2 cmH2O*L-1); cardiac index (CI) decreased, pulmonary vascular resistance (PVR) increased, while neither pulmonary occlusion pressure nor central venous exhibit any variation. After aortic unclamping, EL decreased, although it remained higher than baseline values. CI and PVR returned to the values obtained before aortic cross-clamping. We conclude that 1) the EW variation before aortic cross-clamping was due to retractors' placement. 2) the EL variation after aortic cross-clamping could be partially related to an increase in blood lung volume, although an increased vascular permeability could be responsible for the maintenance of the EL increased values.