Shock, transfusion, and pneumonectomy. Death is due to right heart failure and increased pulmonary vascular resistance.

To determine the physiologic cardiopulmonary abnormalities leading to death when pneumonectomy is required to stop bleeding in patients in hemorrhagic shock, we compared cardiopulmonary responses to resuscitation in pigs undergoing hemorrhagic shock alone, pneumonectomy alone, and hemorrhagic shock plus pneumonectomy. Four shock-plus-pneumonectomy pigs died acutely from right heart failure. When the five remaining shock-plus-pneumonectomy pigs were compared to the two control groups, pulmonary vascular resistance (PVR) increased to significantly higher levels than would be expected from the increase in PVR noted with resuscitation from shock alone and pneumonectomy alone. Right ventricular compensation maintained cardiac index in the hemorrhage-alone group and the pneumonectomy-alone group but could not maintain cardiac index in the shock-plus-pneumonectomy group, despite maximal increases in right ventricular systolic pressure, heart rate, and right ventricular end diastolic volume. These data indicated that resuscitation from shock plus pneumonectomy cannot be effectively accomplished because increased PVR leads to right ventricular failure, which limits left ventricular preload to levels that are insufficient to maintain cardiac index.