Cardiorespiratory Studies in Critical Illness

Abstract

Cardiorespiratory studies in 18 patients with acid aspiration pneumonitis have been correlated with the clinical course. All patients with pH of gastric aspirate less than 1.75 died. Plasma volume deficits measured were moderate and correlated with the degree of systemic hypotension observed. Cardiac failure did not occur except in patients with severe preexisting heart disease or overtransfusion. Routine use of digitalis and fluid restriction is unwarranted. The arterial hypoxemia and increased alveolar arterial oxygen difference (A-aDo₂) suggested maldistribution of ventilation compatible with pulmonary edema. Total compliance was decreased. Intermittent positive pressure breathing with oxygen generally decreased the A-aDo₂ within 48 to 72 hours. In one patient who was markedly hypoxemic the high pulmonary artery pressure was abolished following oxygen administration. The pneumonitis was noninfective at the onset. Prophylactic antibiotics did not prevent subsequent pulmonary infection. The mortality as a direct consequence of aspiration pneumonitis was 40%. The main factors contributing to this mortality were advanced age, low pH of gastric aspirate, prolonged hypoxemia, and infection in the lung and elsewhere.