Pulmonary edema following relief of acute upper airway obstruction.

Five children, aged one to five years, with severe upper airway obstruction, three of whom had epiglottitis and two of whom had laryngotracheobronchitis, developed acute pulmonary edema after the obstruction had been relieved by placement of an artificial airway. Although major physiologic changes, such as hypoxemia and massive sympathetic discharge, play a significant role in the development of acute pulmonary edema, we have postulated a possible etiological cause for the development of pulmonary edema in these children which involves a series of physiologic events. The generation of very high transpulmonary pressure gradients during inspiration is opposed by a decreased venous return due to the obstruction during exhalation. Airway pressures then fall abruptly with the insertion of the artifial airway, resulting in a sudden increase in venous return to the central circulation and marked increase in the intravascular hydrostatic pressures. The final result of this series of events is the development of pulmonary hyperemia and edema. The prevention of this situation must begin the moment the airway is inserted and involves the application of moderate amounts of continuous positive pressure to the airway, thus allowing time for circulatory adaption to take place.