Two hundred thirty-nine episodes of acute respiratory failure were studied prospectively in 146 patients with chronic respiratory insufficiency during 4 years. Survivors were followed from 6 to 48 months. Patients survived 68% of episodes. Sixty percent of patients survived the initial episodes of respiratory failure, and 55% were alive after 6 months. During the next 2 years the mortality of these patients was high so that only 20% survived 30 months, and the same percentage survived 48 months. The plateau of the survival of these patients after 30 months strongly suggested that the survivors had either stable or slowly progressive disease. In contrast, those patients who had insufficiency from progressive pulmonary disease died within 30 months.
Obese patients and bronchitic patients without emphysema survived more frequently than patients with emphysema alone or those with chronic diffuse infiltrative disease. Surviving patients were younger, without recent losses of body mass, edema, or anemia. They had less reduction of expiratory flow rates and vital capacities, less hypercapnia, and mild acidosis and hypoxia. Patients with a poor prognosis were elderly, with decreased body mass, weight below 110 lb, with edema and anemia. They had lower midexpiratory flow rates and vital capacities, more severe hypoxia (PaO2 < 40 mm Hg), or severe hypercapnia (PaCO2 > 80 mm Hg) with acidosis (H ion > 60 nmoles/1, pH < 7.22).