The Metabolic and Respiratory Acidosis of Acute Pulmonary Edema

Abstract

Arterial blood gas tension and pH were measured in 50 consecutive patients with acute pulmonary edema due to left ventricular failure. In contrast to current belief that blood pH is typically normal or slightly alkaline in pulmonary edema, acidemia (pH below 7.36) was found in 38 of the 46 patients studied before treatment. Although patients with pulmonary edema are said to be characteristically hypocapnic, arterial CO2 tension was below 35 mm Hg in only half of these 46 patients. Eleven patients had arterial CO2 tension above 45 mm Hg, and 12 were eucapnic. The hypercapnic patients did not have more severe pulmonary edema or greater underlying chronic airway obstruction than those without CO2 retention. All but four patients survived the acute episode. The arterial CO2 tension and pH returned rapidly to normal, despite the routine cautious use of morphine, and with only the exceptional need for either ventilatory assistance or alkali administration.