Exercise-Induced Pulmonary Edema in Heart Failure

Abstract

Background— In heart failure (HF) patients, exercise may increase pulmonary capillary hydrostatic pressure and thereby generate pulmonary edema. If pulmonary edema developed, alveolar-capillary membrane conductance (D m ), measured immediately after exercise, would decrease. To test this hypothesis, we measured D m before and at 2 and 60 minutes after exercise. Methods and Results— We studied 10 HF patients with exercise-induced periodic breathing, 10 with peak V̇ o 2 ≤15 mL · min −1 · kg −1 (severe HF), 10 with V̇ o 2 =15 to 20 mL · min −1 · kg −1 (moderate HF), and 10 normal subjects (control). Using the Roughton-Forster technique, we measured carbon monoxide diffusion capacity (DL co ) and its components, capillary blood volume (V c ) and D m , at rest and 2 and 60 minutes after exercise. At rest, DL co and D m were lowest in periodic breathing and highest in control subjects. D m decreased in periodic breathing, severe HF, and moderate HF (−7.83±3.98, −5.57±2.03, and −3.85±3.53 mL · min −1 · mm Hg −1 , respectively; P <0.01) at 2 minutes after exercise but not in control subjects. V c increased in all groups at 2 minutes and remained elevated at 60 minutes only in periodic breathing. D m /V c was decreased in periodic breathing, severe HF, and moderate HF at 2 minutes but not in control subjects. D m and D m /V c remained low at 60 minutes only in periodic breathing. Conclusions— D m decreases after exercise in HF patients but not in control subjects, which suggests a decrease in conductance across the alveolar-capillary barrier, as with pulmonary edema. The reductions were most marked in HF patients with periodic breathing and less reduced in less severe HF.