Excessive Gas Exchange Impairment during Exercise in A Subject with A History of Bronchopulmonary Dysplasia And High Altitude Pulmonary Edema

Lovering, Andrew T., Lee M. Romer, Hans C. Haverkamp, John S. Hokanson, and Marlowe W. Eldridge. Excessive gas exchange impairment during exercise in a subject with a history of bronchopulmonary dysplasia and high altitude pulmonary edema. High Alt. Med. Biol. 8:62–67, 2007.—A 27-year-old male subject (V_O2max, 92% predicted) with a history of bronchopulmonary dysplasia (BPD) and a clinically documented case of high altitude pulmonary edema (HAPE) was examined at rest and during exercise. Pulmonary function testing revealed a normal forced vital capacity (FVC, 98.1% predicted) and diffusion capacity for carbon monoxide (D_LCO, 91.2% predicted), but significant airway obstruction at rest [forced expiratory volume in 1 sec (FEV₁), 66.5% predicted; forced expiratory flow at 50% of vital capacity (FEF₅₀), 34.3% predicted; and FEV₁ /FVC 56.5%] that was not reversible with an inhaled bronchodilator. Gas exchange worsened from rest to exercise, with the alveolar to arterial P_O2 difference (AaD_O2) increasing from 0 at rest to 41 mmHg at maximal normoxic exercise (VO₂ = 41.4 mL/kg/min) and from 11 to 31 mmHg at maximal hypoxic exercise (VO₂ = 21.9 mL/kg/min). Arterial P_O2 decreased to 67.8 and 29.9 mmHg at maximal normoxic and hypoxic exercise, respectively. These data indicate that our subject with a history of BPD is prone to a greater degree of exercise-induced arterial hypoxemia for a given VO₂ and F_IO2 than healthy age-matched controls, which may increase the subject's susceptibility to high altitude illness.