Low Pulmonary Diffusing Capacity in Subjects With Acute Mountain Sickness

¹ From the First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan

This study was conducted to investigate whether the changes in the pulmonary diffusing capacity found in individuals with acute mountain sickness (AMS) reflect the early stage of high-altitude pulmonary edema (HAPE). We measured the pulmonary diffusion capacity for carbon monoxide (DCO) by the single-breath method, arterialized capillary blood gas, and spirometry in a group of 32 healthy subjects (24 men, eight women) at an altitude of 2,260 m and after ascent to 4,700 m. Twelve subjects (10 men, two women) had symptoms of AMS (AMS group) by the second day after arrival at 4,700 m, but none had clinical signs of pulmonary or cerebral edema. In the non-AMS group, almost all subjects exhibited an increase in DCO at 2,260 to 4,700 m (DCO, 10.7±1.25 mL/min/mm Hg), while the degree of increase in DCO in the AMS group (n=12) was significantly lower (DCO, 1.26±1.74 mL/min/mm Hg) than that of the non-AMS group (p<0.01). In four of the 12 subjects with AMS who had a high AMS score, DCO decreased from 38.4±4.5 to 33.2±5.3 mL/min/mm Hg (DCO, 5.84±1.1 mL/min/mm Hg). The AMS group showed significantly lower vital capacity, forced expiratory flow during the middle half of FVC, Pa0₂, and a greater alveolar-arterial oxygen pressure difference at 4,700 m compared with the non-AMS group. DCO showed a significant negative correlation with AMS score (r=0.885) and a positive correlation with PaO₂ (r=0.757) at 4,700 m. These results suggest that the decreased pulmonary diffusing capacity in subjects with AMS reflects the presence of pulmonary gas exchange abnormality, which is probably due to subclinical interstitial edema of the lung.

Key Words: acute mountain sickness • blood gas • diffusion capacity • high altitude • lung volume • subclinical edema

Submitted on December 7, 1995
Accepted on July 30, 1996

This article has been cited by other articles:

				R. C. Roach and P. H. Hackett Frontiers of hypoxia research: acute mountain sickness J. Exp. Biol., March 11, 2002; 204(18): 3161 - 3170. [Abstract] [Full Text] [PDF]

				T. C. Carpenter, J. T. Reeves, and A. G. Durmowicz Viral respiratory infection increases susceptibility of young rats to hypoxia-induced pulmonary edema J Appl Physiol, March 1, 1998; 84(3): 1048 - 1054. [Abstract] [Full Text] [PDF]