Mechanical properties of the lungs during acclimatization to altitude

Abstract

Mechanical properties of the lung were studied in nine healthy lowlanders during a 6-day sojourn at an altitude of 3,457 m. In comparison to sea-level values, it was found at altitude that 1) lung volumes measured by plethysmography including total lung capacity, vital capacity, and functional residual capacity (FRC) presented small changes not exceeding 300 ml; 2) static and dynamic lung compliances were not modified but static pressure-volume curves of lungs were shifted progressively to the left (the decrease in lung elastic recoil averaged about 2 cmH2O on days 4-6); and 3) maximal midexpiratory flow, forced expiratory volume in 1 s, and maximal expiratory and inspiratory flows were increased and, conversely, airways and pulmonary flow resistances were decreased on most days at altitude. The unchanged FRC in the face of a decreased lung recoil may be explained by an increase in thoracic blood volume at altitude, but other possible mechanisms are discussed. The decrease in resistances and increase in maximal flows may be partly explained by the decreased air density at altitude, but another contributing factor such as a bronchodilatation is also suggested. It is proposed that changes in lung mechanics at altitude may account for some of the changes in the pattern of breathing and mouth occlusion pressure (P0.1) observed during acclimatization of lowlanders to altitude.

No evidence for interstitial lung oedema by extensive pulmonary function testing at 4,559 m

“…These findings can be explained by reduced air density, and are in agreement with the results of previous studies [5,13,33,43]. Despite normal Reff and sRaw and FEV1, both were improved somewhat by salbutamol, but this improvement was below that considered to be a significant bronchodilator response and was independent of altitude and preceding exercise.…”

“…It is also unlikely that the use of body plethysmography and pneumotachography in the present study accounts for discrepancies with other investigations since GAUTIER et al [5] used the same type of equipment and found a decrease in FVC. The specified range of ambient pressures for the current equipment includes the altitude of 4,559 m, at which it was used.…”

“…Furthermore, seven studies [4][5][6][7][8][9]12] reporting decreased FVC had 4-26 subjects, i.e. had less statistical power than the present study.…”

“…P revious investigations reported reduced forced vital capacity (FVC) [1][2][3][4][5][6][7][8][9][10][11][12] and reduced forced expiratory volume in 1 s (FEV1) [3,7,9,10,12], as well as increased closing volume (CV) [4,12,13], during the first days after ascent to altitudes of 2,800-5,300 m. These findings were interpreted as being consistent with pulmonary interstitial fluid accumulation or subclinical high-altitude pulmonary oedema (HAPE). However, there are several other factors that could also account for or contribute to the observed changes.…”

Valores de referencia para parámetros de espirometría en la población adulta residente en Bogotá, D. C., Colombia

“…Además, se ha encontrado que la ubicación geográfica, la nutrición y la exposición ambiental influyen sobre la función pulmonar (4,(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”