Pre-adaptation, adaptation and de-adaptation to high altitude in humans: cardio-ventilatory and haematological changes.
The aim of this study was first to investigate cardio-ventilatory and haematological responses induced by intermittent acclimation and second to study de-adaptation from high altitude observed after descent. To achieve these objectives nine subjects were submitted to intermittent acclimation in a low barometric chamber (8 h daily for 5 days, day 1 at 4500 m, day 5 at 8500 m) before an expedition to the Himalayas. Cardio-ventilatory changes were measured during a hypobaric poikilocapnic hypoxic test (4500 m, barometric pressure = 589 hPa) and haematological changes were studied at sea level. These measurements were performed before and after acclimation, after return to sea level, but also 1 and 2 months after the expedition. In addition, partial pressures of oxygen and carbon dioxide in arterial blood (PaO2, PaCO2) and arterial erythropoietin concentration [EPO] were measured at rest during the hypoxic test. Results suggested the pre-adaptation protocol was efficient since an increased PaO2 (+12%, P < 0.05), a smaller difference in alveolo-arterial PO2 ( -63%, P < 0.05) and a lower PaCO2 ( -11%, P < 0.05), subsequent to ventilatory changes, were observed after acclimation with a significant increase in reticulocytes and in sea level [EPO] (+44% and +62% respectively, P < 0.05). De-adaptation was characterized by a loss of these cardio-ventilatory changes 1 month after descent, whereas the haematological changes (increased red blood cells and packed cell volume, P < 0.05) persisted for 1 month before disappearing 2 months after descent. This study would also suggest that acute hypoxia performed after a sojourn at high altitude could induce significantly depressed EPO responses (P < 0.05).
Savourey
G
G
Unitè de Thermophysiologie, Centre de Recherches du Service de Santé des Armées Emile Pardé, La Tronche, France.
Garcia
N
N
Besnard
Y
Y
Guinet
A
A
Hanniquet
A M
AM
Bittel
J
J
D000222:Adaptation, Physiological; D000328:Adult; D000531:Altitude; D004906:Erythrocyte Count; D004921:Erythropoietin / Q000097:blood; D015444:Exercise; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006400:Hematocrit; D006403:Hematologic Tests; D006801:Humans; D000860:Hypoxia; D008297:Male; D009390:Nepal; D012119:Respiration / Q000502:physiology*; D017701:Reticulocyte Count; D018609:Tibet
D004921:Erythropoietin