Risk prediction score for severe high altitude illness: a cohort study.

Background: Risk prediction of acute mountain sickness, high altitude (HA) pulmonary or cerebral edema is currently based on clinical assessment. Our objective was to develop a risk prediction score of Severe High Altitude Illness (SHAI) combining clinical and physiological factors. Study population was 1017 sea-level subjects who performed a hypoxia exercise test before a stay at HA.

Physiological risk factors for severe high-altitude illness: a prospective cohort study.

Rationale: An increasing number of persons, exposed to high altitude for leisure, sport, or work, may suffer from severe high-altitude illness.

Objectives: To assess, in a large cohort of subjects, the association between physiological parameters and the risk of altitude illness and their discrimination ability in a risk prediction model.

Methods: A total of 1,326 persons went through a hypoxic exercise test before a sojourn above 4,000 m.

Effects of high-altitude hypoxia on the hormonal response to hypothalamic factors.

Acute and chronic exposure to high altitude induces various physiological changes, including activation or inhibition of various hormonal systems. In response to activation processes, a desensitization of several pathways has been described, especially in the adrenergic system. In the present study, we aimed to assess whether the hypophyseal hormones are also subjected to a hypoxia-induced decrease in their response to hypothalamic factors.

Holmes-Adie syndrome associated with high altitude pulmonary edema and low chemo-responsiveness to hypoxia.

A 63-year-old patient with Holmes-Adie syndrome presented an altered peripheral chemoreflex and suffered from high altitude pulmonary edema, suggesting an alteration of sensitive afferent fibers from the peripheral chemoreceptors. Chemo-responsiveness to hypoxia should be explored before any exposure to moderate altitude in Holmes-Adie patients.

Interaction between hypoxia and training on NIRS signal during exercise: contribution of a mathematical model.

Acute exposure to hypoxia provokes a decrease in peak oxygen consumption ( V(O)(2peak)). At and above 4000 m, the decrease in V(O)(2peak) is greater than expected from the decrease in arterial oxygen content (C(a)O(2)) suggesting the participation of other factors. We hypothesized that O(2) transfer within the active muscle may play a role.

Non-invasive evaluation of the capillary recruitment in the human muscle during exercise in hypoxia.

This study proposes a non-invasive evaluation of capillary recruitment in human muscle from resting state to maximal exercise while under hypoxic conditions. Our work is based on the analysis of oxygen transport variables measured during incremental exercise in endurance-trained men (n=8) and in their sedentary counterparts (n=8). Maximal exercise tests were performed on a cycloergometer in normoxia and at three simulated normobaric levels of hypoxia (altitude equivalent to 1000, 2500 and 4500 m).