Académie royale de Médecine de Belgique

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Résumé Drummond Rennie

(Séance du samedi 23 octobre 1982)  

WATER  RETENTION IN THE PATHOPHYSIOLOGY OF ACUTE MOUNTAIN SICKNESS

par Drummond Rennie (Chicago), invité par le Bureau.

Le mal de montage affecte 50 % de personnes au-delà de 3.000 m. les symptômes se manifestent un ou deux jours après l’ascension. L’étude de 300 indigènes du Népal, originaires des terres bases et conduits à 4.374 mètres d’altitude dans l’Himalaya, nous a montré que l’incidence et la gravite de ces troubles étaient proportionnelles à la rapidité de l’ascension, à la fatigue et à l’âge.

Le syndrome s’estompe en quelques jours au cours de la descente et du repos.  Un à quatre pour cent de sujets peuvent toutefois manifester un œdème cérébral ou pulmonaire fatal et montrer simultanément un œdème périphérique.

L’étude de 102 indigènes, observés à Katmandou au Népal (1.377 m) et à Pheriche (4.273 m), révèle une relation très nette entre le gain de poids durant les six jours après l’ascension ne manifestaient plus aucun symptôme, tandis que ceux qui conservaient des symptômes graves, affichaient un grain pondéral de deux jours  pour cent au moins et cela malgré leur anorexie et leurs vomissements.

SUMMARY

Acute mountain sickness is a disorder afflicting almost 50 per cent of people ascending to altitudes about 3000 m. Its onset is delayed one to two days after ascent. We have shown in some 380 lowland dwellers investigated at 4,374 m altitude in the Nepal Himalaya that both its incidence and its severity are proportional to speed of ascent and to exertion and inversely related to age. Though this disorder is usually transient and relieved by rest and descent, in 1 to 4 per cent it may progress to sometimes fatal cerebral and pulmonary edema. In addition, we have found that there may be an associated peripheral edema.

I, 102 lowlanders investigated both in Kathmandu, Nepal (1.377 m) and at Pheriche (4.273 m), we have demonstrated a clear relationship between rapid weight gain on ascent and incidence and severity of symptoms of acute mountain sickness. All who lost weight in the first six days after ascent felt well. All who had severe symptoms and signs had more than two per cent gain in body weight despite anorexia and vomiting.

Weight gain also correlated with relative hypoventilation on ascient, which itself caused lower blood oxygen values and increased levels of arterial CO2.  There was, however, no apparent relation to hypoxic ventilator response as measured at low altitude. Those with the lowest vital capacities in Kathmandu became the most symptomatic on ascent.

Rapid weight gain, associated with flat neck veins and high urine osmolality is a reflection of body water retention. Our previous work suggests that the retention is all extracellular and this, coupled with the high incidence of clinical edema in our subjects, strongly suggests that extracellular fluid retention is a basic feature of acute mountain sickness of every severity.  

 

(This work was done with Dr Peter Hackett, Dr Robert Grover, and Dr Jack Reeves of the Cardio-Pulmonary Research Laboratory of the University of Colorado, Denver, USA).

(This work was conducted with Peter H. Hackett, M.D. Stephen E. Hofmeister, Robert F. Grove, M.D., and John T. Reeves, M.D. From the Cardiovascular Pulmonary Research laboratory, University of Colorado Health Sciences Center, Denver, Colorado and the Himalayan Rescue Association, Kathmandu, Népal).