Adult subacute mountain sickness--a syndrome at extremes of high altitude

Subacute mountain sickness is distinct syndrome of congestive cardiac failure seen in lowlanders during prolonged stay at extreme high altitude (> 5800 mtrs).

To study the clinical and investigative profile of subacute mountain sickness amongst Indian soldiers stationed at extreme altitude.

Symptomatic individuals who were stationed above 5000 mtrs were evacuated to 3000 mtrs and clinically screened for signs of congestive cardiac failure. ECG and X-ray chest; hematological and biochemical parameters were evaluated. Response to rest, oxygen and diuretics were studied and they were evacuated to the plains. They were followed up at the plains for a period of two weeks at the end of which chest X-ray and ECG were repeated.

Eight patients were diagnosed over a period of one month who had classical features of congestive cardiac failure. The mean age was 28.75 years, the mean altitude 5828.47 mtrs and the mean duration of stay 17.35 weeks. The most common symptom was exertional dyspnea (6 of 8 cases) and the most common sign bilateral pedal edema (7 of 8 cases). Two patients had deep venous thrombosis. Clinical, ECG and X-ray evidence of pulmonary hypertension was seen in seven cases. The mean hemoglobin was 18 gm%. Response to oxygen and diuretics was dramatic. Clinical findings and investigations reverted to normal after two weeks of stay on the plains.

This brief study of subacute mountain sickness reemphasizes the role of pulmonary hypertension as the initiating event. Other factors are salt and water retention and polycythemia. Brisk response to diuretics and oxygen and restoration of normalcy on deinduction to the plains establishes the reversibility of the syndrome.