Background. There is limited knowledge about the medical problems of long t
erm stay at high (> 3000 m) and extreme (> 5000 m) altitudes, as these area
s are generally considered uninhabitable.
Methods. Prospectively collected clinical records of all patients hospitali
zed at Command Hospital, Western Command between November 1998 and February
2000 were reviewed to identify thrombotic complications among patients fro
m high and extreme altitude areas as well as those from non-high altitude a
reas who were < 45 years of age.
Results. Of 20 257 hospital admissions during the study period, 1692 were f
rom high and extreme altitude areas. Forty-six patients from these areas ha
d thrombosis-related diseases compared to 17 from non-high altitude areas (
odds ratio: 30.49; 95% Cl: 17.06-51.67; p <0.001). The mean (SD) age of all
patients with thrombotic complications was 32 (8) years and all were men.
The mean duration of stay at high and extreme altitudes of such patients wa
s 10.2 (5.6) months Only 25 were smokers (mean 5.2 pack-years) and 39 consu
med alcohol (mean 54 ml/day). Apart from frostbite in 5, no other medical c
ondition was noted in these patients. The vascular events were deep vein th
rombosis (20), pulmonary thromboembolism (6),stroke(15), thrombosis of the
abdominal veins (8), and retinal artery and peripheral arterial thrombosis
(1 each). The presenting complaint in all patients with thrombosis of the a
bdominal veins was poorly localized pain in the upper abdomen followed by a
scites (6/8). Five of these patients also had a large spontaneous splenic h
aematoma. None of the patients investigated was found to have a procoagulan
Conclusion. Long term stay at high and extreme altitudes is associated with
a 30 times higher risk of spontaneous vascular thrombosis. Veins are commo
n sites of such thrombotic events. We also encountered thrombosis of the po
rtal, splenic and superior mesenteric veins in our patients who had stayed
at high and extreme altitudes.