Risk of altitude exposure in sickle cell disease.

The risk of altitude-induced hypoxemia causing painful crisis was determined in a group of 45 predominantly adult patients with sickle cell disease. The patients were divided into two groups: those with hemoglobin (Hb) SS and those with Hb SC or Hb S beta-thalassemia. Altitude exposures were divided into airplane travel and mountain visits, and the latter subdivided into stays at 4,400 or 6,320 ft. The average risk of crisis was higher for both groups while in the mountains (37.9 percent and 56.6 percent, respectively) than it was during airplane travel (10.8 percent and 13.5 percent, respectively). The latter group had more splenic crises than the former group and also had a greater risk at 6,320 ft (65.9 percent) than at 4,400 ft (20.0 percent). Patients with sickle cell disease are at high risk of crisis in the mountains, and we advise those with intact spleens to breathe supplemental oxygen during air travel.