Sickling crises and altitude. Occurrence in the Colorado patient population.

Seventy-five black patients with sickle hemoglobinopathies who are followed by the Colorado Sickle Cell Treatment and Research Center, and 172 of their family members were evaluated by retrospective interview for the occurrence of sickling crises when traveling in the Rocky Mountains or by aircraft. Twenty per cent of 39 patients with sickle cell anemia (Hgb SS) (Hgbs S/C and S/T) have developed crises when traveling in the mountains above 2000m. Vaso-occlusive crises predominated in the SS group and splenic crises occurred primarily in those with Hgbs S/C and S/T. Approximately 20 per cent of those with S/C and S/T, but none with SS, had crises when flying in pressurized aircraft. Among 103 family members with sickle cell trait (Hgb AS), no significant risk of developing crises could be identified with either mountain or pressurized aircraft travel.