Altered Oxygenation, Vascular and Ischemic Pain Responses in Adults with Sickle Cell Anemia

The clinical hallmark of sickle cell anemia is the vaso-occlusive pain crisis. Although the exact cause for severe vaso-occlusive painful events is unknown, sickle cell microvasculature occlusion is thought to be the proximate cause producing tissue hypoxia, reperfusion injury and acute pain. Endothelial dysfunction is a prominent characteristic of sickle cell anemia, and it is unclear to what extent this abnormal vascular response contributes to vaso-occlusion and pain. We sought to evaluate the effects of hypoxia on sickle cell pain by performing a forearm ischemic pain test as a potential in vivo model for vaso-occlusion. We hypothesized that sickle cell anemia patients would tolerate a shorter period of ischemia before reaching pain tolerance. We further hypothesized that sickle patients would show more hypoxia and increased vasodilation.