The complications of IVRA is mainly attributable to the use of the tourniquet. On inflation of the touniquet there is physiological deoxygenation. In patients with sickle cell disease this might lead to sickling crisis. In these patients IVRA causes stasis, local acidosis and hypoxia. Hence IVRA is best avoided in sickle cell disease patients. Adequate oxygenation of the patient would be prudent. Ref: Complications of regional anesthesia By Brendan T. Finucane, Page 216; Essentials of Regional Anesthesia By Alan David Kaye, Richard D. Urman, Nalini Vadivelu; McGlamry's comprehensive textbook of foot and ankle surgery, 3rd ed, Vol 2 By Alan S. Banks, E. Dalton MacGlamry, Page 180; Surgery and anesthesia in sickle cell disease (By M Koshy, SJ Weiner, ST Miller, LA Sleeper, E Vichinsky, AK Brown,Y Khakoo, and TR Kinney).