This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Which anesthetic modality is to be avoided in sickle cell disease? \nSelect and explain. \nA. General Anesthesia, B. Brachial Plexus Block, C. Intravenous Regional Anesthesia, D. Spinal Anesthesia', 'role': 'user'}, {'content': "Answer: C \nExplanation: Prevention of conditions that favor suckling is the basis of peri-operative management.\n\nSupplemental oxygen is recommended during and after regional anesthesia/GA.\nCirculatory stasis can be prevented with hydration and anticipation of intraoperative blood loss in order to avoid acute hypovolemia\nNormothermia is desirable because hyperthermia increases the rate of gel formation, and hypothermia produces vasoconstriction that impairs organ blood flow.\nThe use of a tourniquet and hence Bier's block (intravenous regional anesthesia) is contraindicated because blood stasis can cause local acidosis, hypoxia with suckling of cells.\nDrugs commonly used for anesthesia should not have significant effects on the suckling process.", 'role': 'assistant'}]