The sudden hemodynamic disturbance in the perioperative period can occur because of various surgical and anesthetic reasons but hemodynamic collapse due to noxious stimulus of periosteum stripping has not been described. We report two cases of severe hypotension and bradycardia during periosteum stripping in orthopedic surgery under subarachnoid block even though the block level was adequate. In our patients, hemodynamic collapse occurred specifically at a moment when surgeons manipulated periosteum and fall in blood pressure and heart rate was sudden in onset. The hemodynamic disturbance did not appear to be related to vagally mediated or due to blockade of sympathetic fibers but appeared to be related to periosteal nociceptors.
Keywords: Bradycardia; Hypotension; Nociceptors; Periosteum; Spinal anesthesia.