Perioperative Hypothermia: Use and Therapeutic Implications

Abstract

Perioperative cerebral ischemic insults are common in some surgical procedures. The notion that induced hypothermia can be employed to improve outcome in surgical patients has persisted for six decades. Its principal application has been in the context of cardiothoracic and neurosurgery. Mild (32-35 degrees C) and moderate (26-31 degrees C) hypothermia have been utilized for numerous procedures involving the heart, but intensive research has found little or no benefit to outcome. This may, in part, be attributable to confounding effects associated with rewarming and lack of understanding of the mechanisms of injury. Evidence of efficacy of mild hypothermia is absent for cerebral aneurysm clipping and carotid endarterectomy. Deep hypothermia (18-25 degrees C) during circulatory arrest has been practiced in the repair of congenital heart disease, adult thoracic aortas, and giant intracranial aneurysms. There is little doubt of the protective efficacy of deep hypothermia, but continued efforts to refine its application may serve to enhance its utility. Recent evidence that mild hypothermia is efficacious in out-of-hospital cardiac arrest has implications for patients incurring anoxic or global ischemic brain insults during anesthesia and surgery, or perioperatively. Advances in preclinical models of ischemic/anoxic injury and cardiopulmonary bypass that allow definition of optimal cooling strategies and study of cellular and subcellular events during perioperative ischemia can add to our understanding of mechanisms of hypothermia efficacy and provide a rationale basis for its implementation in humans.

Bilateral Carotid Body Tumour: Stormy Physiology and Hemodynamics A Rare Case Report

“…Factors related to perioperative morbidity include tumour size and involvement, surgical manipulation, postoperative edema, injury to nearby nerves, compression and injury to nearby vital structures, blood loss and hemodynamic perturbation during surgery etc. Mild hypothermia (32-35 0 C) 16 and thiopentone infusion 17,18 may offer neuroprotection when cross clamping exceeds 11 minutes. The patient in this discussion had an injury to external carotid which was repaired after application of cross clamps.…”

Neurocognitive outcomes after extracorporeal membrane oxygenation

“…Risks associated with therapeutic hypothermia include coagulopathy and immunosuppression [34]. Therapeutic hypothermia has not been shown to change the rate of intraoperative emboli, or the rate of stroke or cognitive decline in patients undergoing CPB [35e37].…”

Cerebral Ischemia and Post-Ischemic Treatment with Hypothermia

“…For example during cardiac surgery, there are two distinct levels of hypothermia that are commonly used; a target body temperature of 34 -35ºC is now becoming accepted as the standard for Cardiopulmonary Bypass (CPB), while in especially critical cases surgeons may opt to use Deep Hypothermic Circulatory Arrest (DHCA) in which patients are cooled to a rather extreme 15 -26ºC (Choi et al, 2009;Cook, 2009;Mackensen et al, 2009). …”