Mild to Moderate Systemic Hypothermia

Abundant animal and clinical studies have shown that deep hypothermia protects neural tissues from ischemic injury during periods of circulatory arrest [34]. The basis for the protective effect of hypothermia is a combination of various mechanisms including reduced metabolic rate, inhibition of release of excitatory neurotransmitters (particularly glutamate) and reduced production of superoxide anions [64]. Although most of the experimental work on neuronal protection has concerned deep hypothermia, it has also been demonstrated experimentally that mild to moderate degrees of hypothermia [32-35 °C) also afford spinal cord protection [65-67]. Moderate hypothermia has been an integral part of our operative strategy to minimize cord injury since the early 1990s, and it is achieved by a combination of permissive hypothermia and active cooling using a cooling blanket and a heat-exchanger in the distal bypass circuit if necessary [8]. Clinical studies comparing systemic hypothermia with normothermia have not shown a difference in paraplegia outcome [68]; although one study did report fewer transient neurological deficits in patients with moderate hypothermia, paraplegia rates were similar [69]. However, virtually all animal studies on hypothermia have shown that spinal cord hypothermia, achieved via whatever means, reduces spinal injury; notably, none of these studies has shown a higher incidence of spinal injury with hypothermia [34]. The inability to demonstrate benefit in clinical studies is likely due to lack of statistical power, and reflects the success of modern surgical techniques and adjunctive measures in minimizing the incidence of paraplegia. Many surgeons extend the use of hypothermia to all patients because it is simple to apply, and has potential benefit and negligible risk (cardiac arrhythmias are rare, even with core temperature as low as 30°C [70]).

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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