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argeted temperature management has been shown to reduce mortality when applied after resuscitation from cardiac arrest.
Current guidelines recommend targeted temperature management for most patients after resuscitation from cardiac arrest (both out-of-hospital and in-hospital arrest).
Two European randomized trials have suggested that temperature management with an aggressive fever avoidance strategy may suffice for high-quality postarrest care.
Targeted temperature management may have benefit for other disease processes such as myocardial infarction and stroke, although data are less conclusive.
The mechanisms by which temperature management acts are multifaceted and a focus of much current investigation.
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The notion of cooling patients for medical benefit is quite old. In 1814, Baron Larrey, a French surgeon in the service of Napoleon’s army, reflected on soldiers who suffered major injuries on the frozen battlefields in Russia by commenting that “cold acts on the living parts … the parts may remain … in a state of asphyxia without losing their life.”1 A belated resurgence of interest in hypothermia has taken place in the past decade, expanding the possible medical indications for its use. Induced hypothermia, the intentional lowering of body temperature, has been explored in a number of acute critical care settings, including myocardial infarction, stroke, head trauma, and after cardiac arrest. The optimal depth of hypothermia remains a highly active area of research, leading to the use of a more general term, targeted temperature management (TTM), to simply describe the control of temperature for therapeutic benefit regardless of specific temperature targets. While previous randomized trials led many experts to advocate for a temperature goal of 32°C to 34°C for postarrest TTM, more recent trials have called this consensus into question, suggesting that fever avoidance using TTM strategies and technology may be sufficient. Timing of TTM, with respect to both time of induction and duration of therapy, is even more uncertain, although general consensus holds that TTM should be initiated as soon as possible after the morbid event and should be maintained for at least 12 to 24 hours. Regarding specific uses, there is strong evidence from at least three major randomized trials that TTM is protective for the resuscitated cardiac arrest patient after return of spontaneous circulation (ROSC).2–4 Two other trials have suggested that, at a minimum, careful avoidance of fever following ROSC is important to improve outcomes.5,6 The use of TTM in other clinical scenarios remains promising but less clear at present.
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This chapter addresses elements of the history of hypothermia, the laboratory and clinical data that have developed our understanding of its use, some of the various techniques used to apply TTM to patients, and the clinical syndromes for which hypothermia or TTM appears to offer the greatest advantage.
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HISTORY OF INDUCED HYPOTHERMIA
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The protective effects of hypothermia induction have been suggested since the time of Hippocrates, who advocated packing bleeding ...