Therapeutic hypothermia and controlled normothermia in the intensive care unit: Practical considerations, side effects, and cooling methods*

Abstract

Temperature management and hypothermia induction are gaining importance in critical care medicine. Intensive care unit physicians, critical care nurses, and others (emergency physicians, neurologists, and cardiologists) should be familiar with the physiologic effects, current indications, techniques, complications and practical issues of temperature management, and induced hypothermia. In experienced hands the technique is safe and highly effective.

Hypothermia or normothermia after cardiac arrest? Do not throw the baby out with the bath water?

“…Another potential difference is the active re-warming from 33 to 36°C over a 6-h period in the hypothermia arm of the study, which was faster than in the previous studies as well as advised by others [3,4,16,17]. There was also a greater incidence of spontaneous hypothermia (before start of active cooling) in the 33°C group, potentially indicating greater severity of brain injury with a diminished shivering response.…”

Therapeutic Hypothermia for Acute Neurological Injuries

“…Both can be largely prevented by slow and controlled rewarming, with a warming rate of 0.2°C to 0.5°C/h. This allows the kidneys to excrete the excess potassium and prevents rebound ICP elevations [3,61]. A detailed description of the physiological changes and potential side effects of hypothermia is listed in Table 1.…”

“…This was the original method used on patients in 1 of the sentinel studies demonstrating improved survival outcomes in cardiac arrest with therapeutic hypothermia [1]. The cooling rate for ice packs is approximately 1°C/h [3], and these are commonly placed around the head, neck, groin, and axillae. The rate for air-circulating cooling blankets is slower at 0.5°C/h [3], and these are placed over or under the patient.…”

“…Defining Therapeutic Hypothermia TH is defined as intentional reduction of core body temperature (T c ) to 32°C to 35°C [3], although no consensus exists regarding the exact level of cooling. Experts favor the following definitions: mild hypothermia (T c 34°C to 35.9°C), moderate hypothermia (T c 32°C to 33.9°C), moderate-deep hypothermia (T c 30°C to 31.9°C), and deep hypothermia (T c <30°C) [3].…”

“…Experts favor the following definitions: mild hypothermia (T c 34°C to 35.9°C), moderate hypothermia (T c 32°C to 33.9°C), moderate-deep hypothermia (T c 30°C to 31.9°C), and deep hypothermia (T c <30°C) [3]. Despite the lack of consensus in terminology, previous studies demonstrated that body temperature does not need to be less than 32°C to achieve neuroprotection [1,2,[4][5][6][7].…”