Despite advancing technology in surface cooling devices and the introduction of endovascular catheters for core cooling, somehow average periods of 2 to 3 hours are still required to reach temperatures of 32��C to 34��C [71]. The currently available surface cooling devices are also relatively large and cumbersome. This coupled with the need for staff with specialist knowledge of the management of induced hypothermia may prevent its use outside of the intensive care unit [71].A recent study examined the feasibility, speed, and complication rates of infusing refrigerated fluids intravenously to quickly induce hypothermia in patients with various neurological injuries [71]. Results showed that a 1,500 mL infusion of 0.9% saline, administered over the course of 30 minutes in patients without cardiogenic shock, reduced core temperature from 36.

9��C �� 1.9��C to 34.6��C �� 1.5��C at 30 minutes and to 32.9��C �� 0.9��C at 60 minutes. Continuous monitoring of arterial blood pressure, heart rhythm, central venous pressure, arterial blood gasses, and serum levels of electrolytes, platelets, and white blood cells showed no significant adverse events [71].When hypothermia develops, the body will immediately try to counteract the temperature drop to maintain homeostasis [72]. One of the key mechanisms of heat production is shivering, which can lead to an increased oxygen consumption of 40% to 100%, which may be detrimental in this patient population. Sedation drugs are known to increase peripheral blood flow and, in turn, increase the transfer of heat from the core to the peripheries, thus reducing core temperature [72].

Therefore, shivering may be counteracted by the administration of sedatives, anaesthetic agents, opiates, and/or paralysing agents [72].It should be noted, however, that the capacity and effectiveness of the mechanisms of controlling body temperature decrease with age. Younger patients will therefore react earlier and with greater intensity than older patients. For this reason, induction of hypothermia in younger patients often requires high doses of sedation drugs to neutralise the counter-regulatory mechanisms [72].Meta-analysesEight meta-analyses have been published between the years 2000 and 2009 [73-80]. These include various numbers of trials, with varying quality of randomisation and blinding procedures.

All have found a trend to positive effects of hypothermia on neurological outcome, although statistical significance was reached in only two reviews: RR of improved neurological outcome of 0.78 (95% CI 0.63 to 0.98) [73] and RR of 0.68 (95% CI 0.52 to 0.89) [74]. Since submission of this manuscript, two Cochrane systematic reviews (issue 1 [79] and updated issue 2 [80] from 2009) have been published (Figure (Figure1).1). The authors found that hypothermia may Anacetrapib be effective in reducing death and unfavourable outcomes, but significant benefit was found only in low-quality trials.