Normal saline versus colloid solutions for induction of hypothermia: the effect of specific heat capacity on cooling

The prevention of ischemic injury to preserve both end-organ function and improve neurological recovery by the implementation of therapeutic hypothermia has been well established in the literature. However, not only the means by which body temperature is cooled but also the rate by which target temperature is attained remains an area of continued interest and research. The induction of therapeutic hypothermia to begin the process of body temperature lowering through the infusion of a cold solution intravenously into the body may be one variable that influences not only rapidity of cooling but also subsequent clinical outcome. In a recent issue of Critical Care, Skulec and colleagues compared the induction of therapeutic hypothermia by cold normal saline versus cold colloid solution containing hydroxyethyl starch in a porcine animal model of cardiac arrest, assessing both the rate of temperature change and target temperature achieved, in addition to changes in intracranial pressure.