Hypothermia in Trauma Patients
For the past few years, medical professionals have acknowledged the need for temperature management as it applies to maintaining a near normal core body temperature to aid patient recovery. Fluids are generally infused into the body at or near room temperature, which is almost 30ºF below body temperature. The body must then give up its own heat to warm the infused fluids, thus exacerbating the problem of hypothermia. It is well known that a core body temperature of approximately 32ºC (approximately 90ºF) is almost always fatal in trauma situations. Significant risks occur at much higher temperatures, as body organs and circulation begin to shut down. Since blood products must be refrigerated, the problem of blood warming is even more pronounced. In the past, warming methods included placing the IV bags in microwave ovens, submerging them in hot water baths, storing them in small wall-mounted ovens and, in the case of refrigerated blood, placing the bag under the arm and near the body of a compassionate nurse. At the extreme is an expensive and bulky "Level 1" infusion device found in major trauma centers.
Although it is empirically obvious that the incidence of mortality among severely traumatized patients is directly related to the severity of their injury, Drs. Jurkovich, et al, report in a 1987 study that trauma patients in their study with core body temperatures less than 32ºC were ten times more likely to die than those whose core body temperatures were greater than 32ºC. [1] They also observed that 52% of their trauma patients were at one time during the course of their treatment hypothermic to less than 34ºC and that the mortality of this group was 41%. As the core body temperature decreased below 34ºC, the rate of mortality increased dramatically. All shock patients whose core body temperature reached as low as 32ºC died. The volume of fluid introduced into the patients influenced the incidence of hypothermia. A higher percentage of patients receiving more than 5 units of blood became hypothermic. It was not stated in the study whether or not the fluids were warmed, although the implication was that they were not.
In another study reported in the same journal, Drs. Luna, et al, commented on the exacerbation of the hypothermia of trauma patients resulting from the infusion of large volumes of fluids into the body and the importance of using blood-warming devices to mitigate the effects. "In our series, patients who received greater than 10 units of blood (one blood volume) became significantly colder and required twice as long to re-warm compared to patients who received no blood or less than 10 units. Patients who received massive transfusions had the majority of their blood replacement at high flow rates in the operating room. Rapid administration of large volumes of whole blood can obviously overwhelm the heating capacity of one or two conventional blood warmers. Trauma patients who require massive transfusions should benefit from the use of newer warming devices that can deliver large fluid volumes at near-normal body temperatures They observed that the occurrence of hypothermia among severely injured patients is common and that they are at the greatest risk of loss of body heat immediately following injury, during initial resuscitation and surgical intervention. Even though severity of injury and age of the patient were the most critical determinants of survival for most patients, Luna noted that, "the physiologic alterations induced by hypothermia are detrimental and add to the metabolic insult from severe injury. Aggressive efforts to limit heat loss and provide conducted heat to the body do effect the degree and duration of hypothermia and should be used in the treatment of critically injured patients." [2]
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