6.3.1.2 Thermal Regulation

Temperature regulation is altered with a ÒresettingÓ of the hypothalamic temperature above normal values [30Ð32]. The teleological advantage of maintaining an elevated core temperature following burn injury is not fully understood, but major burns destroy the insulating properties of the skin, while the patients strive for a temperature of 38.0Ð38.5 ¡C. Sometimes it is difÞcult to differentiate elevated temperatures due to a central reset or due to other causes such as infection or fever. Our protocol calls for cultures if temperatures are persistently over 39 ¡C.

Catecholamine production contributes to the changes in association with several cytokines, including interleukin-1 and interleukin-6. Any attempt to lower the basal temperature by external means will result in augmented heat loss, thus increasing metabolic rate. Ambient temperature should be maintained between 28 and 33 ¡C to limit heat loss and the subsequent hypermetabolic response [3]. Metabolic rate is increased as a consequence of several factors such as the catecholamine burst, the thermal effects of proinßammatory cytokines, and evaporative losses from the wounds, which consume energy, causing further heat loss. The evaporation causes extensive ßuid losses from the wounds, approximating 4,000 ml/m2/%TBSA burns [2, 4]. Every liter of evaporated ßuid corresponds to a caloric expenditure of about 600 kcal.

Beside hyperthermia another very important contributor to poor outcome is hypothermia. Burn patients frequently experience hypothermia (deÞned as core temperature below 35 ¡C) on admission, on the ICU, during OR, and during sepsis [2, 4]. Time to recover from hypothermia has been shown to be predictive of outcome in adults, with time to revert to normothermia being longer in non-survivors. Considering that hypothermia favors infections and delays wound healing, the maintenance of perioperative normothermia is of utmost importance. Tools include warming the ambient room temperature, intravenous ßuid warming systems, and warming blankets. The temperature of the bed should be set at 38 ± 0.5 ¡C. However, this is contraindicated in the febrile patient, as it complicates ßuid therapy due to largely unpredictable free water losses and respiratory management due to the supine position. The patient may require additional 1Ð4 l of free water per day (as D5W IV or enteral free water) to prevent dehydration. These additional requirements are difÞcult to assess in absence of bed-integrated weight scales. This further exposes the gut to dehydration with subsequent constipation.

6.3.2Heart

The typical complication in severely burned patients is cardiomyopathy requiring inotrope therapy, which was discussed above.

Another complication that can occur is cardiac ischemia. Ischemic events can lead to a manifest heart or to temporary cardiac ischemia. If a heart attack occurs (ECG, Trops, CK, clinical symptoms), cardiology should be immediately involved and guide therapy that usually includes aspirin, beta-blocker, nitro. Cardiology can also refer the patient to interventional cardiology for an angio.