Hypothermia in the Pediatric Patient

Definition

Core body temperature is a vital sign, and the normal core body temperature is 37°C ± 0.2°C. Humans maintain a constant core body temperature within a limited range when exposed to different ambient temperatures. This tightly controlled thermoregulation can be very easily disrupted by anesthesia and surgery, especially in the pediatric population and most commonly in the neonatal patient. Recent studies have shown that older children between the ages of 12 and 18 are also at greater risk of developing postoperative hypothermia. This may be due to the type of procedures done in this age group, or perhaps there is less attention to maintaining normothermia due to the fact that they are older. Mild hypothermia, a change of 1°C to 2°C, is commonly seen in the pediatric patient receiving general anesthesia. It is crucial that the core-to-peripheral gradient is maintained during anesthesia so that core heat is not distributed and lost in the peripheral tissues. Neonatal patients are specifically susceptible to hypothermia due to their immature thermoregulatory system, their lack of subcutaneous fat that can act as an insulator, and their inability to shiver.

Implications

Hypothermia during and after anesthesia causes several derangements in the pediatric population. In older children, postoperative shivering can increase oxygen consumption by 400% to 600%. Hypothermia has an effect on acid-base balance and on the metabolism of anesthetic drugs. It prolongs the duration of action of muscle relaxants and reduces the minimum alveolar concentration of inhaled anesthetics. It increases oxygen consumption, disrupts coagulation factors, and affects wound healing. Mild core hypothermia has been shown to impair immune function, thus directly impairing neutrophil function. Hypothermia also triggers vasoconstriction, which in turn produces tissue hypoxia, which interferes with wound healing and promotes wound infection. Mild hypothermia has been associated with an increased risk of blood loss and increased incidence of blood transfusion. In moderate-to-severe cases, hypothermia can cause cardiac arrhythmias.

Recognition