[Perioperative thermal management]

Perioperative hypothermia can influence clinical outcome negatively. It triples the incidence of adverse myocardial outcomes, significantly increases perioperative blood loss, significantly augments allogenic transfusion requirements, and increases the incidence of surgical wound infections. The major causes are redistribution of heat from the core of the body to the peripheral tissues and a negative heat balance. Adequate thermal management includes preoperative and intraoperative measures. Preoperative measures, e.g., prewarming, enhance heat content of the peripheral tissues, thereby reducing redistribution of heat from the core to the peripheral tissues after induction of anesthesia. Intraoperative measures are active skin surface warming of a large body surface area with conductive or convective warming systems. Intravenous fluids should be warmed when large volumes of more than 500-1000 ml/h are required. The body surfaces that cannot be actively warmed should be insulated. Airway humidification and conductive warming of the back are less efficient.

Maintaining intraoperative normothermia: a meta-analysis of outcomes with costs

The present study used a meta-analysis to examine 4 questions about intraoperative hypothermia. The questions addressed were as follows: (1) Is the difference in adverse patient outcomes between normothermic and mildly hypothermic patient groups significant across studies and within studies? (2) What is the magnitude of the difference in adverse patient outcomes across studies? (3) What are the costs resulting from the difference in adverse patient outcomes? (4) Does a significant difference exist in effectiveness of modality for maintaining intraoperative normothermia? The results of this meta-analytic study provide evidence that the difference in adverse patient outcomes between the normothermic and mildly hypothermic patients is significant across studies for all adverse outcomes examined. The magnitude of this difference and the costs resulting from these adverse outcomes are presented. In addition, a significant difference in effectiveness between warming modalities for maintaining intraoperative normothermia was found. A significant increase in the risk of costly complications occurred when patient temperatures dropped a mean of 1.5 degrees C. For example, patients who become mildly hypothermic are much more likely to receive blood transfusions and to develop infections; both of these outcomes result in increased costs. Minimizing adverse outcomes is critical to cost-effective patient care in today's competitive healthcare environment. The cost of preventing intraoperative hypothermia is much less than the cost of treating the adverse outcomes that affect patients experiencing intraoperative hypothermia. Meta-analytic results allowed us to conclude that hypothermia averaging only 1.5 degrees C less than normal resulted in cumulative adverse outcomes adding between $2,500 and $7,000 per surgical patient to hospitalization costs across a variety of surgical procedures. In conclusion, patients whose temperatures have been maintained at normal levels during the intraoperative period experience fewer adverse outcomes, and their overall hospital costs are lower. Intraoperative normothermia is maintained more effectively with the use of forced air warming.