BAD OUTCOMES Unintended perioperative hypothermia is associated with negative patient outcomes, including an increased rate of wound infections, increased length of hospital stay and higher mortality rates.

The list of negative patient outcomes associated with unintended perioperative hypothermia is surprisingly long: wound infections, myocardial ischemia and cardiac disturbance, coagulopathy, prolonged and altered drug effects, increased mortality, shivering, pain and thermal discomfort, and delayed emergence from anesthesia. And it can all happen surprisingly fast. Unintended hypothermia can develop in the hour immediately following the induction of anesthesia. Even mild hypothermia can be associated with significant morbidity and mortality. Much has been written about how to prevent this frequent complication of surgery, but here's a quick refresher on the top 5 consequences of hypothermia that afflict millions of U.S. surgical patients every year.

• Increased wound infection. Hypothermia may increase patients' susceptibility to perioperative wound infections by causing vasoconstriction and impaired immunity. Hypothermia impairs the immune function and decreases cutaneous blood flow that reduces tissue oxygen delivery. This in turn increases the chance of a wound infection and also impairs the wound-healing process. Vasoconstriction occurs when the core body temperature decreases, which is a protective mechanism to divert blood to the center of the body and help maintain the normal body temperature. The reduction of nutrient and oxygen supply to wounds will increase the frequency of surgical wound infection. A threefold increase in the frequency of surgical site infections is reported in colorectal surgery patients who experience perioperative hypothermia.
• Cardiac dysfunction. Ventricular tachycardia in particular is associated with mild hypothermia. Angina, decreased cardiac output, and dysrhythmias can also be related to unintentional hypothermia. As little as 2°C core hypothermia can significantly increase the incidence of a myocardial ischemia in high-risk patients undergoing peripheral vascular surgery.
• Increased blood loss. Mild hypothermia reduces platelet function and decreases activation of the coagulation cascade. Therefore, hypothermia can increase blood loss and require transfusions during surgery. The literature shows that an approximately 2°C drop in core body temperature can increase blood loss by 500mL. Shivering post-operatively can cause an increase in oxygen demand, bleeding times and blood viscosity, and contribute to a risk for metabolic acidosis, along with hyperventilation and hypoxia.

• Altered drug metabolism. Even with mild hypothermia, there is a decreased drug metabolism of most drugs with colder patients. For example, the duration of the muscle relaxant vecuronium is doubled at 34.5°C compared with at 36.5°C. This can still significantly prolong the post-operative recovery period, which not only causes patient flow issues, but also increases costs.
• Increased healthcare costs. We can attribute this to the delayed recovery and ultimately delayed discharge. Also, wound complications prolong hospitalization and substantially increase medical costs. Reducing the incidence of unplanned hypothermia in the operating room can reduce hospitalization costs, shorten the length of hospital stays, decrease the potential for SSIs, and increase the overall comfort of the patient. Patients that feel warm are generally more satisfied and content. In the current healthcare climate, it is important to consider all measures to cut costs and optimize patient outcomes, including patient satisfaction. Adapting clinical guidelines within your practice setting is one step to cost reduction and optimum patient outcomes.

Preventive measures
Thermoregulation is essential, but it's difficult to counteract the internal redistribution of heat that occurs during surgery. Here's a look at the measures you can take before, during and after surgery to warm the surgical patient.

• Keep your patients covered. Expose only the area necessary for the surgical procedure. A great deal of heat is lost through the skin and also through surgical incisions, but this heat loss can be decreased by covering the skin with the surgical drapes, blankets or even plastic. A single layer of protection reduces heat loss by about 30%. Although adding additional layers does not proportionally increase the benefit, combining a triple layer can reduce heat loss by about 50%. Keeping the patient's hair cover and foot covers on before and during surgery can also reduce thermal loss. As your mother told you as a child, a large amount of heat can be lost through the head and feet.
• Keep the OR warm. According to AORN, you should maintain the operating room at a temperature of approximately 23°C (73.4°F). You can raise it even higher when active skin warming is not possible. It should also be higher than 26°C (78.8°F) and prewarmed for neonates or infants. Cool surgical environments can increase the rate by which metabolic heat is lost. Also, large open cavities decrease the core body temperature quickly, especially over a period of lengthy surgery.
• Actively warm patients. Active warming of patients prevents most heat loss and can reverse this trend. For example, you can use forced hot air for at least 15 minutes before surgery, throughout the surgical procedure and post-operatively. Warming of intravenous fluids and blood further prevents unplanned hypothermia, especially when using 2 liters or more of fluids. It was found that 1 liter of crystalloid solution administered at ambient temperature can decrease the mean body temperature approximately 0.25°C in an average size adult. Irrigation solutions used in the abdomen, pelvis or thorax enhance heat transfer from the body core to the solution and will also increase heat loss. Warm intravenous fluids and irrigation solutions to about 37°C to prevent heat loss.

Monitor the core temperature of patients at risk for unplanned hypothermia pre-operatively, intraoperatively and post-operatively. Consider prewarming the patient for a minimum of 15 minutes immediately prior to induction of anesthesia for any patients at risk of unplanned hypothermia. Prewarming can prevent or at least minimize redistribution hypothermia. It is imperative for the operating room nurse to collaborate with the entire surgical team, especially the anesthesia care provider, to develop and implement appropriate measures for each individual patient's needs.

An increased clinical awareness of unplanned hypothermia can help prevent adverse patient outcomes. Through surgical team cognizance, education and available resources, the surgical team can help maintain the best possible environment to prevent perioperative hypothermia.