COVER ME Limit patients' exposure to ambient OR air to stave off unplanned hypothermia.

Warmed patients are happy patients. They're also less likely to leave your facility with a surgical site infection. Let's look at 5 common questions about avoiding unplanned perioperative hypothermia and why warming patients goes well beyond the scores on their satisfaction surveys.

Let's Stamp Out SSIs, Part 8

This Month: Patient Warming
October: Autoclaving and Flashing
November: Low-Temperature Sterilization

1. How does hypothermia increase SSI risks?
When a patient's body temperature falls as little as 1.5 degrees, oxygen supply to tissue around the surgical site drops, which may set up a perfect environment for infection. White blood cells decrease, for example, along with the antibodies needed to fight off infection. Conversely, warming improves tissue perfusion, thereby lessening the likelihood of SSIs developing. Early research of colon resection surgeries reported increased incidences of infection in patients who were hypothermic. While the research focused on a single type of surgery, the implications are clear: All patients undergoing surgery and anesthesia should be considered at risk for SSIs, and efforts to avoid hypothermia are vital.

RECOMMENDED PRACTICES

Warm Patients Every Step of the Way

Here's how to stave off hypothermia from admission to discharge, based on my own experiences and the clinical guideline for the promotion of perioperative normothermia, developed and published by the American Society of PeriAnesthesia Nurses (tinyurl.com/79nxfs2).

GETTING WARMER Monitor the temperatures of recovering hypothermic patients at least every 15 minutes until normothermia is achieved.

In pre-op
Measure patients' temperatures upon admission. While core temperature is the most clinically accurate, measuring it is not practical. Rely instead on near-core temperature readings taken orally or rectally, or at the bladder, temporal artery, tympanic membrane (using an infrared sensor) or axilla. Actively warm patients with temperatures less than 36 ?C. All other patients should be covered with blankets to maintain normal body temperatures, but active warming is not indicated. Pre-warming for 30 minutes before surgery reduces hypothermia risks. Be sure to maintain ambient temperature in the pre-op area at or above 73 ?F.

Assess risk factors for perioperative hypothermia, including the type and length of surgery. Pediatric and geriatric patients might be at increased risk. So too might patients with systolic blood pressure less than 140mmHg. Document and communicate hypothermia risk factor assessment findings to all members of the anesthesia and surgical teams.

Determine patients' thermal comfort levels and assess them for signs and symptoms of hypothermia, which include shivering, piloerection and cold extremities. Patients should be normothermic before heading to the OR or procedure area.

In the OR
Avoiding hypothermia in the operating room is multifaceted — no single measure alone prevents it. In fact, combining all effective methods minimizes heat loss, specifically for surgeries lasting longer than 30 minutes.

First, ensure the OR's ambient temperature is set at 70 ?F (21 ?C) or greater. Setting the ambient temperature is the easiest, but most often overlooked, method for avoiding temperature loss in patients. The comfort of your surgical team is important, but patients lose the most heat in their first hour in the operating room. After the first hour has passed, however, decreasing the room's ambient temperature for your staff's benefit results in little heat loss in patients.

Keep patients covered to minimize their exposure to ambient air. This measure is easily accomplished with warmed cotton blankets. However, active forced-air warming remains the gold standard for preventing hypothermia. Forced-air warming combined with warmed IV fluids and surgical irrigants, circulating water garments and mattresses, or radiant heat lamps are more effective than using a single intervention.

In PACU
Check patients' temperatures and keep them covered with warm blankets. Provide thermal comfort measures for patients who are normothermic and continue to monitor their temperatures at least hourly until discharge. Implement active warming methods on hypothermic patients and measure their temperatures at least every 15 minutes until normothermia is achieved.

— Shari Burns, CRNA, MSN, EdD

2. Which patients are at risk for developing hypothermia?
All of them, but individuals undergoing open cavity procedures such as bowel resection or open abdominal procedures may be more likely to become hypothermic. Also at risk are the very elderly and the very young. Children and infants have a larger surface area-to-weight ratio as compared to adults, which predisposes them to heat loss through mechanisms such as radiation and convection. Changes associated with thermoregulation and decreased ability to shiver, meanwhile, increase the likelihood of hypothermia in the elderly. Lengthy surgeries also raise the risk of heat loss. Other factors that could increase hypothermia risks include the use of cold IV fluids and surgical irrigations.

3. What's the best way to prevent it?
Apply warming strategies in combination. Warmed cotton blankets (passive warming) are great for surface warming and as a comfort measure, but studies show they fall short in preventing hypothermia when compared to active warming methods such as forced-air warming. Studies support its use before, during and after surgery. Although costly, the benefits of this method remain strong. The versatility in design of forced-air blankets include upper, lower and complete body coverings useful during all types of surgeries. Monitor forced-air warming devices closely to avoid disconnected hoses or faulty systems, and never place hoses between standard-issue blankets or sheets, as this dangerous practice can severely burn patients.

Circulating water mattresses, blankets or table pads are useful in preventing hypothermia, but are not ideal solutions when used alone. They're also often bulky, meaning you'll have to be careful handling equipment around them in order to avoid punctures that can cause leaks. Devices that employ circulating water do offer the advantage of being able to heat and cool patients.

4. Does ambient OR temperature matter?
Yes. Research shows that ambient room temperature is a significant variable influencing heat loss in patients. Studies conducted in the 1960s and 1970s remain the gold standard for measuring the impact of OR temperatures on patients' core temperatures. The studies showed that patients who entered rooms with temperatures less than 70 ?F (21 ?C) lost more body heat than patients who entered ORs with temperatures greater than 70 ?F.

5. When should warming begin?
To transport patients to surgery as close to near-normothermic balance as possible, begin warming them as soon as they enter the pre-op area. (Initiate active warming for patients with temperatures less than 36 ?C upon admission.) Without pre-warming, a period of hypothermia is typical, even if active warming is started after anesthesia induction, according to the clinical guideline for the promotion of perioperative normothermia developed by the American Society of PeriAnesthesia Nurses (see "Warm Patients Every Step of the Way") on page 64.

Warming patients before surgery results in less temperature loss during procedures and less post-op hypothermia. Specifically, says the guideline, pre-warming reduces redistribution hypothermia by 2 mechanisms: first by decreasing the core-to-peripheral temperature gradient and, secondly, by promoting vasodilation.