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Preventing the big chill: Periop RNs keep a close watch on patients’ temps to avoid hypothermia


While doing a chart review in 2008, Kim Serrano, RN, MSN, CNP, CPAN, noticed many patients arrived in the MacNeal Hospital (Berwyn, Ill.) postanesthesia care unit with unplanned perioperative hypothermia. “We noticed that when patients were coming out of the OR their temps were lower than they should be,” said Serrano, director of preadmission testing and the GI lab.

The discovery prompted her to begin an evidence-based research project — with the help of colleague John Coates, RN, BSN, CPAN, PACU clinical coordinator — to examine the best methods to prevent hypothermia in total knee and total hip replacements. Four years later, patients undergoing almost any type of surgical procedure are being warmed preoperatively and intraoperatively and are arriving in the PACU warmer and less vulnerable to hypothermia and its risks.

Normothermic temps the goal

Until fairly recently, patients undergoing surgery would describe the experience as frigid. Patients shivered in presurgical holding areas, slid their backsides onto cold tables in chilly OR rooms, and then struggled to stay warm under layers of blankets in the PACU.

“The things that patients complain about most are nausea, vomiting and being cold,” said Judy Wiley, RN, DNP, CRNA, staff nurse anesthetist, assistant professor in the Rush University College of Nursing, and associate director, nurse anesthesia program, at Rush University Medical Center in Chicago. “Keeping patients warm has been a priority for me my whole practice, but it’s become more of a priority in the OR as a whole in the last five to 10 years.”

A little more than a decade ago, researchers, such as Daniel Sessler, MD, currently at the Cleveland Clinic in Ohio, discovered unplanned hypothermia led to complications such as increased risk of infection, pain, arrhythmias and blood loss. Preventing hypothermia soon became a Centers for Medicare & Medicaid Services’ quality indicator linked to hospital reimbursement.

No longer were trips to the OR allowed to be so chilling. Now patients must be kept as close to normothermic as possible with temperatures consistently and carefully monitored during the entire surgical experience, according to AORN Perioperative Nursing Specialist Sharon Van Wicklin, RN, MSN, CNOR/CRNFA, CPSN, PLNC.
The Recommended Practices for the Prevention of Unplanned Perioperative Hypothermia, published by the Association of periOperative Registered Nurses in 2008, points out that the problem presents a “constant challenge” for periop RNs. “We need to be aware that our patients are at risk for hypothermia. As nurses, we tend to think keeping the patient warm is anesthesia’s problem,” Van Wicklin said

Defining hypothermia

Normothermia is a core temperature range of 36 to 38 degrees Celsius (96.8 to 100.4 degrees Fahrenheit). Hypothermia is a core body temperature that is less than 36 C. If patients are becoming hypothermic, perioperative nurses will notice shivering and piloerection (aka goose bumps). The blood vessels of a hypothermic patient become vasoconstricted, and the body uses more oxygen and calories to produce heat. This results in a cascade of events that puts the patient at risk for various complications, such as increased infection and pain.

In the past, periop nurses may not have understood or recognized the importance of keeping patients warm before they entered the surgical suite, Wiley said. “They may not have realized the negative consequences of hypothermia,” she said. “If you become cold enough, blood doesn’t adequately clot and cardiac conduction is affected. Medications can become trapped in the vessels.”

If patients are cold when they leave the OR, then when they are warmed in the PACU drugs trapped in the periphery are liberated as patients vasodilate, and they still can experience the effects of the drugs at an inappropriate time, she said.

Warming up in the bullpen

Patients begin their surgical experience vulnerable to hypothermia; they are dehydrated and their energy stores are low because they have not had anything to eat or drink since the previous day, said Nancy Vardaro, RN, MAS, CNOR, vice president of clinical operations for Surgem LLC, a corporation that owns and manages surgery centers in New Jersey, New York and Florida.

Patients also are scantily clad in hospital gowns, which do not provide much warmth, and often are nervous or anxious about their imminent surgeries. Studies have shown patients are less anxious when they are covered in a gown or blanket that allows warm air to be blown on their body before surgery, Vardaro said.

Nurses cannot assume their patients are warm before surgery and should do an assessment of their risks for hypothermia. “Nurses need to develop a plan of care that will minimize risks of hypothermia,” Van Wicklin said. “We want to start with the nursing basics of a thorough and careful preoperative assessment and use the equipment available to us to monitor patients’ temperatures and to adjust the environmental conditions, even if it means turning up the heat a couple of degrees in the OR.”

Depending on the hospital, patients may be warmed preoperatively with methods as simple as warm blankets or with 21st century hospital gowns that allow warm air to be blown over the skin. “Prewarming is found to be effective in helping to maintain patients’ temperatures once they are in surgery,” Van Wicklin said. “Use whatever device you have to warm them up for 15 minutes before bringing them into the OR.

Who is at risk?

Any patient is at risk for hypothermia. But certain patients are at greater risk than others. They include —
• Neonates, infants and children because of the high ratio of body surface to weight.
• Elderly patients, who lose heat more rapidly because of decreased vascular tone and compromised circulation.
• Patients with extensive burns because the natural insulating property of the skin is impaired in burned tissue.
• Trauma patients experiencing blood loss, infusion of cold fluids and the removal of clothing in the ED or OR.
• Patients with metabolic disorders that inhibit thermoregulation, such as hypothyroidism, diabetes, neuropathy and neurological disorders.
• Patients who are taking antidepressants or antipsychotics because of their effects on the hypothalamus.

Detecting core temps

The challenge of monitoring the body’s core temperature is finding the most accurate device. AORN’s recommended practices states, “Equipment to monitor core temperatures should be selected based upon reliability and access to the route.” The four most reliable sites to monitor core temperature, according to AORN, are the tympanic membrane, distal esophagus, nasopharynx and pulmonary artery.

Coates said at MacNeal they found the most reliable device to monitor and record core temperature is a noninvasive temporal artery thermometer. “It was a device that was new to us, and it was easier to use across (patient) populations than other devices,” he said. “It measures blood flow in the temporal artery through an infrared beam.”

Besides forced-air and other warming devices, some of the techniques used during surgery to maintain normothermia include foil-like reflective OR bonnets that keep patients’ heads warm, the warming of IV and irrigation fluids, preventing patients’ body surfaces from unnecessary exposure, and sending patients to the PACU with warming devices.
At Rush, OR nurses prewarm surgical beds, Wiley said. In addition, almost every patient who has a surgical procedure lasting more than 60 minutes is warmed during surgery by a forced-air warming device, she said. Preop nurses in the surgical prep area also prewarm patients scheduled for procedures at high risk for hypothermia — including major orthopedic, general, gynecologic and spine surgeries — using forced air warming gowns.
Once Serrano and Coates documented the ill effects of hypothermia on their patients, anesthesia personnel took the prevention of hypothermia “to a new level,” taking every patient’s temperature from the moment they enter the OR and using devices such as fluid warmers to ensure the patient remains as warm as possible.
PACU sees benefits of warmer patients

Patients who have not been warmed during surgery come to the PACU at increased risk for hypothermia. Restoring a patient’s normal body temperature can take several hours.

Four years after Serrano started collecting her data, surgical patients entering MacNeal’s PACU are coming in normothermic, she and Coates said. In 2009 the average temperature of patients arriving to the MacNeal PACU was 35.8 degrees Celsius, said Serrano. In 2010, the average temperature was 36.1 upon arrival — a result of the staff’s efforts and collaboration.

“It’s had a big impact on our patients’ length of stay and pain levels,” Coates said.
In the beginning, convincing personnel of the value of keeping patients normothermic took some effort. But together Coates and Serrano proved keeping patients warm helped lead to better outcomes for patients. “Now it’s a quality focus for everybody,” Serrano said.


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Janet Boivin, RN, is a freelance writer.

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