ONE STEP UP Forced-air warming is often the preferred choice in preventing unintentional hypothermia.

In an effort to standardize how we warm patients, we tested 3 warming options on more than 800 patients at our hospital-affiliated surgery center: forced air, heat reflective technology and warmed cotton blankets. Rather than let our anesthesia providers decide which method was the most effective and economical choice to prevent hypothermia, we wanted to put the warming methods to the test. The results might surprise you.

Living proof
Our center hosts a wide range of major and minor procedures that last from 15 minutes to 8-plus hours. Our warming policy was whatever the anesthetist prefers. Determining if any method outperformed the others would help standardize the process and could potentially save on case costs if we could forgo the use of forced-air blankets or heat reflective technology in favor of warmed cotton blankets.

During the study period, we assigned patients in pre-op bays 1, 3 and 5 to receive warming with heat reflective technology and patients in bays 2, 4 and 6 to receive warmed cotton blankets for shorter-duration procedures or forced-air warming for procedures expected to last longer than 1 hour.

We recorded temporal artery temperature readings every 30 minutes in pre-op, every 30 minutes in the OR after anesthesia induction and every 30 minutes in PACU until normothermia was maintained for an hour. We set the ambient temperature in the ORs between 69 ?F and 72 ?F, as recommended by AORN, and conducted daily checks in the ORs and in each pre- and post-op patient bay to ensure temperatures stayed within the recommended range.

Temperature readings from at least one phase of care were missing for 242 patients, so they weren't included in the final results, which showed that of the remaining 595 patients, 549 (92%) maintained normothermia and 46 (8%) experienced a hypothermic event. Our findings fell within the reported 4% to 9% range of patients who typically experience hypothermia. I expected our rate would be less, because some of our minor procedures are over in minutes.

COVER ME A warmed cotton blanket might be all patients need to remain normothermic.

We found that each of the warming options was equally effective in maintaining normothermia. Women were 0.46 times less likely than men to remain normothermic, but the difference was not statistically significant. In addition, there was no association between pre-warming and normothermia. Surprisingly, we also couldn't identify a statistically significant predictor of hypothermia. At first we assessed (low) body-mass index and age (the elderly and the very young), 2 commonly associated risk factors, but saw no correlation. That was hard for me to accept, so we added more data and crunched the numbers to assess the potential impact of ASA status, time in pre-op, pre-warming, pre-warming duration, case duration and procedure type. Still, no link was discovered.

The price you pay
Our findings are based on real-life observations in a busy surgery center. They aren't published in a peer-reviewed journal, so drawing definitive conclusions is a challenge. But they provided some interesting insights and a jumping-off point for additional research that could help identify how to best prevent hypothermia and, if there's no significant difference between active warming methods and warmed cotton blankets, a more economical choice.

The surgery center ultimately decided to maintain its current policy of leaving patient warming to the discretion of individual anesthesia providers, perhaps because we use forced-air warming so seldom that we wouldn't save significantly if we eliminated it. As a general rule, patients undergoing minor procedures lasting 15 to 30 minutes receive warmed cotton blankets. Only patients scheduled to undergo procedures expected to last longer than an hour receive forced-air warming gowns. We also keep IV fluid in warming units until it's administered.

We need to extend the research we conducted in the surgery center to the hospital's main ORs to see if the results are consistent and to determine if we can realize significant savings. Anesthesia providers in the hospital administer warmed IV fluids and apply forced-air warming to every patient who undergoes surgery, regardless of procedure type or length. When you consider the main ORs host 50 to 100 patients a day, eliminating the $35 to $100 that active warming adds to the cost of a case could produce significant savings over the course of a year.

However, CMS's Surgical Care Improvement Project recommends active warming for patients who undergo procedures lasting longer than an hour. Medicare won't fully reimburse hospitals for the care of a patient if a hypothermic event occurs during surgery or if a surgical site infection can be linked to hypothermia, so there are significant financial implications associated with failing to maintain normothermia that drive the policy of applying forced-air warming to all patients in our main ORs. ASCs don't yet have Medicare reimbursements tied to meeting SCIP guidelines, but it's moving in that direction, and at some point they will be held to the same patient warming standards.

A neurosurgeon has offered to help me conduct the surgery center study in the medical center's main ORs with the hope of publishing the results in a peer-reviewed journal. If a clinical trial can definitely prove that warmed blankets are as effective as active warming in preventing hypothermia, CMS might have to reconsider its SCIP standards. Will that ever happen? Maybe. But until it does, active warming remains a key component of hypothermia prevention efforts. Combining it with warmed IV fluid and warmed cotton blankets helps keep patients normothermic.

Take care of our own
You want to prevent hypothermia because when the core body temperatures dips below 36 ?C, a cascade of adverse events can occur, including delayed wound healing, increased risk of infection, poor drug metabolism, heightened risk of post-op heart attack, hypertension and delayed discharge. In fact, published research has shown that maintaining normothermia decreases post-op lengths of stay by 40% and risk of surgical site infections by 64%. Even if none of those unwanted outcomes happen, cold patients might be more anxious during their stay and shivering patients aren't usually happy, meaning your satisfaction scores might also take a hit. Cost considerations and reimbursement implications are important, but isn't improving patient care the bottom line that matters most?