RIGHT TEMP Make sure you keep warming cabinets at the temperature noted in the manufacturer's instructions for use.

If patients become hypothermic during the perioperative period, they face a host of potential adverse events, including an increased risk of infection, cardiac complications and blood loss. While you certainly know that patients should be warmed, you might not fully understand best practices in safely maintaining normothermia. Let's look at some of the most common ways to warm patients, and the mistakes to avoid when using each one.

1. Forced-air warming
If you're careless, forced-air warming can do more harm than good. "Free hosing" is an especially dangerous practice. Inserting the unit's hose under drapes or a blanket can cause serious burns to the patient. Always use the blankets designed for forced-air warming when using these systems.

Additionally, if you're using forced air intraoperatively, be careful to avoid placing the forced-air warming blanket on a limb that's not being perfused. For example, if you have a tourniquet on a patient's arm and use forced-air warming on that arm, you're heating up the tissue and not letting that heat distribute throughout the body. This, in turn, can cause a burn.

While these injuries are rare, a more common mistake is not using the blankets before anesthesia induction. For forced-air warming to be effective, evidence shows that you must apply the blanket 30 minutes before surgery, in addition to using it intraoperatively. If you start using forced-air warming only after anesthesia induction, the patient may already be hypothermic.

BAIR HUGGER LAWSUITS
Is Forced-Air Warming an Invisible Infection Risk?

HOT AIR? Should you be concerned that forced-air warmers could cause SSIs?

Can forced-air warming lead to surgical site infections, as a flood of recent patient lawsuits contend, or is it just a bunch of hot air?

Fifteen total joint replacement patients have filed lawsuits against 3M Health Care, the manufacturer of the popular Bair Hugger forced-air patient warming device, and the number is expected to rise. The patients allege that forced-air warming devices circulate more than just hot air. They say the blowers stir up contaminated air from the OR floor and deposit it in the surgical site, causing deep joint infections that resulted in the need for repeat surgeries, amputation and other complications.

Details of the 2 most recent lawsuits are harrowing. A patient's leg was amputated after he became infected with Methicillin-resistant Staphylococcus aureus during a knee replacement surgery. An artificial hip patient who suffered an SSI needed 15 additional surgeries, including one to remove the implanted joint.

While attorneys work to have these cases consolidated in a single federal court, more suits could be coming. One law firm has set up a website, infectionlawsuits.com, trolling for patients.

3M launched its own web site, fawfacts.com, "The Facts About Forced-Air Warming," to refute such claims, which a company official calls "baseless."

"There is no evidence that forced-air warming increases the risk of infection," says 3M attorney Christiana Jacxsens of Greenberg Traurig in Atlanta, Ga. "In its entire history, not one hospital, doctor, or medical provider has reported a single confirmed incidence of infection believed to be caused by the Bair Hugger device."

Many of the allegations linking surgical site infections to forced-air warming were started by a surprising source — the inventor of the Bair Hugger, anesthesiologist Scott Augustine, MD, who after a contentious split from the company that sold the Bair Hugger to 3M, invented the HotDog patient warming system, an air-free device that works similarly to an electric blanket, warming the patient from above and below simultaneously. Dr. Augustine claims in an article in the The New York Times that the company selling the Bair Hugger knew of the infection risk as far back as 2010 and was covering up this danger to keep sales strong.

"We didn't recognize the problem when I was running the company and remarkably over 20 years no one else did either," says Dr. Augustine. "About 6 years after I left the company, we accidentally discovered the unintended consequence of [forced-air warming]; the waste hot air vents near the floor, heats the contaminated air resident near the floor, and then rises alongside the table into the sterile surgical field. We became very concerned about patient safety in ultra-clean surgeries such as total joint replacements. A single airborne germ landing on an implant can cause a devastating infection by protecting itself with biofilm."

3M vehemently denies the allegation, and several independent researchers, including the Association of PeriOperative Registered Nurses (AORN), say that studies showing evidence of a link are limited or use flawed methodologies. In a 2013 review (osmag.net/8nYxEY), AORN says that "given the efficacy of these devices in preventing inadvertent perioperative hypothermia" facilities can continue using forced-air warming "until well-conducted, large-scale trials can further examine the issue."

— Kendal Gapinski

Prevention of Perioperative Hypothermia (PPH) Toolkit
How to Warm Patients Effectively

Download the Patient Warming Toolkit at osmag.net/qPU2Ky for useful tips to improve patient warming practices, including an educational program about the evidence supporting the different methods and why patient warming is essential.

2. Warmed blankets and fluids
Do you wrap warm cotton blankets around patients to try to maintain normothermia? Evidence has shown that this technique is not overly effective. While a patient may enjoy the comfort a warm cotton blanket provides, the blanket cools quickly and doesn't keep the patient's skin or muscles warm. Use warmed cotton blankets to enhance the comfort of patients, not as a primary method of patient warming.

If you store cotton blankets in a warming cabinet, keep in mind that it must be set to the correct temperature, which can be found in the manufacturer's instructions for use. Staff should check cabinets periodically to ensure that the set temperature is correct and that the cabinet is working properly.

Warming IV or irrigation fluid is another useful adjunct to patient warming. Evidence shows that patients benefit most from warming IV and irrigation fluid if more than 1 L of fluid is used during the case. Both warming cabinets and in-line warmers have shown evidence of being effective in preventing hypothermia when used in addition to another active warming method.

Never place IV fluids in a cabinet designed to warm irrigation solutions or cotton blankets, as the high temperatures could seriously burn and injure the patient. Instead, follow manufacturers' directions for use and have staff check the temperature of the fluid warmers periodically to ensure they are correct.

3. Low-voltage polymer blankets
These "electric blankets" are effective as a primary patient warming method. However, there are some potential issues staff should be aware of while using these newer technologies. Specifically, staff must be cautious when positioning towel clips around the patient, since these clips can perforate the blanket and cause it to malfunction.

As with any electrical component you're adding to the OR, have your bioengineering department or consultant periodically check the blankets to ensure they're in proper working condition and aren't at risk for electrical hazards. Also be sure to read the manufacturers' instructions for use before using the blankets.

One risk that's often overlooked is mismanagement of the blanket's cords. Make sure all cords are sealed so that they can't come in contact with any fluids in the OR that could shock patients or staffers. Also keep the cords organized and away from high-traffic areas to limit risks of trips and falls.

COMFORT MEASURE Warmed blankets should be used to augment other active warming methods.

4. Positioning pads and warming mattresses
If you're still using the old-fashioned warm water circulating pads, it may be time to invest in a new method of patient warming, as evidence has shown these devices are linked to pressure injuries. Newer gel-filled or memory foam pads may address these concerns, but their effectiveness has not been fully studied. Therefore, they should not be your primary method of patient warming.

A carbon-fiber warming mattress is a conductive heat mattress that warms patients from below, and can be used in pre-op then easily transferred to the OR, thanks to its battery-powered design. While evidence has shown promising results so far, this method of patient warming is still very new and has yet to be studied extensively.

Finally, it's worth mentioning that many facilities have begun heating their insufflation gases for laparoscopic procedures as a defense against hypothermia. However, a meta-analysis published by the Cochrane System of Database Reviews has shown that there is no evidence to support doing this. While some surgeons say it also helps prevent fogging, if you're using this solely as a method to warm patients you may want to reconsider, especially since it can tack an additional cost of up to $50 onto each case.