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April 15, 2021
OSD Staff
Publish Date: April 15, 2021   |  Tags:   Patient Safety
eNews Briefs April 15, 2021


When Active Warming Becomes the Obvious Choice

Tag! Here's Why You're Being Warmed

Perioperative Warming Reduces Intraoperative Hypothermia

Does Robotic Surgery Increase the Risk of Intraoperative Hypothermia?

Active Warming Is a Necessity for Patients With CAD


When Active Warming Becomes the Obvious Choice

Increased patient comfort, clinical benefits and cost savings make the intervention a winner at this California medical center.

WRAPPED IN COMFORT WRAPPED IN COMFORT Active patient warming is a relatively inexpensive upgrade that increases patients' thermal comfort while decreasing their anxiety.

Actively prewarming patients has proven invaluable in the fight against inadvertent perioperative hypothermia (IPH), but do you know about the other vital advantages of this relatively inexpensive tool? According to a trial performed at MemorialCare's Long Beach (Calif.) Medical Center on 500 patients in pre-op, 30 minutes of forced-air warming resulted in numerous benefits, including:

  • A more comfortable experience. Patients in the trial reported an increase in thermal comfort and a decrease in anxiety. "You know the feeling you get when you wrap up in a towel that has come right out of the dryer? That's the feeling warming provides," says Marci Trump, MSN, RN, CNOR, a clinical educator at the center.
  • Substantial cost savings. Before the trial, pre-op staff routinely covered patients with as many as five cotton blankets; more blankets were applied before draping in the OR, and even more blankets were added in recovery. Now, staff apply only a single cotton blanket on top of the warming device for privacy purposes when patients are moved through the hallways. As a result, says Ms. Trump, "we realized significant cost savings on the laundering of cotton blankets."
  • Improved outcomes. The trial resulted in a decrease in surgical site infections and IPH-related blood transfusions in spinal and total joint patients. Just as significantly, the staff learned about the positive effects of the warming techniques. "Using online surveys pre- and post-intervention, we noted significant improvement in staff knowledge of the causes of IPH and the most effective interventions for maintaining normothermia," says Ms. Trump. "A lot of our staff didn't even know prewarming made a difference."

The clinical and patient-centered benefits have brought home the concept of active warming at the facility. "There's no doubt prewarming leads to a better overall patient experience," says Ms. Trump.

Tag! Here's Why You're Being Warmed

Laminated info scripts attached to active warming devices inform patients and staff about the importance of maintaining normothermia.

ANOTHER LAYER CREDIT: Pamela Bevelhymer ANOTHER LAYER Connecting patients to active warming devices during each stop along the perioperative pathway helps to maintain normothermia.

A 115-bed major medical center in the southwest U.S. that included a Level III trauma unit had a numbers problem: 30% of the incentives it received from CMS were directly connected to patient satisfaction, but surveys showed that 33% of its patients were unsatisfied with their thermal comfort.

The facility studied over a six-month time period whether an inexpensive solution — space blankets — could be an effective pre- and post-operative replacement for its traditional warming measures in conjunction with active intraoperative warming methods. The disposable reflective blankets, used for survival purposes, cost approximately $1 per case, according to the facility's study.

Patients arrived at least two hours before a procedure and were given a single unwarmed cotton blanket. The intervention was the simple addition of a $1 space blanket that was placed under the cotton one. The space blanket traveled with patients for use at every stop before and after the OR. Every patient in the facility's same-day surgery units received space blankets in the pre-op bays, a pre-op holding area and the PACU.

The result was a 14% increase in patients' thermal comfort satisfaction ratings. Patients who responded to surveys said things like: "I am basically a cold person, but loved the space blankets and this has been the only time I've had surgery where I can say I was actually warm in the recovery room"; "The silver cover blankets kept me warm. They can be a little noisy when you move"; and "Silver blankets are great. Keep using them."

The study's authors say rural surgery centers, as well as smaller surgery centers on tight budgets, could particularly benefit from this inexpensive yet effective way to maintain normothermia in patients. While the study didn't include an economic analysis, the authors said the practice would likely reduce a facility's linen costs while freeing staff from the burden of repeatedly stocking and distributing multiple cotton blankets.

Perioperative Warming Reduces Intraoperative Hypothermia

Total joint arthroplasty surgeries benefit from active warming.

Perioperative hypothermia is common in patients undergoing total joint arthroplasty (TJA). According to a recent study, the focus on patient warming should include the time of entry into the OR to the start of surgery.1

Keeping surgical patients warm and their core body temperature above 36ºC is not only critical to their safety, but also for their comfort. Unplanned perioperative hypothermia can lead to an increased risk of surgical site infection, prolonged duration of anesthesia and longer recovery times.

Additionally, active warming is needed to counteract the negative effects of anesthesia on normal core body temperature.2 Best practices for maintaining normothermia include compliance with guidelines that emphasize the importance of using some form of warming for every patient.3-5

For TJA surgeries, research shows that reducing the rate of PH is important for positive outcomes. According to authors Andrew B. Kay, Derek M. Klavas, et al., "A previous study at our institution identified the largest drop in core body temperature between preoperative holding and induction of anesthesia." Their study aimed to evaluate the effect of preoperative warming measures on PH in TJA patients.1

A retrospective review was conducted of 672 patients undergoing TJA between April 1 and October 31, 2017. Under the new normothermia protocol, patients received warmed intravenous fluids and forced-air warming gowns in the preoperative holding area. Time and temperature data for the perioperative period were collected from the electronic health record. Chi-square and paired t-tests were used to compare between total knee arthroplasty and total hip arthroplasty patients and between new and old protocols.

In the new protocol, 173 of 672 (26%) patients were hypothermic at incision compared with 140 of 383 (37%) patients in the previous protocol (P < 0.05). The largest drop in core body temperature occurred between preoperative holding and induction of anesthesia.

The duration of time from operating room entry to incision was less for normothermic than for hypothermic patients. The duration of hypothermia was similar between new and old protocols overall, but markedly fewer total hip arthroplasty patients remained hypothermic for the entire surgery under the new protocol. The authors concluded, "Adding forced-air warming preoperatively to our warming protocol reduced the rate of PH by approximately 30%. The time from entry into the operating room to the start of surgery should be minimized because patients are vulnerable to PH during this interval."

Total joint procedures benefit from warming strategies to keep patients comfortable and safe before, during and after surgery. With solutions that offer air, water and electric warming options throughout all stages of the patient's journey the vulnerable times are limited as the patient is warmed continuously.

Note: Gentherm offers a broad portfolio of patient temperature management products and is the only site-of-care provider in perioperative temperature management across all 4 modalities. Visit Right Now Campaign | Gentherm for more information.


1. Kay AB, Klavas DM, Hirase T, Cotton MO, Lambert BS, Incavo SJ. Preoperative warming reduces intraoperative hypothermia in total joint arthroplasty patients. J Am Acad Orthop Surg. 2019; doi: 10.5435/JAAOS-D-19-00041.

2. The Association of periOperative Registered Nurses. AORN guidelines update: 4 updates for more effective hypothermia prevention. https://www.aorn.org/about-aorn/aorn-newsroom/periop-today-newsletter/2019/2019-articles/hypothermia-prevention. Published August 28, 2019. Accessed November 2019.

3. AORN Guidelines: Recommended practices for the prevention of unplanned perioperative hypothermia. AORN Journal. 2007; 85(5):972-983.

4. Hooper VD, Chard R, Clifford T, et al. ASPAN's evidence-based clinical practice guideline for the promotion of perioperative normothermia: Second edition. J Perianesth Nurs. 2010;25(6):346-365.

5. National Institute for Health and Care Excellence (NICE). Hypothermia: prevention and management in adults having surgery. https://www.nice.org.uk/guidance/cg65. Published April 2008 (2016 updates). Accessed November 2019.

Does Robotic Surgery Increase the Risk of Intraoperative Hypothermia?

The possibility was revealed during a study involving bladder cancer patients.

Recent research shows intraoperative hypothermia did not increase the risk of post-op death in patients who underwent radical cystectomy to treat bladder cancer. Interestingly, patients whose procedures were performed robotically experienced hypothermia at a much higher rate than those undergoing open surgery (63% vs. 28%).

Of the 852 patients included in the study, 274 (32%) experienced intraoperative hypothermia. However, two-year survival rates were not significantly different between hypothermic and normothermic patients. The full study can be read here.

The adverse effects of intraoperative hypothermia on surgical outcomes are well documented and thought to be related to suppression of cell-mediated immunity, which could also have impacted the risk of cancer recurrence in the study's patients.

"We wondered whether the relative immunosuppression brought on by intraoperative hypothermia might increase the risk of metastasis or cancer-related death after surgery for bladder cancer," says Timothy D. Lyon, MD, senior associate consultant in the department of urology at the Mayo Clinic in Jacksonville, Fla. "If it had, the stakes would have been raised for the potential consequences of decisions we make in the operating room."

Dr. Lyon was surprised that patients who underwent robotic-assisted cystectomy were at increased risk of becoming hypothermic. He isn’t sure why that occurred — it could have been due to different temperature measuring methods or warming techniques — and believes the potential link between robotic surgery and hypothermia requires further study.

"Although we didn't see a difference in survival based on intraoperative temperature, the benefits of maintaining normothermia in terms of reduced postoperative complications are well established, and I would encourage surgical professionals to continue focusing on keeping patients warm during surgery," says Dr. Lyon. "Particular attention could be paid to those having major robotic pelvic surgery given our observation that these patients were more likely to become hypothermic than those undergoing open pelvic operations."

Active Warming Is a Necessity for Patients With CAD

Exposure to cold temperatures can lead to devastating results for patients with the rare disorder.

Some patients are more sensitive to temperature than others. That's especially true for those with cold agglutinin disease (CAD), a rare acquired autoimmune disorder. For those who suffer from it, exposure to temperatures between 32°F and 50°F causes their autoantibodies, also known as cold agglutinins, to bind tightly to red blood cells, inducing their disintegration and resulting in conditions such as anemia, hemoglobinuria renal failure and myocardial damage.

It's little surprise that effectively warming these rare patients requires particular care and consideration. A team of Korean researchers recently decided to find out exactly the proper multimodal method for doing so, publishing its case study in the Korean Journal of Anesthesiology.

A 63-year-old man who had been diagnosed with severe CAD two years previous presented for a lumbar laminectomy. The patient had been taking prednisolone 10 mg daily but often experienced hemoglobinuria and acrocyanosis of the distal extremities upon exposure to cold. Three hours before surgery, the patient was infused with amino acid warmed at 41°C. Active warming was added 30 minutes before surgery.

The patient was brought to the OR, which was pre-warmed to 26°C. After induction of anesthesia, a temperature probe was inserted into the esophagus immediately before orotracheal intubation. The patient then was placed in a prone position, and active warming devices set at 37°C to 40°C were immediately applied to the upper and lower body as well as anterior skin surfaces. Hands and feet were covered with gloves and socks. Prior to incision, an IV of 100 mg hydrocortisone was administered.

During surgery, active warming and IV infusion of amino acid warmed at 41°C continued, while other irrigation solutions were pre-warmed to approximately 40°C. For 24 hours after surgery, active warming and the warmed amino acid infusions continued.

All told, the measures were successful, as hypothermia was prevented and there was no evidence of hemolysis.

"In patients with CAD, when the blood cools below a critical temperature, often ranging from 30°C to 37°C, antibodies cause red blood cell agglutination and complement fixation," the researchers wrote. "Thus, it is extremely crucial to maintain the core temperature and further prevent heat transfer from the core to the peripheries in these patients." With this patient's normal temperature around 36.5ºC, the team strove to maintain both core and peripheral temperatures at 37ºC using multimodal warming measures.

"It appeared that while pre-warmed amino acid infusions mainly contributed to the maintenance of the core temperature, skin-surface warming helped maintain both the core and peripheral temperatures by avoiding heat transfer from the core to the peripheries because of raised peripheral temperatures," noted the researchers. "The most striking difference between the present case and previous reports is that warmed amino acid infusion and other preventive measures were simultaneously applied in our severe case."