EP Review

Making the Case for Prewarming Electrophysiology Patients

Christina Ferentinos VanDerveer, RN, BSN, BC-RN, EP Lab Education Coordinator

University of Virginia Health System;

Charlottesville, Virginia

Christina Ferentinos VanDerveer, RN, BSN, BC-RN, EP Lab Education Coordinator

University of Virginia Health System;

Charlottesville, Virginia

The practice of prewarming patients prior to surgery is to prevent unintended hypothermia. According to the Association of periOperative Registered Nurses (AORN), hypothermia causes discomfort for the patient and can contribute to complications, including myocardial events, incision-site infection, and slower healing time, among others, and may result in a longer hospital stay.1 AORN recommends prewarming patients to 36º C prior to surgery.1 

In this article, we propose prewarming patients to 36º C prior to undergoing cardiac electrophysiology (EP) procedures. This literature review supports a practice change in perioperative temperature management of EP cases.  

About Our Practice 

In our academic medical center, we have 5 EP labs with 7 electrophysiologists and 29 staff. Typical EP procedures last between four to nine hours, and are performed either under monitored anesthesia care or conscious sedation. 

EP cases are performed in an operating room (OR) setting that is kept at 17.78º C. The patients arrive in the OR at 34-36º C. To achieve and maintain normothermia in patients, we utilize a heated air mattress (3M Bair Hugger Warming Blanket System), which is the same product used in our main operating rooms. 

The current practice in our facility’s surgical admission suites is to prewarm patients. However, the cardiac transition unit, which admits patients to the EP lab, does not initiate this. Therefore, some patients’ core temperature upon admission to the EP lab can be less than 36º C. 

In addition, it can be difficult to obtain and maintain a core temperature of >36º C during procedures when the patient’s core temperature is low. Core temperatures of <36º C have been shown to lead to procedural complications such as an increase in bleeding during surgery, infection rate, length of stay, altered medication metabolism, and mortality rate.2 Advocating for prewarming patients seems clear.

Evidence Summary

Table 1 provides a brief review of the literature on prewarming of surgical patients. Rosenkilde et al published a case-control study of 60 patients, in which 30 patients were prewarmed for 30 minutes with a self-warming blanket and intraoperative forced-air warming, while the other 30 patients received only intraoperative forced-air warming. Their results indicated that prewarming patients lowered the incidence of unintended perioperative hypothermia in the operating room.3

In the next study, Su and Nieh determined the efficacy of forced-air warming for preventing perioperative hypothermia in patients undergoing laparoscopic surgery. Sixty-four patients were allocated to forced-air warming, and 63 were in the control group (passive insulation). Esophageal temperature was measured during surgery, and tympanic temperature was measured every 30 minutes preoperatively as well as during postanesthesia care. Their results showed that the forced-air warming group had increased warming efficacy and reduced complications.4

Broback et al conducted a systematic literature review of the use of forced-air warming blankets to prevent accidental hypothermia during surgery. Their results indicated that prewarming patients with this method helped to maintain normothermia and reduce the rate of hypothermia, suggesting that complications of hypothermia can therefore be prevented.5 

Maleki et al assessed the effect of warming patients’ central body temperature with forced air during general anesthesia. Their study randomized 60 patients into three groups, and found the incidence of hypothermia to be 45% in the prewarming group (warmed up for 30 minutes before anesthesia), 55% in the control group (warming not performed), and 10% in the total warming (lasting from half an hour before anesthesia until the end of anesthesia) group. Therefore, active warming of the patients in the OR was shown to prevent the occurrence of hypothermia.6

Wasfie and Barber evaluated the value of extending normothermia by using a portable warming gown. A total of 94 patients undergoing elective surgery were randomized preoperatively to either a portable warming gown at the time of preoperative preparation or the standard warming procedure at the time of induction in the OR. The extended warming group had prewarming from the preop stage through surgery and into recovery. They concluded that use of extended warming reduced hypothermic events and improved patient satisfaction.

This review of literature suggests that hypothermia can be prevented. The evidence-based practice recommendation is to prewarm patients prior to going to the procedural area for 30 minutes before the procedure. Patients can also be provided with a prewarming apparatus while in the perioperative area. Warming garments support evidence-based research on the benefits of maintaining a core body temperature of 36º C. 

Other Considerations

We propose using a warming gown (3M Bair Hugger Warming Gown System) in addition to a heated air mattress during procedures to maintain normothermia. The heated air mattresses are still utilized in the OR, even if warming gowns are used in the preadmission area. The warming gowns are located in the preop area. The patient’s temperature is first taken as part of the admission process. The prewarming gowns are then provided to patients and connected to a temperature-regulated blower. This would occur presurgery and if needed in the PACU as well.

Cost is also always a consideration prior to implementation. Since our hospital already uses these gowns in the surgical admissions suite, having the gowns available in the hospital inventory has provided a smooth transition of procurement for the cardiac transition unit. However, for other programs considering purchase of gowns and blowers, executive approval is required. 

Implementing the Change

Some staff may be resistant to a change in workflow, which could result in a delay of the case start time. Kurt Lewin’s Change Theory is an ideal method for implementing this type of change. This change theory model is based on a three-step process: unfreezing, moving, and refreezing.7 Lewin’s Change Theory can guide a team through the process of implementing a change, including unfreezing of the current process of preparing patients for EP procedures, understanding the reasons for moving forward with this change, and refreezing the new concept of prewarming patients.7

Therefore, to prevent any resistance, the project leader should clearly explain why the practice change is being initiated and describe the plan in place to proceed with the change, work should be standardized to adhere to the new guidelines, and the practice of prewarming patients to 36º C for 30 minutes prior to arrival to the operating room can then be implemented.


This brief literature review provides support for prewarming patients before EP cases. Evidence-based practice indicates that prewarming of patients should be considered for all anesthesia cases and is supported by AORN as their standard of practice. The identification of patients having a core temperature of less than 36º C upon arrival to the procedural area prompted our investigation of this practice change. The transition of this practice within the electrophysiology lab can be done smoothly when the following changes are made. 

Disclosures: Ms. VanDerveer has no conflicts of interest to report regarding the content herein.

  1. Bashaw MA. Guideline implementation: preventing hypothermia. AORN J. 2016;103(3):305-310. 
  2. Wasfie KR, Barber KR. Value of extended warming in patients undergoing elective surgery. Int Surg. 2015;100(1):105-108. 
  3. Rosenkilde C, Vamosi M, Lauridsen JT, Hasfeldt D. Efficacy of prewarming with a self-warming blanket for the prevention of unintended perioperative hypothermia in patients undergoing hip or knee arthroplasty. J Perianesth Nurs. 2017;32(5):419-428. 
  4. Su SF, Nieh HC. Efficacy of forced-air warming for preventing perioperative hypothermia and related complications in patients undergoing laparoscopic surgery: a randomized controlled trial. Int J Nurs Pract. 2018;24(5):e12660. 
  5. Broback BE, Skutle GO, Dysvik E, Eskeland A. Preoperative warming with a forced-air warming blanket prevents hypothermia during surgery. Sykepleien Forskning. 2018;13(65819):e-65819. doi: https://doi.org/10.4220/Sykepleienf.2018.65819.
  6. Maleki A, Soltani AE, Goudarzi M, et al. Assessing the effect of warming up the patient with forced air on the body central temperature during general anesthesia in patients aged 20 - 70 years under eye surgery in Farabi Hospital. World Family Medicine. 2018;16(1):48-54.
  7. Leading, Managing, Following. In: Sullivan EJ (eds). Effective Leadership and Management in Nursing (9th edition). New York, NY: Pearson; 2017:46-62.