The Prevention of Perioperative Hypothermia Toolkit
I am sometimes asked, “Is perioperative hypothermia really a big deal?” The answer is “yes, it is.” Most patients undergoing surgery will become hypothermia unless we use effective interventions to prevent it.
Why is preventing perioperative hypothermia important?
It is important to prevent perioperative hypothermia because it is associated with negative patient outcomes. Perioperative hypothermia increases:
- surgical site infection risk,1
- morbid cardiac events,2
- blood loss,3,4
- length of stay in the recovery room,5 and
- impairment of drug metabolism.5
All of this increases the cost of healthcare.
Why does hypothermia occur?
One common misconception is that perioperative hypothermia is caused by the operating room being cool, and if the room temperature is increased, hypothermia will not occur. This is a myth. Although the room temperature plays a role, anesthesia plays the primary role. General and regional anesthesia impair the normal thermoregulatory responses.6 Upon induction of anesthesia, heat is redistributed from the core to the peripheral tissues, which are much (2-4oC) cooler. This causes the core temperature to drop significantly during the first hour of anesthesia.7 Anesthesia also impairs the body’s ability to respond to cold. Normally, the body would respond to a drop in temperature of 0.4oC. An anesthetized patient does not respond until there is a 4oC drop in core temperature.8 So, the patient does not produce enough heat to overcome the initial hypothermia.
Will using cotton blankets prevent hypothermia?
Passive warming with blankets retains heat. But, because the anesthetized patient is unable to produce enough heat, retention of heat alone is inadequate. Applying heated cotton blankets is only slightly more effective, and the benefit only lasts 10 minutes.9 In a randomized clinical trial, applying heated cotton blankets failed to prevent hypothermia.10
Will heating insufflation gases for laparoscopy prevent hypothermia?
Another commonly used, ineffective way of preventing hypothermia is heating the carbon dioxide used for insufflation during laparoscopy. A meta-analysis of 16 randomized clinical trials found that heating CO2 gas had no effect on core temperature, and there was no evidence to support the use of heated CO2 gas, with our without humidification, for laparoscopic surgery.11
How can we prevent hypothermia?
Applying heat to actively warm the patient is required to prevent perioperative hypothermia. The most common method of active warming is forced air warming (FAW), which distributes warm air over the skin surface, heating peripheral tissues, and minimizing core-to-periphery temperature gradient. Intraoperative FAW is more effective in maintaining body temperature than cotton blankets,10,12 reflective blankets,12 or thermo-lite® insulation.12,13
What patients should receive active warming?
Patients undergoing surgery that will be at least 30 minutes long, with general or regional anesthesia (spinal, epidural) should be actively warmed.
When should we use active warming?
To be most effective, active warming should be initiated preoperatively for at least 30 minutes and also used intraoperatively. Actively warming the patient preoperatively minimizes heat lost during redistribution of heat from the core to periphery upon induction of anesthesia, and minimizes the incidence of hypothermia.14-16
Why are hospitals not using these evidence-based practices?
Unfortunately, active warming is not always used when needed and is often not used correctly. First, practitioners are not knowledgeable enough about perioperative hypothermia, and do not always consider it a priority. Secondly, they do not understand the importance of prewarming the patient, and often start active warming after induction of anesthesia. Third, there was a quality performance measure that has been retired that required active warming or normothermia. Practitioners were in compliance with the measure even if they used active warming incorrectly, starting it after induction of anesthesia, and the patient became hypothermic.17 Actual evaluation of patient outcomes and reducing the incidence of hypothermia were not emphasized, resulting in a “checklist mentality”. And, lastly, complacency is an incredibly strong force, and a concentrated effort is required to make a change in practice.
How can we get practitioners to use this evidence to prevent perioperative hypothermia?
We need to use a combination of strategies to engage busy professionals and integrate a change into their work processes. For that reason, a team at the University of Iowa developed the Prevention of Perioperative Hypothermia Toolkit©. Use of this toolkit has been tested for the past two years, and refined with lessons learned. The toolkit includes is a list of steps for planning the implementation of changes. The second component is a template for a risk assessment, a Healthcare Failure Mode and Effect Analysis (HFMEA), to identify potential issues that can arise during implementation. The next component is an educational program that can be modified with taped statements of support from key perioperative leaders in the setting. A list of data elements to use for modifying the electronic documentation system is included to allow for the generation of reports. And, there are spreadsheets that can be used as templates for audit and feedback.
The Prevention of Perioperative Hypothermia Toolkit© is available free of charge.
For more information, watch the 3M webinar Strategies for Infusing Evidence-based Practices for Prevention of Perioperative Hypothermia.
The Prevention of Perioperative Hypothermia (PPH) Toolkit was funded by the Agency for Healthcare Research and Quality, grant 3 IR18HS021422-01A1.
Dr. Steelman has been a perioperative nurse for over 25 years. As a perioperative advanced practice nurse at the University of Iowa Hospitals and Clinics, she focused on implementing evidence-based practice changes for 20 years. She is currently Associate Professor in the College of Nursing at the University of Iowa where she teaches graduate students evidence-based practice. Her program of research focuses on perioperative safety and quality. She has extensively published and presented about issues related safe patient care in the operating room, including five research studies focusing on prevention of retained surgical sponges. She is well recognized for her contributions and received AORN’s Outstanding Achievement awards for Research and Evidence-based Practice. In 2008, she received the AORN’s highest award, the Award for Excellence in recognition of her contributions to perioperative nursing. In 2007, she was inducted into the American Academy of Nursing in recognition of the national and global impact of her work.
1. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. N Engl J Med. 1996;334:1209-1215.
2. Frank SM, Fleisher LA, Breslow MJ, et al. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial. JAMA. 1997;277:1127-1134.
3. Schmied H, Kurz A, Sessler DI, Kozek S, Reiter A. Mild hypothermia increases blood loss and transfusion requirements during total hip arthroplasty. Lancet. 1996;347:289-292.
4. Winkler M, Akca O, Birkenberg B, et al. Aggressive warming reduces blood loss during hip arthroplasty. Anesth Analg. 2000;91:978-984.
5. Lenhardt R, Marker E, Goll V, et al. Mild intraoperative hypothermia prolongs postanesthetic recovery. Anesthesiology. 1997;87:1318-1323.
6. Sessler DI. Temperature monitoring and perioperative thermoregulation. Anesthesiology. 2008;109:318-338.
7. Sessler DI. Perioperative heat balance. Anesthesiology. 2000;92:578-596.
8. Torossian A. Thermal management during anaesthesia and thermoregulation standards for the prevention of inadvertent perioperative hypothermia. Best Pract Res Clin Anaesthesiol. 2008;22:659-668.
9. Sessler DI, Schroeder M. Heat loss in humans covered with cotton hospital blankets. Anesth Analg. 1993;77:73-77.
10. Fossum S, Hays J, Henson MM. A comparison study on the effects of prewarming patients in the outpatient surgery setting. J Perianesth Nurs. 2001;16:187-194.
11. Birch DW, Manouchehri N, Shi X, Hadi G, Karmali S. Heated CO(2) with or without humidification for minimally invasive abdominal surgery. Cochrane Database Syst Rev. 2011;(1):CD007821.
12. Ng SF, Oo CS, Loh KH, Lim PY, Chan YH, Ong BC. A comparative study of three warming interventions to determine the most effective in maintaining perioperative normothermia. Anesth Analg. 2003;96:171-176.
13. Borms SF, Engelen SL, Himpe DG, Suy MR, Theunissen WJ. Bair hugger forced-air warming maintains normothermia more effectively than thermo-lite insulation. J Clin Anesth. 1994;6:303-307.
14. Andrzejowski J, Hoyle J, Eapen G, Turnbull D. Effect of prewarming on post-induction core temperature and the incidence of inadvertent perioperative hypothermia in patients undergoing general anaesthesia. Br J Anaesth. 2008;101:627-631.
15. Horn EP, Schroeder F, Gottschalk A, et al. Active warming during cesarean delivery. Anesth Analg. 2002;94:409-414.
16. Vanni SM, Braz JR, Modolo NS, Amorim RB, Rodrigues GR,Jr. Preoperative combined with intraoperative skin-surface warming avoids hypothermia caused by general anesthesia and surgery. J Clin Anesth. 2003;15:119-125.
17. Steelman, V. M., Perkhounkova, Y. S., & Lemke, J. H. The gap between compliance with the quality performance measure “Perioperative Temperature Management” and normothermia. J Healthc Qual. 2014 January 13. PMID: 24417607. doi: 10.1111/jhq.12063.