The Mölnlycke O.R. blog
Patient pre-warming: Staying ahead of perioperative hypothermia
"Inadvertent perioperative hypothermia can adversely affect the outcome of surgery and the patient’s postoperative course. It should be actively prevented.1"
The potentially adverse effects of even mild perioperative hypothermia are well-documented2. Among the possible consequences are cardiovascular problems or morbidity3, blood loss and need for transfusion4, and a higher risk of post-surgical infection5. These consequences in patient outcomes have the domino effect of possible longer recovery times, leading to longer, more expensive hospital stays5 and a higher overall total cost of care.
Knowing these potential outcomes, and knowing that perioperative hypothermia is a very common but also highly preventable phenomenon, it stands to reason that surgical healthcare professionals would introduce every possible evidence-based preventive measure into practice. The evidence shows6,7, that preventing perioperative hypothermia, then, is about ensuring that the core body temperature drops as little as possible. The process of maintaining normothermia, in fact, starts well before the operative period.
Prewarming: Getting warmed up
When discussing perioperative hypothermia, we use the term "perioperative", meaning the entire operative period, for a reason. The preparation and the post-op phases of the perioperative period are important as well. The outcome of a surgical procedure can be affected, as highlighted above, by the preparatory work and follow-up care. More specifically in this case, temperature management is key from the moment the surgical patient checks in for his or her procedure.
Patient prewarming allows surgical patients to be warmed in the pre-operative period, which has been shown to help reduce the post-anaesthesia drop in core body temperature (even more than the use of intraoperative warming)8: Horn et al found that as little as 10 to 20 minutes of prewarming before general anaesthesia mostly prevented hypothermia and reduced shivering, and prewarming for 60 minutes was sufficient to avoid postoperative hypothermia entirely8.
Another study, a 2016 retrospective observatory trial, looked at the effects of prehospital hypothermia on outcomes and found that a low body temperature at admission was associated with a higher risk of transfusion and death9. The recommendation of that study, and indeed of the German S3 guideline "Prevention of perioperative hypothermia" (2014) is not only the importance of awareness of maintaining normothermia but also the importance of introducing strategies for patient prewarming as a prophylactic measure.
If the evidence and outcomes demonstrate time and again that prevention of the drop in core body temperature makes the difference, we should indeed be doing everything we can to raise awareness and work toward introducing prewarming as part of standard perioperative practice.
- Torossian A, Bräuer A, Höcker J, Bein B, Wulf H, Horn E-P. Preventing Inadvertent Perioperative Hypothermia. Deutsches Ärzteblatt International. 2015;112(10):166-172. doi:10.3238/arztebl.2015.0166, accessed at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4383851/
- Sessler DI. Complications and treatment of mild hypothermia. Anesthesiology 2001 Aug; 95(2):531-43.
- Frank S, Fleischer L, Breslow M, Higgins M, Olson K, Kelly S, Beattie C. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events: A randomized trial. JAMA 1997; 227 (14): 1127-34.
- Rajagopalan S, Mascha E, Na J, Sessler DI. The effects of mild perioperative hypothermia on blood loss and transfusion requirement. Anesthesiology 2008; 94: 108:71-7.
- Kurz A, Sessler D, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical wound infection and shorten hospitalization. N Engl J Med 1996; 334: 1209-16.
- National Institute for Health and Care Excellence. Inadvertent perioperative hypothermia: The management of inadvertent perioperative hypothermia in adults [CG65] [Internet]. London: National Institute for Health and Care Excellence (GB); 2008. Available at: http://www.ncbi.nlm.nih.gov/pubmed/21678626.
- Hooper VD, Chard R, Clifford T, Fetzer S, Fossum S, Godden B, et al. ASPAN’s evidence-based clinical practice guideline for the promotion of perioperative normothermia: second edition. J Perianesth Nurs. 2010;25(6):346-65.
- Horn EP, Bein B, Böhm R, Steinfath M, Sahili N, Höcker J. The effect of short time periods of preoperative warming in the prevention of perioperative hypothermia. Anaesthesia 2012 June; 67 (6): 612-7, doi: 10.1111/j.1365-2044.2012.07073.x.
- Klauke N et al. Effects of prehospital hypothermia on transfusion requirements and outcomes: a retrospective observatory trial. BMJ Open 2016;6:e009913 doi:10.1136/bmjopen-2015-009913, http://bmjopen.bmj.com/content/6/3/e009913.full