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Monitoring patients can reduce the risks of hypothermia
Today, despite a growing focus on safety and quality among global healthcare institutions, inadvertent perioperative hypothermia continues to be a common and serious problem.
This can be addressed by introducing patient temperature monitoring as a quality process measure and using patient warming techniques.
Numerous randomised outcome trials have shown that even mild perioperative hypothermia triples the risk of morbid myocardial outcomes,1,2 triples the risk of surgical wound infection,3,4 increases blood loss and transfusion requirements,5,6 and prolongs recovery and time spent in hospital in a wide variety of surgical procedures.7,8
Unless preventive measures are taken, inadvertent perioperative hypothermia could occur in 50 to 90 per cent of surgical patients, even those undergoing relatively short procedures lasting between one and one-and-a-half hours.9 It is, therefore, not surprising that healthcare organisations around the world have emphasised the importance of maintaining perioperative normothermia.
Despite published evidence and recommendations, temperature monitoring often remains a low clinical priority. A 2007 survey carried out in 17 European countries revealed that only 19% of all surgical patients had their temperature measured throughout the perioperative process and only 38% received patient warming. The conclusion of this paper was that awareness of perioperative hypothermia is critical to its prevention, making temperature monitoring a prerequisite.10
The continuing widespread infrequency of monitoring and tracking of inadvertent hypothermia may stem from several causes, among them:
- A collective (and mistaken) assumption that if any kind of perioperative warming is taking place, the problem is being adequately addressed
- A lack of understanding about the prevalence and seriousness of inadvertent perioperative hypothermia (complications and costs)
- Doubts about the reliability of existing temperature monitoring methods, or the inconvenience (or lack) of monitoring equipment
- Confusion about when and how monitoring should take place: as there is no standardised approach to patient temperature monitoring and data collection.
For these reasons, incorporating patient temperature monitoring as a quality process measure, with hypothermia rates as an outcome measure, needs to be a focal point for hospital quality improvement.
The NICE clinical guideline11 on inadvertent perioperative hypothermia recommends:
- Preoperatively: Patient temperature should be measured before transfer to the operating room
- Intraoperatively: Patient temperature should be measured and documented before induction of anaesthesia and then every 30 minutes until the end of surgery
- Postoperatively: Patient temperature should be measured and documented on admission to the recovery room and then at 15-minute intervals.
There is some debate about the effectiveness and financial savings delivered by different types of patient warming systems.12 In a study comparing underbody forced-air warming with resistive mattress heating and passive insulation during hypothermic on-pump cardiac surgery, forced-air warming was found to be significantly more effective. Resistive mattress heating and passive insulation were considered to be as effective as each other.12 It is only by incorporating a standard temperature monitoring protocol and data collection approach that hospitals can assess the clinical and cost effectiveness of their chosen patient warming method.
Due to the morbidity associated with hypothermia and the availability of simple and effective prevention strategies that can keep temperatures stable, existing normothermia guidelines call for temperature monitoring as a basic requirement for both regional and general anaesthesia patients.
Widespread education and information sharing on the need for this quality measure – in other words, on the substantial risks and costs of inadvertent hypothermia – is also called for in order to advance improvements in patient care.
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- Frank SM, Beattie C, Christopherson R, Norris EJ, Perler BA, Williams GM et al. Unintentional hypothermia is associated with postoperative myocardial ischemia. The Perioperative Ischemia Randomized Anesthesia Trial Study Group. Anesthesiology 1993; 78: 468-476.
- Frank SM, Fleisher LA, Breslow MJ, Higgins MS, Olson KF, Kelly S et al. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial. Jama 1997; 277: 1127-1134.
- 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
- Flores-Maldonado A, Medina-Escobedo CE, Rios-Rodriguez HM, Fernandez-Dominguez (2001) Mild perioperative hypothermia and the risk of wound infection. Arch Med Res 32:227-231
- 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
- Rajagopalan S, Mascha E, Na J, Sessler DI. The effects of mild perioperative hypothermia on blood loss and transfusion requirement. Anesthesiology 2008; 108: 71-77.
- Kurz A, Sessler DI, Narzt E, Bekar A, Lenhardt R, Huemer G et al. Postoperative hemodynamic and thermoregulatory consequences of intraoperative core hypothermia. J Clin Anesth 1995; 7: 359-366
- Lenhardt R, Marker E, Goll V, Tschernich H, Kurz A, Sessler DI et al. Mild intraoperative hypothermia prolongs postanesthetic recovery. Anesthesiology 1997; 87: 1318-1323
- Young L, Watson M. Prevention of Perioperative Hypothermia in Plastic Surgery. Aesthetic Surgery Journal. Vol. 26, No. 5. pp. 552, Sept/Oct 2006.
- A. Torossian, The TEMMP Study Group; Survey on intraoperative temperature management in Europe; European Journal of Anesthesia 2007; 24:668-675
- National Institute of Clinical Excellence, Clinical Guideline 65, Inadvertent peroperative hypothermia, The management of inadvertent perioperative hypothermia in adults, April 2008
- S. Engelen, D Himpe, et al (2011), An evaluation of underbody forced-air resistive heating during hypothermic , on-pump cardiac surgery, Journal of Anaesthesia, Vol. 66, pp. 104-110