title: Effectiveness of active and passive warming for the prevention of inadvertent hypothermia in patients receiving neuraxial anesthesia: A systematic review and meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  Perioperative hypothermia is a common complication of anesthesia that can result in negative outcomes. The purpose of this review is to answer the question: Does the type of warming intervention influence the frequency or severity of inadvertent perioperative hypothermia (IPH) in surgical patients receiving neuraxial anesthesia?
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  Perioperative care areas.
  
  
  METHODS
  Adults undergoing surgery with neuraxial anesthesia.
  
  
  METHODS
  Perioperative active warming (AW) or passive warming (PW).
  
  
  METHODS
  PubMed, CINAHL, Embase, and Cochrane Central Register of Controlled Trials were searched. Inclusion criteria were: randomized controlled trials; adults undergoing surgery with neuraxial anesthesia; comparison(s) of AW and PW; and temperature measured at end of surgery/upon arrival in the Postanesthesia Care Unit. Exclusion criteria were: no full-text available; not published in English; studies of: combined neuraxial and general anesthesia, warm intravenous or irrigation fluids without using AW, and rewarming after hypothermia. Two independent reviewers screened abstracts and titles, and selected records following full-text review. The Cochrane Collaboration's tool for assessing risk of bias was used to evaluate study quality. A random-effects model was used to calculate risk ratios for dichotomous data and mean differences for continuous data.
  
  
  RESULTS
  Of 1587 records, 25 studies (2048 patients) were included in the qualitative synthesis. Eleven studies (1189 patients) comparing AW versus PW were included in the quantitative analysis. Meta-analysis found that intraoperative AW is more effective than PW in reducing the incidence of IPH during neuraxial anesthesia (RR=0.71; 95% CI 0.61-0.83; p<0.0001; I2=32%). The qualitative synthesis revealed that IPH continues despite current AW technologies.
  
  
  CONCLUSIONS
  During neuraxial anesthesia, AW reduces IPH more effectively than PW. Even with AW, IPH persists in some patients. Continued innovation in AW technology and additional comparative effectiveness research studying different AW methods are needed.
authors.affiliation: University of Iowa, College of Nursing, CNB 50 Newton Road, Iowa City, IA 52242-1121, USA. Electronic address: clarissa-shaw@uiowa.edu.
authors.forename: Clarissa A
authors.initials: CA
authors.lastname: Shaw
authors.affiliation: University of Iowa, College of Nursing, CNB 50 Newton Road, Iowa City, IA 52242-1121, USA. Electronic address: victoria-steelman@uiowa.edu.
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Steelman
authors.affiliation: University of Iowa, Hardin Library for the Health Sciences, 600 Newton Road, Iowa City, IA 52242-1098, USA. Electronic address: jennifer-deberg@uiowa.edu.
authors.forename: Jennifer
authors.initials: J
authors.lastname: DeBerg
authors.affiliation: University of Iowa, Internal Medicine and the Iowa City Veterans' Affairs Health Care System, 601 Highway 6 West, Iowa City, IA 52246, USA. Electronic address: marin-schweizer@uiowa.edu.
authors.forename: Marin L
authors.initials: ML
authors.lastname: Schweizer
mesh_terms: D001833:Body Temperature Regulation; D006801:Humans; D007035:Hypothermia / Q000517:prevention & control*; D007430:Intraoperative Care / Q000379:methods*; D007431:Intraoperative Complications / Q000517:prevention & control*; D009407:Nerve Block / Q000009:adverse effects* / Q000379:methods; D059035:Perioperative Period; D011183:Postoperative Complications / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D017694:Rewarming / Q000379:methods*
keywords: Anesthesia; Body temperature; Heating; Hypothermia; Intraoperative complications; Perioperative care