The clinical effectiveness of interventions to assist perioperative temperature management for women undergoing cesarean section: a systematic review

Abstract

Background Women undergoing cesarean sections are vulnerable to the adverse effects associated with inadvertent perioperative hypothermia. Effective methods for preventing or managing hypothermia in this group would be valuable. Objectives To synthesize the best available evidence in relation to preventing and/or treating hypothermia in mothers after cesarean sections. Inclusion criteria Types of participants Adult patients of any ethnic background, with or without co-morbidities, undergoing any mode of anesthesia for any type of cesarean section were included. Types of interventions Active or passive warming methods, versus usual care or placebo, that aim to limit or manage core heat loss as applied to women undergoing cesarean sections are included. Types of studies Randomized controlled trials that met the inclusion criteria were considered. Types of outcomes Primary outcome: maternal core temperature during preoperative, intraoperative and postoperative phases of care. Secondary outcomes: newborn core temperature at birth, umbilical pH measured via blood gas analysis, Apgar scores, length of Post Anesthetic Care Unit stay, maternal thermal comfort. Search strategy A comprehensive search was undertaken of the following databases from their inception until May 2012: ProQuest, Web of Science, Scopus, Dissertation and Theses PQDT (via ProQuest), Current Contents, CENTRAL, MedNar, OpenGrey and Clinical Trials. There were no language restrictions. Methodological quality Retrieved papers were assessed for methodological quality by two independent reviewers using the standardized critical appraisal instruments for randomized controlled trials from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instruments (JBI-MAStARI). Data collection Two independent reviewers extracted data from the included papers using a customized data extraction tool. Data synthesis Where meta-analysis was possible, results were combined in a fixed effects meta-analysis using the Cochrane Collaboration Review Manager software. Due to heterogeneity for one comparison/outcome, random effects meta-analysis was also used. Results Twelve studies with a combined total of 719 participants were included. Intravenous fluid warming was found to be effective at maintaining maternal temperature and also aided in shivering prevention. Intravenous fluids did not improve thermal comfort or neonatal temperature, and the effectiveness on Apgar scores and umbilical pH remains unclear. Warming devices, including forced air warming devices and under-body carbon polymer mattresses, were effective at preventing hypothermia; however effectiveness increased if applied preoperatively. Preoperative body warming devices also reduced shivering. Preoperative forced air warming improves neonatal temperatures. Forced air warming did not improve Apgar scores. The effectiveness of body warming devices on umbilical pH and thermal comfort remains unclear. Leg wrapping was not effective for maintaining maternal temperature. Conclusions Intravenous fluid warming, by any method, improves maternal temperature for women undergoing cesarean section and reduces shivering. Preoperative body warming devices also improve maternal temperature, in addition to reducing shivering. Implications for practice Preoperative warming strategies should be utilized where possible for women undergoing cesarean section (Level 2) and preoperative and/or intraoperative warmed IV fluids should be standard practice (Level 1). Under-body warming mattresses should be used (Level 1) and upper body forced air warming should be utilized preoperatively (Level 2). Additional strategies, such as ambient temperature maintenance, should be used to maintain thermal comfort (Level 2). Warming strategies have less effect when intrathecal opioids are administered (Level 2). Implications for research Research is needed to investigate the effectiveness of interventions in emergency caesarean section surgery. Larger scale studies of warming interventions using standardized and clinically meaningful temperature measurement time points are also required.