A systematic review of the effectiveness of warming interventions for women undergoing cesarean section

Perioperative Health Care Professionals' Knowledge of Evidence-Based Inadvertent Perioperative Hypothermia Management

PURPOSE

To evaluate the perioperative health care professionals' knowledge of evidence-based inadvertent perioperative hypothermia management.

DESIGN

A descriptive, cross-sectional study.

METHODS

The research sample consisted of 219 perioperative nurses and anesthesia technicians working in the university hospital and participating in perioperative care. Data were collected by the researchers using a questionnaire that included descriptive characteristics of health care professionals and inadvertent perioperative hypothermia management between March and April 2021. Descriptive statistics, Shapiro-Wilk normality, Kruskal Wallis, Mann Whitney U, and Spearman correlation test were used to analyze the data.

FINDINGS

In this study, only 29.2% of the health care professionals knew that the threshold value for inadvertent perioperative hypothermia was <36 °C. The mean knowledge score of health care professionals on the management of inadvertent perioperative hypothermia was 13.78 ± 3.47. The knowledge score of 79.5% of health care professionals was moderate level. A significant correlation was determined between inadvertent perioperative hypothermia management knowledge score and education status (P = .032), task (P < .001), and mean years in the profession (P = .02).

CONCLUSIONS

The knowledge of the health care professionals working in the perioperative process about evidence-based practices related to inadvertent perioperative hypothermia management was determined to be moderate. We recommend increasing the level of knowledge of health care professionals by providing education on guidelines regarding inadvertent perioperative hypothermia management.

Prewarming Parturients for Cesarean Section Does Not Raise Wound Temperature But Body Heat and Level of Comfort: A Randomized Trial

PURPOSE

Prewarming before cesarean section lowers the rates of surgical site infections (SSIs). We hypothesized that this effect is explained due to a higher core temperature resulting in a higher wound temperature.

DESIGN

We conducted an open-labeled randomized study with on-term parturients scheduled for elective cesarean section under spinal anesthesia. Participants were randomized into an intervention group (prewarming) and a control group.

METHODS

Core and wound temperature, comfort level, and examination results were taken at defined times until discharge from the postanesthesia care unit (PACU). There was a follow-up visit and interview 1 day after the procedure. The primary outcome was a difference in wound temperature. The secondary outcomes were differences in core temperature, patient comfort, blood loss, SSI, and neonatal outcome.

FINDINGS

We randomized a total of 60 patients, 30 per group. Prewarming lead to a significantly higher core temperature. Additionally, patient comfort was significantly higher in the prewarming group even after discharge from PACU. We did not find a difference in wound temperature, SSI, neonatal outcome, or blood loss.

CONCLUSIONS

Prewarming before cesarean section under spinal anesthesia maintains core temperature and improves patient comfort but does not affect wound temperature.

Verification of an intravenous fluid warmer: A prospective, two-center observational trial

Objectives

Avoiding inadvertent hypothermia during surgery is important. Intravenous fluid warmers used intraoperatively are critical for maintaining euthermia. We sought to prospectively evaluate the performance of the parylene-coated enFlow™ intravenous fluid warmer in patients undergoing surgery.

Methods

This was a prospective two-center observational clinical trial performed in inpatient surgical services of two large academic hospital systems. After written informed consent, patients were enrolled in the trial. All patients were adults scheduled for a surgery that was expected to last for at least 1 h with the administration of at least 1 L of fluid warmed prior to infusion. Patient temperature was recorded in the preoperative unit, at the induction of anesthesia, and then every 15 or 30 min until the end of surgery. Temperature monitoring continued in the recovery unit. The parylene-coated enFlow™ intravenous fluid warmer was used in addition to the usual patient warming techniques. The primary outcome was the average core temperature, and secondary analyses assessed individual temperature measurements, temperature measurements during specific time periods, and rate of hypothermic events.

Results

In all, 50 patients (29 males) with a mean age of 64 years were included in the analysis. The mean surgical time was 195 min and patients received an average of 1142 mL of fluids. Core temperature dropped by only 0.3°C approximately 60 min after induction and recovered back to the baseline level approximately 60 min later. There was no correlation between flow rate and measured core body temperature.

Conclusions

The parylene-coated enFlow intravenous fluid warmer was able to warm fluids at all flow rates during prolonged surgery. The results showed that enFlow performed as expected.

Combined Forced Air Warming and Warm Intravenous Fluid Strategy for Perioperative Hypothermia in Cesarean Delivery: A Systematic Review and Meta-Analysis

PURPOSE

Evaluate the effect of a combined forced-air warming (FAW) and warm intravenous fluid (IVF) modality on maternal and neonatal outcomes in cesarean delivery under neuraxial anesthesia.

DESIGN

Systematic Review and Meta-analysis.

METHODS

An extensive search was conducted using PubMed, Cochrane Library, MEDLINE, CINAHL, Google Scholar, and other grey literature. Only randomized controlled trials examining the combined modality on maternal temperatures were included. Risk ratio (RR), mean difference (MD), and standardized mean difference (SMD) were used to estimate outcomes with suitable effect models. Quality of evidence was assessed using the Risk of Bias and GRADE system.

FINDINGS

Nine trials involving 595 patients were included. Combined strategy showed a smaller change in maternal temperature from baseline by 0.42°C (MD, -0.42; 95% CI, -0.62 to -0.22; P < .0001), higher temperature on PACU arrival (MD, 0.46; 95% CI, 0.11-0.82; P = .01), 15 minutes (MD, 0.43; 95% CI, 0.19-0.67; P = .0004) and 30 minutes after surgery (MD, 0.38; 95% CI, 0.12-0.64; P = .005). Combined strategy also reduced the incidence of hypothermia (RR, 0.55; 95% CI, 0.31-0.95; P = .03), and shivering (RR, 0.40; 95% CI, 0.28-0.58; P < .00001) with improvement in maternal comfort score (SMD; 0.38; 95% CI, 0.08-0.69; P = .01). However, there were no differences in clinical indicators of adverse neonatal outcomes. Lack of participants blinding, and substantial heterogeneity were limitations of this review.

CONCLUSION

The use of combined FAW and warm IVF is an effective strategy in mitigating perioperative hypothermia in cesarean delivery under neuraxial anesthesia.

Effectiveness of Combined Strategies for the Prevention of Hypothermia Measured by Noninvasive Zero-Heat Flux Thermometer During Cesarean Section

Background: Perioperative hypothermia (body temperature <36°C) is a common complication of anesthesia increasing the risk for maternal cardiovascular events and coagulative disorders, and can also influence neonatal health. The aim of our work was to evaluate the impact of combined warming strategies on maternal core temperature, measured with the SpotOn. We hypothesized that combined modalities of active warming prevent hypothermia in pregnant women undergoing cesarean delivery with spinal anesthesia. Methods: Seventy-eight pregnant women were randomly allocated into three study groups receiving warmed IV fluids and forced-air warming (AW), warmed IV fluids (WF), or no warming (NW). Noninvasive core temperature device (SpotOn) measured maternal core temperature intraoperatively and for 30 min after surgery. Maternal mean arterial pressure, incidence of shivering, thermal comfort and newborn's APGAR, axillary temperature, weight, and blood gas analysis were also recorded. Results: Incidence of hypothermia was of 0% in AW, 4% in WF, and 47% in NW. Core temperature in AW was constantly higher than WF and NW groups. Incidence of shivering in perioperative time was significantly lower in AW and WF groups compared with the NW group (p < 0.04). Thermal comfort was higher in both AW and WF groups compared with NW group (p = 0.02 and p = 0.008, respectively). There were no significant differences among groups for the other evaluated parameters. Conclusion: Combined modalities of active warming are effective in preventing perioperative hypothermia. The routine uses of combined AW are suggested in the setting of cesarean delivery.

Prevention and management of perioperative hypothermia in adult elective surgical patients: A systematic review

BACKGROUND

Body temperature is tightly regulated with hormonal and cellular metabolism for normal functioning; however perioperative hypothermia is common secondary to anesthesia and surgical exposure.Prevention and maintaining body temperature should be started 1-2hrs before induction of anesthesia, to do this both active and passive warming system are effective to prevent complications associated with perioperative hypothermia.

METHODS

The aim of this systematic review is to develop a clear clinical practice protocol in prevention and management of perioperative hypothermia for elective adult surgical patients.The study is conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline 2020. After formulating clear criteria for the evidences to be included an appropriate method of searching was conducted by using the Pub Med, Google scholar and Cochrane library using the following MeSH terms: (inadvertent hypothermia AND anesthesia, hypothermia AND perioperative management and thermoregulation AND anesthesia) were used to draw evidences.After a reasonable amount of evidences were collected, appraisal and evaluation of study quality was based on WHO 2011 level of evidence and degree of recommendation. Final conclusions and recommendations are done by balancing the benefits and downsides of alternative management strategies for perioperative management of hypothermia.This systematic review registered with research registry unique identifying number (UIN) of "reviewregistry1253" in addition the overall AMSTAR 2 quality of this systematic review is moderate level.

DISCUSSION

Preserving a patient's body temperature during anesthesia and surgery is to minimize heat loss by reducing radiation and convection from the skin, evaporation from exposed surgical areas, and cooling caused by the introduction of cold intravenous fluids.

CONCLUSION

Hypothermia is least monitored complication during anesthesia and surgery results cardiac abnormalities, impaired wound healing, increased surgical site infections, shivering and delayed postoperative recovery, and coagulopathies.

Using a Normothermia Bundle With Perioperative Prewarming to Reduce Patient Hypothermia

PURPOSE

To determine if implementing a normothermia bundle, which includes preoperative forced-air warming blankets, reduces incidence of inadvertent perioperative hypothermia (IPH).

DESIGN

Intervention study using retrospective chart review.

METHODS

Patients received a preoperative forced-air warming blanket and temperature management with the normothermia bundle. Temperature status data was collected from patient charts to evaluate the incidences of IPH and findings from this data analysis was used to measure improvement in perioperative temperature management.

FINDINGS

Of 200 patients, 63 (31.5%) remained normothermic, 37 (18.5%) had at least one documented hypothermic temperature, and 100 (50%) had no documented temperature during the intraoperative phase of care. Although compliance with intraoperative temperature monitoring decreased by 13% postintervention, the incidence of documented IPH in reviewed records was decreased by 3.6-fold.

CONCLUSION

Implementing a normothermia bundle that includes a preoperative forced-air warming blanket may lower the incidences of IPH, especially in surgical cases lasting over 120 minutes.

Maternal and fetal hypothermia: more preventive compliance is required for a mother and her fetus while undergoing cesarean delivery; a quality improvement review

OBJECTIVE

Cesarean delivery is common, involves two patients, has numerous multi-disciplinary health care providers involved in the delivery management, but has variable levels of anesthesia and health services implementation for decreasing maternal hypothermia and the maternal and neonatal morbidity (and mortality). Limited implementation for either of the ERAS-CD or the ERAC guidelines, for inadvertent or preventive maternal hypothermia, is likely to be occurring on labor delivery floors. This Quality Improvement (QI) review focuses on cesarean delivery and maternal hypothermia.

METHODS

This quality and safety initiative used SQUIRE 2.0 methodology and concurrent PubMed searches to identify systematic review, meta-analysis, topic directed studies, additional published cohorts in the topic area not included in SR/MA, limited case reports that had specific clinical outcomes related to maternal hypothermia and fetal effects.

RESULTS

Two quality and safety improvement guidelines have defined the hypothermia activity element differently, with ERAS-CD recommending to prevent hypothermia, while ERAC recommending to maintain normothermia. The peer-reviewed literature indicates that the knowledge associated with surgical hypothermia outcome is known but it is not implemented for maternal cesarean delivery care. Increased maternal-effect recognition, surveillance, triage, and evidenced-based protocol management is required for the maternal - neonatal dyad undergoing cesarean delivery for the clinical reduction/prevention of neonatal hypothermia that has proven evidence-based maternal morbidity and neonatal morbidity/mortality.

CONCLUSION

TEAM-based anesthesia, obstetrical, neonatology-pediatrics and nursing research collaboration is required through quality-safety-ERAS-ERAC directed processes. Healthcare system recognition and financial support is required for maternal-fetal-neonatal hypothermia prevention protocols implementation.

Optimal Application of Forced Air Warming to Prevent Peri-Operative Hypothermia during Abdominal Surgery: A Systematic Review and Meta-Analysis

Patients who undergo abdominal surgery under general anesthesia develop hypothermia in 80–90% of the cases within an hour after induction of anesthesia. Side effects include shivering, bleeding, and infection at the surgical site. However, the surgical team applies forced air warming to prevent peri-operative hypothermia, but these methods are insufficient. This study aimed to confirm the optimal application method of forced air warming (FAW) intervention for the prevention of peri-operative hypothermia during abdominal surgery. A systematic review and meta-analysis were conducted to provide a synthesized and critical appraisal of the studies included. We used PubMed, EMBASE, CINAHL, and Cochrane Library CENTRAL to systematically search for randomized controlled trials published through March 2020. Twelve studies were systematically reviewed for FAW intervention. FAW intervention effectively prevented peri-operative hypothermia among patients undergoing both open abdominal and laparoscopic surgery. Statistically significant effect size could not be confirmed in cases of only pre- or peri-operative application. The upper body was the primary application area, rather than the lower or full body. These findings could contribute detailed standards and criteria that can be effectively applied in the clinical field performing abdominal surgery.

Complications of Cesarean Birth: Clinical Recommendations for Prevention and Management

The increase in severe maternal morbidity and mortality in the United States correlates with a significant rise in U.S. cesarean birth rates from 5.5% in 1970 to a rate of 31.9% of all births in 2018, far beyond the World Health Organization goal of 10% to 15%. Three key contributors to maternal morbidity and mortality related to cesarean birth include complications of hemorrhage, surgical site infection, and venous thromboembolism. All women should be screened for risk factors associated with these major complications during the antepartum, intrapartum, and postpartum period to assure the availability of immediate resources based on the assessment. Implementing evidence-based maternity care safety bundles, toolkits, and protocols to manage these complications can reduce adverse outcomes.

Shivering prevention and treatment during cesarean delivery under neuraxial anesthesia: a systematic review

INTRODUCTION

Perioperative shivering during cesarean sections (CSs) under neuraxial anesthesia (NA) is clinically common but often under-treated. It may prominently increase oxygen consumption, which can be catastrophic for parturients with ischemic cardiovascular disease. Thus, the prevention and treatment of shivering may be of great significance in parturients. The purpose of this systematic review was to investigate the effectiveness of several drugs on shivering prevention and treatment during CSs under NA.

EVIDENCE ACQUISITION

A literature search was carried out using PubMed, EMBASE and the Cochrane Library to identify relevant studies. After literature screening and information extraction, a systematic review was performed.

EVIDENCE SYNTHESIS

Eighteen randomized controlled trials met the inclusion criteria. Intrathecal dexmedetomidine effectively reduced shivering, but effectiveness depended on the dose administered. Intrathecal fentanyl, intrathecal sufentanil, intrathecal meperidine, intravenous ketamine and intravenous tramadol were beneficial for reducing shivering during CSs under NA. MgSO4 administered intrathecally resulted in transient alleviation of shivering, and the effect did not persist. Two trials investigated the antishivering effect of intravenous ondansetron. The medication appeared to be effective in one trial, but ineffective in the other.

CONCLUSIONS

Appropriate use of dexmedetomidine, fentanyl, sufentanil, ketamine, meperidine, tramadol and MgSO4 may effectively reduce the incidence and severity of shivering during CSs under NA, while trials on the effect of intravenous ondansetron reached inconclusive results.

Intrathecal Morphine-Related Perioperative Hypothermia in Women Undergoing Cesarean Delivery: A Retrospective Case-Control Study

PURPOSE

Rates of inadvertent perioperative hypothermia among women undergoing spinal anesthesia for cesarean delivery are reported to be high. Intrathecal morphine has been noted to have a potentially potent effect on thermoregulation. This retrospective case-control study sought to investigate the incidence of perioperative hypothermia in women undergoing cesarean delivery with and without intrathecal morphine and to describe any clinical factors associated with the condition, the identification of which would provide direction for nursing priorities in the care of the condition.

DESIGN

A retrospective case-controlled study design was used.

METHODS

The charts of 358 women who had undergone emergency or elective cesarean delivery under spinal anesthesia were reviewed: 179 having received intrathecal morphine and 179 having received spinal anesthesia without intrathecal morphine (control group). SPSS (IBM, Armonk, New York), version 22, was used for data analysis, including logistic regression to predict the outcome of hypothermia across the study population.

FINDINGS

There was no significant difference (P = .62; 95% confidence interval, -0.09 to 0.15) in mean postoperative temperature for the morphine group (mean postanesthesia care unit arrival temperature, 35.91°C; standard deviation, 0.59) and the no morphine group (mean postanesthesia care unit arrival temperature, 35.88°C; standard deviation, 0.52). However, within groups, the temperature decline preoperatively to postoperatively was statistically (and clinically) significant.

CONCLUSIONS

The results refute the suggestion that intrathecal morphine contributes to greater core temperature decline in this population; however, it does confirm that perioperative hypothermia is a prevalent concern for women undergoing cesarean delivery and that pre-emptive measures should be routinely considered by health care providers.

Consensus Review of Optimal Perioperative Care in Breast Reconstruction: Enhanced Recovery after Surgery (ERAS) Society Recommendations

BACKGROUND

Enhanced recovery following surgery can be achieved through the introduction of evidence-based perioperative maneuvers. This review aims to present a consensus for optimal perioperative management of patients undergoing breast reconstructive surgery and to provide evidence-based recommendations for an enhanced perioperative protocol.

METHODS

A systematic review of meta-analyses, randomized controlled trials, and large prospective cohorts was conducted for each protocol element. Smaller prospective cohorts and retrospective cohorts were considered only when higher level evidence was unavailable. The available literature was graded by an international panel of experts in breast reconstructive surgery and used to form consensus recommendations for each topic. Each recommendation was graded following a consensus discussion among the expert panel. Development of these recommendations was endorsed by the Enhanced Recovery after Surgery Society.

RESULTS

High-quality randomized controlled trial data in patients undergoing breast reconstruction informed some of the recommendations; however, for most items, data from lower level studies in the population of interest were considered along with extrapolated data from high-quality studies in non-breast reconstruction populations. Recommendations were developed for a total of 18 unique enhanced recovery after surgery items and are discussed in the article. Key recommendations support use of opioid-sparing perioperative medications, minimal preoperative fasting and early feeding, use of anesthetic techniques that decrease postoperative nausea and vomiting and pain, use of measures to prevent intraoperative hypothermia, and support of early mobilization after surgery.

CONCLUSION

Based on the best available evidence for each topic, a consensus review of optimal perioperative care for patients undergoing breast reconstruction is presented.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Enhanced recovery after elective caesarean: a rapid review of clinical protocols, and an umbrella review of systematic reviews

BACKGROUND

The rate of elective Caesarean Section (CS) is rising in many countries. Many obstetric units in the UK have either introduced or are planning to introduce enhanced recovery (ER) as a means of reducing length of stay for planned CS. However, to date there has been very little evidence produced regarding the necessary components of ER for the obstetric population. We conducted a rapid review of the composition of published ER pathways for elective CS and undertook an umbrella review of systematic reviews evaluating ER components and pathways in any surgical setting.

METHODS

Pathways were identified using MEDLINE, EMBASE and the National Guideline Clearing House, appraised using the Appraisal of Guidelines for Research and Evaluation (AGREE II) tool and their components tabulated. Systematic reviews were identified using the Cochrane Library and Database of Abstracts of Reviews of Effects (DARE) and appraised using The Grading of Recommendations Assessment, Development and Evaluation (GRADE). Two reviewers aggregated summaries of findings for Length of Stay (LoS).

RESULTS

Five clinical protocols were identified, involving a total of 25 clinical components; 3/25 components were common to all five pathways (early oral intake, mobilization and removal of urinary catheter). AGREE II scores were generally low. Systematic reviews of single components found that minimally invasive Joel-Cohen surgical technique, early catheter removal and post-operative antibiotic prophylaxis reduced LoS after CS most significantly by around half to 1 and a half days. Ten meta-analyses of multi-component Enhanced Recovery after Surgery (ERAS) packages demonstrated reductions in LoS of between 1 and 4 days. The quality of evidence was mostly low or moderate.

CONCLUSIONS

Further research is needed to develop, using formal methods, and evaluate pathways for enhanced recovery in elective CS. Appropriate quality improvement packages are needed to optimise their implementation.

The effect of 30 to 60 minutes of forced-air pre-warming on maintaining intraoperative core temperatures during the first hour post-anesthesia induction in adult patients undergoing general anesthesia: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to identify the effectiveness of 30 to 60 minutes of forced-air pre-warming on maintaining intraoperative core temperatures in adult patients undergoing general anesthesia. The review question will focus on the effects of forced-air pre-warming on preventing redistribution hypothermia in the first hour post induction of anesthesia, which is considered the most critical due to an internal core-to-peripheral redistribution of body heat and subsequent loss of heat to the operative room surroundings.

Meta-analysis: effectiveness of forced-air warming for prevention of perioperative hypothermia in surgical patients

AIM

The aim of this study was to evaluate the effectiveness of forced-air warming for preventing perioperative hypothermia.

BACKGROUND

Perioperative hypothermia commonly occurs in patients receiving anaesthesia during surgeries. However, the effectiveness of warming systems requires verification.

DESIGN

Systematic review incorporating meta-analysis.

DATA SOURCES

We searched OVID, PubMed, Cochrane Library, Medline, CINAHL, CETD and CEPS databases (2001-2015) for randomized controlled trials published in English and Chinese. Outcome measures of interests were body temperature and thermal comfort.

REVIEW METHODS

Cochrane methods, Quality of evidence (GRADE) assessments and Jadad Quality Score were used.

RESULTS

Twenty-nine trials (1875 patients) met inclusion criteria, including seven trials (502 patients) related to thermal comfort. Results showed that: (1) forced-air warming was more effective than passive insulation and circulating-water mattresses; (2) there was no statistically significant difference among forced-air warming, resistive heating blankets, radiant warming systems and circulating-water garments; and (3) that thermal comfort provided by forced-air warming was superior to that of passive insulation, resistive heating blankets and radiant warming systems, but inferior to that of circulating-water mattresses.

CONCLUSIONS

Forced-air warming prevents perioperative hypothermia more effectively than passive insulation and circulating-water mattresses, whereas there is no statistically significant difference in its effectiveness compared with circulating-water garments, resistive heating blankets and radiant warming systems.

Intrathecal Sufentanil Does Not Reduce Shivering During Neuraxial Anesthesia: A Meta-Analysis

BACKGROUND

We performed this meta-analysis to evaluate the efficacy of intrathecal sufentanil in preventing shivering during neuraxial anesthesia.

MATERIAL/METHODS

We searched the Cochrane Library, PubMed, and Embase for all randomized controlled trials (RCT) on use of intrathecal sufentanil for preventing shivering during neuraxial anesthesia. References of retrieved articles were also screened. The quality of the studies was evaluated by the method recommended by the Cochrane Collaboration. Meta-analysis was conducted using the Cochrane Collaboration's RevMan 5.3 software. The primary outcome was incidence and severity of shivering, and the secondary outcomes were drug-related complications of pruritus, nausea, vomiting, hypotension, and bradycardia.

RESULTS

Eight original RCTs investigating a total of 1032 patients, of whom 599 received sufentanil and 473 received placebo, met the inclusion criteria. Compared to the placebo group, sufentanil did not reduce incidence of shivering (OR, 0.60; 95% CI, 0.35 to 1.01; P=0.06), but it increased the incidence of pruritus (OR, 12.52; 95% CI, 5.07 to 30.91; P<0.00001). Compared to the placebo group, sufentanil did not increase the incidence of nausea (OR, 0.69; 95% CI, 0.41 to 1.16; P=0.16), hypotension (OR, 0.93; 95% CI, 0.62 to 1.41; P=0.74), or bradycardia (OR, 0.86; 95% CI, 0.41 to 1.82; P=0.70). In addition, sufentanil reduced the incidence of vomiting during neuraxial anesthesia (OR, 0.45; 95% CI, 0.22 to 0.92; P=0.03).

CONCLUSIONS

Neither epidural nor subarachnoid intrathecal sufentanil reduced shivering during neuraxial anesthesia, but it did increase the incidence of pruritus.

The Effect of patient warming during Caesarean delivery on maternal and neonatal outcomes: a meta-analysis

BACKGROUND

Perioperative warming is recommended for surgery under anaesthesia, however its role during Caesarean delivery remains unclear. This meta-analysis aimed to determine the efficacy of active warming on outcomes after elective Caesarean delivery.

METHODS

We searched databases for randomized controlled trials utilizing forced air warming or warmed fluid within 30 min of neuraxial anaesthesia placement. Primary outcome was maximum temperature change. Secondary outcomes included maternal (end of surgery temperature, shivering, thermal comfort, hypothermia) and neonatal (temperature, umbilical cord pH and Apgar scores) outcomes. Standardized mean difference/mean difference/risk ratio (SMD/MD/RR) and 95% confidence interval (CI) were calculated using random effects modelling (CMA, version 2, 2005).

RESULTS

13 studies met our criteria and 789 patients (416 warmed and 373 controls) were analysed for the primary outcome. Warming reduced temperature change (SMD -1.27°C [-1.86, -0.69]; P=0.00002); resulted in higher end of surgery temperatures (MD 0.43 °C [0.27, 0.59]; P<0.00001); was associated with less shivering (RR 0.58 [0.43, 0.79]; P=0.0004); improved thermal comfort (SMD 0.90 [0.36, 1.45]; P=0.001), and decreased hypothermia (RR 0.66 [0.50, 0.87]; P=0.003). Umbilical artery pH was higher in the warmed group (MD 0.02 [0, 0.05]; P=0.04). Egger's test (P=0.001) and contour-enhanced funnel plot suggest a risk of publication bias for the primary outcome of temperature change.

CONCLUSIONS

Active warming for elective Caesarean delivery decreases perioperative temperature reduction and the incidence of hypothermia and shivering. These findings suggest that forced air warming or warmed fluid should be used for elective Caesarean delivery.