Effect of preoperative warming during cesarean section under spinal anesthesia

Non-pharmacological treatments for shivering post neuraxial anaesthesia for caesarean section: a scoping review

BACKGROUND

Shivering occurs more frequently for women having caesarean section under neuraxial anaesthesia compared to other patient groups and causes an increase in pain and interrupts bonding with her newborn.

AIM

This study aimed to report the evidence on non-pharmacological methods to treat shivering, defined as uncontrollable shaking, because of being cold, frightened, or excited, post neuraxial anaesthesia; the use of local anaesthesia inserted around the nerves of the central nervous system such as spinal anaesthesia and epidural in women having a caesarean section.

METHODS

A scoping review was conducted using six electronic health databases that were searched with no restrictions placed on language, date, or study type.

FINDINGS

Of the 1399 studies identified, following screenings only one study was deemed suitable for inclusion. The study, a randomised controlled trial, compared forced air warming blankets (intervention) with the usual care of warmed cotton blankets (control) and its impact on maternal and newborn outcomes. The only statistically significant difference found was the perceived thermal comfort of the mother.

DISCUSSION

Non-pharmacological treatments for shivering are underrepresented in the literature; only one study identified where the impact of active warming was compared to warmed cotton blankets (usual care) for the measures of: oral temperature; degree of shivering; and thermal comfort pain scores. There was a decline in temperature in both groups at odds with some women reporting feeling too warm such that they asked for the active warmer to be turned down.

CONCLUSION

Social engagement strategies are interventions that send a signal of safety to the nervous system leading to a sense of calm and wellbeing and have biological plausibility and warrant evaluation. Recommendations for further research: design a robust study to test the effectiveness of social engagement strategies on shivering for women having caesarean section under neuraxial anaesthesia.

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.

Effects of Active Heating Methods on Body Temperature, Shivering, Thermal Comfort, Pain, Nausea and Vomiting During General Anesthesia: A Randomized Controlled Trial

To investigate the effect of forced-air warming and heated intravenous (IV) and irrigation fluids alone and in combination on body temperature, shivering, thermal comfort, pain, nausea and vomiting in adult patients undergoing surgery under general anesthesia in a prospective, four-group, randomized controlled trial. After induction of anesthesia, 120 patients were divided into the following groups: patients warmed with forced-air warming (n = 30), patients receiving warmed IV and irrigation fluid (n = 30), patients receiving warmed IV and irrigation fluid with forced-air warming (n = 30), and the control group without any intervention (n = 30). Body temperature, shivering, thermal comfort, pain, nausea and vomiting were monitored in the first 24 hours after surgery. The general characteristics of the groups, mean body temperature, length of stay, ambient temperature, and duration of surgery in the preoperative waiting unit were similar (p > 0.05). Compared with the other groups, patients in the control group had a significant decrease in body temperature from the 30th minute during surgery (p < 0.001), lower body temperature in the first 2 hours and thermal comfort in the first three hours after surgery (p < 0.01), and higher shivering levels in the first hour after surgery (p < 0.01). There was no significant difference between the groups in terms of postoperative pain, nausea and vomiting (p > 0.05). The study findings showed that normothermia was maintained in all three intervention groups during the surgery and in the first 24 hours after surgery. Moreover, postoperative thermal comfort increased and shivering levels decreased compared with the control group, but pain, nausea and vomiting levels were not affected. The study was registered on ClinicalTrials.gov (NCT04907617).

The effect of forced-air warming in the cesarean section on maternal hypothermia, shivering, and thermal comfort: A randomized controlled trial

This trial was carried out to investigate the effect of forced air warming in various body areas of women on hypothermia during cesarean delivery. The patients in the study groups (n = 76) were assigned to the full-body warming group, upper-extremity warming group, lower-extremity warming group, and control groups. The intervention groups received forced-air warming 30 min before the surgery and continued until 30 min after surgery. The incidence of hypothermia was significantly higher in the control group than in the other groups at the 60th minute of the operation (p < 0.01). The intervention and control groups showed significant differences in the frequency of shivering at the entrance to the PACU (p = 0.001). Thermal comfort scores have significant difference between the control group and all of the intervention groups (p<.001). It is said that the full-body forced-air warming technique prevents hypothermia, shivering, and thermal discomfort in women Cesarean Section (CS).

Intraoperative phenylephrine infusion to reduce perioperative shivering in lower segment caesarean section: A randomised controlled study

BACKGROUND

Shivering is described as an involuntary, repetitive activity of the skeletal muscles that can have deleterious effects on anaesthetized patients. This study aimed to evaluate the effectiveness of phenylephrine infusion in preventing perioperative shivering in patients undergoing lower segment cesarean section under spinal anesthesia and to observe the change in the patient's core temperature between the study and control groups.

METHODS

A total of 118 patients scheduled for elective lower segment cesarean section under spinal anesthesia were recruited for this prospective, double-blind, randomized controlled study. The patients were randomized into 2 groups with 59 patients per group. The phenylephrine Group received phenylephrine infusion at a rate of 0.5 mcg/kg/minutes, while the Control Group received normal saline at an equivalent rate. Systolic and diastolic blood pressure, heart rate, core temperature, and the presence and intensity of shivering were recorded before induction and every 15 minutes intraoperatively and postoperatively.

RESULTS

The incidence of intraoperative shivering was significantly lower in the Phenylephrine Group compared to control group (29.1% vs 47.5% respectively; P = .044). Postoperatively, the Phenylephrine Group also had a lower incidence of shivering (34.5% vs 42.4%), but the difference was not statistically significant (P value = 0.391). There were no significant differences in the intensity of shivering between the 2 groups perioperatively, as well as in the systolic and diastolic blood pressure and core temperature. The phenylephrine Group showed a significantly lower heart rate at 15, 30, and 45 minutes after spinal block (P value = .005, .000, and .008, respectively), and at 0 and 30 minutes (P value = .004 and .020 respectively) in the recovery room. There were no significant differences in perioperative adverse events such as hypotension, hypertension, and bradycardia.

CONCLUSION

Phenylephrine infusion reduces the incidence of perioperative shivering in lower segment cesarean sections under spinal anesthesia.

Intraoperative hypothermia in the neonate population: risk factors, outcomes, and typical patterns

The risk factors, outcomes, and typical patterns of intraoperative hypothermia were studied in neonates to better guide the application of insulation measures in the operating room. This retrospective study enrolled 401 neonates undergoing surgery under general anaesthesia with tracheal intubation, including abdominal surgery, thoracic surgery, brain surgery, and others. The study collected basic characteristics, such as age, sex, weight, birth weight, gestational week, primary diagnosis and American Society of Anaesthesiologists (ASA) grade. Perioperative data included preoperative body temperature, length of hospital stay, length of intensive care unit (ICU) stay, intubation time, postoperative bleeding, postoperative pneumonia, postoperative death, and total cost of hospitalization. Intraoperative data included surgical procedures, anaesthesia duration, operation duration, blood transfusion, fluid or albumin infusion, and application of vasoactive drugs. The incidence of intraoperative hypothermia (< 36 °C) was 81.05%. Compared to normothermic patients, gestational week (OR 0.717; 95% CI 0.577-0.890; P = 0.003), preoperative temperature (OR 0.228; 95% CI 0.091-0.571; P = 0.002), duration of anaesthesia (OR 1.052; 95% CI 1.027-1.077; P < 0.001), and type of surgery (OR 2.725; 95% CI 1.292-5.747; P = 0.008) were associated with the risk of intraoperative hypothermia. Patients with hypothermia had longer length of ICU stay (P = 0.001), longer length of hospital stay (P < 0.001), and higher hospital costs (P < 0.001). But there were no association between clinical outcomes and intraoperative hypothermia in the multivariable regression adjusted analysis. The lowest point of intraoperative body temperature was approximately 1 h 30 min. Then, the body temperature of patients successively entered a short plateau phase and a period of slow ascent. The greatest decrease in body temperatures occurred in preterm babies and neonates with preoperative hypothermia. The lowest core temperatures that occurred in neonates with preoperative hypothermia was lower than 35 °C. This study shows that there is a high incidence of intraoperative hypothermia in the neonate population. The intraoperative body temperature of neonates dropped to the lowest point in 1-1.5 h. The greatest decrease in core temperatures occurred in preterm babies and neonates with lower preoperative temperature.

The Effects of Active Warming on Core Body Temperature and Thermal Comfort in Patients After Transurethral Resection of the Prostate: A Randomized Clinical Trial

Prevention and treatment of hypothermia by active warming in perioperative period care is recommended but scientific evidence of its effectiveness in a clinical setting is scarce. The purpose of this study was to determine the effects of warmed intravenous fluids (WIVF) on the core body temperature and the patients' thermal comfort. Baseline data of 105 male patients undergoing TUR-P surgery and bladder irrigation were analyzed. The experimental group was warmed using active WIVF, and the control group's routine care was conducted using a cotton blanket. Body temperature was higher in patients in the experimental group than those in the control group. Repeated measures Manova revealed significantly different core temperature changes between groups (F = 34.446, p = .001). The thermal comfort scores were also higher in the experimental group than in the control group (x² = 203.552, p = .001). The findings indicated that WIVF can enhance body temperature and improve the thermal comfort of patients.

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.

The effects of intravenous remifentanil on umbilical artery serum-derived exosomes in parturients undergoing epidural anesthesia: a randomized trail

BACKGROUND

Umbilical artery serum-derived exosomes (UEs) serve as messengers for maternal-fetal information exchange and cellular regulation. Intravenous remifentanil could be considered as an effective adjunct to epidural anesthesia in providing a favorable analgesia effect for cesarean section (C-section), but its effects on UEs are currently unknown.

METHODS

From 01/12/2021 to 30/06/2022, eligible parturients scheduled for repeated C-section at the First Affiliated Hospital of Wenzhou Medical University were randomized to receive either an intravenous bolus (0.15 μg/kg) followed by a continuous infusion (0.075 μg/kg/min) of remifentanil or normal saline throughout the procedure. The primary outcome was the number of UEs. Secondary outcomes included the size and protein amount of UEs, the vital signs, visceral pain score, sedation score, maternal satisfaction score, Apgar score, the incidence of neonatal asphyxia, umbilical arterial pH, and the presence of complications.

RESULTS

Nanoparticle tracking analysis indicated similar size of UEs between the two groups, but the number and protein amount of UEs were increased in the remifentanil group  compared to the control group (P < 0.05). In parturients receiving remifentanil, visceral pain scores were decreased, which was accompanied by the increased scores of maternal satisfaction with the anesthetic method (P < 0.05). Other maternal and neonatal outcomes were comparable between the two groups (P > 0.05).

CONCLUSION

The intravenous administration of remifentanil increased the number of UEs in parturients undergoing repeated C-section under epidural anesthesia, with improved birth experience and minimal neonatal complications.

Comparison of the Effect of Forced-air Warming and Warmed Intravenous Fluid on the Comfort and Prevention of Shivering After Spinal Anesthesia in Patients Undergoing Orthopedic Surgery

PURPOSE

This study aimed to compare the effect of forced-air warming and warmed intravenous fluid on the comfort and prevention of shivering after spinal anesthesia in patients undergoing orthopaedic surgery.

DESIGN

Randomized controlled clinical trial.

METHODS

A total of 120 patients were randomly divided into three groups: forced-air warming (38°C), warmed intravenous fluid (37°C), and the control group. Patients' comfort and severity of shivering were measured and recorded five times (immediately and 15 minutes after spinal anesthesia, end of the surgery, time of entrance to the recovery room, and 15 minutes after entering the recovery room), and compared with each other.

FINDINGS

There was a significant difference between the three groups in terms of comfort at all points of evaluation times (P < .001). The comfort score in the control group was significantly higher than the two intervention groups (P < .001). Moreover, the comfort score in the warmed intravenous fluid group was significantly higher than the forced-air warming group (P < .001). In addition, there was a significant difference in shivering severity between the three groups at the end of the surgery, entrance to the recovery room, and 15 minutes after surgery (P < .001). The majority of patients in the forced-air warming group (90%) had no shivering at all three times, while the warmed IV fluid and control groups was 65% and 30% respectively.

CONCLUSIONS

Non-pharmacological methods such as forced-air warming and warmed intravenous fluid can provide comfort and prevent shivering in orthopaedic patients undergoing spinal anesthesia. However, the use of forced-air warming is more effective than warmed intravenous fluid in providing comfort and preventing shivering in these patients. It is recommended that these methods be used in the operating room to provide comfort and prevent shivering in these patients.

Effect of active and passive warming on preventing hypothermia and shivering during cesarean delivery: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Perioperative hypothermia and shivering commonly occur in pregnant women undergoing cesarean section. The warming method is usually used to prevent hypothermia and shivering. However, the effect of active warming (AW) prior to passive warming (PW) on the perioperative outcomes of pregnant women and their offspring remains controversial.

METHODS

This study aimed to investigate the effects of AW and PW on maternal and newborn perioperative outcomes during cesarean delivery. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, PubMed, Embase, Scopus, and the Cochrane Library were used to search for randomized controlled trials (RCTs) up to August 7, 2022. The Cochrane risk of bias assessment tool was used to assess articles selected for the systematic review. Continuous data were analyzed using weighted mean differences (WMDs) with 95% confidence intervals (CIs), and categorical data were analyzed by the random-effects model.

RESULTS

A total of 1241 participants from twelve RCTs were selected for the final meta-analysis. AW was associated with a lower risk of maternal hypothermia (RR: 0.77, 95% CI: 0.63-0.93, P = 0.007) and shivering (RR: 0.56, 95% CI: 0.37-0.85; P = 0.007). AW was associated with high maternal temperature (WMD: 0.27, 95%CI: 0.14 to 0.40, P < 0.001). No significant difference was observed between AW and PW in terms of hypothermia (RR: 0.60, 95% CI: 0.24-1.51, P = 0.278), temperature (WMD: 0.31, 95% CI: - 0.00 to 0.62; P = 0.050), and umbilical vein PH in newborns (WMD: -0.00; 95% CI: - 0.02 to 0.02, P = 0.710).

CONCLUSIONS

These findings suggested that AW can better prevent maternal hypothermia and shivering than PW. In contrast, no significant effect was observed in newborns. Overall, the quality of the included studies is high due to RCTs, low risk of bias, consistency, and precision. We identified the quality of the overall evidence from the survey to be GRADE I.

Evidence-Based Guideline on Prevention and Management of Shivering After Spinal Anesthesia in Resource-Limited Settings: Review Article

Background

Perioperative shivering is a common problem faced in anesthesia practice. Unless it is properly managed and prevented, it causes discomfort and devastating problems, especially in patients with cardiorespiratory problems. Surgery, anesthesia, exposure of skin in a cool operating theater, and administration of unwarmed fluids are some of the major causes for the development of shivering among surgical patients. Currently, a variety of non-pharmacological and pharmacological techniques are available to prevent and manage this problem. The available options to prevent and treat shivering include but are not limited to pre-warming the patient for 15 minutes before anesthesia administration, administration of low dose ketamine, dexamethasone, pethidine, clonidine, dexmedetomidine, tramadol, and magnesium sulfate.

Objective

To develop evidence-based recommendations for the prevention and management of shivering after spinal anesthesia in a resource-limited settings.

Methods

The kinds of literature are searched from Google Scholar, PubMed, Cochrane library, and HINARI databases to get access to current and update evidence on the prevention and management of shivering after spinal anesthesia. The keywords for the literature search were (shivering or prevention) AND (shivering or management) AND (anesthesia or shivering).

Conclusion

Pre-warming the patient with cotton, blanket, gown warming, and administering warm IV fluid 15 minutes before spinal anesthesia are possible non-pharmacologic options for the prevention of shivering. Furthermore, pharmacological medications like low dose ketamine, dexamethasone, magnesium sulfate, ad tramadol can be used as alternative options for the prevention and management strategies for shivering of different degrees in resource-limited areas.

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.

Preoperative perfusion index as a predictor of post-anaesthetic shivering in caesarean section with spinal anaesthesia

BACKGROUND

Post-anaesthetic shivering is frequently preceded by a decrease in peripheral blood flow. Perfusion index is a fast non-invasive method to assess peripheral blood flow, thus might be correlated with post-anaesthetic shivering.

AIM

To analyse the relationship between preoperative perfusion index and post-anaesthetic shivering in patients undergoing caesarean section with spinal anaesthesia.

METHODS

In this prospective observational study, preoperative perfusion index measurements were performed on 40 participants who were undergoing elective caesarean section under spinal anaesthesia. Spinal anaesthesia was performed using Lidodex (Lignocaine + Dextrose 5%) at vertebrae L4-L5 or L3-L4 interspace. Shivering was observed until 120 minutes according to the Crossley and Mahajan scale. Statistical analysis was performed to examine the correlation and cut-off of preoperative perfusion index as a predictor for post-anaesthetic shivering.

RESULT

There was a significant relationship between preoperative perfusion index with the incidence (p = 0.005) and the degree (p = 0.014) of post-anaesthetic shivering. The preoperative perfusion index cut-off value based on the ROC curve was 4.2 (AUC = 0.762, p = 0.002) with a sensitivity of 73.9% and specificity of 88.2%. Participants with preoperative PI < 4.2 had a greater risk of post-anaesthetic shivering (p < 0.001, RR = 3.13).

CONCLUSION

Preoperative perfusion index less than 4.2 can predict post-anaesthetic shivering in patients undergoing caesarean section with spinal anaesthesia.

The effect of combination of warm intravenous fluid infusion and forced air warming versus forced air warming alone on maternal temperature and shivering during cesarian delivery under spinal anesthesia

Objective

Administration of warm intravenous (IV) fluid infusion and use of forced air warmers is the most easy and physiologically viable method for maintaining normothermia during surgery and postsurgical periods This study was conducted to assess the effect of combination of active warming (AW) methods namely warm IV fluid infusion and forced air warming versus forced air warming only (WA) on maternal temperature during elective C-delivery under spinal anesthesia.

Materials and Methods

A total of 100 patients scheduled for elective c-section were grouped into those who received both warmed IV fluid infusion and forced air warmer (Combination of active warming WI= 50) and those who received only forced air warmer (WA = 50). Core body temperature and shivering incidence were recorded using a tympanic thermometer from prespinal till the end of surgery every 10 min and in postanesthesia care unit (PACU) at 0, 15, and 30 min.

Results

Core temperature showed statistically significant difference in 15, 35, 45, and 55 min between air warmer and warm infusion groups and in PACU at 0, 15, and 30 min, it was statistically significant (P = 0.000) among WI group (mean temperature = 36.79°C) when compared to WA group (mean temperature = 35.96°C). There was a lower incidence of shivering in WI compared to WA group, which is statistically significant.

Conclusion

Combination of warm Intravenous fluid infusion and Forced air warming is better than forced air warming alone. In maintaining near normal maternal core body temperature during elective cesarean section following spinal anesthesia. Combined warming method also reduces shivering incidence.

Improving intraoperative temperature management in elective repeat cesarean deliveries: a retrospective observational cohort study

Background

Inadvertent perioperative hypothermia (< 36 °C) occurs frequently during elective cesarean delivery and most institutions do employ perioperative active warming. The purpose of this retrospective observational cohort study was to determine if the addition of preoperative forced air warming in conjunction with intraoperative underbody forced air warming improved core temperature and reducing inadvertent perioperative hypothermia during elective repeat elective cesarean delivery with neuraxial anesthesia.

Methods

We evaluated the addition of perioperative active warming to standard passive warming methods (preheated intravenous/irrigation fluids and cotton blankets) in 120 parturients scheduled for repeat elective cesarean delivery (passive warming, n = 60 vs. active + passive warming, n = 60) in a retrospective observational cohort study. The primary outcomes of interest were core temperature at the end of the procedure and a decrease in inadvertent perioperative hypothermia (< 36 °C). Secondary outcomes were surgical site infections and adverse markers of neonatal outcome.

Results

The mean temperature at the end of surgery after instituting the active warming protocol was 36.0 ± 0.5 °C (mean ± SD, 95% CI 35.9–36.1) vs. 35.4 ± 0.5 °C (mean ± SD, 95% CI 35.3–35.5) compared to passive warming techniques (p <  0.001) and the incidence of inadvertent perioperative hypothermia at the end of the procedure was less in the active warming group - 68% versus 92% in the control group (p <  0.001). There was no difference in surgical site infections or neonatal outcomes.

Conclusions

Perioperative active warming in combination with passive warming techniques was associated with a higher maternal temperature and lower incidence of inadvertent perioperative hypothermia with no detectable differences in surgical site infections or indicators of adverse neonatal outcomes.

Effects of combined warmed preoperative forced-air and warmed perioperative intravenous fluids on maternal temperature during cesarean section: a prospective, randomized, controlled clinical trial

Background

Preventing the frequent perioperative hypothermia incidents that occur during elective caesarean deliveries would be beneficial. This trial aimed at evaluating the effect of preoperative forced-air warming alongside perioperative intravenous fluid warming in women undergoing cesarean sections under spinal anesthesia.

Methods

We randomly allocated 135 women undergoing elective cesarean deliveries to either the intervention group (preoperative forced-air and intravenous fluid warming, n = 69) or the control group (no active warming, n = 66). The primary outcome measure was the core temperature change between groups from baseline to the end of the surgical procedure. Secondary outcomes included thermal comfort scores, the incidences of shivering and hypothermia (< 36 °C), the core temperature on arrival at the post-anesthesia care unit, neonatal axillary temperature at birth, and Apgar scores.

Results

Two-way repeated measures ANOVA revealed significantly different core temperature changes (from the pre-spinal temperature to that at the end of the procedure) between groups (F = 13.022, P < 0.001). The thermal comfort scores were also higher in the intervention group than in the control group (F = 9.847, P = 0.002). The overall incidence of perioperative hypothermia was significantly lower in the intervention group than in the control group (20.6% vs. 51.6%, P < 0.0001).

Conclusions

Warming preoperative forced-air and perioperative intravenous fluids may prevent maternal hypothermia, reduce maternal shivering, and improve maternal thermal comfort for patients undergoing cesarean sections under spinal anesthesia.

Trial registration

The study was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR1800019117) on October26, 2018.

Prospective observational study of the effectiveness of prewarming on perioperative hypothermia in surgical patients submitted to spinal anesthesia

Prewarming has been shown to prevent intraoperative inadvertent hypothermia. Nevertheless, data about optimal prewarming-time from published clinical trials report contradictory results. We conducted this pilot study to evaluate routine clinical practice regarding prewarming and its effect on the prevalence of perioperative hypothermia in patients undergoing transurethral resection (TUR) under spinal anesthesia. This was a prospective, observational, pilot study to examine clinical practice in a tertiary hospital regarding prewarming in 140 consecutive patients. When prewarming (pw) was performed, forced-air warming was provided in the pre-anesthesia room for 15 (pw15), 30 (pw30), or 45 (pw45) min. Tympanic temperature was recorded upon entering the pre-anesthesia room, at the time of initiating surgery, and every 15 min intra-operatively. We also recorded duration of the surgical procedure and length of stay in the Post-Anesthesia Care Unit (PACU). Pw15 was performed in 34 patients, pw30 in 29 patients, and pw45 in 21 patients. Fifty-six patients did not receive pw and 96% of them developed hypothermia at the end of the surgical procedure, compared to 73% of patients in pw15 (p = 0.002), 75% in pw30 (p = 0.006) and 90% in pw45 (p = 0.3). Length of stay in the PACU was markedly shorter in pw15 (131 ± 69 min) and pw30 (123 ± 60 min) than in the non-pw group (197 ± 105 min) (p = 0.015 and p = 0.011, respectively). This difference was not significant in pw45 (129 ± 56 min) compared to non-pw patients. In conclusion, prewarming for 15 or 30 min before TUR under spinal anesthesia prevents development of hypothermia at the end of the surgical procedure.

Evaluation of Warming Effectiveness on Physiological Indices of Patients Undergoing Laparoscopic Cholecystectomy Surgery: A Randomized Controlled Clinical Trial

PURPOSE

The present study aimed to evaluate the impact of warming on physiological indices of patients undergoing laparoscopic cholecystectomy.

DESIGN

The study was a three-group randomized controlled clinical trial.

METHODS

In the present study, 96 patients were assigned to three groups: forced-air warming system group; warmed intravenous fluid group; and control group. The intervention was performed immediately after the anesthesia induction. Physiological indices (core body temperature, blood pressure, and heart rate) were evaluated at 15-minute intervals, and postoperative shivering was also recorded.

FINDINGS

The mean systolic blood pressure and the mean heart rate were significantly different in each warming group before, during, and after surgery, but the three groups had no significant differences in terms of physiological indices at any time (P > .05). Postoperative shivering was not seen in any group.

CONCLUSIONS

Both interventions had similar effects on physiological indices. Therefore, the recommendation is to use the warming method according to patient's other conditions.

A prospective comparative study between prewarming and cowarming to prevent intraoperative hypothermia

Background and Aims:

Inadvertent perioperative hypothermia defined as the perioperative core temperature of <36°C is a common problem in day-to-day anesthesia practice. It is not clear from the literature whether prewarming, that is, initiation of convective warming of the patient at a time point prior to induction of anesthesia is superior or comparable to cowarming, that is, initiation of convective warming simultaneously with induction of anesthesia. We conducted this study to find whether cowarming is as good as prewarming in preventing the occurrence of intraoperative hypothermia.

Material and Methods:

Sixty-two adult patients undergoing major abdominal surgery under general anesthesia were randomized to receive either prewarming for 60 min at 40° C or cowarming using the Level 1® Equator ® body warmer. All patients who were prewarmed also received cowarming during induction of anesthesia. In both the groups, convective warming was continued during intraoperative period. Incidence of intraoperative hypothermia, core, and peripheral body temperatures were compared between the two groups.

Results:

Among 27 patients in each group who completed the study core temperature decreased to <35° C toward the end of surgery in 17 patients in group prewarming [mean (SD) 34.59 (1.17° C)] and 18 patients in group cowarming [mean (SD) 34.31 (1.34° C)]. The incidence of intraoperative hypothermia and the core temperature at the end of surgery were comparable (P = 0.42).

Conclusion:

Cowarming is as effective as prewarming to prevent intraoperative hypothermia.

The Effect of Forced-Air Warmer, Ondansetron or their Combination on Shivering in Pregnant Women Coming for Elective Cesarean Section under Spinal Anesthesia: A Prospective, Randomized Controlled Comparative Study

Context:

Perioperative shivering can occur in up to 85% of patients undergoing cesarean section under spinal anesthesia. It has many detrimental effects and disrupts early mother-child bonding. Therefore, it should ideally be prevented by either pharmacologic or nonpharmacological means.

Aims:

The primary aim of this study was to evaluate the efficacy of intraoperative forced-air warming, ondansetron or their combination in preventing perioperative shivering in patients undergoing elective cesarean section under spinal anesthesia.

Settings and Design:

A prospective randomized controlled comparative study done at the tertiary care center.

Subjects and Methods:

A total of 120 patients undergoing elective cesarean section under spinal anesthesia were randomly assigned to three groups. Group O received ondansetron 4 mg intravenously (i.v.) after giving block with no forced air warming. Group W received forced-air warming intraoperatively. Group C received ondansetron 4 mg i.v. after giving block plus intraoperative forced-air warming. Core temperature (tympanic membrane) and the arm skin temperature were measured and shivering was graded simultaneously.

Statistical Analysis Used:

Parametric data were analyzed using one-way ANOVA and Student's paired t-test where ever appropriate. Nonparametric data were analyzed using the Kruskal–Wallis and the Chi-square test. Values of P < 0.05 were considered statistically significant.

Results:

Shivering incidence was higher in Group O and Group W being 17.5% and 20%, respectively, and least in Group C being 5%. The incidence of Grade ≥3 shivering requiring rescue drug was lower in Group C (2.5%) compared to that of the Groups W (5%) and O (10%) but was not statistically significant (P = 0.21).

Conclusions:

Combined use of ondansetron and forced- air warmer was more effective in reducing the incidence of shivering in pregnant women during elective cesarean section than when used individually.

The effects of crystalloid warming on maternal body temperature and fetal outcomes: a randomized controlled trial

Background and objectives

Hypothermia occurs in about 60% of patients under anesthesia and is generally not managed properly during short lasting surgical procedures. Hypothermia is associated with adverse clinical outcomes. The current study is designed to assess the effects of crystalloid warming on maternal and fetal outcomes in patients undergoing elective cesarean section with spinal anesthesia.

Methods

In this prospective randomized controlled trial, sixty parturients scheduled for elective cesarean section with spinal anesthesia were randomly allocated to receive crystalloid at room temperature or warmed at 37 °C. Spinal anesthesia was performed at L3–L4 interspace with 10 mg of hyperbaric bupivacaine without adding opioids. Core temperature, shivering, and hemodynamic parameters were measured every minute until 10th minute and 5-min intervals until the end of operation. The primary outcome was maternal core temperature at the end of cesarean section.

Results

There was no difference for baseline tympanic temperature measurements but the difference was significant at the end of the operation (p = 0.004). Core temperature was 36.8 ± 0.5 °C at baseline and decreased to 36.3 ± 0.5 °C for isothermic warmed crystalloid group and baseline tympanic core temperature was 36.9 ± 0.4 °C and decreased to 35.8 ± 0.7 °C for room temperature group at the end of the operation. Shivering was observed in 43.3% in the control group. Hemodynamic parameter changes and demographic data were not significant between groups.

Conclusions

Isothermic warming crystalloid prevents the decrease in core temperature during cesarean section with spinal anesthesia in full-term parturients. Fetal Apgar scores at first and fifth minute are higher with isothermic warming.

Clinical practice guideline. Unintentional perioperative hypothermia

The importance of the safety of our patients in the surgical theatre, has driven many projects. The majority of them aimed at better control and clinical performance; mainly of the variables that intervene or modulate the results of surgical procedures, and have a direct relationship with them. The Spanish Society of Anesthesiology, Critical Care and Therapeutic Pain (SEDAR), maintains a constant concern for a variable that clearly determines the outcomes of our clinical processes, "unintentional hypothermia" that develops in all patients undergoing an anesthetic or surgical procedure. SEDAR has promoted, in collaboration with other scientific Societies and patient Associations, the elaboration of this clinical practice guideline, which aims to answer clinical questions not yet resolved and for which, up to now, there are no documents based in the best scientific evidence available. With GRADE methodology and technical assistance from the Ibero-American Cochrane Collaboration office, this clinical practice guideline presents three recommendations (weak in favor) for active heating methods for the prevention of hypothermia (skin, fluid or gas); three for the prioritization of strategies for the prevention of hypothermia (too weak in favor and one strongly in favor); two of preheating strategies prior to anesthetic induction (both weak in favor); and two for research.

[The effects of crystalloid warming on maternal body temperature and fetal outcomes: a randomized controlled trial]

BACKGROUND AND OBJECTIVES

Hypothermia occurs in about 60% of patients under anesthesia and is generally not managed properly during short lasting surgical procedures. Hypothermia is associated with adverse clinical outcomes. The current study is designed to assess the effects of crystalloid warming on maternal and fetal outcomes in patients undergoing elective cesarean section with spinal anesthesia.

METHODS

In this prospective randomized controlled trial, sixty parturients scheduled for elective cesarean section with spinal anesthesia were randomly allocated to receive crystalloid at room temperature or warmed at 37°C. Spinal anesthesia was performed at L3-L4 interspace with 10mg of hyperbaric bupivacaine without adding opioids. Core temperature, shivering, and hemodynamic parameters were measured every minute until 10th minute and 5-min intervals until the end of operation. The primary outcome was maternal core temperature at the end of cesarean section.

RESULTS

There was no difference for baseline tympanic temperature measurements but the difference was significant at the end of the operation (p=0.004). Core temperature was 36.8±0.5°C at baseline and decreased to 36.3±0.5°C for isothermic warmed crystalloid group and baseline tympanic core temperature was 36.9±0.4°C and decreased to 35.8±0.7°C for room temperature group at the end of the operation. Shivering was observed in 43.3% in the control group. Hemodynamic parameter changes and demographic data were not significant between groups.

CONCLUSIONS

Isothermic warming crystalloid prevents the decrease in core temperature during cesarean section with spinal anesthesia in full-term parturients. Fetal Apgar scores at first and fifth minute are higher with isothermic warming.

Postanaesthetic shivering - from pathophysiology to prevention

Postoperative shivering is a common complication of anaesthesia. Shivering is believed to increase oxygen consumption, increase the risk of hypoxemia, induce lactic acidosis, and catecholamine release. Therefore, it might increase the postoperative complications especially in high-risk patients. Moreover, shivering is one of the leading causes of discomfort for postsurgical patients. Shivering is usually triggered by hypothermia. However, it occurs even in normothermic patients during the perioperative period. The aetiology of shivering has been understood insufficiently. Another potential mechanism is pain and acute opioid withdrawal (especially with the use of short-acting narcotics). Besides that shivering is poorly understood, the gold standard for the treatment and prevention has not been defined yet. Perioperative hypothermia prevention is the first method to avoid shivering. Many therapeutic strategies for treating shivering exist and most are empiric. Unfortunately, the overall quality of the antishivering guidelines is low. Two main strategies are available: pharmacological and non-pharmacological antishivering methods. The combination of forced-air warming devices and intravenous meperidine is the most validated method. We also analysed different medications but final conclusion about the optimal antishivering medication is difficult to be drawn due to the lack of high-quality evidence. Nevertheless, control of PS is possible and clinically effective with simple pharmacological interventions combined with non pharmacological methods. However, to be consistent with the most up-to-date, evidence-based practice, future antishivering treatment protocols should optimize methodological rigor and transparency.

Preoperative Warming Versus no Preoperative Warming for Maintenance of Normothermia in Women Receiving Intrathecal Morphine for Cesarean Delivery: A Single-Blinded, Randomized Controlled Trial

BACKGROUND

Rates of hypothermia for women undergoing spinal anesthesia for cesarean delivery are high and prevention is desirable. This trial compared the effectiveness of preoperative warming versus usual care among women receiving intrathecal morphine, which is thought to exacerbate perioperative heat loss.

METHODS

A prospective, single-blinded, randomized controlled trial compared 20 minutes of forced air warming (plus intravenous fluid warming) versus no active preoperative warming (plus intravenous fluid warming) in 50 healthy American Society of Anesthesiologists graded II women receiving intrathecal morphine as part of spinal anesthesia for elective cesarean delivery. The primary outcome of maternal temperature change was assessed via aural canal and bladder temperature measurements at regular intervals. Secondary outcomes included maternal thermal comfort, shivering, mean arterial pressure, agreement between aural temperature, and neonatal outcomes (axillary temperature at birth, Apgar scores, breastfeeding, and skin-to-skin contact). The intention-to-treat population was analyzed with descriptive statistics, general linear model analysis, linear mixed-model analysis, χ test of independence, Mann-Whitney, and Bland-Altman analysis. Full ethical approval was obtained, and the study was registered on the Australia and New Zealand Clinical Trials Registry (Trial No: 367160, registered at http://www.ANZCTR.org.au/).

RESULTS

Intention-to-treat analysis (n = 50) revealed no significant difference in aural temperature change from baseline to the end of the procedure between groups: F (1, 47) = 1.2, P = .28. There were no other statistically significant differences between groups in any of the secondary outcomes.

CONCLUSIONS

A short period of preoperative warming is not effective in preventing intraoperative temperature decline for women receiving intrathecal morphine. A combination of preoperative and intraoperative warming modalities may be required for this population.

A novel thermal compression device for perioperative warming: a randomized trial for feasibility and efficacy

Background

Inadvertent perioperative hypothermia (IPH) leads to surgical complications and increases length of stay. IPH rates are high with the current standard of care, forced air warming (FAW). Our hypothesis is that a prototype thermal compression device that heats the popliteal fossa and soles of the feet, with lower leg compression, increases perioperative temperatures and reduces IPH compared to the current standard of care.

Methods

Thirty six female breast surgery patients, at a tertiary academic hospital, were randomized to the device or intraoperative FAW (stage I) with a further 18 patients randomized to the device with a single heating area only (stage II, popliteal fossa or sole of the feet). Stage I: 37 patients recruited (final 36). Stage II: 18 patients recruited (final 18). Inclusion criteria: general anesthesia with esophageal monitoring for over 30 min, legs available and able to fit the device and no contraindications to leg heating or compression. The intervention was: Stage I: Investigational prototype thermal compression device (full device group) or intraoperative FAW. Stage II: Device with only a single heating location. Primary outcomes were perioperative temperatures and incidence of IPH. Secondary outcomes were local skin temperature, general and thermal comfort scores and presence of perioperative complications, including blood loss.

Results

Mean temperatures in the full device group were significantly higher than the FAW group in the pre-operative (36.7 vs 36.4 °C, p < 0.001), early intraoperative (36.3 vs 35.9 °C, p < 0.001), intraoperative (36.6 vs 36.2 °C, p < 0.001) and postoperative periods (36.8 vs 36.5 °C, p < 0.001). The incidence of IPH in the device group was also significantly lower (16.7% vs 72.0%, p = 0.001). Thermal comfort scores were significantly higher in the full device group and hypothermia associated wound complications were higher in the FAW group.

Conclusions

The thermal compression device is feasible and has efficacy over the FAW. Further studies are recommended to investigate clinically significant outcomes.

Trial registration

clinicaltrials.gov (NCT02155400)

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0395-2) contains supplementary material, which is available to authorized users.

Predictive factors of maternal hypothermia during Cesarean delivery: a prospective cohort study

PURPOSE

Although perioperative hypothermia may increase maternal morbidity, active warming is infrequently performed to maintain normothermia during Cesarean delivery (CD). The aim of this prospective observational study was to determine the factors associated with maternal hypothermia in this setting.

METHODS

Women scheduled for elective or emergency CD were consecutively included in this study from November 2014 to October 2015. Maternal temperature was measured using an infrared tympanic thermometer on the patient's arrival in the operating room, at skin incision, and at the end of skin suture. Maternal hypothermia was defined by tympanic temperature < 36°C at the end of skin suture. Univariate analysis was performed, followed by multivariate logistic regression analysis, in order to determine the factors associated with maternal hypothermia at the end of the surgery.

RESULTS

Three hundred fifty-nine women were included and analyzed during this study. The incidence of hypothermia was 23% (95% confidence interval, 18 to 27) among the total population included. According to multivariate analysis, obesity, oxytocin augmentation of labour, and use of active forced-air warming were associated with a decreased risk of maternal hypothermia, while maternal temperature < 37.1°C on arrival in the operating room, maternal temperature < 36.6°C at skin incision, and an infused volume of fluids > 650 mL were significantly associated with maternal hypothermia. Both goodness of fit and predictive value of multivariate analysis were high.

CONCLUSION

Several predictive factors for maternal hypothermia during CD were identified. These factors should be taken into account to help prevent maternal hypothermia during CD.

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

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?

DESIGN

Systematic review and meta-analysis.

SETTING

Perioperative care areas.

PATIENTS

Adults undergoing surgery with neuraxial anesthesia.

INTERVENTION

Perioperative active warming (AW) or passive warming (PW).

MEASUREMENTS

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.

MAIN 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.

Active body surface warming systems for preventing complications caused by inadvertent perioperative hypothermia in adults

BACKGROUND

Inadvertent perioperative hypothermia is a phenomenon that can occur as a result of the suppression of the central mechanisms of temperature regulation due to anaesthesia, and of prolonged exposure of large surfaces of skin to cold temperatures in operating rooms. Inadvertent perioperative hypothermia has been associated with clinical complications such as surgical site infection and wound-healing delay, increased bleeding or cardiovascular events. One of the most frequently used techniques to prevent inadvertent perioperative hypothermia is active body surface warming systems (ABSW), which generate heat mechanically (heating of air, water or gels) that is transferred to the patient via skin contact.

OBJECTIVES

To assess the effectiveness of pre- or intraoperative active body surface warming systems (ABSW), or both, to prevent perioperative complications from unintended hypothermia during surgery in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 9, 2015); MEDLINE (PubMed) (1964 to October 2015), EMBASE (Ovid) (1980 to October 2015), and CINAHL (Ovid) (1982 to October 2015).

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared an ABSW system aimed at maintaining normothermia perioperatively against a control or against any other ABSW system. Eligible studies also had to include relevant clinical outcomes other than measuring temperature alone.

DATA COLLECTION AND ANALYSIS

Several authors, by pairs, screened references and determined eligibility, extracted data, and assessed risks of bias. We resolved disagreements by discussion and consensus, with the collaboration of a third author.

MAIN RESULTS

We included 67 trials with 5438 participants that comprised 79 comparisons. Forty-five RCTs compared ABSW versus control, whereas 18 compared two different types of ABSW, and 10 compared two different techniques to administer the same type of ABSW. Forced-air warming (FAW) was by far the most studied intervention.Trials varied widely regarding whether the interventions were applied alone or in combination with other active (based on a different mechanism of heat transfer) and/or passive methods of maintaining normothermia. The type of participants and surgical interventions, as well as anaesthesia management, co-interventions and the timing of outcome measurement, also varied widely. The risk of bias of included studies was largely unclear due to limitations in the reports. Most studies were open-label, due to the nature of the intervention and the fact that temperature was usually the principal outcome. Nevertheless, given that outcome measurement could have been conducted in a blinded manner, we rated the risk of detection and performance bias as high.The comparison of ABSW versus control showed a reduction in the rate of surgical site infection (risk ratio (RR) 0.36, 95% confidence interval (CI) 0.20 to 0.66; 3 RCTs, 589 participants, low-quality evidence). Only one study at low risk of bias observed a beneficial effect with forced-air warming on major cardiovascular complications (RR 0.22, 95% CI 0.05 to 1.00; 1 RCT with 12 events, 300 participants, low-quality evidence) in people at high cardiovascular risk. We found no beneficial effect for mortality. ABSW also reduced blood loss during surgery but the magnitude of this effect seems to be irrelevant (MD -46.17 mL, 95% CI -82.74 to -9.59; I² = 78%; 20 studies, 1372 participants). The same conclusion applies to total fluids infused during surgery (MD -144.49 mL, 95% CI -221.57 to -67.40; I² = 73%; 24 studies, 1491 participants). These effects did not translate into a significant reduction in the number of participants being transfused or the average amount of blood transfused. ABSW was associated with a reduction in shivering (RR 0.39, 95% CI 0.28 to 0.54; 29 studies, 1922 participants) and in thermal comfort (standardized mean difference (SMD) 0.76, 95% CI 0.29 to 1.24; I² = 77%, 4 trials, 364 participants).For the comparison between different types of ABSW system or modes of administration of a particular type of ABSW, we found no evidence for the superiority of any system in terms of clinical outcomes, except for extending systemic warming to the preoperative period in participants undergoing major abdominal surgery (one study at low risk of bias).There were limited data on adverse effects (the most relevant being thermal burns). While some trials included a narrative report mentioning that no adverse effects were observed, the majority made no reference to it. Nothing so far suggests that ABSW involves a significant risk to patients.

AUTHORS' CONCLUSIONS

Forced-air warming seems to have a beneficial effect in terms of a lower rate of surgical site infection and complications, at least in those undergoing abdominal surgery, compared to not applying any active warming system. It also has a beneficial effect on major cardiovascular complications in people with substantial cardiovascular disease, although the evidence is limited to one study. It also improves patient's comfort, although we found high heterogeneity among trials. While the effect on blood loss is statistically significant, this difference does not translate to a significant reduction in transfusions. Again, we noted high heterogeneity among trials for this outcome. The clinical relevance of blood loss reduction is therefore questionable. The evidence for other types of ABSW is scant, although there is some evidence of a beneficial effect in the same direction on chills/shivering with electric or resistive-based heating systems. Some evidence suggests that extending systemic warming to the preoperative period could be more beneficial than limiting it only to during surgery. Nothing suggests that ABSW systems pose a significant risk to patients.The difficulty in observing a clinically-relevant beneficial effect with ABSW in outcomes other than temperature may be explained by the fact that many studies applied concomitant procedures that are routinely in place as co-interventions to prevent hypothermia, whether passive or active warming systems based in other physiological mechanisms (e.g. irrigation fluid or gas warming), as well as a stricter control of temperature in the context of the study compared with usual practice. These may have had a beneficial effect on the participants in the control group, leading to an underestimation of the net benefit of ABSW.

The effects of warmed intravenous fluids, combined warming (warmed intravenous fluids with humid-warm oxygen), and pethidine on the severity of shivering in general anesthesia patients in the recovery room

Background:

Shivering is a common complication of general and epidural anesthesia. Warming methods and many drugs are used for control of shivering in the recovery room. The present study is a randomized clinical trial aimed to investigate the effects of two interventions in comparison with pethidine which is the routine treatment on shivering in patients undergoing abdominal surgery with general anesthesia.

Materials and Methods:

Eighty-seven patients undergoing abdominal surgery by general anesthesia were randomly assigned to three groups (two intervention groups in comparison with pethidine as routine). Patients in warmed intravenous fluids group received pre-warmed Ringer serum (38°C), patients in combined warming group received pre-warmed Ringer serum (38°C) accompanied by humid-warm oxygen, and patients in pethidine group received intravenous pethidine routinely. The elapsed time of shivering and some hemodynamic parameters of the participants were assessed for 20 min postoperatively in the recovery room. Then the collected data were analyzed by software SPSS (v. 16) with the significance level being P < 0.05.

Results:

The mean of elapsed time in the warmed intravenous serum group, the combined warming group, and the pethidine group were 7 (1.5) min, 6 (1.5) min, and 2.8 (0.7) min, respectively, which was statistically significant (P < 0.05). The body temperatures in both combined warming and pethidine groups were increased significantly (P < 0.05).

Conclusions:

Combined warming can be effective in controlling postoperative shivering and body temperature increase.

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.

Warming of intravenous and irrigation fluids for preventing inadvertent perioperative hypothermia

BACKGROUND

Inadvertent perioperative hypothermia (a drop in core temperature to below 36°C) occurs because of interference with normal temperature regulation by anaesthetic drugs, exposure of skin for prolonged periods and receipt of large volumes of intravenous and irrigation fluids. If the temperature of these fluids is below core body temperature, they can cause significant heat loss. Warming intravenous and irrigation fluids to core body temperature or above might prevent some of this heat loss and subsequent hypothermia.

OBJECTIVES

To estimate the effectiveness of preoperative or intraoperative warming, or both, of intravenous and irrigation fluids in preventing perioperative hypothermia and its complications during surgery in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 2), MEDLINE Ovid SP (1956 to 4 February 2014), EMBASE Ovid SP (1982 to 4 February 2014), the Institute for Scientific Information (ISI) Web of Science (1950 to 4 February 2014), Cumulative Index to Nursing and Allied Health Literature (CINAHL) EBSCOhost (1980 to 4 February 2014) and reference lists of identified articles. We also searched the Current Controlled Trials website and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomized controlled trials or quasi-randomized controlled trials comparing fluid warming methods versus standard care or versus other warming methods used to maintain normothermia.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from eligible trials and settled disputes with a third review author. We contacted study authors to ask for additional details when needed. We collected data on adverse events only if they were reported in the trials.

MAIN RESULTS

We included in this review 24 studies with a total of 1250 participants. The trials included various numbers and types of participants. Investigators used a range of methods to warm fluids to temperatures between 37°C and 41°C. We found that evidence was of moderate quality because descriptions of trial design were often unclear, resulting in high or unclear risk of bias due to inappropriate or unclear randomization and blinding procedures. These factors may have influenced results in some way. Our protocol specified the risk of hypothermia as the primary outcome; as no trials reported this, we decided to include data related to mean core temperature. The only secondary outcome reported in the trials that provided useable data was shivering. Evidence was unclear regarding the effects of fluid warming on bleeding. No data were reported on our other specified outcomes of cardiovascular complications, infection, pressure ulcers, bleeding, mortality, length of stay, unplanned intensive care admission and adverse events.Researchers found that warmed intravenous fluids kept the core temperature of study participants about half a degree warmer than that of participants given room temperature intravenous fluids at 30, 60, 90 and 120 minutes, and at the end of surgery. Warmed intravenous fluids also further reduced the risk of shivering compared with room temperature intravenous fluidsInvestigators reported no statistically significant differences in core body temperature or shivering between individuals given warmed and room temperature irrigation fluids.

AUTHORS' CONCLUSIONS

Warm intravenous fluids appear to keep patients warmer during surgery than room temperature fluids. It is unclear whether the actual differences in temperature are clinically meaningful, or if other benefits or harms are associated with the use of warmed fluids. It is also unclear if using fluid warming in addition to other warming methods confers any benefit, as a ceiling effect is likely when multiple methods of warming are used.

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

BACKGROUND

Women undergoing cesarean section are vulnerable to adverse effects associated with inadvertent perioperative hypothermia, but there has been a lack of synthesized evidence for temperature management in this population. This systematic review aimed to synthesize the best available evidence in relation to preventing hypothermia in mothers undergoing cesarean section surgery.

METHODS

Randomized controlled trials meeting the inclusion criteria (adult patients of any ethnic background, with or without comorbidities, undergoing any mode of anesthesia for any type of cesarean section) were eligible for consideration. Active or passive warming interventions versus usual care or placebo, aiming to limit or manage core heat loss in women undergoing cesarean section were considered. The primary outcome was maternal core temperature. A comprehensive search with no language restrictions was undertaken of multiple databases from their inception until May 2012. Two independent reviewers using the standardized critical appraisal instrument for randomized controlled trials from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instruments (JBI-MASTARI) assessed retrieved papers for methodological quality and conducted data collection. Where possible, results were combined in a fixed effects meta-analysis using the Cochrane Collaboration Review Manager software. Due to heterogeneity for one outcome, random effects meta-analysis was also used.

RESULTS

A combined total of 719 participants from 12 studies were included. Intravenous fluid warming was found to be effective at maintaining maternal temperature and preventing shivering. Warming devices, including forced air warming and under-body carbon polymer mattresses, were effective at preventing hypothermia. However, effectiveness increased if the devices were applied preoperatively. Preoperative warming devices reduced shivering and improved neonatal temperatures at birth. Intravenous fluid warming did not improve neonatal temperature, and the effectiveness of warming interventions on umbilical pH remains unclear.

LINKING EVIDENCE TO ACTION

Intravenous fluid warming by any method improves maternal temperature and reduces shivering during and after cesarean section, as does preoperative body warming. Preoperative warming strategies should be utilized where possible. Preoperative or intraoperative warmed IV fluids should be standard practice. Warming strategies are less effective when intrathecal opioids are administered. Further research is needed to investigate interventions in emergency cesarean section surgery. Larger scale studies using standardized, clinically meaningful temperature measurement time points are required.

[Prewarming. Yesterday's luxury, today's minimum requirement]

Prewarming is a useful and effective measure to reduce perioperative hypothermia. Due to §23(3) of the German Infektionsschutzgesetz (Gesetz zur Verhütung und Bekämpfung von Infektionskrankheiten beim Menschen, Infection Act, act on protection and prevention of infectious diseases in man) and the recommendations of the Hospital Hygiene and Infection Prevention Committee of the Robert Koch Institute, implementation of prewarming is clearly recommended. There are several technically satisfactory and practicable devices available allowing prewarming on the normal hospital ward, in the preoperative holding area or in the induction room of the operating theater (OR) The implementation of prewarming requires additional equipment and training of staff. Using a locally adapted concept for the implementation of prewarming does not lead to inefficiency in the perioperative process. In contrast, the implementation can help to achieve stable arrival times for patients in the OR.

The effect of pre-warmed intravenous fluids on prevention of intraoperative hypothermia in cesarean section

BACKGROUND

Hypothermia is one of the problems occurring during surgery, which can happen due to thermoregulation mechanism disorders and intake of low temperature IV fluids, and may cause increase in blood pressure, heart rate, intracranial pressure, oxygen consumption, pain, and discomfort to the patient. The rate of cesarean section in our country is three times more than the global standard. As one of the responsibilities of the nurse is patient's advocacy, s/he should support them. This study aimed to investigate the effect of pre-warmed intravenous fluids on prevention of hypothermia during general anesthesia in cesarean section.

MATERIALS AND METHODS

Sixty-two women undergoing elective cesarean section by general anesthesia were randomly allocated in two groups of intervention and control. Women in the intervention group received pre-warmed serum (37°C) while those in the control group received serum at room temperature (25.5°C). The core body temperature and some hemodynamic parameters of the participants were assessed during the operation.

RESULTS

The mean of pulse rate, systolic blood pressure, diastolic blood pressure, and arterial O2 saturation in the two groups were not statistically significant (P > 0.05). But the mean of mothers' core body temperature at the end of anesthesia in the intervention and control groups were 36 ± 0.5°C and 35.34 ± 0.6°C, respectively (P < 0.05).

CONCLUSION

Infusion of pre-warmed serum (37°C) would prevent intraoperative hypothermia and improve the nursing care for women who undergo cesarean section by general anesthesia.