Active perioperative patient warming using a self-warming blanket (BARRIER EasyWarm) is superior to passive thermal insulation: a multinational, multicenter, randomized trial

Core temperature following pre-hospital induction of anaesthesia in trauma patients

INTRODUCTION

Hypothermia is a well-recognised finding in trauma patients, which can occur even in warmer climates. It is an independent predictor of increased morbidity and mortality. It is associated with pre-hospital intubation, although the reasons for this are likely to be multifactorial. Core temperature drop after induction of anaesthesia is a well-known phenomenon in the context of elective surgery, and the mechanisms of this are well established.

METHODS

We conducted a prospective observational study to examine the behaviour of core temperature in patients undergoing pre-hospital anaesthesia for traumatic injuries.

RESULTS

Between 2017 and 2021 data were collected on 48 patients. The data from 40 of these were included in the final analysis.

DISCUSSION

Our data do not show a decrease in the core temperatures of patients who receive pre-hospital anaesthesia, unlike patients who are anaesthetised without pre-warming, in operating theatres. The lack of a change could relate to patient, anaesthetic or environmental factors.

Effect of Prewarming on Postoperative Hypothermia, Vital Signs, and Thermal Comfort: A Randomized Controlled Trial

This study aimed to determine the effects of preoperative active and passive warming on postoperative hypothermia, vital signs, and perception of thermal comfort in patients scheduled to undergo elective open abdominal surgery. This was a randomized controlled study. The study sample comprised 90 patients (30 in the active warming group, 30 in the passive warming group, and 30 in the control group) who agreed to participate and met the research criteria. According to the comparison of patients' vital signs, a statistically significant difference was observed in terms of patients' preoperative body temperature values (χ2 = 56.959; p = 0.000). A comparison of the patients' postoperative thermal comfort perception scores yielded a statistically significant difference (χ2 = 39.693; p = 0.000). Postoperative comfort scores in the active warming group were significantly higher than those in the passive warming and control groups. In conclusion, warming methods are effective in preventing undesirable postoperative hypothermia. The time to reach normothermia after surgery was shorter, vital signs were at a desirable level, and thermal comfort perceptions were higher in patients who were prewarmed. ClinicalTrials.gov (Identifier: NCT04997694).

The Effects of Actively Warming the Patient on Maternal and Infant Well-Being in a Cesarean Section Operation

PURPOSE

Intraoperative warming is recommended for surgical patients under anesthesia, but there are insufficient studies on this topic in cesarean delivery patients under spinal anesthesia. The purpose of this study was to determine the effects of active warming on the mother and newborn during elective cesarean section.

DESIGN

This research was carried out in an experimental design with a pretest-posttest randomized intervention and control group.

METHODS

The research was conducted with 34 women (17 intervention and 17 control), who gave birth by cesarean section. The study examined outcomes for both mother and newborn. Women in the intervention group were heated by both active (warmed with carbon fiber resistive underbody heaters during surgery) and passive heating (preoperative- socks, nonelectrified wool blankets, etc). Only passive heating methods were applied to the women in the control group (preoperative). Neonatal Activity - Pulse - Grimace - Appearence - Respiration (APGAR) score, body temperature, cortisol, and blood glucose levels in the intervention and control groups were evaluated, while body temperature and shivering conditions were evaluated in the mother.

FINDINGS

Body temperature and first minute APGAR score of the infants in the intervention and control groups after cesarean section were 36.88 ± 0.27, 36.52 ± 0.32 (P = .002); 7.00 ± 0.36, 7.47 ± 0.64 (P = .009), respectively. Cortisol and blood glucose levels in the intervention and control groups were 3.55 ± 1.09, 4.51 ± 0.70 (P = .010), 77.94 ± 7.07, 72.47 ± 10.24 (P > .05), respectively. The body temperatures of the women in the intervention and control groups at 15, 30, and 45 minutes were significantly different (P < .05), while they were similar (P > .05) at 60 minutes. Oxygen saturation measured at 30 minutes during the operation was 97.10 ± 1.41 in the intervention group and 95.20 ± 1.78 in the control group (P < .05).

CONCLUSIONS

Active warming before, during, and after cesarean section affected body temperature, pulse, respiration, blood pressure, and oxygen saturation of women, and while it increased the body temperature and APGAR score of newborns, it decreased cortisol level.

Effects of Three Different Heating Devices on Patients Undergoing Surgery: A Network Meta-Analysis

PURPOSE

Perioperative hypothermia is a common anesthesia-related complication that can result in negative outcomes. Intraoperative active heating can positively impact these outcomes. Therefore this study aimed to investigate the effectiveness of three common heating devices for controlling hypothermia, improving thermal comfort, and reducing anesthesia recovery time.

DESIGN

Systematic review and meta-analysis.

METHODS

Seven electronic literature databases were searched from the inception date of the databases to March 18, 2022. RevMan 5.4 and Stata 15.1 were used to perform meta-analyses on the obtained data, and the Cochrane Evaluation Manual was used for quality risk assessment of the included studies.

FINDINGS

A total of 18 studies involving 1,511 patients undergoing surgery using heating devices were included. In this meta-analysis, a ranking method known as the Surface Under the Cumulative Ranking Curve (SUCRA) was used. SUCRA provides a numerical measure of the effectiveness of treatments, with higher values indicating superior efficacy. Findings demonstrated that the concurrent use of three heating devices led to an elevation in core body temperatures (SUCRA = 69.2%) and enhanced delayed recovery (SUCRA = 88.6%) as compared to the application of a single device. Furthermore, for thermal comfort, the employment of heating blankets proved to be the most effective (SUCRA = 87.8%).

CONCLUSIONS

This study showed the core body temperatures and reductions in delayed recovery were greater when three heating devices were used together as compared to use one of them alone. Heating blankets was the most effective option for improving the thermal comfort of patients. Thus, clinicians should opt for appropriate heating equipment according to the type of surgery and the characteristics and needs of patients. The choice of appropriate heating equipment will ensure surgical safety, improve patient comfort, and reduce surgical risks.

Maternal hypothermia during elective caesarean delivery: A prospective observational study

BACKGROUND

Patients undergoing caesarean delivery are at risk of developing unintended perioperative hypothermia, defined as a core temperature <36.0°C. Most previous studies of core temperature in caesarean delivery patients have not been conducted with accurate measurements for the complete perioperative period. Therefore, we conducted a prospective observational study to identify the incidence and duration of pre- and post-operative maternal hypothermia with a high accuracy continuous temperature monitoring system.

METHODS

Women ≥18 years old presenting for elective caesarean delivery under spinal anaesthesia were invited to participate in the study. The primary outcomes were the incidence and duration of perioperative maternal hypothermia (<36.0°C). Maternal core temperatures were measured with the non-invasive zero-heat-flux thermometer (Bair Hugger Temperature Monitoring System, 3M) throughout the perioperative course.

RESULTS

A total of 40 participants were recruited to the study. The incidence of perioperative hypothermia was 32.5%, with a duration of 77 ± 40 min (mean ± standard deviation). The hypothermic patients had similar core temperature as the normothermic patients at baseline preoperatively, but significantly lower temperature at operating room arrival and during the remaining study period. Forty percent of all patients reported thermal discomfort and felt cold on admission to post anaesthesia care unit, whereas 33% had shivering. Neither thermal discomfort nor shivering were associated with hypothermia.

CONCLUSION

In the present study almost a third of the women undergoing elective caesarean delivery developed perioperative hypothermia with a core temperature <36.0°C. The mean duration of maternal hypothermia was 77 min, lasting well into the postoperative period for many patients. These data should remind healthcare professionals of the importance of measuring core temperature in all phases of the perioperative setting and to consider optimal warming measures to avoid and treat hypothermia.

Self-warming blanket versus forced-air warming blanket during total knee arthroplasty under spinal anaesthesia: A randomised non-inferiority trial

BACKGROUND

Arthroplasty patients are at high risk of hypothermia. Pre-warming with forced air has been shown to reduce the incidence of intraoperative hypothermia. There is, however, a lack of evidence that pre-warming with a self-warming (SW) blanket can reduce the incidence of perioperative hypothermia. This study aims to evaluate the effectiveness of an SW blanket and a forced-air warming (FAW) blanket peri-operatively. We hypothesised that the SW blanket is inferior to the FAW blanket.

METHODS

In total, 150 patients scheduled for primary unilateral total knee arthroplasty under spinal anaesthesia were randomised to this prospective study. Patients were pre-warmed with SW blanket (SW group) or upper-body FAW blanket (FAW group) set to 38°C for 30 min before spinal anaesthesia induction. Active warming was continued with the allocated blanket in the operating room. If core temperature fell below 36°C, all patients were warmed using the FAW blanket set to 43°C. Core and skin temperatures were measured continuously. The primary outcome was core temperature on admission to the recovery room.

RESULTS

Both methods increased mean body temperature during pre-warming. However, intraoperative hypothermia occurred in 61% of patients in the SW group and in 49% in the FAW group. The FAW method set to 43°C could rewarm hypothermic patients. Core temperature did not differ between groups on admission to the recovery room, p = .366 (CI: -0.18-0.06).

CONCLUSIONS

Statistically, the SW blanket was non-inferior to the FAW method. Yet, hypothermia was more frequent in the SW group, requiring rescue warming as we strictly held to the NICE guideline.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT03408197.

Perioperative active warming strategies in children: a protocol for a multicentre, prospective, randomized controlled trial

Introduction

Inadvertent perioperative hypothermia (IPH) refers to a core body temperature lower than 36.0 °C, which can contribute to many adverse events. The special physiological characteristics in children further increase the incidence of IPH. Therefore, it is very important to perform effective perioperative warming measures for children. Traditional passive warming measures with additional layers have limited thermal insulation effects. Active warming measures might be the better choice, and most measures have achieved good effects in adults. This study combines a variety of active warming measures to propose perioperative active warming strategies and aims to verify the feasibility and thermal insulation effects of perioperative active warming strategies in children.

Methods

This study is a multicentre, prospective, randomized controlled trial. From August 2022 to July 2024, 400 paediatric patients undergoing elective surgery will be recruited in four centres and randomly divided into the active warming strategies group and control group at a ratio of 1:1. The primary outcome is the perioperative cumulative hypothermia effect value (Σ ΔTi × Δti, i = 1…, n). Multiple complications covering the anaesthesia recovery period and postoperative hospitalization will be considered as secondary outcomes to comprehensively analyse the prognosis.

Trial registration

ClinicalTrials.gov identifier: ChiCTR2200062168. Registered on July 26th, 2022. Registered with the name of "Perioperative Active Warming Strategies in Children: A multicenter, prospective, randomized controlled trial". URL:http://www.chictr.org.cn/showproj.aspx?proj=172778.

A qualitative study of nurse-perceived barriers to body temperature management in postoperative patients

Although evidence-based practices exist for preventing hypothermia in patients during surgery, few studies have focused on this concern in postoperative patients. The aim of this qualitative study was to explore the most challenging issues experienced by surgical ward nurses while managing the body temperature of adult surgical patients. To address this research gap, this study used a qualitative descriptive design to document barriers to body temperature management as reported by a sample of 16 perioperative nurses. The semi-structured, face-to-face interviews were digitally recorded, transcribed verbatim and analysed using inductive content analysis. The main barriers fell into three categories: professional nursing ability limitations, unfavourable working conditions and management of human resources. The eight subcategories were disadvantageous professional views, professional knowledge limitations, low motivation to provide nursing care, non-standard treatment environment, inadequate equipment and care protocols, heavy nursing care loads, inadequate staff training and ineffective staff supervision. These findings highlighted the importance of adequate resources, proper education and evidence-based care protocols in the effective delivery of body temperature management to postoperative patients.

The Effect of Postinduction Blood Glucose on Intraoperative Hypothermia

Background and Objectives: Hypothermia frequently occurs in patients undergoing surgery and is associated with adverse complications. Therefore, this study aimed to investigate the postinduction blood glucose and occurrence of intraoperative hypothermia in patients undergoing laparoscopic surgery. Materials and Methods: This retrospective observational study included 334 patients aged ≥20 years who had undergone elective laparoscopic surgery. The primary outcome of this study was the incidence of intraoperative hypothermia. Stratified analysis revealed differences between patients with and without diabetes. Results: Hypothermia occurred in 200 (59.9%) patients. In multivariate analysis, out-of-range postinduction glucose was independently associated with hypothermia (>150 mg/dL: odds ratio 2.17, 95% confidence interval (1.02, 4.61), p = 0.045; <110 mg/dL: odds ratio 2.02, 95% confidence interval (1.15, 3.55), p = 0.015), whereas preoperative HbA1c >6% was not significantly associated with hypothermia (odds ratio 1.02, 95% confidence interval (0.56, 1.84), p = 0.961). Considering only patients with diabetes, the incidence of hypothermia was lower (p = 0.002), the duration of hypothermia was shorter (p = 0.007), and the minimum temperature was higher (p = 0.006) in those with a postinduction glucose level of 110-150 mg/dL. Conclusions: The postinduction glucose level is independently associated with intraoperative hypothermia. Out-of-range postinduction glucose appeared to have an impact on the development of hypothermia in patients with diabetes, especially those with a postinduction glucose level <110 mg/dL.

Incidence of postoperative hypothermia and shivering and risk factors in patients undergoing malignant tumor surgery: a retrospective study

BACKGROUND

Perioperative hypothermia and shivering are common and can cause adverse outcomes. The aim of this study was to investigate the incidence of postoperative hypothermia and shivering and their risk factors in patients undergoing malignant tumor surgery.

METHODS

This retrospective study collected data from patients with American Society of Anesthesiologists physical status (ASA) I or II who underwent scheduled surgery from November 2020 to March 2021 at Fudan University Shanghai Cancer Center. Each patient's core body temperature was measured at three time points: time point 1 (arrival at the postanesthesia care unit (PACU)), time point 2 (after 30-min care in the PACU), and time point 3 (at discharge from the PACU). At time point 1, if the patient's body temperature was below 36 ℃, we provided an active forced-air warmer. At time point 2, if it was still below 36 ℃, the forced-air warmer was still applied until the patient was discharged from the PACU. If it reached 36 ℃, the forced-air warmer would be switched off. Univariate and multivariate logistic regression combined with stepwise methods and linear regression were used to explore risk factors for postoperative hypothermia and shivering.

RESULTS

The numbers (percentage) of 202 patients who developed postoperative hypothermia at the different time points were 52 (25.7%), 37 (18.3%) and 28 (13.9%). Eight patients (4.0%) experienced shivering. Multivariate logistic regression showed that high weight (OR = 0.923, 95% CI: 0.884 to 0.964, P = 0.0003) and low estimated blood loss (OR = 0.252, 95% CI: 0.115 to 0.550, P = 0.0005) were protective factors against hypothermia, while long surgical duration (OR = 3.339, 95% CI: 1.675 to 6.655, P = 0.0006) was an independent risk factor for hypothermia at time point 1. There was no risk factor associated with the occurrence of shivering (P > 0.05). There was a significant difference between the hypothermia and normothermia groups in the median length of stay in the PACU (59.0 vs. 49.0 min, P = 0.0123).

CONCLUSIONS

Postoperative hypothermia occurred frequently. Weight, estimated blood loss and surgical duration were significantly associated with hypothermia on arrival at the PACU.

Redistributional Hypothermia Prevention by Prewarming with Forced-Air: Exploratory, Open, Randomized, Clinical Trial of Efficacy

Avoiding redistributional hypothermia that decreases core temperature by 0.5-1.5°C within the 1st hour of surgery is difficult. The efficacy of prewarming using a forced-air warming (FAW) device with a lower-body blanket on redistribution hypothermia during epidural procedures have not been investigated. After ethics approval, 113 patients undergoing laparoscopic surgery under general anesthesia combined with epidural anesthesia were enrolled. Intervention (prewarming) group patients who were warmed from operating room entry, including during epidural anesthesia, was compared with the control group that was warmed from just before surgery started. In total, 104 patients (52, control; 52, prewarming) were analyzed. In the prewarming group, compared to the control group, the core temperature 20 minutes after anesthesia induction (36.9 ± 0.4 vs. 37.1 ± 0.4°C, p < 0.02) was significantly higher. The core temperature was higher in the prewarming group than in the control group until 3 hours after the surgery. In the prewarming group, compared to the control group, the core temperature-time integral below baseline till 180 minutes after surgery start (65.1 ± 64.0 vs. 8.1 ± 18.6°C/min, p < 0.0001) or 30 minutes after anesthesia induction (5.3 ± 6.2 vs. 2.0 ± 4.7°C/min, p < 0.0001) were significantly smaller. Postoperative shivering was comparable between the groups. Prewarming during epidural catheter insertion with a FAW device could safely prevent a core temperature decrease induced by redistribution or heat loss without additional preparation, effort, space, or time requirements.

Effect of Forced-Air Warming Blanket on Perioperative Hypothermia in Elderly Patients Undergoing Laparoscopic Radical Resection of Colorectal Cancer

The study aimed to evaluate the effect of forced-air warming blanket combined with conventional thermal insulation measures on inadvertent perioperative hypothermia (IPH) in elderly patients undergoing laparoscopic radical resection of colorectal cancer. A total of 70 elderly patients undergoing laparoscopic radical resection of colorectal cancer with general anesthesia were included, and divided into conventional warming treatment (CT) group or forced-air warming treatment (FT) group. In the FT group, based on the conventional warming strategy, patients received prewarming with the forced-air warming blanket (38°C) for ≥20 minutes before induction of anesthesia, and received this treatment continuously during operation. The core body temperature, recovery time from anesthesia, extubating time, and length of stay in the postanesthesia care unit were recorded. The incidence of IPH and postoperative shivering was observed. The incidence of IPH was significantly lower, and average minimum body temperature during the operation was significantly higher in the FT group than that in the CT group (5.7% vs. 22.8% and 36.23°C vs. 35.89°C, respectively). The intraoperative body temperature decreased less (0.32°C vs. 0.69°C), the recovery time from anesthesia was faster (12.8 minutes vs. 17.1 minutes), and the incidence of postoperative shivering was less (2.8% vs. 28.6%) in the FT group than the CT group. In elderly patients undergoing laparoscopic radical resection of colorectal cancer, use of forced-air warming blankets combined with conventional warming measures is more effective to maintain normal body temperature during the perioperative period and reduce the incidence of IPH.

Effects of a preoperative forced-air warming system for patients undergoing video-assisted thoracic surgery: A randomized controlled trial

BACKGROUND

The incidence of intraoperative hypothermia is still high despite the proposal of different preventive measures during thoracoscopic surgery. This randomized control study evaluated the effects of 30-minute prewarming combined with a forced-air warming system during surgery to prevent intraoperative hypothermia in patients undergoing video-assisted thoracic surgery under general anesthesia combined with erector spinae nerve block.

METHODS

Ninety-eight patients were randomly and equally allocated to prewarming or warming groups (n = 49 each). The primary outcome was the incidence of intraoperative hypothermia. Secondary outcomes were core temperature, irrigation and infused fluid, estimated blood loss, urine output, type of surgery, intraoperative anesthetic dosage, hemodynamics, recovery time, the incidence of postoperative shivering, thermal comfort, postoperative sufentanil consumption and pain intensity, patient satisfaction, and adverse events.

RESULTS

The incidence of intraoperative hypothermia was significantly lower in the prewarming group than the warming group (12.24% vs 32.65%, P = .015). Core temperature showed the highest decrease 30 minutes after surgery start in both groups; however, the rate was lower in the prewarming than in the warming group (0.31 ± 0.04°C vs 0.42 ± 0.06°C, P < .05). Compared with the warming group, higher core temperatures were recorded for patients in the prewarming group from T1 to T6 (P < .05). Significantly fewer patients with mild hypothermia were in the prewarming group (5 vs 13, P = .037) and recovery time was significantly reduced in the prewarming group (P < .05). Although the incidence of postoperative shivering was lower in the prewarming group, it was not statistically significant (6.12% vs 18.37%, P = .064). Likewise, the shivering severity was similar for both groups. Thermal comfort was significantly increased in the prewarming group, although patient satisfaction was comparable between the 2 groups (P > .05). No adverse events occurred associated with the forced-air warming system. Both groups shared similar baseline demographics, type of surgery, total irrigation fluid, total infused fluid, estimated blood loss, urine output, intraoperative anesthetic dosage, hemodynamics, duration of anesthesia and operation time, postoperative sufentanil consumption, and pain intensity.

CONCLUSION

In patients undergoing video-assisted thoracic surgery, prewarming for 30 minutes before the induction of anesthesia combined with a forced-air warming system may improve perioperative core temperature and the thermal comfort, although the incidence of postoperative shivering and severity did not improve.

Effect of competence health cultivation on the prevention and control of inadvertent perioperative hypothermia

OBJECTIVE To explore the feasibility of health competence cultivation on the prevention and control of Inadvertent Perioperative Hypothermia (IPH). METHODS Patients with expected spinal surgery were divided into group A and group B by the random number method. Group B followed routine IPH management, and health training measures for performance and ability were implemented in Group A. The scores of the health competence questionnaire, the temperature at different times, IPH complications, and hospitalization for the two groups were observed and compared. RESULTS The main evaluation indexes, such as the health competence questionnaire score, temperature fluctuations, and IPH complications, during the perioperative period in group A were significantly better than those in group B (p < 0.05). The indexes of anesthesia, total hospital expenses, and health service satisfaction in group A were also significantly better than those in group B, which shows the advantages of cultivating health capabilities in both doctors and patients. CONCLUSION Through health competence cultivation and feasible health management measures, the medical staff can improve the quality of IPH prevention and management.

Comparison of two forced-air warming devices during foot and ankle surgery: a randomised controlled trial

Inadvertent perioperative hypothermia is a frequent problem associated with surgical patients which can have significant consequences during surgery and in the immediate postoperative period. We compared 35 randomised patients using over vs. under body forced air heating. There were no statistically significant differences between some demographic and surgical parameters such as: age, weight, height, body mass index, length of anaesthesia and operation. Statistically significant differences were found between the patient's admission to the operating room and 30 minutes and the end of the procedure on the under body patients group. This study analyses a uniform population of patients (Foot and Ankle Surgery) previously not studied and supports the use of under body blankets.

Nurse Anesthetists' and Operating Theater Nurses' Experiences with Inadvertent Hypothermia in Clinical Perioperative Nursing Care

PURPOSE

To deepen the understanding of and describe nurse anesthetists' and operating theater nurses' experiences with inadvertent hypothermia in clinical perioperative nursing care.

DESIGN

Qualitative, explorative, and descriptive study that carries an inductive nature.

METHODS

Focus group interviews with 16 nurse anesthetists and operating theater nurses from four hospitals in Norway. Gadamer's hermeneutics has guided the study's interpretation.

FINDINGS

Taking the temperature and measures against inadvertent hypothermia perioperatively are not always systematically implemented. In the data material, three thematic units emerged: routines and habits, the culture of the perioperative unit, and silent suffering.

CONCLUSIONS

Complications caused by inadvertent hypothermia in surgical patients can lead to unnecessary suffering and prolong the hospital stay. The surgical team's cooperation and responsibility are linked to routine nursing interventions. These depend on the nurses' knowledge and experience as well as their clinical and subjective assessment of the patient's physical condition and the surgical techniques used.

Short interruptions between pre-warming and intraoperative warming are associated with low intraoperative hypothermia rates

BACKGROUND

Prevention of inadvertent hypothermia is recommended for procedures >30 minutes because hypothermia increases the risk of myocardial ischemia, intraoperative blood loss, transfusion and wound complications. Therefore, short warming interruptions between pre-warming and intraoperative warming might result in lower hypothermia rates. The aim of this retrospective investigation was to determine whether the incidence of inadvertent intraoperative hypothermia was affected by the warming interruption.

METHODS

The lowest intraoperative body core temperature value and the warming interruption time were taken from anaesthesia records. Body core temperature was recorded continuously, and a patient was classified to be hypothermic if the lowest recorded temperature value was <36°C. Hypothermia rates and the correlation between warming interruption times and intraoperative hypothermia rates were calculated.

RESULTS

Five thousand eighty-four patients were analysed. The intraoperative hypothermia rate was 15.3%. Nineteen patients (0.4%) had a recorded temperature of <35.0°C. An increase in forced-air warming interruption time was significantly associated with an increase in intraoperative hypothermia rates (P < .0001). Patients with interruptions in forced-air warming >20 minutes showed significantly higher hypothermia rates than those with interruptions of ≤20 minutes (P < .0001).

CONCLUSION

Intraoperative hypothermia rates increased significantly with longer forced-air warming interruptions between pre-warming and intraoperative warming. Short warming interruptions can preserve the effect of pre-warming and are associated with low intraoperative hypothermia rates.

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.

The Design and Manufacture of a Multilayer Low-Temperature Protective Composite Fabric Based on Active Heating Materials and Passive Insulating Materials

Based on active heating materials (the phase change microcapsules (microPCMs)) and passive insulating materials (SiO₂ aerogel), a new-type multilayer low temperature protective composite fabric (MPF) was designed and manufactured to meet the demands of protection and operation in a short time under a low-temperature environment. Results showed that the MPF consisted of three layers including the fabric layer, the microPCM function layer, and the SiO₂ aerogel thermal insulation layer. The differential scanning calorimeter (DSC) results demonstrated that the phase transition enthalpy of the composite was 96.2 J/g during the cooling process. The low-temperature resistance and thermal insulation performance at −50 °C were investigated. The results also demonstrated that the low-temperature resistance time of the MPF was 660 s and the power consumption of the MPFs needed to maintain 37 °C for 10 and 20 min were 629 J and 1872 J, respectively. Compared with the microPCM function layer and the thermal insulation layer, which have the same thickness as the MPF, the low-temperature resistance time of the MPF was prolonged for about 2 and 3 min, respectively. The MPF could provide effective protection of the low-temperature work in a short time and could be applied as potential materials in low-temperature protection.

Preventing hypothermia in outpatient plastic surgery by self-warming or forced-air-warming blanket: A randomised controlled trial

BACKGROUND

In our outpatient post anaesthesia unit patients reported that they were feeling cold with or without shivering. Anaesthetic agents cause reduced thermoregulation, initially by redistribution of blood flow from core to periphery, later by negative balance between thermogenesis and heat loss. Even mild peri-operative hypothermia increases the risk of surgical wound infections, bleeding, impaired cardiac function, shivering, and decreases comfort.

OBJECTIVE(S)

We aimed to evaluate which of our current active warming measures, self-warming blanket or forced-air-warming blanket, were most effective in preventing inadvertent intraoperative heat loss. Secondarily, we assessed whether they prevented inadvertent peri-operative hypothermia when defined as core body temperature below 36 °C.

DESIGN

Randomised controlled trial, parallel group design.

SETTING

Aleris Solsiden hospital for outpatient surgery, Trondheim, Norway, from March to June 2016.

PATIENTS

A total of 112 consecutive patients planned for outpatient plastic surgery. Reasons for noninclusion: failing to meet the criteria for outpatient surgery according to the standard of the national society of anaesthesiology.

INTERVENTION(S)

Patients were randomised to active warming by a self-warming blanket or a forced-air-warming blanket. All patients received routine measures to prevent hypothermia with a high temperature in the operation theatres, prewarmed fluids, cotton blankets and surgical draping outside the surgical field.

MAIN OUTCOMES

Temperature, measured pre-operatively, every 10 min during general anaesthesia and postoperatively with a zero-heat-flux temperature sensor.

RESULTS

Core temperature was significantly lower in the self-warming blanket compared with the forced-air-warming blanket group during anaesthesia, P less than 0.0001. Hypothermia (<36 °C) was recorded in 47%, n = 22, patients in the self-warming blanket group and 25%, n = 16, in the forced-air-warming blanket group during the registration period, P = 0.02.

CONCLUSION

An underbody forced-air-warming blanket reduced heat loss to a greater extent than a self-warming blanket. But none of the interventions were sufficient to prevent inadvertent peri-operative hypothermia.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03163563.

Effects of Inadvertent Perioperative Hypothermia on Metabolic and Inflammatory Mediators

Objective

The aim of the present study was to investigate the effects of perioperative undesirable hypothermia on inflammatory (interleukin (IL)-8, IL-10, IL-18, IL-23 and pentraxin (PTX)-3) and metabolic responses (cortisol and insulin) and recovery time.

Methods

A total of 60 patients between the ages of 18 and 65 years who were in the lumbar stabilisation operation were included in the study. In this prospective, randomised controlled study, two groups were constituted as with warmed (Group N) and not warmed (Group C) patients before and during the operation. Diuresis, blood loss, body temperature and side effects were recorded with IL-8, IL-10, IL-18, IL-23, PTX-3, cortisol and insulin levels.

Results

Perioperative diuresis was significantly higher in Group C. Aldrete score was significantly higher in Group N with less shivering and vomiting in the postoperative period. IL-10, PTX-3 and cortisol levels were found to be significantly higher in Group C in the first postoperative hour. PTX-3 and cortisol were found to be significantly higher in Group C after 24 h of the operation. Insulin was significantly higher in Group N. In 72 h, IL-8 in Group N and cortisol level in Group C were significantly higher.

Conclusion

Positive effects of heating the patients in the perioperative period on haemorrhage, diuresis, complications and recovery time were observed in our study. In addition, maintenance of normothermia appeared to modulate the biomarkers that indicate the inflammatory and metabolic responses.

Prevention of inadvertent perioperative hypothermia - Guideline compliance in German hospitals

Patients undergoing elective surgery are at risk for inadvertent postoperative hypothermia, defined as a core body temperature below 36°C. This study was conducted to investigate the acceptance of the recommendations of the German S3 Guideline, in particular with respect to the concept of pre-warming and sublingual temperature measurement. The main focus was to gather data concerning the postoperative core temperature and the frequency of perioperative hypothermia in patients receiving a pre-warming regime and those without. The study team investigated the local concept and measures employed to avoid inadvertent perioperative hypothermia with respect to defined outcome parameters following a specific protocol. In summary, the study hospitals vary greatly in their perioperative processes to prevent postoperative hypothermia. However, each hospital has a strategy to prevent hypothermia and was more or less successful in keeping its patients normothermic during the perioperative process. Our data could not demonstrate major differences between hospitals in the implementation strategy to prevent perioperative hypothermia in regard to the hospital size. The results of our study suggest a wide-spread acceptance, as no postoperative hypothermia was detected in a cohort of 431 patients.

Preventing Inadvertent Hypothermia in Patients Undergoing Major Spinal Surgery: A Nonrandomized Controlled Study of Two Different Methods of Preoperative and Intraoperative Warming

PURPOSE

To evaluate if a Full Access Underbody (FAU) blanket used preoperatively and intraoperatively in patients undergoing major spinal surgery prevents hypothermia compared with current practice and to explore patients' experiences of comfort.

DESIGN

A nonrandomized controlled trial.

METHODS

Sixty patients were included, 30 in each group. Temperature was assessed on arrival, after connecting to the bladder catheter, and at the start and end of surgery. In the FAU group, comfort was evaluated at arrival and after 10 minutes of prewarming.

FINDINGS

The incidence of hypothermia at the start of surgery was significantly lower (relative risk [95% confidence interval], 0.28 [0.13 to 0.59]). Before prewarming, 77% felt comfortable, 20% cold, and 3% hot. After prewarming 60% felt comfortable, 37% hot, and 3% very hot.

CONCLUSIONS

Patients using the FAU blanket had a 72% lower incidence of hypothermia at the start of the operation. Attention to thermal comfort during surgery is important.

Comparison of the EasyWarm® self-heating blanket with the Cocoon forced-air warming blanket in preventing intraoperative hypothermia

The importance of preventing hypothermia in the perioperative period cannot be overemphasised. The use of active warming devices is advocated and practised widely. The forced-air warming (FAW) blanket is currently a popular modality. The BARRIER® EasyWarm® (Mölnlycke Healthcare, Belrose, Australia) self-heating blanket, which does not require a power unit, has been proposed as an easy-to-use alternative to the FAW blanket. We conducted a single-centre, randomized controlled trial to compare the efficacy of the EasyWarm® self-heating blanket to the Cocoon blanket (Care Essentials, North Geelong, Australia), a conventional FAW blanket, in preventing intraoperative hypothermia. Forty patients undergoing elective surgery under general anaesthesia lasting >1 h were randomized in a 1:1 ratio. Prewarming was not allowed; 39 patients were analysed (19 EasyWarm® group and 20 Cocoon blanket group). There was no statistically significant difference between the two groups with regard to the mean (±standard deviation) final nasopharyngeal temperature (35.89 ± 0.82 °C versus 35.74 ± 0.77 °C; P = 0.72 in the Cocoon and EasyWarm® blanket groups, respectively). Similarly, the difference between average temperatures at 1, 2 and 3 h was not statistically significant. We found the EasyWarm® blanket to be as effective as the Cocoon FAW blanket in preventing intraoperative hypothermia. Due to its ease of use, the EasyWarm® blanket may have an additional benefit in preoperative warming of patients.

The effects of a forced-air warming system plus electric blanket for elderly patients undergoing transurethral resection of the prostate: A randomized controlled trial

BACKGROUND

Perioperative inadvertent hypothermia in elderly urology patients undergoing transurethral resection of the prostate (TURP) is a well-known serious complication, as it increases the risk of myocardial ischemia, blood loss, and surgical wound infection. We conducted this prospective randomized controlled trial to evaluate the combined effect of a forced-air warming system and electric blanket in elderly TURP patients.

METHODS

Between January 2015 and October 2017, we recruited 443 elderly male patients undergoing elective TURP with subarachnoid blockade (SAB). These were randomly divided into 3 groups: group E (intraoperative warming using electric blankets set to 38°C; n = 128); group F (intraoperative warming using a forced-air warmer set to 38°C; n = 155) and group FE (intraoperative warming using a forced-air warmer plus electric blankets, both set to 38°C; n = 160). The primary outcome was shivering and their grades. Hemodynamic changes, esophageal temperature, recovery time, incidences of adverse effects, and patient and surgeon satisfaction were also recorded.

RESULTS

Baseline characteristics showed no significant differences when compared across the 3 groups (P >.05). Compared with groups E and F, both HR and mean arterial pressure (MAP) in group FE were significantly decreased from T6 to T10 (P <.05). Compared with groups E and F, esophageal temperature in group FE increased significantly from T5 to T10 (P <.05). Compared with group E, esophageal temperature in group F was significantly increased from T5 to T10 (P <.05). Compared with groups F and FE, post-anesthesia care unit (PACU) recovery time was longer in group E, while compared with group F, PACU recovery time was shorter in group FE (P <.05). Compared to patients in groups E and F, those in group FE had a significantly lower incidence of arrhythmia and shivering (P <.05). The number of patients with shivering grades 0 to 3 was higher in group E than in other groups, while the number of patients with shivering grade 2 was significantly higher in group F than in group FE (P <.05). Patient and surgeon satisfaction scores were higher in group FE than in groups E and F (P <.05).

CONCLUSIONS

Use of a forced-air warming system combined with an electric blanket was an effective method with which to retain warmth among elderly TURP patients.

Heated humidified high-flow nasal oxygen prevents intraoperative body temperature decrease in non-intubated thoracoscopy

PURPOSE

In patients receiving non-intubated video-assisted thoracic surgery (NIVATS), transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) has been applied instead of oxygen mask for better oxygenation. However, the THRIVE effects on intraoperative temperature decrease have not been investigated.

METHODS

Pre- and postoperative temperatures, measured by an infrared tympanic ear thermometer, taken before sending patients to the operation room and immediately upon their arrival in the postoperative anesthesia unit, were collected from medical records of patients who received NIVATS either with oxygen mask or THRIVE. Intraoperative temperature decrease, calculated by preoperative temperature minus postoperative temperature, was compared between different groups. Multiple linear regression analysis was performed to determine factors associated with intraoperative temperature decrease.

RESULTS

Records of 256 adult patients with forced-air warming were retrospectively analyzed. 172 patients of them received THRIVE and 84 patients received oxygen mask. Preoperative temperatures were comparable between groups (THRIVE: 36.25 ± 0.46 °C; mask: 36.30 ± 0.39 °C, p = 0.43). Postoperative temperatures were significantly higher in patients using THRIVE than those using oxygen masks (36.05 ± 0.59 vs 35.87 ± 0.62 °C, p = 0.025). Significantly less intraoperative temperature decrease was shown in THRIVE group (THRIVE: 0.20 ± 0.69 °C; mask: 0.43 ± 0.69 °C, p = 0.04). According to the multiple linear regression analysis, significant temperature decrease was associated with the advanced age (β_age = 0.01) but not the anesthetic duration. Using THRIVE was correlated with significantly less body temperature decrease (β_TRIVE = - 0.24).

CONCLUSIONS

THRIVE effectively prevents intraoperative temperature decrease during NIVATS, especially in old patients.

Perioperative hypothermia during colectomy: when do patients get cold?

BACKGROUND

Hypothermia has been associated with an increase in the rate of infectious complications following colectomy. We hypothesized that a substantial fraction of temperature loss in patients undergoing elective colectomy occurs prior to operation.

METHODS

Temperature data were collected from 105 consecutive patients undergoing elective colectomy at a single institution.

RESULTS

The study population consisted of 105 patients; 67(64%) male, median age 59 years (range 17-95 years), median body mass index 27 kg/m² (range 15-48 kg/m²). Median preoperative temperature was 36.7 °C (range 35.2-39.2 °C), dropping to 35.7 °C (range 34.0-37.3 °C) immediately following intubation and then rising to 36.2 °C (range 34.0-38.0 °C) prior to leaving the operating room. The median first postoperative temperature was 36.3 °C (range 34.4-37.7 °C). Temperatures were significantly different from one another (p < 0.05, ANOVA), except for the last operative and first postoperative temperature. A first postoperative temperature of ≥ 36.0 °C (meeting Surgical Care Improvement criteria Inf-10) was achieved in 78 (74%) of patients. A preoperative temperature of ≥ 36.5 °C was associated with a first postoperative temperature of ≥ 36.0 °C, but operative approach (laparoscopic versus open) was not.

CONCLUSIONS

Most temperature loss occurs prior to operation in patients undergoing colectomy. Patients are rewarmed during the operative procedure. The time period prior to operation should be the focus of efforts designed to ensure normothermia.

[Prewarming according to the AWMF S3 guidelines on preventing inadvertant perioperative hypothermia 2014 : Retrospective analysis of 7786 patients]

BACKGROUND

Inadvertent perioperative hypothermia, which is defined as a core body temperature of less than 36.0 °C, can have serious consequences in surgery patients. These include cardiac complications, increased blood loss, wound infections and postoperative shivering; therefore, the scientific evidence that inadvertent perioperative hypothermia should be avoided is undisputed and several national guidelines have been published summarizing the scientific evidence and recommending specific procedures. The German AWMF guidelines were the first to emphasize the importance of prewarming for surgery patients to avoid inadvertant perioperative hypothermia; however, in contrast to intraoperative warming, prewarming is so far not sufficiently implemented in clinical practice in many hospitals. Furthermore, a recent study has questioned the effectiveness of prewarming.

OBJECTIVE

The aim of this retrospective investigation was to evaluate the hypothermia rates that can be achieved when prewarming in the anesthesia induction room is introduced into the clinical practice and performed in addition to intraoperative warming.

MATERIAL AND METHODS

The ethics committee of the Medical Faculty of the Martin Luther University Halle Wittenberg gave approval for data storage and retrospective data analysis from the anesthesia database. According to the existing local standard operating procedure, prewarming with forced air was performed in addition to intraoperative warming in the anesthesia induction room in 3899 patients receiving general anesthesia with a duration of 30 min or longer from January 2015 to December 2016. The results were compared with a control group of 3887 patients from July 2012 to August 2014 who received intraoperative warming but were not subjected to prewarming. Tracheal intubation was carried out in all patients and temperature measurements after the induction of anesthesia were performed using esophageal, urinary catheter or intra-arterial temperature probes.

RESULTS

The mean duration of prewarming was 25 min in the treatment group. Patients subjected to prewarming showed an intraoperative hypothermia rate of 15.8% and a postoperative hypothermia rate of 5.1%. Patients without prewarming showed an intraoperative hypothermia rate of 30.4% and a postoperative hypothermia rate of 12.4%. This means a 52% reduction of the intraoperative hypothermia rate and a 41% reduction of the postoperative hypothermia rate for patients who received prewarmimg (p < 0.0001). Multivariate logistic regression revealed that the lack of prewarming was independently associated with intraoperative hypothermia with an odds ratio of 2.5 (95% confidence interval CI 2.250-2.841; p < 0.0001) and postoperative hypothermia with an odds ratio of 2.8 (95% CI 2.316-3.277; p < 0.0001).

CONCLUSION

Prewarming, as recommended in the AWMF guidelines, resulted in a significant and clinically relevant reduction in the incidence of inadvertent perioperative hypothermia; therefore, prewarming can still be regarded as an effective method to avoid perioperative hypothermia. Hypothermia rates of 15.8% intraoperatively and 5.1% postoperatively can be achieved in clinical practice, when prewarming is performed in addition to intraoperative warming in the anesthesia induction room directly before the start of surgical procedures.

Effectiveness of Early Warming With Self-Warming Blankets on Postoperative Hypothermia in Total Hip and Knee Arthroplasty

BACKGROUND

Hypothermia is an important complication in joint arthroplasty. Commonly, forced air warming (FAW) devices are used intraoperatively to maintain body temperature in patients undergoing surgery. However, it is believed that these convective warming systems could increase the risk of deep surgical site infections due to disruption of unidirectional downward laminar airflow. Conductive warming devices have no noticeable effect on ventilation airflow. Nevertheless, the effectiveness of the self-warming (SW) blanket, a novel conductive warming device, on postoperative hypothermia in elective joint arthroplasty is unknown.

PURPOSE

The purpose of this study was to evaluate the effectiveness of early warming with SW blankets in the prevention of postoperative hypothermia in elective total hip (THA) and knee arthroplasty (TKA) compared with FAW devices.

METHODS

Patients who underwent elective THA or TKA between May and June 2014 were assigned in the FAW or SW group. A total of 105 patients were enrolled into the study. In the FAW group, the FAW devices were applied after disinfection of the surgical site. In the SW group, the SW blankets were already applied in the orthopaedic department. The duration of warming with SW blankets before anesthetic induction was documented. The body temperature was measured preoperatively upon arrival in the orthopaedic department and postoperatively upon arrival in the postanesthesia care unit. The patient's body temperature was measured at the tympanic membrane, and hypothermia was defined as a body temperature of less than 35.5°C.

RESULTS

The SW blankets were applied for a median of 86.8 minutes (78.8-94.8) before anesthetic induction. Postoperative hypothermia was observed in 15 (31.3%) and eight (14.0%) patients in the FAW group and the SW group, respectively (p = .029). The median postoperative body temperature was 35.59°C (35.44-35.74) and 35.95°C (35.83-36.06) in the FAW group and the SW group, respectively (p < .001).

CONCLUSION

Early warming with SW blankets was more effective than FAW devices in the prevention of postoperative hypothermia in elective THA and TKA.