The effect of short time periods of pre-operative warming in the prevention of peri-operative hypothermia

The Relationship of Perioperative Inadvertent Hypothermia with Anxiety and Comfort

The study aimed to investigate the relationship of perioperative inadvertent hypothermia with anxiety and thermal and general comfort in surgical patients. Inadvertent perioperative hypothermia occurs after surgery and affects many patient outcomes. However, the relationship between hypothermia and anxiety has been given little attention. The research is of descriptive type. A total of 117 surgical patients who met the inclusion criteria were sampled and divided into two groups: hypothermic (n = 54) and normothermic (n = 63). Patients undergoing surgery were monitored for body temperature, systolic and diastolic blood pressure, heart rate, pain intensity, anxiety (Numeric Rating Scale [NRS] and State Anxiety Scale [SAI]), and comfort (Perianesthesia Comfort Questionnaire) levels. The groups were similar in terms of descriptive characteristics (p > 0.05). Among the patients undergoing surgical intervention, 46.1% were hypothermic. Compared with the normothermic group, the hypothermic group had significantly lower body temperature until the second postoperative hour, lower thermal comfort score until the third postoperative hour, and higher heart rate and anxiety (NRS) score until the first postoperative day. Furthermore, there was a significant difference between the groups in terms of pain intensity up to the first 30 minutes after surgery (p < 0.05). Moreover, there was no significant difference between the groups in terms of pre and postoperative day one anxiety (SAI) and Periantesthesia Comfort Scale mean scores (p > 0.05). The study findings showed that hypothermia affected thermal comfort up to the first 3 hours after surgery, pain intensity up to the first 30 minutes, and heart rate and anxiety (NRS) levels up to the first day.

Effect of a Forced-Air Warming Blanket on Different Parts of the Body on Core Temperature of Patients Undergoing Elective Open Abdominal Surgery: A Randomized Controlled Single-Blind Trial

PURPOSE

This study aimed to determine the effect of a forced-air warming blanket placed on different body parts on the core temperature of patients undergoing elective open abdominal surgery.

DESIGN

Prospective, single-center, randomized, controlled, single-blind trial.

METHODS

A total of 537 patients who underwent open abdominal surgery were randomized into groups A, B, and C and provided with different forced-air warming blankets. Group A was given an upper body blanket, group B a lower body blanket, and group C an underbody blanket. The incidence of intraoperative hypothermia, the time maintaining the core temperature over 36 ℃ before hypothermia, the duration of hypothermia, the rewarming rate, and relevant complications were compared among three groups.

FINDINGS

Intraoperative hypothermia occurred in 51.4% of patients in group B, 37.6% of patients in group A, and 34.1% of patients in group C (P = .002). Maintaining the core temperature above 36 ℃ was longer before hypothermia in groups A and C (log-rank P = .006). In groups A and C, the duration of hypothermia was shorter, the rewarming rate was higher, and the incidence of shivering and postoperative nausea and vomiting were lower, compared to group B.

CONCLUSIONS

In patients undergoing elective open abdominal surgery, a forced-air warming blanket on the upper body part or underbody area decreased intraoperative hypothermia, prolonged the time to maintain the core temperature above 36 ℃ before hypothermia, and could better prevent further hypothermia when the core temperature had decreased below 36 ℃. In addition, it was significantly superior in reducing shivering and postoperative nausea and vomiting in the postanesthesia care unit.

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).

Hypothermia and rewarming times during general anesthesia in Hispaniolan Amazon parrots (Amazona ventralis): A comparative study between isoflurane, sevoflurane and desflurane

OBJECTIVE

To evaluate induced hypothermia and rewarming times in Hispaniolan Amazon parrots (HAP; Amazona ventralis) anesthetized using isoflurane, sevoflurane or desflurane, and to describe selected cardiovascular and respiratory effects.

STUDY DESIGN

Randomized, balanced, crossover experimental study.

ANIMALS

A group of 12 adult HAP.

METHODS

Parrots were premedicated with intramuscular butorphanol (0.5 mg kg-1) and anesthetized with the three inhalants with a 7 day washout period between events. Anesthesia was induced using isoflurane at 4 vol%, sevoflurane at 6 vol% or desflurane 12 vol% carried in oxygen, delivered via face mask. After orotracheal intubation, anesthesia maintenance was with end-tidal concentrations of 1.4-2% (Fe'Iso), 2.4-3% (Fe'Sevo) and 8.5-9.2% (Fe'Des). Hypothermia was defined as an esophageal temperature (BT) below 37.8 °C. External heat support was provided when BT dropped to 37.5 °C. Time for temperature decrease from 38.9 °C to 37.5 °C (T1), time to first increase in BT above 37.5 °C (T2) and time from external heat support to achieving 38.9 °C (T3) were recorded and compared via Friedman tests with post hoc Dunn's test. Heart rate, respiratory rate and end-tidal carbon dioxide, amongst other variables, were evaluated.

RESULTS

All inhalants caused hypothermia (T1): isoflurane, 12 (2-37) minutes [median (range)]; sevoflurane, 12 (4-18) minutes; desflurane, 11.5 (6-24) minutes, with no significant differences between treatments (p > 0.05). T2 was significantly (p = 0.042) longer for sevoflurane than for desflurane but not isoflurane. Transient apnea was observed with all inhalants, including 25% of birds anesthetized with sevoflurane. Second-degree atrioventricular block and ventricular escape beats occurred with all inhalants with hypothermia potentially exacerbating cardiac arrhythmias.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypothermia rapidly developed in butorphanol-sedated HAP anesthetized using isoflurane, sevoflurane or desflurane. Sevoflurane prolonged warming time. Hypothermia may be associated with an increased likelihood of bradyarrhythmia in parrots anesthetized with inhalants.

The Effect of Prewarming on Perioperative Hypothermia: A Systematic Review and Meta-analysis of Randomized Controlled Studies

PURPOSE

One of the methods for maintaining perioperative normothermia is prewarming. This study was conducted to investigate the effect of a preoperative prewarming intervention on perioperative body temperature.

DESIGN

Systematic review and meta-analysis.

METHODS

A literature review was conducted using PubMed, CINAHL, Cochrane Central, Science Direct, Springer Link, Scopus, Web of Science, and Ovid databases. Randomized controlled trials that investigate the effect of prewarming on body temperature in the prevention of perioperative hypothermia were included. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. Methodological quality was assessed using the Cochrane Collaboration "risk of bias" tool. Meta-analysis was performed with Comprehensive Meta-Analysis, version 2. Moderator analysis and publication bias assessment were performed. Funnel plots were analyzed using Orwin's fail-safe N, Trim, and Fill test method to investigate the source of heterogeneity.

FINDINGS

A total of 907 studies were found. The systematic review included 27 studies. Of these, 23 were included in the intraoperative meta-analysis, and 16 were included in the postoperative meta-analysis. According to the meta-analysis results, the prewarming intervention was effective in maintaining normothermia in the intraoperative (Hedge's g = 0.972, 95% confidence intervaI = 0.674 to 1.270) and postoperative (Hedge's g = 0.818, 95% confidence intervaI = 0.520 to 1.114) periods.

CONCLUSIONS

The findings of this systematic review and meta-analysis showed that preoperative prewarming played a significant role in providing and maintaining perioperative normothermia.

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.

A multi-center study to predict the risk of intraoperative hypothermia in gynecological surgery patients using preoperative variables

OBJECTIVES

Hypothermia is highly common in patients undergoing gynecological surgeries under general anesthesia, so the length of hospitalization and even the risk of mortality are substantially increased. Our aim was to develop a simple and practical model to preoperatively identify gynecological surgery patients at risk of intraoperative hypothermia.

METHODS

In this retrospective study, we collected data from 802 patients who underwent gynecological surgery at three medical centers from June 2022 to August 2023. We further allocated the patients to a training group, an internal validation group, or an external validation group. The preliminary predictive factors for intraoperative hypothermia in gynecological patients were determined using the least absolute shrinkage and selection operator (LASSO) method. The final predictive factors were subsequently identified through multivariate logistic regression analysis, and a nomogram for predicting the occurrence of hypothermia was established.

RESULTS

A total of 802 patients were included, with 314 patients in the training cohort (mean age 48.5 ± 12.6 years), 130 patients in the internal validation cohort (mean age 49.9 ± 12.5 years), and 358 patients in the external validation cohort (mean age 47.6 ± 14.0 years). LASSO regression and multivariate logistic regression analyses indicated that body mass index, minimally invasive surgery, baseline heart rate, baseline body temperature, history of previous surgery, and aspartate aminotransferase level were associated with intraoperative hypothermia in gynecological surgery patients. This nomogram was constructed based on these six variables, with a C-index of 0.712 for the training cohort.

CONCLUSIONS

We established a practical predictive model that can be used to preoperatively predict the occurrence of hypothermia in gynecological surgery patients.

CLINICAL TRIAL REGISTRATION

chictr.org.cn, identifier ChiCTR2300071859.

Clinical Efficacy of 10 Min of Active Prewarming for Preserving Patient Body Temperature during Percutaneous Nephrolithotomy: A Prospective Randomized Controlled Trial

Background: Percutaneous nephrolithotomy (PNL) poses a risk of hypothermia. Additionally, general anesthesia lowers the thresholds for shivering and vasoconstriction, which leads to dysfunction of central thermoregulation. Perioperative hypothermia is associated with adverse outcomes after surgery. In this study, we aimed to demonstrate that prewarming for 10 min can effectively prevent early hypothermia during PNL. Methods: A total of 68 patients scheduled for elective PNL were recruited to this study from January to June 2022, but two patients were excluded because of a change in the surgical plan. After randomization, patients in the prewarming group (n = 32) received warming using a forced-air warming device for 10 min in the preoperative area before being transferred to the operating room, while the controls (n = 34) did not. The incidence of hypothermia within the first hour after inducing general anesthesia was the primary outcome. Perioperative body temperatures and postoperative recovery findings were also evaluated. Results: Early intraoperative hypothermia decreased significantly more in the prewarming group than in the control group (9.4% vs. 41.2%, p = 0.003). Moreover, the net decrease in core body temperature during surgery was smaller in the prewarming group than in the control group (0.2 °C, vs. 0.5 °C, p = 0.003). In addition, the prewarmed patients had a lower incidence of postoperative shivering and a shorter post-anesthesia-care unit (PACU) stay (12.5% vs. 35.3%, p = 0.031; and 46 vs. 50 min, p = 0.038, respectively). Conclusions: Prewarming for 10 min decreased early hypothermia, preserved intraoperative body temperature, and improved postoperative recovery in the PACU.

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.

Prevention of peri-interventional hypothermia during endoscopic retrograde cholangiopancreatography using a forced-air heating system

Background and study aims Perioperative hypothermia is associated with significant complications and can be prevented with forced-air heating systems (FAHS). Whether hypothermia occurs during prolonged endoscopic sedation is unclear and prevention measures are not addressed in endoscopic sedation guidelines. We hypothesized that hypothermia also occurs in a significant proportion of patients undergoing endoscopic interventions associated with longer sedation times such as endoscopic retrograde cholangiopancreaticography (ERCP), and that FAHS may prevent it. Patients and methods In this observational study, each patient received two consecutive ERCPs, the first ERCP following current standard of care without FAHS (SOC group) and a consecutive ERCP with FAHS (FAHS group). The primary endpoint was maximum body temperature difference during sedation. Results Twenty-four patients were included. Median (interquartile range) maximum body temperature difference was -0.9°C (-1.2; -0.4) in the SOC and -0.1°C (-0.2; 0) in the FAHS group ( P < 0.001). Median body temperature was lower in the SOC compared with the FAHS group after 20, 30, 40, and 50 minutes of sedation. A reduction in body temperature of > 1°C ( P < 0.001) and a reduction below 36°C ( P = 0.01) occurred more often in the SOC than in the FAHS group. FAHS was independently associated with reduced risk of hypothermia ( P = 0.006). More patients experienced freezing in the SOC group ( P = 0.004). Hemodynmaic and respiratory stability were comparable in both groups. Conclusions Hypothermia occurred in the majority of patients undergoing prolonged endoscopic sedation without active temperature control. FAHS was associated with higher temperature stability during sedation and better patient comfort.

Effect of preoperative warming on intraoperative hypothermia and postoperative functional recovery in total hip arthroplasty: a randomized clinical trial

BACKGROUND

Intraoperative hypothermia is associated with increased morbidity and impaired postoperative recovery. Direct anterior-approached total hip arthroplasty (ATHA) may lead to significant thermal loss. We aimed to assess whether preoperative warming had an impact on intraoperative hypothermia and postoperative functional recovery after ATHA.

METHODS

In this prospective randomized controlled clinical trial 40 patients scheduled for ATHA were randomly divided into two groups of 20 patients each. Group W received, prior to the induction of general anesthesia, a 30 minutes 43 °C forced-air preoperative warming. Group C did not receive any preoperative warming. A blinded observer noted the core body temperature at the time of induction and at fixed time points, i.e. every five minutes during the first hour of surgery. The evolution of postoperative patient perceived thermal comfort (TC) and functional recovery (QoR-15) was assessed 24, 48 and 72 hours after surgery. Length of stay in the post-anesthesia care unit (PACU) was noted.

RESULTS

The temperature drop was significantly faster and of higher amplitude in group C than in group W, during first hour of surgery (P<0.001). Evolution of QoR-15 and TC was significantly better in group W than in group C (P<0.001 for QoR-15 and P<0.001 for thermal comfort), with shorter length of stay (median [IQR]) in the PACU (minutes; 73 [61-79] for group C and 98 [83-129] for group W, P<0.001).

CONCLUSIONS

In ATHA, pre-warming delays and reduces intraoperative heat loss, impacting patient comfort and postoperative functional recovery.

Accuracy of non-invasive sensors measuring core body temperature in cardiac surgery ICU patients - results from a monocentric prospective observational study

PURPOSE

Temperature monitoring in the perioperative setting often represents a compromise between accuracy, invasiveness of probe placement, and patient comfort. Transcutaneous sensors using the Zero-Heat-Flux (ZHF) and Double-Sensor (DS) technology have been developed and evaluated in a variety of clinical settings. The present study is the first to compare the performance of both sensors simultaneously with temperature measured by a Swan-Ganz catheter (PAC) in patients admitted to the intensive care unit (ICU) after cardiac surgery.

METHODS

In this monocentric prospective observational study patients were postoperatively transferred to the ICU and both sensors were placed on the patients' foreheads. Core body temperature measured by intraoperatively placed PAC served as gold standard. Measurements were recorded at 5-minute intervals and up to 40 data sets per patient were recorded. Bland and Altman's method for repeated measurements was used to analyse agreement. Subgroup analyses for gender, body-mass-index, core temperature, airway status and different time intervals were performed. Lin's concordance correlation coefficient (LCCC) was calculated, as well as sensitivity and specificity for detecting hyperthermia (≥ 38 °C) and hypothermia (< 36 °C).

RESULTS

Over a period of six month, we collected 1600 sets of DS, ZHF, and PAC measurements, from a total of 40 patients. Bland-Altman analysis revealed a mean bias of -0.82 ± 1.27 °C (average ± 95% Limits-of-Agreement (LoA)) and - 0.54 ± 1.14 °C for DS and ZHF, respectively. The LCCC was 0.5 (DS) and 0.63 (ZHF). Mean bias was significantly higher in hyperthermic and hypothermic patients. Sensitivity and specificity were 0.12 / 0.99 (DS) and 0.35 / 1.0 (ZHF) for hyperthermia and 0.95 / 0.72 (DS) and 1.0 / 0.85 (ZHF) for hypothermia.

CONCLUSION

Core temperature was generally underestimated by the non-invasive approaches. In our study, ZHF outperformed DS. In terms of agreement, results for both sensors were outside the range that is considered clinically acceptable. Nevertheless, both sensors might be adequate to detect postoperative hypothermia reliably when more invasive methods are not available or appropriate.

TRIAL REGISTRATION

German Register of Clinical Trials (DRKS-ID: DRKS00027003), retrospectively registered 10/28/2021.

Effect of Prewarming on Perioperative Hypothermia in Patients Undergoing Loco-Regional or General Anesthesia: A Randomized Clinical Trial

Background and Objectives: Redistribution hypothermia occurs during anesthesia despite active intraoperative warming. Prewarming increases the heat absorption by peripheral tissue, reducing the central to peripheral heat gradient. Therefore, the addition of prewarming may offer a greater preservation of intraoperative normothermia as compared to intraoperative warming only. Materials and Methods: A single-center clinical trial of adults scheduled for non-cardiac surgery. Patients were randomized to receive or not a prewarming period (at least 10 min) with convective air devices. Intraoperative temperature management was identical in both groups and performed according to a local protocol. The primary endpoint was the incidence, the magnitude and the duration of hypothermia (according to surgical time) between anesthetic induction and arrival at the recovery room. Secondary outcomes were core temperature on arrival in operating room, surgical site infections, blood losses, transfusions, patient discomfort (i.e., shivering), reintervention and hospital stay. Results: In total, 197 patients were analyzed: 104 in the control group and 93 in the prewarming group. Core temperature during the intra-operative period was similar between groups (p = 0.45). Median prewarming lasted 27 (17-38) min. Regarding hypothermia, we found no differences in incidence (controls: 33.7%, prewarming: 39.8%; p = 0.37), duration (controls: 41.6% (17.8-78.1), prewarming: 45.2% (20.6-71.1); p = 0.83) and magnitude (controls: 0.19 °C · h-1 (0.09-0.54), prewarming: 0.20 °C · h-1 (0.05-0.70); p = 0.91). Preoperative thermal discomfort was more frequent in the prewarming group (15.1% vs. 0%; p < 0.01). The interruption of intraoperative warming was more common in the prewarming group (16.1% vs. 6.7%; p = 0.03), but no differences were seen in other secondary endpoints. Conclusions: A preoperative prewarming period does not reduce the incidence, duration and magnitude of intraoperative hypothermia. These results should be interpreted considering a strict protocol for perioperative temperature management and the low incidence of hypothermia in controls.

[Correlation Between 6 Characteristics of Perioperative Hypothermia and Allogeneic Red Blood Cell Transfusion in Abdominal Surgery Patients]

Objective

To explore the correlation between six characteristics of perioperative hypothermia and allogeneic red blood cell (RBC) transfusions in patients who underwent abdominal surgeries.

Methods

Patients who underwent abdominal surgeries at West China Hospital, Sichuan University between October 2019 and July 2021 were retrospectively enrolled. A wearable wireless temperature sensor was used to continuously monitor the core body temperature of patients throughout the perioperative period. The perioperative temperature nadir, maximum temperature loss, percentage of time with hypothermia, time-weighted average temperature, area under the curve (AUC) at 36 ℃, and AUC at 37 ℃ were calculated for the period from entering the operation room to 24 hours after the end of anesthesia. The restricted cubic spline (RCS) and multiple logistic regression models were used to explore the correlation between these temperature characteristics and perioperative allogeneic RBC transfusions.

Results

A total of 3119 patients were included in the study, with an allogeneic RBC transfusion rate of 2.8%. The RCS model showed that allogeneic RBC transfusion was associated with the perioperative temperature nadir (Poverall=0.048) and AUC at 36 ℃ (Poverall=0.026) and no statistical significance was found in the nonlinear test. The association between allogeneic RBC transfusions and other temperature characteristics was not statistically significant. According to the RCS model results, cut-off points were taken to form groups based on the body temperature characteristics. Multivariate logistic regression showed that the perioperative temperature nadir<35.5 ℃ (odds ratio [OR]=2.47, 95% confidence interval [CI]: 1.21-5.03) and AUC at 36 ℃≥100 ℃·min (OR=2.24, 95% CI:1.09-4.58) were associated with increased demand for allogeneic RBC transfusion.

Conclusion

Hypothermia is associated with an increased need for perioperative allogeneic RBC transfusions and has a cumulative effect over time. For patients at high risk of bleeding, attention should be paid to the prevention of perioperative hypothermia and reduction in the cumulative exposure to hypothermia, thereby reducing the need for blood transfusion.

Risk factors for intraoperative hypothermia in infants during general anesthesia: A retrospective study

This study aimed to determine the incidence and evaluate the risk factors and outcomes of intraoperative hypothermia (IH) during general anesthesia in infants. Retrospective analysis of prospectively collected data. A total of 754 infants younger than 1 year old who underwent surgery under general anesthesia were included. Intraoperative body temperature fluctuations, surgical and anesthetic data, postoperative complications, and infant outcomes were recorded. Logistic regression algorithms were used to evaluate potential risk factors. Among the 754 infants, 47.88% developed IH (<36 °C) and 15.4% of them experienced severe hypothermia (<35 °C). The average lowest temperature in hypothermia patients was 35.06 ± 0.69°C with a duration of 82.23 ± 50.59 minutes. Neonates tended to experience hypothermia (37.7% vs 7.6%, P < .001) and prematurity was more common in patients with IH (29.4% vs 16.8%, P < .001). Infants with hypothermia experienced a longer length of stay in the post anesthesia care units and intensive care units, postoperative hospitalizations, and tracheal extubation as well as a higher rate of postoperative hemorrhage than those with normothermia (all P < .05). Several factors were proved to be associated with an increased risk of IH after multivariate analysis: neonate (odds ratio [OR] = 3.685, 95% CI 1.839-7.382), weight (OR = 0.599, 95% CI 0.525-0.683), American society of anesthesiologists (OR = 3.418, 95% CI 2.259-5.170), fluid > 20 mL/kg (OR = 2.380, 95% CI 1.389-4.076), surgery time >60 minutes (OR = 1.785, 95% CI 1.030-3.093), and pre-warming (OR = 0.027, 95% CI 0.014-0.052). This retrospective study found that neonates, lower weight, longer surgery times, more fluid received, higher American society of anesthesiologists stage, and no pre-warming were all significant risk factors for IH during general anesthesia in infants.

Forced-air prewarming prevents hypothermia during living donor liver transplantation: a randomized controlled trial

Despite various intraoperative thermal strategies, core heat loss is considerable during liver transplantation and hypothermia is common. We tested whether forced-air prewarming prevents hypothermia during liver transplantation. Adult patients undergoing living donor liver transplantation were randomly assigned to non-prewarming group (n = 20) or prewarming group (n = 20). Patients in prewarming group underwent 30-min forced-air warming before anesthetic induction. During surgery, core temperature was measured in the pulmonary artery. The primary outcome was intraoperative hypothermia (< 36.0 °C). The secondary outcomes included plasma lactate concentration. Intraoperative hypothermia risk was significantly lower in prewarming group than in non-prewarming group (60.0% vs. 95.0%, P = 0.020). The difference in hypothermia incidence between groups was greater in the post-induction phase (20.0% vs. 85.0%, P < 0.001) than in the anhepatic or post-reperfusion phase, suggesting that prewarming mainly acts on preventing post-induction core-to-peripheral heat redistribution. Hypothermia duration was significantly shorter in prewarming group (60 [0-221] min vs. 383 [108-426] min, P = 0.001). Lactate concentration decreased during 3 h after graft reperfusion in prewarming group, whereas it continuously increased in non-prewarming group (- 0.19 [- 0.48 to 0.13] mmol/L vs. 1.17 [3.31-0.77] mmol/L, P = 0.034). In conclusion, forced-air prewarming decreases the incidence and duration of intraoperative hypothermia with potential clinical benefit while mainly acting by preventing the core-to-peripheral heat redistribution.Clinical trial registration: Registered at the Clinical Research Information Service ( https://cris.nih.go.kr , [KCT0003230]) on 01/10/2018.

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.

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.

European Neuromuscular Centre consensus statement on anaesthesia in patients with neuromuscular disorders

BACKGROUND AND PURPOSE

Patients with neuromuscular conditions are at increased risk of suffering perioperative complications related to anaesthesia. There is currently little specific anaesthetic guidance concerning these patients. Here, we present the European Neuromuscular Centre (ENMC) consensus statement on anaesthesia in patients with neuromuscular disorders as formulated during the 259th ENMC Workshop on Anaesthesia in Neuromuscular Disorders.

METHODS

International experts in the field of (paediatric) anaesthesia, neurology, and genetics were invited to participate in the ENMC workshop. A literature search was conducted in PubMed and Embase, the main findings of which were disseminated to the participants and presented during the workshop. Depending on specific expertise, participants presented the existing evidence and their expert opinion concerning anaesthetic management in six specific groups of myopathies and neuromuscular junction disorders. The consensus statement was prepared according to the AGREE II (Appraisal of Guidelines for Research &amp; Evaluation) reporting checklist. The level of evidence has been adapted according to the SIGN (Scottish Intercollegiate Guidelines Network) grading system. The final consensus statement was subjected to a modified Delphi process.

RESULTS

A set of general recommendations valid for the anaesthetic management of patients with neuromuscular disorders in general have been formulated. Specific recommendations were formulated for (i) neuromuscular junction disorders, (ii) muscle channelopathies (nondystrophic myotonia and periodic paralysis), (iii) myotonic dystrophy (types 1 and 2), (iv) muscular dystrophies, (v) congenital myopathies and congenital dystrophies, and (vi) mitochondrial and metabolic myopathies.

CONCLUSIONS

This ENMC consensus statement summarizes the most important considerations for planning and performing anaesthesia in patients with neuromuscular disorders.

Prewarming for Prevention of Hypothermia in Older Patients Undergoing Hand Surgery Under Brachial Plexus Block

Background

Older patients are more vulnerable to inadvertent perioperative hypothermia. Prewarming contributes to the prevention of inadvertent perioperative hypothermia in patients under general or neuraxial anesthesia. However, the effects of brachial plexus block (BPB) on thermoregulation and the efficacy of prewarming in the prevention of hypothermia in older patients undergoing surgery with BPB remain unclear. This study evaluated the effects of BPB on thermoregulation and the efficacy of prewarming during BPB in older patients.

Methods

Patients aged ≥65 years were randomly allocated to receive either standard preoperative insulation (control group, n=20) or preanesthetic forced-air warming for 20 minutes before BPB (prewarming group, n=20). During the perioperative period, tympanic temperatures were measured. Thermal comfort scores and shivering grades were also obtained.

Results

The tympanic temperatures at the end of surgery did not differ between the groups (36.9°C±0.5°C and 37.0°C±0.4°C in the control and prewarming groups, respectively; p=0.252). The maximum temperature change was significantly lower in the prewarming group compared to the control group (0.36°C±0.4°C and 0.65°C±0.3°C, respectively; p=0.013). The hypothermia incidence and severity, thermal comfort scores, and shivering grades did not differ between the groups.

Conclusion

Regardless of the application of prewarming, BPB did not cause a clinically significant impairment of thermoregulation. Moreover, the efficacy of prewarming appeared to be low; thus, it may not be routinely required in patients undergoing orthopedic hand surgery under BPB.

Perioperative Prewarming: Heat Transfer and Physiology

To appreciate the strategy of prewarming, perioperative personnel should have a basic understanding of the physics of heat transfer and the thermoregulatory pathophysiology of anesthesia. The dominant cause of postinduction hypothermia is anesthesia-related redistribution of heat within the body; the role of cutaneous heat loss is minimal. Physiologic thermoregulatory system changes that occur in response to anesthesia make it almost impossible to reverse intraoperative hypothermia. However, prewarming is an effective strategy to prevent postinduction hypothermia from redistribution because it creates a temporary excess of heat in the body's peripheral thermal compartment. Perioperative nurses should implement active and passive prewarming strategies in accordance with the warming devices at their facility and available time. This article focuses on two major topics necessary to understand prewarming: the effect of anesthesia on postinduction thermoregulation and thermodynamic conditions that successful treatment strategies must exploit to produce desired outcomes.

Perioperative hypothermia in open and laparoscopic colorectal surgery

BACKGROUND

The consequences of even mild inadvertent perioperative hypothermia (IPH) are significant. There is a perception laparoscopic abdominal surgery is less prone to cause hypothermia than open surgery. However, during laparoscopic surgery, the peritoneal cavity is insufflated with carbon dioxide, which has a greater evaporative capacity than ambient air. This study compared the intra-operative temperature profile of patients undergoing open and laparoscopic colorectal surgery to define the incidence and severity of hypothermia.

METHODS

All adult patients undergoing colorectal surgery between May 2005 and August 2013 were identified from an electronic database. Cases were categorized into laparoscopic and open cases. Hypothermic episodes were defined as a temperature less than 36°C lasting for more than two consecutive minutes. The incidence of hypothermic episodes, the total time under 36°C and the area under the curve (degree-minutes) were calculated.

RESULTS

A total of 1547 cases were analysed. The overall incidence of hypothermia was 67.0%. The incidence of cases with a hypothermic episode was greater in the laparoscopic group compared to the open group (71.23% versus 63.16%; chi-squared P-value 0.001). However, when other factors were considered, there was no significant difference in the relative risk of a hypothermic episode between types of surgery. There were significant differences in the severity of hypothermia.

CONCLUSION

Despite current measures to reduce the incidence, IPH remains a significant problem in colorectal surgery irrespective of the surgical approach. Further research is required to better characterize techniques that can reduce its incidence.

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

BACKGROUND

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

METHODS

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

DISCUSSION

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

CONCLUSION

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

Development and internal validation of an algorithm to predict intraoperative risk of inadvertent hypothermia based on preoperative data

Intraoperative hypothermia increases perioperative morbidity and identifying patients at risk preoperatively is challenging. The aim of this study was to develop and internally validate prediction models for intraoperative hypothermia occurring despite active warming and to implement the algorithm in an online risk estimation tool. The final dataset included 36,371 surgery cases between September 2013 and May 2019 at the Vienna General Hospital. The primary outcome was minimum temperature measured during surgery. Preoperative data, initial vital signs measured before induction of anesthesia, and known comorbidities recorded in the preanesthetic clinic (PAC) were available, and the final predictors were selected by forward selection and backward elimination. Three models with different levels of information were developed and their predictive performance for minimum temperature below 36 °C and 35.5 °C was assessed using discrimination and calibration. Moderate hypothermia (below 35.5 °C) was observed in 18.2% of cases. The algorithm to predict inadvertent intraoperative hypothermia performed well with concordance statistics of 0.71 (36 °C) and 0.70 (35.5 °C) for the model including data from the preanesthetic clinic. All models were well-calibrated for 36 °C and 35.5 °C. Finally, a web-based implementation of the algorithm was programmed to facilitate the calculation of the probabilistic prediction of a patient's core temperature to fall below 35.5 °C during surgery. The results indicate that inadvertent intraoperative hypothermia still occurs frequently despite active warming. Additional thermoregulatory measures may be needed to increase the rate of perioperative normothermia. The developed prediction models can support clinical decision-makers in identifying the patients at risk for intraoperative hypothermia and help optimize allocation of additional thermoregulatory interventions.

Effect of prewarming on body temperature in short-term bladder or prostatic transurethral resection under general anesthesia: A randomized, double-blind, controlled trial

Perioperative hypothermia causes postoperative complications. Prewarming reduces body temperature decrease in long-term surgeries. We aimed to assess the effect of different time-periods of prewarming on perioperative temperature in short-term transurethral resection under general anesthesia. Randomized, double-blind, controlled trial in patients scheduled for bladder or prostatic transurethral resection under general anesthesia. Eligible patients were randomly assigned to receive no-prewarming or prewarming during 15, 30, or 45 min using a forced-air blanket in the pre-anesthesia period. Tympanic temperature was used prior to induction of anesthesia and esophageal temperature intraoperatively. Primary outcome was the difference in core temperature among groups from the induction of general anesthesia until the end of surgery. Repeated measures multivariate analysis of covariance modeled the temperature response at each observation time according to prewarming. We examined modeled contrasts between temperature variables in subjects according to prophylaxis. We enrolled 297 patients and randomly assigned 76 patients to control group, 74 patients to 15-min group, 73 patients to 30-min group, and 74 patients to the 45-min group. Temperature in the control group before induction was 36.5 ± 0.5 °C. After prewarming, core temperature was significantly higher in 15- and 30-min groups (36.8 ± 0.5 °C, p = 0.004; 36.7 ± 0.5 °C, p = 0.041, respectively). Body temperature at the end of surgery was significantly lower in the control group (35.8 ± 0.6 °C) than in the three prewarmed groups (36.3 ± 0.6 °C in 15-min, 36.3 ± 0.5 °C in 30-min, and 36.3 ± 0.6 °C in 45-min group) (p < 0.001). Prewarming prior to short-term transurethral resection under general anesthesia reduced the body temperature drop during the perioperative period. These time-periods of prewarming also reduced the rate of postoperative complications.Study Registration Registered at ClinicalTrials.gov (Identifier: NCT03630887).

Perioperative Hypothermia-A Narrative Review

Unintentional hypothermia (core temperature < 36 °C) is a common side effect in patients undergoing surgery. Several patient-centred and external factors, e.g., drugs, comorbidities, trauma, environmental temperature, type of anaesthesia, as well as extent and duration of surgery, influence core temperature. Perioperative hypothermia has negative effects on coagulation, blood loss and transfusion requirements, metabolization of drugs, surgical site infections, and discharge from the post-anaesthesia care unit. Therefore, active temperature management is required in the pre-, intra-, and postoperative period to diminish the risks of perioperative hypothermia. Temperature measurement should be done with accurate and continuous probes. Perioperative temperature management includes a bundle of warming tools adapted to individual needs and local circumstances. Warming blankets and mattresses as well as the administration of properly warmed infusions via dedicated devices are important for this purpose. Temperature management should follow checklists and be individualized to the patient's requirements and the local possibilities.

Perioperative Hypothermia in Children

Background: First described by paediatric anaesthesiologists, perioperative hypothermia is one of the earliest reported side effects of general anaesthesia. Deviations from normothermia are associated with numerous complications and adverse outcomes, with infants and small children at the highest risk. Nowadays, maintenance of normothermia is an important quality metric in paediatric anaesthesia. Methods: This review is based on our collection of publications regarding perioperative hypothermia and was supplemented with pertinent publications from a MEDLINE literature search. Results: We provide an overview on perioperative hypothermia in the paediatric patient, including definition, history, incidence, development, monitoring, risk factors, and adverse events, and provide management recommendations for its prevention. We also summarize the side effects and complications of perioperative temperature management. Conclusions: Perioperative hypothermia is still common in paediatric patients and may be attributed to their vulnerable physiology, but also may result from insufficient perioperative warming. An effective perioperative warming strategy incorporates the maintenance of normothermia during transportation, active warming before induction of anaesthesia, active warming during anaesthesia and surgery, and accurate measurement of core temperature. Perioperative temperature management must also prevent hyperthermia in children.

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.

Efficacy of active forced air warming during induction of anesthesia to prevent inadvertent perioperative hypothermia in intraoperative warming patients: Comparison with passive warming, a randomized controlled trial

BACKGROUND

This study aimed to evaluate the efficacy of peri-induction forced air warming to prevent inadvertent perioperative hypothermia, defined as a reduction in body temperature to <36.0°C during the perioperative period, in intraoperatively warmed patients receiving major surgery lasting >120 minutes.

METHODS

In total, 130 patients scheduled for elective surgery under general anesthesia lasting >120 minutes were divided into 2 groups: peri-induction warming (n = 65) and control (n = 65). Patients in the peri-induction warming group were warmed during the anesthetic induction period using a forced-air warmer set at 47°C, whereas patients in the control group were covered passively with a cotton blanket. All patients were warmed with a forced-air warmer during surgery. Body temperature was measured using a tympanic membrane thermometer in the pre- and postoperative periods and using a nasopharyngeal temperature probe during surgery. Patients were evaluated for shivering scale score, thermal comfort scale score, and satisfaction score in the post-anesthesia care unit.

RESULTS

The incidence rates of intraoperative and postoperative hypothermia were lower in the peri-induction warming group than in the control group (19.0% vs 57.1%, P < .001; 3.3% vs 16.9%, P = .013, respectively). Body temperature was higher in the peri-induction warming group (P < .001). However, intraoperative blood loss, as well as postoperative thermal comfort scale score, shivering scale score, and patient satisfaction score, were similar between groups. Post-anesthesia care unit duration was also similar between groups.

CONCLUSIONS

Peri-induction active forced air warming is an effective, simple, and convenient method to prevent inadvertent perioperative hypothermia in intraoperatively warmed patients undergoing major surgery lasting >120 minutes.

Short-Periods of Pre-Warming in Laparoscopic Surgery. A Non-Randomized Clinical Trial Evaluating Current Clinical Practice

Background: Pre-warming prevents perioperative hypothermia. We evaluated the current clinical practice of pre-warming and its effects on temperature drop and postoperative complications; Methods: This prospective, observational pilot study examines clinical practice in a tertiary hospital on 99 patients undergoing laparoscopic urological surgery. Pre-warming was performed in the pre-anesthesia room. Patients were classified into three groups: P 0 (non-prewarmed), P 5–15 (pre-warming 5–15 min) and P > 15 (pre-warming 15–30 min). Tympanic temperature was recorded in the pre-anesthesia room, prior to anesthesia induction, and in the PACU. Esophageal temperature was recorded intraoperatively. The occurrence of shivering, pain intensity, length of stay in PACU, and postoperative complications during hospital stay were also recorded; Results: After pre-warming, between-group difference in body temperature was higher in P > 15 than in P 0 (0.4 °C, 95% CI 0.14–0.69, p = 0.004). Between P 5–15 and P 0 difference was 0.2 °C (95% CI 0.04–0.55, p = 0.093). Temperature at the end of surgery was higher in pre-warmed groups [mean between-group difference 0.5 °C (95% CI 0.13–0.81, p = 0.007) for P 5–15; 0.9 °C (95% CI 0.55–1.19, p < 0.001) for P > 15]. Pain and shivering was less common in pre-warmed groups. Postoperative transfusions and surgical site infections were lower in P > 15; Conclusion: Short-term pre-warming prior to laparoscopic urological surgery decreased temperature perioperative drop and postoperative complications.

Thermal suit connected to a forced-air warming unit for preventing intraoperative hypothermia: A randomised controlled trial

BACKGROUND

Inadvertent intraoperative hypothermia is a common occurrence in surgical patients. A thermal suit is an option for passive insulation. However, active warming is known to be more effective. Therefore, we hypothesised that a forced-air warming (FAW) unit connected to the thermal suit is superior to a commercial FAW blanket and a warming mattress in breast cancer surgery.

METHODS

Forty patients were randomised to this prospective, clinical trial to wear either the thermal suit or conventional hospital clothes under general anaesthesia. The Thermal suit group had a FAW unit set to 38°C and connected to the legs of the suit. The Hospital clothes group had a lower body blanket set to 38°C and a warming mattress set to 37°C. Core temperature was measured with zero-heat-flux sensor. The primary outcome was core temperature on admission to the recovery room.

RESULTS

There was no difference in mean core temperatures at anaesthetic induction (P = .4) or on admission to the recovery room (P = .07). One patient in the Thermal suit group (5%) vs six patients in the Hospital clothes group (32%) suffered from intraoperative hypothermia (P = .04, 95% CI 1.9%-49%). Mean skin temperatures (MSTs) were higher in the Thermal suit group during anaesthesia. No burns or skin irritations were reported. Two patients in the Thermal suit group sweated.

CONCLUSIONS

A thermal suit connected to a FAW unit was not superior to a commercial FAW blanket, although the incidence of intraoperative hypothermia was lower in patients treated with a thermal suit.

Incidence of Unintentional Intraoperative Hypothermia in Pediatric Scoliosis Surgery and Associated Preoperative Risk Factors

Introduction

Intraoperative hypothermia is associated with perioperative complications such as blood loss and wound infection. Thus, perioperative heat retention methods to prevent perioperative hypothermia such as providing a warmed blanket and active patients' warming are important. Although major surgery and pediatric patient age are noted as risk factors, only a few studies focus on hypothermia as an intraoperative complication in pediatric scoliosis surgery. The aim of this study is to investigate the incidence of intraoperative hypothermia in pediatric scoliosis surgery and the associated preoperative risk factors.

Methods

We retrospectively reviewed the records of pediatric patients who underwent posterior spinal fusion at a single institution between 2015 and 2019. We recorded the background data, perioperative data, lowest recorded core temperature, and perioperative complications. Patients were divided into those whose temperature decreased below 36°C (Group H) and those who maintained a temperature of 36°C or greater (Group N) during surgery. We compared the two groups and performed multivariate analysis to identify preoperative risk factors for intraoperative hypothermia.

Results

A total of 103 patients underwent posterior spinal fusion; 56 for adolescent idiopathic scoliosis and 47 for neuromuscular scoliosis. Hypothermia was observed in 40 patients (38.8%). Group H had more non-adolescent idiopathic scoliosis (AIS) patients, lower mean body mass index, greater mean blood loss, greater number of fused vertebrae, larger preoperative Cobb angle, and lower initial core body temperature (immediately after induction of anesthesia). On multivariate analysis, a diagnosis of neuromuscular scoliosis, a lower body mass index, and a lower initial core body temperature were identified as independent risk factors for intraoperative hypothermia.

Conclusions

The incidence of hypothermia in pediatric posterior scoliosis surgery is 38.8%. Diagnosis of non-AIS, lower body mass index, and lower core body temperature at the time of anesthesia induction are preoperative risk factors for intraoperative hypothermia.

Effects of 10-min prewarming on core body temperature during gynecologic laparoscopic surgery under general anesthesia: a randomized controlled trial

Background

Previous research has shown a beneficial effect of prewarming for preventing inadvertent perioperative hypothermia. However, there are few studies of the effects of a short prewarming period, especially in gynecologic laparoscopic surgery.

Methods

Fifty-four patients were randomly assigned to 2 groups. Patients in the non-prewarming group were only warmed intraoperatively with a forced air warming device, while those in the prewarming group were warmed for 10 min before anesthetic induction and during the surgery. The primary outcome was incidence of intraoperative hypothermia.

Results

Intraoperative hypothermia was observed in 73.1% of the patients in the non-prewarming group and 24% of the patients in the prewarming group (P < 0.001). There were significant differences in core temperature changes between the groups (P < 0.001). Postoperative shivering occurred in 8 of the 26 (30.8%) patients in the non-prewarming group and in 1 of the 25 (4.0%) patients in the prewarming group (P = 0.024).

Conclusions

Forced air warming for 10 min before induction on the operating table combined with intraoperative warming was an effective method to prevent hypothermia in patients undergoing gynecologic laparoscopic surgery.

Effects of 10-min of pre-warming on inadvertent perioperative hypothermia in intraoperative warming patients: a randomized controlled trial

Background

This study aimed to evaluate the efficacy of 10-min pre-warming in preventing inadvertent perioperative hypothermia, which is defined as a reduction in body temperature to less than 36.0℃ during the perioperative period in intraoperative warming patients.

Methods

In this prospective randomized study, 60 patients scheduled for elective surgery under general anesthesia lasting less than 120 min were divided into two groups: the 10-min pre-warming group (n = 30) and the control group (n = 30). Patients in the 10-min pre-warming group were pre-warmed for 10 min in the pre-anesthetic area using a forced-air warmer set at 47ºC. Intraoperatively, we warmed all patients with a forced-air warmer. Body temperature was measured using a tympanic membrane thermometer pre- or postoperatively and a nasopharyngeal temperature probe intraoperatively. Patients were evaluated on the shivering and thermal comfort scale in the pre-anesthetic area and post-anesthesia care unit.

Results

The incidences of intraoperative hypothermia and postoperative hypothermia were similar in both groups (10.7% vs. 28.6%, P = 0.177; 10.7% vs. 10.7%, P = 1.000 respectively). Body temperature was higher in the 10-min pre-warming group (P = 0.003). Thermal comfort during the pre-warming period was higher in the 10-min pre-warming group (P < 0.001). However, postoperative thermal comfort and shivering grades of both groups were similar.

Conclusions

Ten minutes of pre-warming has no additional effect on the prevention of inadvertent perioperative hypothermia in intraoperative warming patients.

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.

Pre-warming before general anesthesia with isoflurane delays the onset of hypothermia in rats

General anesthesia causes hypothermia by impairing normal thermoregulatory mechanisms. When using inhalational anesthetic agents, Redistribution of warm blood from the core to the periphery is the primary mechanism in the development of hypothermia and begins following induction of anesthesia. Raising skin temperature before anesthesia reduces the temperature gradient between core and periphery, decreasing the transfer of heat. This prospective, crossover study (n = 17 adult male and female SD rats) compared three treatment groups: PW1% (pre-warming to increase core temperature 1% over baseline), PW40 (pre-warming to increase core temperature to 40°C) and NW (no warming). The PW1% group was completed first to ensure tolerance of pre-warming. Treatment order was then randomized and alternated after a washout period. Once target temperature was achieved, anesthesia was induced and maintained with isoflurane in oxygen without further external temperature support. Pre-warming was effective at delaying the onset of hypothermia, with a significant difference between PW1% (12.4 minutes) and PW40 (19.3 minutes, p = 0.0044 (95%CI -12 to -2.2), PW40 and NW (7.1 minutes, p < 0.0001 (95%CI 8.1 to 16.0) and PW1% and NW (p = 0.003, 95%CI 1.8 to 8.7). The rate of heat loss in the pre-warmed groups exceed that of the NW group: PW1% versus NW (p = 0.005, 95%CI 0.004 to 0.027), PW40 versus NW (p < 0.0001, 95%CI 0.014 to 0.036) and PW1% versus PW40 (p = 0.07, 95%CI -0.021 to 0.00066). Pre-warming alone confers a protective effect against hypothermia during volatile anesthesia; however, longer duration procedures would require additional heating support.

Prevalence of hypothermia on admission to recovery room remains high despite a large use of forced-air warming devices: Findings of a non-randomized observational multicenter and pragmatic study on perioperative hypothermia prevalence in France

BACKGROUND

Despite the availability of effective warming systems, the prevalence of hypothermia remains high in patients undergoing surgery. Occurrence of perioperative hypothermia may influence the rate of postoperative complications. Recommendations for the prevention of inadvertent perioperative hypothermia have been developed and are effective to reduce the frequency of perioperative hypothermia when professionals comply with. French Society of Anesthesiology (SFAR) decided to promote guidelines for the prevention of inadvertent hypothermia, and to conduct beforehand a pragmatic assessment of the prevalence of hypothermia in France. The hypothesis was that the rate of hypothermic patients (Tc<36°C) admitted to the RR remains high (around 50%), and that was the consequence of a warming device underutilization and/or was related to the type of health facilities.

METHODS

An observational, prospective and multi-centric study was conducted in France between October 2014 and May 2016 among patients over 45 years undergoing non-cardiac, non-outpatient surgery with anesthesia lasting >30 minutes in 52 centers. Patients undergoing pulmonary or proctologic surgery and those having non-invasive procedures performed under general anesthesia (for example, digestive endoscopy) were excluded from our study. Patients being operated under plexus anesthesia alone, surgeries involving hemorrhaging or infection, and patients presenting at least one organ failure were also excluded. The primary endpoint was the percentage of patients with a core temperature (Tc) <36°C on admission to the recovery room (RR).

RESULTS

Among 893 subjects (median age 66.9 years), prevalence of hypothermia on admission to the RR was 53.5%. At least one warming system was used for 90.4% of the patients. Identified risk factors for Tc<36°C included age≥70 years (OR = 1.41 [CI95%: 1.02-1.94]), duration of anesthesia from 1 to 2 hours (OR = 1.94 [CI95%: 1.04-3.64]) and a decrease in Tc of >0.5°C between anesthesia induction and surgical incision (OR = 1.82 [CI95%: 1.15-2.89]). Only a combination of pre-warming and intraoperative warming prevented a Tc<36°C (OR = 0.48 [CI95%: 0.24-0.96]).

CONCLUSIONS

The prevalence of hypothermia among patients admitted to the RR remains high. Our results suggest that only the combination of pre-warming and intraoperative warming significantly decreases it.

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.

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.

Impact of brief prewarming on anesthesia-related core-temperature drop, hemodynamics, microperfusion and postoperative ventilation in cytoreductive surgery of ovarian cancer: a randomized trial

Background

General (GA)- and epidural-anesthesia may cause a drop in body-core-temperature (BCT_drop), and hypothermia, which may alter tissue oxygenation (StO₂) and microperfusion after cytoreductive surgery for ovarian cancer. Cell metabolism of subcutaneous fat- or skeletal muscle cells, measured in microdialysis, may be affected. We hypothesized that forced-air prewarming during epidural catheter placement and induction of GA maintains normothermia and improves microperfusion.

Methods

After ethics approval 47 women scheduled for cytoreductive surgery were prospectively enrolled. Women in the study group were treated with a prewarming of 43 °C during epidural catheter placement. BCT (Spot on®, 3 M) was measured before (T₁), after induction of GA (T₂) at 15 min (T₃) after start of surgery, and until 2 h after ICU admission (T_ICU2h). Primary endpoint was BCT_drop between T₁ and T₂. Microperfusion-, hemodynamic- and clinical outcomes were defined as secondary outcomes. Statistical analysis used the Mann-Whitney-U- and non-parametric-longitudinal tests.

Results

BCT_drop was 0.35 °C with prewarming and 0.9 °C without prewarming (p < 0.005) and BCT remained higher over the observation period (ΔT₄ = 0.9 °C up to ΔT₇ = 0.95 °C, p < 0.001). No significant differences in hemodynamic parameters, transfusion, arterial lactate and dCO₂ were measured. In microdialysis the ethanol ratio was temporarily, but not significantly, reduced after prewarming. Lactate, glucose and glycerol after PW tended to be more constant over the entire period. Postoperatively, six women without prewarming, but none after prewarming were mechanical ventilated (p < 0.001).

Conclusion

Prewarming at 43 °C reduces the BCT_drop and maintains normothermia without impeding the perioperative routine patient flow. Microdialysis indicate better preserved parameters of microperfusion.

Trial registration

ClinicalTrials.gov; ID: NCT02364219; Date of registration: 18-febr-2015.

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.

The effectiveness of air-free warming systems on perioperative hypothermia in total hip and knee arthroplasty: A systematic review and meta-analysis

BACKGROUND

Perioperative hypothermia is a common and serious complication during surgery. Different warming systems are used to prevent perioperative hypothermia. However, there have been no previous meta-analyses of the effectiveness of air-free warming systems on perioperative hypothermia in patients undergoing joint arthroplasty.

METHODS

We systematically searched PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure (CNKI) databases to collect randomized controlled trials (RCTs) from inception to August 2018. These RCTs compared the effects of air-free warming with forced-air (FA) warming system in patients undergoing joint arthroplasty. Postoperative temperature, core temperature during surgery, thermal comfort, blood loss and incidence of shivering and hypothermia were analyzed.

RESULTS

A total of 287 patients from 6 clinical studies were included in the analysis. In summary, there was no significant difference in the postoperative temperature (WMD -0.043, 95% CI -0.32 to 0.23, P = .758) between the air-free warming and FA warming groups. No statistical difference (WMD 0.058, 95% CI -0.10 to 0.22, P = .475) was found in core temperatures at 0 minutes during surgery between the air-free warming and FA warming groups. Furthermore, there was no statistical difference in thermal comfort, blood loss or incidence of shivering and hypothermia between the air-free warming and FA warming groups.

CONCLUSIONS

Air-free warming system was as effective as FA warming system in patients undergoing joint arthroplasty.

Influence of oral premedication and prewarming on core temperature of cardiac surgical patients: a prospective, randomized, controlled trial

Background

Perioperative hypothermia is still very common and associated with numerous adverse effects. The effects of benzodiazepines, administered as premedication, on thermoregulation have been studied with conflicting results. We investigated the hypotheses that premedication with flunitrazepam would lower the preoperative core temperature and that prewarming could attenuate this effect.

Methods

After approval by the local research ethics committee 50 adult cardiac surgical patients were included in this prospective, randomized, controlled, single-centre study with two parallel groups in a university hospital setting. Core temperature was measured using a continuous, non-invasive zero-heat flux thermometer from 30 min before administration of the oral premedication until beginning of surgery. An equal number of patients was randomly allocated via a computer-generated list assigning them to either prewarming or control group using the sealed envelope method for blinding. The intervention itself could not be blinded. In the prewarming group patients received active prewarming using an underbody forced-air warming blanket. The data were analysed using Student’s t-test, Mann-Whitney U-test and Fisher’s exact test.

Results

Of the randomized 25 patients per group 24 patients per group could be analysed. Initial core temperature was 36.7 ± 0.2 °C and dropped significantly after oral premedication to 36.5 ± 0.3 °C when the patients were leaving the ward and to 36.4 ± 0.3 °C before induction of anaesthesia. The patients of the prewarming group had a significantly higher core temperature at the beginning of surgery (35.8 ± 0.4 °C vs. 35.5 ± 0.5 °C, p = 0.027), although core temperature at induction of anaesthesia was comparable. Despite prewarming, core temperature did not reach baseline level prior to premedication (36.7 ± 0.2 °C).

Conclusions

Oral premedication with benzodiazepines on the ward lowered core temperature significantly at arrival in the operating room. This drop in core temperature cannot be offset by a short period of active prewarming.

Trial registration

This trial was prospectively registered with the German registry of clinical trials under the trial number DRKS00005790 on 20th February 2014.

Effect of pre-warming on perioperative hypothermia during holmium laser enucleation of the prostate under spinal anesthesia: a prospective randomized controlled trial

Background

The purpose of this study is to assess whether the application of preoperative forced air warming set to high temperature (> 43 °C) for brief period can increase temperature on admission to the postanesthesia care unit (PACU) and prevent hypothermia or shivering during holmium laser enucleation of the prostate performed under spinal anesthesia.

Methods

Fifty patients were enrolled were assigned randomly to receive passive insulation (control group, n = 25) or forced-air skin surface warming for 20 min before spinal anesthesia (pre-warming group, n = 25). The primary outcome was temperature at PACU admission.

Results

The pre-warming group had a significantly higher temperature on admission to the PACU than the control group (35.9 °C [0.1] vs 35.6 °C [0.1], P = 0.023; 95% confidence interval of mean difference, 0.1 °C–0.5 °C). The trend of decreasing core temperature intraoperatively was not different between groups (P = 0.237), but intraoperative core temperature remained approximately 0.2 °C higher in the pre-warming group (P = 0.005). The incidence of hypothermia on admission to the PACU was significantly lower in the pre-warming group (56% vs 88%, P = 0.025). Shivering occurred in 14 patients in the control group, and 4 patients in the pre-warming group (P = 0.007).

Conclusion

Brief pre-warming at 45 °C increased perioperative temperature and decreased the incidence of hypothermia and shivering. However, it was not sufficient to modify the decline of intraoperative core temperature or completely prevent hypothermia and shivering. Continuing pre-warming to immediately before induction of spinal anesthesia or combining pre-warming with intraoperative active warming may be necessary to produce clearer thermal benefits in this surgical population.

Trial registration

This trial was registered with Clinicaltrials.gov, NCT03184506, 5th June 2017.

Investigation of inadvertent hypothermia incidence and risk factors

OBJECTIVE

This study was conducted to determine the incidence of inadvertent hypothermia in operative patients and the risk factors that are involved in the development of hypothermia.

MATERIAL AND METHODS

This prospective, descriptive, cross-sectional study was conducted from January 2016to August 2016 with 144 patients who over the age of 18 years, underwent general surgery, orthopedic surgery, urologic surgery, neurosurgery, and plastic and reconstructive surgery. Data was collected with the "Hypothermia Data Collection Form." Body temperature was measured by the tympanic membrane in the waiting room, operating room, and PACU.

RESULTS

Overall, 89% of the patients (n=129) were normothermic in the preoperative phase; 74.30% of the patients (n=107) in intraoperative phase and 75.70% of the patients (n=109) in postoperative phase were hypothermic. American Society of Anesthesiologist (ASA) score, preoperative body temperature, operating room temperature, and using heating method at operation were found to be effective in the development of inadvertent hypothermia during the operating period. It was determined that premedication, preoperative and postoperative body temperature, and the operating room temperature were effective for inadvertent hypothermia in the postoperative period.

CONCLUSION

As a result of the study, it was determined the rate of inadvertent hypothermia was high during and after surgery. Preoperative and intraoperative patient body temperature and operating room temperature were found to be effective in preventing inadvertent hypothermia.