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.

Delayed Rewarming Thrombocytopenia: A Suggested Preventable and Treatable Cause of Rewarming Deaths.

The lack of a consensus of accepted prognostic factors in hypothermia suggests an additional factor has been overlooked. Delayed rewarming thrombocytopenia (DRT) is a novel candidate for such a role. At body temperature, platelets undergoing a first stage of aggregation are capable of progression to a second irreversible stage of aggregation. However, we have shown that the second stage of aggregation does not occur below 32°C and that this causes the first stage to become augmented (first-stage platelet hyperaggregation). In aggregometer studies performed below 32°C, the use of quantities of ADP that cause a marked first-stage hyperaggregation can cause an augmented second-stage activation of the platelets during rewarming (second-stage platelet hyperaggregation). In vivo, after 24 hours of hypothermia, platelets on rewarming seem to undergo second-stage hyperaggregation, from ADP released from erythrocytes, leading to life-threatening thrombocytopenia. This hyperaggregation is avoidable if heparin is given before the hypothermia or if aspirin, alcohol or platelet transfusion is given during the hypothermia before reaching 32°C on rewarming. Many of the open questions existing in this field are explained by DRT. Prevention and treatment of DRT could be of significant value in preventing rewarming deaths and some cases of rescue collapse. Performing platelet counts during rewarming will demonstrate potentially fatal thrombocytopenia and enable treatment with platelet infusions aspirin or alcohol.

Effect of 10 Minutes of Prewarming and Prewarmed Intravenous Fluid Administration on the Core Temperature of Patients Undergoing Transurethral Surgery under General Anesthesia.

Background: Patients undergoing transurethral urologic procedures using bladder irrigation are at increased risk of perioperative hypothermia. Thirty minutes of prewarming prevents perioperative hypothermia. However, its routine application is impractical. We evaluated the effect of 10 minutes of prewarming combined with the intraoperative administration of warmed intravenous fluid on patients' core temperature. Methods: Fifty patients undergoing transurethral bladder or prostate resection under general anesthesia were included in this study and were randomly allocated to either the control group or the prewarming group. Patients in the prewarming group were warmed for 10 minutes before anesthesia induction with a forced-air warming device and received warmed intravenous fluid during operations. The patients in control group did not receive preoperative forced-air warming and were administered room-temperature fluid. Participants' core body temperature was measured on arrival at the preoperative holding area (T0), on entering the operating room, immediately after anesthesia induction, and in 10-minute intervals from then on until the end of the operation (Tend), on entering PACU, and in 10-minute intervals during the postanesthesia care unit stay. The groups' incidence of intraoperative hypothermia, change in core temperature (T0 - Tend), and postoperative thermal comfort were compared. Results: The incidence of hypothermia was 64% and 29% in the control group and prewarming group, respectively (P = 0.015). Change in core temperature was 0.93 ± 0.3 °C and 0.55 ± 0.4 °C in the control group and prewarming group, respectively (P = 0.0001). Thermal comfort was better in the prewarming group (P = 0.004). Conclusions: Ten minutes of prewarming combined with warmed intravenous fluid significantly decreased the incidence of intraoperative hypothermia and resulted in better thermal comfort in patients undergoing transurethral urologic surgery under general anesthesia.

Factors Influencing the Occurrence of Intraoperative Hypothermia in Patients Undergoing General Anesthesia Intervention: A Study in a Tertiary Care Hospital.

BACKGROUND Intraoperative and postoperative hypothermia of patients can be caused by the use of anesthetic drugs and the complicated and time-consuming procedures of interventional surgery. This retrospective study included 184 patients to investigate the incidence and factors associated with hypothermia during intraoperative anesthesia in a single center in China between January and October 2023. MATERIAL AND METHODS A convenient sampling method was used to select 184 patients who underwent general anesthesia intervention in a tertiary hospital in Sichuan Province from January to October 2023 as the study population. The independent factors influencing the occurrence of intraoperative hypothermia were analyzed. A survey was conducted to collect 5 demographic factors, 4 preoperative-related factors, and 10 surgically related factors. According to the occurrence of intraoperative hypothermia, the independent influencing factors of unplanned hypothermia during perioperative period were further analyzed. RESULTS Among 184 patients, 64 (34.78%) experienced perioperative unplanned hypothermia, of which 5 (7.81%) cases occurred before the start of surgery, 7 (10.94%) occurred before the start of surgery after anesthesia, and 52 (81.25%) occurred during surgery. Logistic regression analysis showed that body temperature at the beginning of surgery (P<0.001), set operating room temperature (P<0.001), duration of anesthesia (P=0.006), and age (P=0.001) were independent influencing factors for unplanned hypothermia during perioperative period. CONCLUSIONS The incidence of intraoperative hypothermia is high in patients undergoing general anesthesia interventions. Age, duration of anesthesia, set operating room temperature, and body temperature at the beginning of the operation were independent influencing factors for the occurrence of unplanned hypothermia during the perioperative period.

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.

A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 3: Heat and cold tolerance during exercise.

In this third installment of our four-part historical series, we evaluate contributions that shaped our understanding of heat and cold stress during occupational and athletic pursuits. Our first topic concerns how we tolerate, and sometimes fail to tolerate, exercise-heat stress. By 1900, physical activity with clothing- and climate-induced evaporative impediments led to an extraordinarily high incidence of heat stroke within the military. Fortunately, deep-body temperatures > 40 °C were not always fatal. Thirty years later, water immersion and patient treatments mimicking sweat evaporation were found to be effective, with the adage of cool first, transport later being adopted. We gradually acquired an understanding of thermoeffector function during heat storage, and learned about challenges to other regulatory mechanisms. In our second topic, we explore cold tolerance and intolerance. By the 1930s, hypothermia was known to reduce cutaneous circulation, particularly at the extremities, conserving body heat. Cold-induced vasodilatation hindered heat conservation, but it was protective. Increased metabolic heat production followed, driven by shivering and non-shivering thermogenesis, even during exercise and work. Physical endurance and shivering could both be compromised by hypoglycaemia. Later, treatments for hypothermia and cold injuries were refined, and the thermal after-drop was explained. In our final topic, we critique the numerous indices developed in attempts to numerically rate hot and cold stresses. The criteria for an effective thermal stress index were established by the 1930s. However, few indices satisfied those requirements, either then or now, and the surviving indices, including the unvalidated Wet-Bulb Globe-Thermometer index, do not fully predict thermal strain.

Impact of intraoperative hypothermia on the recovery period of anesthesia in elderly patients undergoing abdominal surgery.

BACKGROUND: This study aimed to investigate the impact of intraoperative hypothermia on the recovery period of anesthesia in elderly patients undergoing abdominal surgery. METHODS: A prospective observational study was conducted based on inclusion and exclusion criteria. A total of 384 elderly patients undergoing abdominal surgery under general anesthesia were enrolled in a grade A tertiary hospital in Chengdu, Sichuan Province from October 2021 and October 2022. After anesthesia induction, inflatable warming blankets were routinely used for active heat preservation, and nasopharyngeal temperature was monitored to observe the occurrence of intraoperative hypothermia. Patients were divided into hypothermia group and nonhypothermia group according to whether hypothermia occurred during the operation. Anesthesia recovery time and the incidence of adverse events or unwanted events during anesthesia recovery between the two groups were compared. RESULTS: The numbers (percentage) of 384 patients who underwent abdominal surgery developed intraoperative hypothermia occurred in 240 (62.5%) patients, all of whom had mild hypothermia. There were statistically significant differences between mild hypothermia after active warming and nonhypothermia in the occurrence of shivering (χ2 = 5.197, P = 0.023) and anesthesia recovery time (Z = -2.269, P = 0.02) in elderly patients undergoing abdominal surgery during anesthesia recovery, and there were no statistically significant differences in hypoxemia, nausea or vomiting, hypertension, hypokalemia, hypocalcemia, analgesic drug use,postoperative wound infection or postoperative hospitalization days. CONCLUSIONS: The incidence of intraoperative mild hypothermia after active warming was high in elderly patients who underwent abdominal surgery. Mild hypothermia increased the incidence of shivering and prolonged anesthesia recovery time in elderly patients undergoing abdominal surgery.

Effects of an early transfer from incubator to a warming crib in very low birthweight preterm infants.

PURPOSE: Very low birth weight infants are cared for postnatally in the incubator because of adverse consequences of hypothermia. Data on the optimal weight of transfer to a warming crib are rare. The aim of this study was to determine the course of temperature and body weight during a standardized transfer to a warming crib at a set weight. METHODS: Prospective intervention study in very low birthweight infants who were transferred from the incubator to a warming crib at a current weight between 1500 g and 1650 g. RESULTS: No infant had to be transferred back to an incubator. Length of hospital stay was equal compared to a historical cohort from the two years directly before the intervention. The intervention group showed an increase in the volume fed orally on the day after transfer to the warming crib, although this did not translate into an earlier discontinuation of gavage feedings. Compared to the historical group, infants in the intervention group could be transferred to an unheated crib at an earlier postmenstrual age and weight. CONCLUSIONS: Early transfer from the incubator to a warming crib between 1500 g and 1650 g is feasible and not associated with adverse short-term events or outcomes. TRIAL REGISTRATION: DRKS-IDDRKS00031832.

Incidence and risk factors of neonatal hypothermia: A systematic review and meta-analysis.

AIM: Hypothermia poses a threat to the health and lives of newborns. Therefore, it is essential to identify the factors that influence neonatal hypothermia and provide targeted intervention suggestions for clinical practice to reduce its occurrence. METHODS: We conducted a literature search to identify factors influencing neonatal hypothermia and performed a meta-analysis to determine the prevalence of neonatal hypothermia and its associated factors. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of cohort and case-control studies, while the Agency for Healthcare Research and Quality (AHRQ) was used to evaluate the quality of cross-sectional studies. RESULTS: Eighteen studies involving 44 532 newborns from 13 countries were included. The incidence of neonatal hypothermia was 52.5% (95% CI: 0.37, 0.68). Factors such as no skin-to-skin contact, prematurity, low birth weight, delayed breastfeeding, asphyxiation and resuscitation after birth, low APGAR score, not wearing a cap, and caesarean section were found to affect neonatal hypothermia. CONCLUSION: Multiple factors influence neonatal hypothermia, and clinicians can utilise these factors to develop targeted intervention measures to prevent and reduce the incidence of neonatal hypothermia.

Simulations of the human heat balance during Mount Everest summit attempts in spring and winter.

The majority of research dealing with the impacts of the Himalayan climate on human physiology focuses on low air temperature, high wind speed, and low air pressure and oxygen content, potentially leading to hypothermia and hypoxia. Only a few studies describe the influence of the weather conditions in the Himalayas on the body's ability to maintain thermal balance. The aim of the present research is to trace the heat exchange between humans and their surroundings during a typical, 6-day summit attempt of Mount Everest in the spring and winter seasons. Additionally, an emergency night outdoors without tent protection is considered. Daily variation of the heat balance components were calculated by the MENEX_HA model using meteorological data collected at automatic weather stations installed during a National Geographic expedition in 2019-2020. The data represent the hourly values of the measured meteorological parameters. The research shows that in spite of extreme environmental conditions in the sub-summit zone of Mount Everest during the spring weather window, it is possible to keep heat equilibrium of the climbers' body. This can be achieved by the use of appropriate clothing and by regulating activity level. In winter, extreme environmental conditions in the sub-summit zone make it impossible to maintain heat equilibrium and lead to hypothermia. The emergency night in the sub-peak zone leads to gradual cooling of the body which in winter can cause severe hypothermia of the climber's body. At altitudes < 7000 m, climbers should consider using clothing that allows variation of insulation and active regulation of their fit around the body.

A Warm Air Blanket is Superior to a Heated Mattress in Preventing Perioperative Hypothermia in Orthopedic Arthroplasties, a Time-Series Analyses.

BACKGROUND: Hypothermia is a common perioperative problem that can lead to severe complications. We evaluated whether a heated mattress (HM) is superior to a warm air blanket (WA) in preventing perioperative hypothermia in patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA). METHODS: A retrospective cohort study was performed in a teaching hospital and data were collected for all patients undergoing THA or TKA between January 1, 2015 and May 1, 2022. We used logistic and linear regressions to analyze hypothermia occurrence and important complications. Results were adjusted for confounders and time, and was present in all subgroups and after imputation of missing data. RESULTS: In total, 4,683 of 5,497 patients had information on type of heating. We found more perioperative hypothermia in patients treated with an HM compared to a WA for both THA (odds ratio-adjusted 1.42 [1.0 to 1.6] P = .06) and TKA (odds ratio-adjusted 2.10 [1.5 to 3.0] P < .01). There was no difference in postoperative infections between groups (all between 0.5% and 1.3%). Patients who had an HM significantly stayed longer in the postoperative ward (a mean difference of 4 [TKA] to 6 [THA] minutes, P < .01), but there was no difference in hospital stay. CONCLUSION: A WA is superior compared to an HM in preventing perioperative hypothermia, with no increased risk of complications. Patients who have an HM stayed longer at the postoperative ward, potentially because of higher hypothermia rates. Therefore, it is suggested to use a WA instead of an HM.

Clinical Characteristics, Etiology, and Outcomes of Hypothermia in Well-appearing Children Referred to the Emergency Department.

BACKGROUND: Hypothermia, as a sign of serious bacterial infection (SBI) in children and infants older than 90 days is poorly characterized, especially in the post-pneumococcal vaccine era. OBJECTIVES: To assess the prevalence of SBI in children and infants presenting to the pediatric emergency department (PED) with reported or documented hypothermia. METHODS: Retrospective data analysis was conducted of all well-appearing children aged 0-16 years who presented with a diagnosis of hypothermia at two tertiary PEDs from 2010 to 2019. RESULTS: The study comprised 99 children, 15 (15.2%) age 0-3 months, 71 (71.7%) 3-36 months, and 13 (13.1%) > 36 months. The youngest age group had increased length of stay in the hospital (P < 0.001) and increased rates of pediatric intensive care unit admissions (P < 0.001). Empirical antibiotic coverage was initiated in 80% of the children in the 0-3 months group, 21.1% in the 3-36 months group, and 15.4% in > 36 months (P < 0.001). Only one case of SBI was recorded and no bacteremia or meningitis. Hypothermia of unknown origin was the most common diagnosis in all age groups (34%, 42%, 46%), respectively, followed by bronchiolitis (26%) and hypoglycemia (13.3%) for 0-3 month-old children, unspecified viral infection (20%) and otitis media (7%) for 3-36-month old, and unspecified viral infection (23%) and alcohol intoxication (15.2%) in > 36 months. CONCLUSIONS: There is a low incidence of SBI in well-appearing children presenting to the PED with hypothermia and a benign course and outcome in those older than 3 months.

Effects of Heated Infiltration Solutions and Forced-Air Heating Blankets on Intraoperative Hypothermia During Liposuction: A Factorial Randomized Controlled Trial.

BACKGROUND: This study was conducted to compare the effects of heat preservation by two recommended methods, heated infiltration solutions and forced-air heating blankets, in patients undergoing liposuction under general anesthesia. METHODS: Forty patients were divided into four groups based on whether heated infiltration solutions or forced-air heating blankets were used. Group A received general anesthesia liposuction plastic surgery routine temperature care. Based on the care measures of group A, heated infiltration solutions were used in group B; forced-air heating blanket was used in group C; and heated infiltration solutions and forced-air heating blankets were both used in group D. The primary end point was intraoperative and perioperative temperature measured with an infrared tympanic membrane thermometer. Secondary end points included surgical outcomes, subjective experience, and adverse events. RESULTS: Compared with group A, the intraoperative body temperatures of groups B, C, and D were significantly higher, indicating that the two intervention methods were helpful on increasing the core body temperature. Pairwise comparisons of these three groups showed that there was no significant difference between group C and group D. However, using forced-air heating blankets had a marked effect compared with using heated infiltration solutions alone at three time points. The same trend could be seen in other surgical outcomes. CONCLUSIONS: Heated infiltration solutions and forced-air heating blankets could reduce the incidence of intraoperative hypothermia and improve patients' prognosis after liposuction under general anesthesia. Compared with the heated infiltration fluid, the forced-air heating blanket may have a better thermal insulation effect. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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.

The Effect of Warmed Serum on Shivering and Recovery Period of Patients Under General and Spinal Anesthesia: A Randomized Clinical Trial.

PURPOSE: Postoperative hypothermia followed by shivering is a common phenomenon in patients undergoing surgery under anesthesia, and should be prevented and treated in postoperative patient care units. This study was conducted to investigate the effect of warmed serum injection on postoperative shivering and recovery period of patients operated under general and spinal anesthesia. DESIGN: In this clinical trial, patients to be operated on under general and spinal anesthesia were randomly assigned into two groups of test and control. In the test group, patients received warmed intravenous fluids and blood products. All patients were monitored to record vital signs, incidences of hypothermia and shivering, and recovery period. METHODS: The collected data were analyzed with repeated measures analysis of variance to detect significant differences between groups and significant changes within groups over time. FINDINGS: The incidence of nausea, vomiting, and shivering in the intervention and control groups was (4.7%, 42%), (2.8%, 16.8%), and (6.6%, 43%), respectively. Patients in the intervention group had higher body temperature than the control group (<0.001). Also, patients under spinal anesthesia had higher body temperature than patients under general anesthesia (<0.001). Blood pressure reduction was also significantly higher in the control group than in the intervention group. The patients who received warm intravenous serum, and especially those who had received spinal anesthesia spent less time in the recovery room (<0.001). CONCLUSIONS: The use of warmed intravenous serum increased the patients' core temperature, reduced their postoperative shivering, and shortened their recovery period. Considering the potential risks associated with hypothermia, using such methods for hypothermia prevention can be highly effective in preventing shivering and prolongation of the recovery period and other potential complications. Anesthesia specialists and technicians are therefore encouraged to use this method as a preventive measure.

[Association between intraoperative hypothermia and outcomes in neonatal patients undergoing non-cardiac surgery].

Objective: To investigate the impact of intraoperative hypothermia on postoperative outcome in neonatal patients undergoing non-cardiac surgery. Methods: The data of 1 008 neonates undergoing non-cardiac surgery in Children's Hospital, Zhejiang University School of Medicine from January 2020 to October 2022 were retrospectively collected,which included 558 males and 450 females, with a midian age [M (Q1, Q3)] of 6 (2, 14) days. Neonates were divided into 4 groups according to whether hypothermia (below 36 ℃) occurred and the lowest body temperature during the surgery: normal temperature group (n=246), mild hypothermia group (the lowest temperature ranged 35.0-35.9 ℃, n=434), moderate hypothermia group (the lowest temperature ranged 34.0-34.9 ℃, n=232) and severe hypothermia group (the lowest temperature<34 ℃, n=96). The primary outcome was the incidence of intraoperative hypothermia. The four groups' difference of postoperative hospital stay, postoperative mortality within 30 days, postoperative pulmonary complications, postoperative hemorrhage/blood transfusion and acidosis were compared. Multivariate logistic regression was used to analyze the relationship between intraoperative hypothermia and prolonged postoperative hospital stay (>14 d), 30 d-mortality and other complications. Results: In the 1 008 neonatal patients, 762 (75.6%) cases suffered intraoperative hypothermia, among which the incidence of mild, moderate and severe hypothermia was 43.1% (434/1008), 23.0% (232/1008) and 9.5% (96/1008), respectively. The postoperative hospital stay in normal, mild, moderate and severe hypothermia groups was 9.0 (5.8, 18.0), 12.0 (7.0, 21.0), 17.0 (10.0, 34.5) and 31.5 (12.5, 55.8) days. The mortality rate with 30 days after surgery was 2.9% (7/246), 4.4% (19/434), 6.9% (16/232) and 14.7% (14/96), the incidence of postoperative pulmonary complications was 31.7%(78/246), 39.9%(173/434), 44.8%(104/232) and 67.4%(64/96), the rate of postoperative hemorrhage/blood transfusion was 19.9%(49/246), 32.3%(140/434), 49.1%(114/232) and 79.0%(75/96), and the incidence of acidosis was 26.8%(66/246), 35.7%(155/434), 44.4%(103/232) and 46.3%(44/96), respectively. All differences were statistically significant (all P<0.05). According to the adjusted logistic regression analysis, compared with the normal body temperature group, severe hypothermia was associated with prolonged postoperative hospital stay (OR=1.962, 95%CI: 1.063-3.619) and postoperative pulmonary complications (OR=2.020, 95%CI: 1.149-3.553). The mild, moderate and severe hypothermia group could increase the risk of postoperative blood/transfusion rate (mild: OR=1.690, 95%CI: 1.080-2.644; Moderate: OR=2.382, 95%CI: 1.444-3.927; Severe: OR=8.334, 95%CI: 3.123-8.929). The mild and moderate hypothermia could raise the risk of acidosis (mild: OR=1.458, 95%CI: 1.009-2.107; Moderate: OR=1.949, 95%CI: 1.279-2.972). Conclusion: Intraoperative hypothermia can prolong the postoperative hospital stay, and increase the risk of postoperative mortality, postoperative pulmonary complications, postoperative hemorrhage/transfusion, and acidosis.

The Effect of Brief Warming during Induction of General Anesthesia and Warmed Intravenous Fluid on Intraoperative Hypothermia in Patients Undergoing Urologic Surgery.

Background and Objectives: Transurethral urologic surgeries frequently lead to hypothermia due to bladder irrigation. Prewarming in the preoperative holding area can reduce the risk of hypothermia but disrupts surgical workflow, preventing it from being of practical use. This study explored whether early intraoperative warming during induction of anesthesia, known as peri-induction warming, using a forced-air warming device combined with warmed intravenous fluid could prevent intraoperative hypothermia. Materials and Methods: Fifty patients scheduled for transurethral resection of the bladder (TURB) or prostate (TURP) were enrolled and were randomly allocated to either the peri-induction warming or control group. The peri-induction warming group underwent whole-body warming during anesthesia induction using a forced-air warming device and was administered warmed intravenous fluid during surgery. In contrast, the control group was covered with a cotton blanket during anesthesia induction and received room-temperature intravenous fluid during surgery. Core temperature was measured upon entrance to the operating room (T0), immediately after induction of anesthesia (T1), and in 10 min intervals until the end of the operation (Tend). The incidence of intraoperative hypothermia, change in core temperature (T0-Tend), core temperature drop rate (T0-Tend/[duration of anesthesia]), postoperative shivering, and postoperative thermal comfort were assessed. Results: The incidence of intraoperative hypothermia did not differ significantly between the two groups. However, the peri-induction warming group exhibited significantly less change in core temperature (0.61 ± 0.3 °C vs. 0.93 ± 0.4 °C, p = 0.002) and a slower core temperature drop rate (0.009 ± 0.005 °C/min vs. 0.013 ± 0.004 °C/min, p = 0.013) than the control group. The peri-induction warming group also reported higher thermal comfort scores (p = 0.041) and less need for postoperative warming (p = 0.034) compared to the control group. Conclusions: Brief peri-induction warming combined with warmed intravenous fluid was insufficient to prevent intraoperative hypothermia in patients undergoing urologic surgery. However, it improved patient thermal comfort and mitigated the absolute amount and rate of temperature drop.

Aggressive intraoperative warming versus routine thermal management during non-cardiac surgery (PROTECT): a multicentre, parallel group, superiority trial.

BACKGROUND: Moderate intraoperative hypothermia promotes myocardial injury, surgical site infections, and blood loss. Whether aggressive warming to a truly normothermic temperature near 37°C improves outcomes remains unknown. We aimed to test the hypothesis that aggressive intraoperative warming reduces major perioperative complications. METHODS: In this multicentre, parallel group, superiority trial, patients at 12 sites in China and at the Cleveland Clinic in the USA were randomly assigned (1:1) to receive either aggressive warming to a target core temperature of 37°C (aggressively warmed group) or routine thermal management to a target of 35·5°C (routine thermal management group) during non-cardiac surgery. Randomisation was stratified by site, with computer-generated, randomly sized blocks. Eligible patients (aged ≥45 years) had at least one cardiovascular risk factor, were scheduled for inpatient non-cardiac surgery expected to last 2-6 h with general anaesthesia, and were expected to have at least half of the anterior skin surface available for warming. Patients requiring dialysis and those with a body-mass index exceeding 30 kg/m2 were excluded. The primary outcome was a composite of myocardial injury (troponin elevation, apparently of ischaemic origin), non-fatal cardiac arrest, and all-cause mortality within 30 days of surgery, as assessed in the modified intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT03111875. FINDINGS: Between March 27, 2017, and March 16, 2021, 5056 participants were enrolled, of whom 5013 were included in the intention-to-treat population (2507 in the aggressively warmed group and 2506 in the routine thermal management group). Patients assigned to aggressive warming had a mean final intraoperative core temperature of 37·1°C (SD 0·3) whereas the routine thermal management group averaged 35·6°C (SD 0·3). At least one of the primary outcome components (myocardial injury after non-cardiac surgery, cardiac arrest, or mortality) occurred in 246 (9·9%) of 2497 patients in the aggressively warmed group and in 239 (9·6%) of 2490 patients in the routine thermal management group. The common effect relative risk of aggressive versus routine thermal management was an estimated 1·04 (95% CI 0·87-1·24, p=0·69). There were 39 adverse events in patients assigned to aggressive warming (17 of which were serious) and 54 in those assigned to routine thermal management (30 of which were serious). One serious adverse event, in an aggressively warmed patient, was deemed to be possibly related to thermal management. INTERPRETATION: The incidence of a 30-day composite of major cardiovascular outcomes did not differ significantly in patients randomised to 35·5°C and to 37°C. At least over a 1·5°C range from very mild hypothermia to full normothermia, there was no evidence that any substantive outcome varied. Keeping core temperature at least 35·5°C in surgical patients appears sufficient. FUNDING: 3M and the Health and Medical Research Fund, Food and Health Bureau, Hong Kong. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

The effect of combining prewarming with intraoperative phenylephrine infusion on the prevention of hypothermia in patients undergoing urological surgery: a prospective, randomized, and controlled trial.

Background: Hypothermia is common in patients undergoing urological surgery; however, no single preventative modality is completely effective. This study evaluated the effects of combining prewarming with intraoperative phenylephrine infusion for the prevention of hypothermia in patients undergoing urological surgery. Methods: This prospective study enrolled 58 patients scheduled for urological surgery under general anesthesia. The patients were randomized into two groups (n = 29). Patients in the experimental (prewarming and phenylephrine infusion) group (PP group) received prewarming for 20 min and intraoperative phenylephrine infusion, whereas those in the control group (C group) received no active prewarming with only intermittent administration of vasoactive agents. The patient's sublingual temperatures before and after anesthesia and nasopharyngeal temperature during anesthesia were recorded as core temperatures. Results: The incidence of intraoperative hypothermia was higher in the C group than in the PP group (57.7% [15/26] vs. 23.1% [6/26], P = 0.01). The severity of intraoperative hypothermia was higher in the C group than in the PP group (P = 0.004). The nasopharyngeal temperature at the end of surgery was lower in the C group than in the PP group (35.8 ± 0.6°C vs. 36.3 ± 0.4°C, P = 0.002). The trend of core temperature decline during the first hour after anesthesia induction differed between the two groups (P = 0.003; its decline was more gradual in the PP group). Conclusions: The combination of prewarming for 20 min and intraoperative phenylephrine infusion reduced the incidence and severity of intraoperative hypothermia and modified the trend of decreasing core temperatures in patients undergoing urological surgery.

Rewarming Young Children After Drowning-Associated Hypothermia and Out-of-Hospital Cardiac Arrest: Analysis Using the CAse REport Guideline.

OBJECTIVES: Extracorporeal membrane oxygenation (ECMO) is recommended in adults with drowning-associated hypothermia and out-of-hospital cardiac arrest (OHCA). Our experience of managing a drowned 2-year-old girl with hypothermia (23°C) and cardiac arrest (58 min) prompted this summary using the CAse REport (CARE) guideline to address the question of optimal rewarming procedure in such patients. DESIGN/PATIENTS: Following the CARE guideline, we identified 24 reports in the "PubMed database" describing children less than or equal to 6 years old with a temperature less than or equal to 28°C who had been rewarmed using conventional intensive care ± ECMO. Adding our patient, we were able to analyze a total of 57 cases. MAIN RESULTS: The two groups (ECMO vs non-ECMO) differed with respect to submersion time, pH and potassium but not age, temperature or duration of cardiac arrest. However, 44 of 44 in the ECMO group were pulseless on arrival versus eight of 13 in the non-ECMO group. Regarding survival, 12 of 13 children (92%) undergoing conventional rewarming survived compared with 18 of 44 children (41%) undergoing ECMO. Among survivors, 11 of 12 children (91%) in the conventional group and 14 of 18 (77%) in the ECMO group had favorable outcome. We failed to identify any correlation between "rewarming rate" and "outcome." CONCLUSIONS: In this summary analysis, we conclude that conventional therapy should be initiated for drowned children with OHCA. However, if this therapy does not result in return of spontaneous circulation, a discussion of withdrawal of intensive care might be prudent when core temperature has reached 34°C. We suggest further work is needed using an international registry.