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

How three linked clinical observations led to an understanding of perioperative heat balance: A personal reflection on the scientific process

Three linked clinical observations prompted our current understanding of perioperative heat balance. The first was the extraordinarily rapid decrease in core temperature after induction of general anesthesia which led to an understanding of redistribution hypothermia. The second was the linear reduction in core temperature during the subsequent 2-3 h which led to an understanding of anesthetic effects on metabolic heat production and factors that influence cutaneous heat loss. And the third was the observation that core temperature reaches a plateau at about 34.5 °C which led to the understanding that thermoregulatory vasoconstriction re-emerges when patients become sufficiently hypothermic, and that arteri-venous shunt constriction constrains metabolic heat to the core thermal compartment.

Efficacy of a single low dose of esketamine after childbirth for mothers with symptoms of prenatal depression: randomised clinical trial

OBJECTIVE

To determine whether a single low dose of esketamine administered after childbirth reduces postpartum depression in mothers with prenatal depression.

DESIGN

Randomised, double blind, placebo controlled trial with two parallel arms.

SETTING

Five tertiary care hospitals in China, 19 June 2020 to 3 August 2022.

PARTICIPANTS

364 mothers aged ≥18 years who had at least mild prenatal depression as indicated by Edinburgh postnatal depression scale scores of ≥10 (range 0-30, with higher scores indicating worse depression) and who were admitted to hospital for delivery.

INTERVENTIONS

Participants were randomly assigned 1:1 to receive either 0.2 mg/kg esketamine or placebo infused intravenously over 40 minutes after childbirth once the umbilical cord had been clamped.

MAIN OUTCOME MEASURES

The primary outcome was prevalence of a major depressive episode at 42 days post partum, diagnosed using the mini-international neuropsychiatric interview. Secondary outcomes included the Edinburgh postnatal depression scale score at seven and 42 days post partum and the 17 item Hamilton depression rating scale score at 42 days post partum (range 0-52, with higher scores indicating worse depression). Adverse events were monitored until 24 hours after childbirth.

RESULTS

A total of 364 mothers (mean age 31.8 (standard deviation 4.1) years) were enrolled and randomised. At 42 days post partum, a major depressive episode was observed in 6.7% (12/180) of participants in the esketamine group compared with 25.4% (46/181) in the placebo group (relative risk 0.26, 95% confidence interval (CI) 0.14 to 0.48; P<0.001). Edinburgh postnatal depression scale scores were lower in the esketamine group at seven days (median difference -3, 95% CI -4 to -2; P<0.001) and 42 days (-3, -4 to -2; P<0.001). Hamilton depression rating scale scores at 42 days post partum were also lower in the esketamine group (-4, -6 to -3; P<0.001). The overall incidence of neuropsychiatric adverse events was higher in the esketamine group (45.1% (82/182) v 22.0% (40/182); P<0.001); however, symptoms lasted less than a day and none required drug treatment.

CONCLUSIONS

For mothers with prenatal depression, a single low dose of esketamine after childbirth decreases major depressive episodes at 42 days post partum by about three quarters. Neuropsychiatric symptoms were more frequent but transient and did not require drug intervention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04414943.

Construct validation of machine learning for accurately predicting the risk of postoperative surgical site infection following spine surgery

BACKGROUND

This study aimed to evaluate the risk factors for machine learning (ML) algorithms in predicting postoperative surgical site infection (SSI) following spine surgery.

METHODS

This prospective cohort study included 986 patients who underwent spine surgery at Taizhou People's Hospital Affiliated to Nanjing Medical University from January 2015 to October 2022. Supervised ML algorithms included support vector machine, logistic regression, random forest, XGboost, decision tree, k-nearest neighbour, and naïve Bayes (NB), which were tested and trained to develop a predicting model. The ML model performance was evaluated from the test dataset. We gradually analysed their accuracy, sensitivity, and specificity, as well as the positive predictive value, negative predictive value, and area under the curve.

RESULTS

The rate of SSI was 9.33%. Using a backward stepwise approach, we identified that the remarkable risk factors predicting SSI in the multi-variate Cox regression analysis were age, body mass index, smoking, cerebrospinal fluid leakage, drain duration and pre-operative albumin level. Compared with other ML algorithms, the NB model had the highest performance in seven ML models, with an average area under the curve of 0.95, sensitivity of 0.78, specificity of 0.88, and accuracy of 0.87.

CONCLUSIONS

The NB model in the ML algorithm had excellent calibration and accurately predicted the risk of SSI compared with the existing models, and might serve as an important tool for the early detection and treatment of SSI following spinal infection.

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.

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.

Estimation of the contribution to intraoperative pathogen transmission from bacterial contamination of patient nose, patient groin and axilla, anesthesia practitioners' hands, anesthesia machine, and intravenous lumen

BACKGROUND

Earlier studies showed net cost saving from anesthesia practitioners' use of a bundle of infection prevention products, with feedback on monitored Staphylococcus aureus intraoperative transmission. ESKAPE pathogens also include Enterococcus and gram-negative pathogens: Klebsiella, Acinetobacter, Pseudomonas, and Enterobacter. We evaluated whether bacterial contamination of patient nose, patient groin and axilla, anesthesia practitioners' hands, anesthesia machine, and intravenous lumen all contribute meaningfully to ESKAPE pathogen transmission within anesthesia work areas.

METHODS

The retrospective cohort study used bacterial count data from nine hospitals, 43 months, and 448 ESKAPE pathogen transmission events within anesthesia areas of 86 operating rooms. Transmission was measured within and between pairs of successive surgical cases performed in the same operating room on the same day.

RESULTS

There were 203 transmission events with S. aureus, 72 with Enterococcus, and 173 with gram negatives. ESKAPE pathogens in the nose contributed to transmission for 50% (99% confidence limit ≥45%) of case pairs, on the groin or axilla for 54% (≥49%), on the hands for 53% (≥47%), on the anesthesia machine for 21% (≥17%), and in the intravenous lumen for 24% (≥20%). ESKAPE pathogens in the nose started a transmission pathway for 27% (≥22%) of case pairs, on the groin or axilla for 24% (≥19%), on the hands for 38% (≥33%), on the anesthesia machine for 11% (≥7.6%), and in the intravenous lumen for 8.0% (≥5.3%). All P ≤ 0.0022 compared with 5%.

CONCLUSIONS

To prevent intraoperative ESKAPE pathogen transmission, anesthesia practitioners would need to address all five categories of infection control approaches: nasal antisepsis (e.g., povidone-iodine applied the morning of surgery), skin antisepsis (e.g., chlorhexidine wipes), hand antisepsis with dispensers next to the patient, decontamination of the anesthesia machine before and during anesthetics, and disinfecting caps for needleless connectors, disinfecting port protectors, and disinfecting caps for open female Luer type connectors.

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.

Inadvertent perioperative hypothermia and surgical site infections after liver resection

BACKGROUND

In the overall surgical population, inadvertent perioperative hypothermia has been associated with an increased incidence of surgical site infection (SSI). However, recent clinical trials did not validate this notion. This study aimed to investigate the potential correlation between inadvertent perioperative hypothermia and SSIs following liver resection.

METHODS

This retrospective cohort study included all consecutive patients who underwent liver resection between January 2019 and December 2021 at the First Affiliated Hospital, Zhejiang University School of Medicine. Perioperative temperature managements were implemented for all patients included in the analysis. Estimated propensity score matching (PSM) was performed to reduce the baseline imbalances between the normothermia and hypothermia groups. Before and after PSM, univariate analyses were performed to evaluate the correlation between hypothermia and SSI. Multivariate regression analysis was performed to determine whether hypothermia was an independent risk factor for postoperative transfusion and major complications. Subgroup analyses were performed for diabetes mellitus, age > 65 years, and major liver resection.

RESULTS

Among 4000 patients, 2206 had hypothermia (55.2%), of which 150 developed SSI (6.8%). PSM yielded 1434 individuals in each group. After PSM, the hypothermia and normothermia groups demonstrated similar incidence rates of SSI (6.3% vs. 7.0%, P = 0.453), postoperative transfusion (13.3% vs. 13.7%, P = 0.743), and major complications (9.0% vs. 10.1%, P = 0.309). Univariate regression analysis revealed no significant effects of hypothermia on the incidence of SSI in the group with the highest hypothermia exposure [odds ratio (OR) = 1.25, 95% confidence interval (CI): 0.84-1.87, P = 0.266], the group with moderate exposure (OR = 1.00, 95% CI: 0.65-1.53, P = 0.999), or the group with the lowest exposure (OR = 1.11, 95% CI: 0.73-1.65, P = 0.628). The subgroup analysis revealed similar results. Regarding liver function, patients in the hypothermia group demonstrated lower γ-glutamyl transpeptidase (37 vs. 43 U/L, P = 0.001) and alkaline phosphatase (69 vs. 72 U/L, P = 0.016). However, patients in the hypothermia group exhibited prolonged activated partial thromboplastin time (29.2 vs. 28.6 s, P < 0.01).

CONCLUSIONS

In our study of patients undergoing liver resection, we found no significant association between mild perioperative hypothermia and SSI. It might be due to the perioperative temperature managements, especially active warming measures, which limited the impact of perioperative hypothermia on the occurrence of SSI.

Factors associated with surgical site infection in myocardial revascularization: a retrospective longitudinal study

OBJECTIVES

to analyze the influence of sociodemographic and clinical variables, as well as the surgical checklist adherence score, on the occurrence of surgical site infection among patients undergoing myocardial revascularization.

METHODS

an observational, longitudinal, retrospective study was conducted at a university hospital, involving 266 medical records of patients who underwent myocardial revascularization surgery. Instruments containing sociodemographic, clinical, and infection-related variables were used, along with the Perioperative Surgical Safety Checklist. Descriptive, bivariate, and logistic regression analyses were employed.

RESULTS

surgical site infection occurred in 89 (33.5%) patients. There was a statistically significant association between body temperature outside the range of 36 degrees Celsius to 36.5 degrees Celsius (p=0.01), the presence of invasive devices (p=0.05), surgical procedures with the anticipation of critical events (p<0.001), and the occurrence of infection.

CONCLUSIONS

body temperature, the presence of invasive devices, and surgical procedures with the anticipation of critical events were significant factors contributing to an increased risk of infection.

Droperidol lowers the shivering threshold in rabbits

PURPOSE

Perioperative shivering is common and can occur as a result of hypothermia or changes in the threshold of thermoregulation. Droperidol usage for anesthesia is currently limited to its sedative and antiemetic effects. We investigated the effects of high and low doses of droperidol on the shivering threshold in rabbits.

METHODS

Forty-two male Japanese white rabbits were anesthetized with isoflurane and randomly assigned to the control, high-dose, or low-dose group. Rabbits in the high-dose group received a 5 mg/kg droperidol bolus followed by continuous infusion at 5 mg/kg/h, those in the low-dose group received a 0.5 mg/kg droperidol bolus, and those in the control group received the same volume of saline as the high-dose group. Body temperature was reduced at a rate of 2-3 °C/h, and the shivering threshold was defined as the subject's core temperature (°C) at the onset of shivering.

RESULTS

The shivering thresholds in the control, high-dose, and low-dose groups were 38.1 °C ± 1.1 °C, 36.7 °C ± 1.2 °C, and 36.9 °C ± 1.0 °C, respectively. The shivering thresholds were significantly lower in the high-dose and low-dose groups than in the control group (P < 0.01). The thresholds were comparable between the high-dose and low-dose groups.

CONCLUSIONS

Droperidol in high and low doses effectively reduced the shivering threshold in rabbits. Droperidol has been used in low doses as an antiemetic. Low doses of droperidol can reduce the incidence of shivering perioperatively and during the induction of therapeutic hypothermia.

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.

Perioperative hypothermia prevention: development of simple principles and practice recommendations using a multidisciplinary consensus-based approach

OBJECTIVES

To develop a consensus on evidence-based principles and recommendations for perioperative hypothermia prevention in the Australian context.

DESIGN

This study was informed by CAN-IMPLEMENT using the ADAPTE process: (1) formation of a multidisciplinary development team; (2) systematic search process identifying existing guidance for perioperative hypothermia prevention; (3) appraisal using the AGREE II Rigor of Development domain; (4) extraction of recommendations from guidelines meeting a quality threshold using the AGREE-REX tool; (5) review of draft principles and recommendations by multidisciplinary clinicians nationally and (6) subsequent round of discussion, drafting, reflection and revision by the original panel member team.

SETTING

Australian perioperative departments.

PARTICIPANTS

Registered nurses, anaesthetists, surgeons and anaesthetic allied health practitioners.

RESULTS

A total of 23 papers (12 guidelines, 6 evidence summaries, 3 standards, 1 best practice sheet and 1 evidence-based bundle) formed the evidence base. After evidence synthesis and development of draft recommendations, 219 perioperative clinicians provided feedback. Following refinement, three simple principles for perioperative hypothermia prevention were developed with supporting practice recommendations: (1) actively monitor core temperature for all patients at all times; (2) warm actively to keep body temperature above 36°C and patients comfortable and (3) minimise exposure to cold at all stages of perioperative care.

CONCLUSION

This consensus process has generated principles and practice recommendations for hypothermia prevention that are ready for implementation with local adaptation. Further evaluation will be undertaken in a large-scale implementation trial across Australian hospitals.

Accuracy of a Dual-Sensor Heat-Flux (DHF) Non-Invasive Core Temperature Sensor in Pediatric Patients Undergoing Surgery

Accurate temperature measurement is crucial for the perioperative management of pediatric patients, and non-invasive thermometry is necessary when invasive methods are infeasible. A prospective observational study was conducted on 57 patients undergoing elective surgery. Temperatures were measured using a dual-sensor heat-flux (DHF) thermometer (Tcore™) and a rectal temperature probe (TRec), and the agreement between the two measurements was assessed. The DHF measurements showed a bias of +0.413 °C compared with those of the TRec. The limits of agreement were broader than the pre-defined ±0.5 °C range (-0.741 °C and +1.567 °C). Although the DHF sensors tended to overestimate the core temperature compared to the rectal measurements, an error grid analysis demonstrated that 95.81% of the DHF measurements would not have led to a wrong clinical decision, e.g., warming or cooling when not necessary. In conclusion, the low number of measurements that would have led to incorrect decisions suggests that the DHF sensor can be considered an option for continuous temperature measurement when more invasive methods are infeasible.

Analysis of hospital and payer costs of care: aggressive warming versus routine warming in abdominal major surgery

Background

Hypothermia is common and active warming is recommended in major surgery. The potential effect on hospitals and payer costs of aggressive warming to a core temperature target of 37°C is poorly understood.

Methods

In this sub-analysis of the PROTECT trial (clinicaltrials.gov, NCT03111875), we included patients who underwent radical procedures of colorectal cancer and were randomly assigned to aggressive warming or routine warming. Perioperative outcomes, operation room (OR) scheduling process, internal cost accounting data from the China Statistical yearbook (2022), and price lists of medical and health institutions in Beijing were examined. A discrete event simulation (DES) model was established to compare OR efficiency using aggressive warming or routine warming in 3 months. We report base-case net costs and sensitivity analyses of intraoperative aggressive warming compared with routine warming. Costs were calculated in 2022 using US dollars (USD).

Results

Data from 309 patients were analyzed. The aggressive warming group comprised 161 patients and the routine warming group comprised 148 patients. Compared to routine warming, there were no differences in the incidence of postoperative complications and total hospitalization costs of patients with aggressive warming. The potential benefit of aggressive warming was in the reduced extubation time (7.96 ± 4.33 min vs. 10.33 ± 5.87 min, p < 0.001), lower incidence of prolonged extubation (5.6% vs. 13.9%, p = 0.017), and decreased staff costs. In the DES model, there is no add-on or cancelation of operations performed within 3 months. The net hospital costs related to aggressive warming were higher than those related to routine warming in one operation (138.11 USD vs. 72.34 USD). Aggressive warming will have an economic benefit when the OR staff cost is higher than 2.37 USD/min/person, or the cost of disposable forced-air warming (FAW) is less than 12.88 USD/piece.

Conclusion

Despite improving OR efficiency, the economic benefits of aggressive warming are influenced by staff costs and the cost of FAW, which vary from different regions and countries.

Clinical trial registration

clinicaltrials.gov, identifier (NCT03111875).

High levels of high-sensitivity C reactive protein to albumin ratio can increase the risk of cardiovascular disease

BACKGROUND

The high levels of C reactive protein (CRP) to albumin ratio (CAR) is thought to increase the risk of poor outcomes for cancer and cardiovascular disease (CVD). However, the association between CAR and CVD in the Chinese community population has not been investigated.

OBJECTIVE

The aim of this study was to investigate the association between CAR and CVD in the Chinese community population.

METHODS

A total of 62 067 participants without a history of CVD or cancer were included in this study. Kaplan-Meier survival curves were used to calculate the cumulative incidence of endpoint events in CAR quartile groups, and the results were tested by log-rank test. Fine-Gray model was used to analyse the competing risk of death. C-index, Net Reclassification Index (NRI) and Integrated Discrimination Improvement Index (IDI) of different indicators were calculated to distinguish the predictive performance of different indicators.

RESULTS

During an average follow-up period of 10.3±2.1 years, 4025 participants developed CVD. In multivariable Cox regression analysis, compared with Q1 group, model 3 showed that the hazard ratio (HR) (95% confidence interval (95%CI)) of CVD in Q4 group was 1.26 (1.15 to 1.38) (p<0.01), and the HR (95% CI) per 1 SD increase was 1.06 (1.03 to 1.08) (p<0.01). The C-index, continuous NRI and IDI for predicting 10-year CVD were 73.48%, 0.1366 (0.1049 to 0.1684) (p<0.01) and 0.0002 (0.0001 to 0.0004) (p<0.01), respectively, which were higher than those of hs-CRP (C-index:0.7344, NRI:0.0711, IDI: 0.0001) and albumin (C-index:0.7339, NRI: -0.0090, IDI: 0.0000).

CONCLUSION

High levels of CAR can increase the risk of CVD and the predictive performance of CAR for CVD is better than that of hs-CRP or albumin alone.

Construction and validation of a risk prediction model for intraoperative hypothermia in elderly patients undergoing total hip arthroplasty

AIMS

To construct and validate an intraoperative hypothermia risk prediction model for elderly patients undergoing total hip arthroplasty (THA).

METHODS

We collected data from 718 patients undergoing THA in a tertiary hospital from January 2021 to December 2022. Of these patients, 512 were assigned to the modeling group from January 2021 to April 2022, and 206 participants were assigned to the validation group from May 2022 to December 2022. A logistic regression analysis was performed to construct the model. The area under the curve (AUC) was used to test the model's predictive ability.

RESULTS

The incidence rate of intraoperative hypothermia was 51.67%. The risk factors entered into the risk prediction model were age, preoperative hemoglobin level, intraoperative blood loss, postoperative hemoglobin level, and postoperative systolic blood pressure. The model was constructed as follows: logit (P) = - 10.118 + 0.174 × age + 1.366 × 1 (preoperative hemoglobin level) + 0.555 × 1 (postoperative hemoglobin level) + 0.009 × 1 (intraoperative blood loss) + 0.066 × 1 (postoperative systolic blood pressure). Using the Hosmer-Lemeshow test, the P value was 0.676 (AUC, 0.867). The Youden index, sensitivity, and specificity were 0.602, 0.790, and 0.812, respectively. The incidence rates of intraoperative hypothermia in the modeling and validation groups were 53.15% and 48.06%, respectively. The correct practical application rate was 89.81%. This model had good application potential.

CONCLUSIONS

This risk prediction model has good predictive value and can accurately predict the occurrence of intraoperative hypothermia in patients who undergo THA, which provides reliable guidance for clinical work and has good clinical application value.

Continuous Finger-cuff versus Intermittent Oscillometric Arterial Pressure Monitoring and Hypotension during Induction of Anesthesia and Noncardiac Surgery: The DETECT Randomized Trial

BACKGROUND

Finger-cuff methods allow noninvasive continuous arterial pressure monitoring. This study aimed to determine whether continuous finger-cuff arterial pressure monitoring helps clinicians reduce hypotension within 15 min after starting induction of anesthesia and during noncardiac surgery. Specifically, this study tested the hypotheses that continuous finger-cuff-compared to intermittent oscillometric-arterial pressure monitoring helps clinicians reduce the area under a mean arterial pressure of 65 mmHg within 15 min after starting induction of anesthesia and the time-weighted average mean arterial pressure less than 65 mmHg during noncardiac surgery.

METHODS

In this single-center trial, 242 noncardiac surgery patients were randomized to unblinded continuous finger-cuff arterial pressure monitoring or to intermittent oscillometric arterial pressure monitoring (with blinded continuous finger-cuff arterial pressure monitoring). The first of two hierarchical primary endpoints was the area under a mean arterial pressure of 65 mmHg within 15 min after starting induction of anesthesia; the second primary endpoint was the time-weighted average mean arterial pressure less than 65 mmHg during surgery.

RESULTS

Within 15 min after starting induction of anesthesia, the median (interquartile range) area under a mean arterial pressure of 65 mmHg was 7 (0, 24) mmHg × min in 109 patients assigned to continuous finger-cuff monitoring versus 19 (0.3, 60) mmHg × min in 113 patients assigned to intermittent oscillometric monitoring (P = 0.004; estimated location shift: -6 [95% CI: -15 to -0.3] mmHg × min). During surgery, the median (interquartile range) time-weighted average mean arterial pressure less than 65 mmHg was 0.04 (0, 0.27) mmHg in 112 patients assigned to continuous finger-cuff monitoring and 0.40 (0.03, 1.74) mmHg in 115 patients assigned to intermittent oscillometric monitoring (P < 0.001; estimated location shift: -0.17 [95% CI: -0.41 to -0.05] mmHg).

CONCLUSIONS

Continuous finger-cuff arterial pressure monitoring helps clinicians reduce hypotension within 15 min after starting induction of anesthesia and during noncardiac surgery compared to intermittent oscillometric arterial pressure monitoring.

EDITOR’S PERSPECTIVE

Intraoperative accidental hypothermia as a probable cause of malignant ventricular arrhythmias in an elderly patient undergoing transurethral resection of prostate: A case report

Background

Intraoperative hypothermia is a common but severe condition that is defined as a core body temperature below 36 °C. Accidental hypothermia can produce coagulopathy, immunosuppression and peripheral hypoperfusion that can ultimately lead to life-threatening ventricular arrhythmias and vital organ injury, and it is significantly associated with perioperative complications and mortality.

Case description

We report the case of an 82-year-old man who presented with persistent ventricular tachycardia intraoperatively due to accidental hypothermia. The patient was diagnosed with benign prostatic hypertrophy and scheduled for transurethral resection of the prostate. Laboratory tests showed moderate anemia, and echocardiography indicated mild tricuspid and mitral regurgitation. The patient received general anesthesia with endotracheal intubation. Four hours after the start of surgery, the patient developed sudden ventricular tachycardia with severe hypotension. Arterial blood gas sampling indicated that there was no disturbance of electrolytes, acid-base balance or excessive bleeding. The rectal temperature was measured immediately, and the core temperature was 32 °C. The patient received antiarrhythmic therapy and rewarming measures. No additional ventricular arrhythmias appeared after the core temperature rose to 35 °C and the blood pressure returned to normal. The patient was transferred to the intensive care unit after surgery for further observation and was moved to the general ward the next day. He was discharged 4 days later without significant organ damage.

Conclusions

Intraoperative hypothermia may increase ventricular arrhythmia risk, especially in elderly patients. Surgeons and anesthesiologists should pay more attention to preventing and reversing accidental hypothermia, necessitating aggressive efforts to maintain normothermia during surgery.

Aggressive intraoperative warming and postoperative pulmonary complications in elderly patients recovering from esophageal cancer surgery: sub-analysis of a randomized trial

Background

Elderly patients having esophagectomies often become hypothermic which may promote complications. We tested the hypothesis that aggressive warming to a core temperature of 37°C reduces postoperative pulmonary complications (PPCs) in elderly patients having esophageal cancer resections.

Methods

This study was a pre-defined sub-study of a multi-center, parallel group, superiority trial (PROTECT). Patients aged >65 years and having elective radical resection of esophageal cancer in a single center were randomly allocated into either aggressive warming group (target intraoperative core temperatures of 37°C) or routine thermal management group (target intraoperative core temperatures of 35.5°C). The primary endpoint was the incidence of PPCs. Secondary endpoints included duration of chest tube drainage and other postoperative complications.

Results

A total of 300 patients were included in the primary analysis. PPCs occurred in 27 (18%) of 150 patients in the aggressive warming group and 31 (21%) of 150 patients in the routine thermal management group. The relative risk (RR) of aggressive versus routine thermal management was 0.9 (95% CI: 0.5, 1.4; p = 0.56). The duration of chest drainage in patients assigned to aggressive warming was shorter than that assigned to routine thermal management: 4 (3, 5) days vs. 5 (4, 7) days; hazard ratio (HR) 1.4 [95% CI: 1.1, 1.7]; p = 0.001. Fewer aggressively warmed patients needed chest drainage for more than 5 days: 30/150 (20%) vs. 51/150 (34%); RR:0.6 (95% CI: 0.4, 0.9; p = 0.03). The incidence of other postoperative complications were similar between the two groups.

Conclusion

Aggressive warming does not reduce the incidence of PPCs in elderly patients receiving esophagectomy. The duration of chest drainage was reduced by aggressive warming. But as a secondary analysis of a planned sub-group study, these results should be considered exploratory.

Clinical trial registration

https://www.chictr.org.cn/showproj.aspx?proj=37099, ChiCTR1900022257.

Predicting Intraoperative Hypothermia Burden during Non-Cardiac Surgery: A Retrospective Study Comparing Regression to Six Machine Learning Algorithms

BACKGROUND

Inadvertent intraoperative hypothermia is a common complication that affects patient comfort and morbidity. As the development of hypothermia is a complex phenomenon, predicting it using machine learning (ML) algorithms may be superior to logistic regression.

METHODS

We performed a single-center retrospective study and assembled a feature set comprised of 71 variables. The primary outcome was hypothermia burden, defined as the area under the intraoperative temperature curve below 37 °C over time. We built seven prediction models (logistic regression, extreme gradient boosting (XGBoost), random forest (RF), multi-layer perceptron neural network (MLP), linear discriminant analysis (LDA), k-nearest neighbor (KNN), and Gaussian naïve Bayes (GNB)) to predict whether patients would not develop hypothermia or would develop mild, moderate, or severe hypothermia. For each model, we assessed discrimination (F1 score, area under the receiver operating curve, precision, recall) and calibration (calibration-in-the-large, calibration intercept, calibration slope).

RESULTS

We included data from 87,116 anesthesia cases. Predicting the hypothermia burden group using logistic regression yielded a weighted F1 score of 0.397. Ranked from highest to lowest weighted F1 score, the ML algorithms performed as follows: XGBoost (0.44), RF (0.418), LDA (0.406), LDA (0.4), KNN (0.362), and GNB (0.32).

CONCLUSIONS

ML is suitable for predicting intraoperative hypothermia and could be applied in clinical practice.

Comparative effects of warming systems applied to different parts of the body on hypothermia in adults undergoing abdominal surgery: A systematic review and network meta-analysis of randomized controlled trials

STUDY OBJECTIVE

The prevention of perioperative hypothermia after anesthesia induction is a critical concern in patients undergoing abdominal surgery. The effectiveness of various warming systems for preventing hypothermia and shivering when applied to specific areas of the body remains undetermined.

DESIGN

Systematic review and network meta-analysis.

SETTING

Operating room.

INTERVENTION

Five electronic databases were searched, including only randomized control trials (RCTs) reporting the effects of warming systems applied to specific body sites on the intraoperative core temperature and postoperative risk of shivering in adults undergoing abdominal surgery. A multivariate random-effects network meta-analysis with a frequentist framework was implemented for data analysis.

MEASUREMENTS

The primary outcome was the core body temperature 60 and 120 min after anesthesia induction for abdominal surgery. The secondary outcome was the incidence of postoperative shivering.

RESULTS

This review comprised a total of 24 RCTs including 1119 patients. At 60 and 120 min after anesthesia induction, a forced-air warming system applied to the upper body (0.3 °C and 95% confidence intervals = [0.3 to 0.4], 1.0 °C [0.7 to 1.3]), lower body (0.4 °C [0.3 to 0.5], 0.9 °C [0.5 to 1.2]), and underbody (0.5 °C [0.5 to 0.6], 1.2 °C [0.9 to 1.6]) was superior to passive insulation in terms of core body temperature regulation. Compared with passive insulation, the forced-air warming system applied to the lower body (odds ratio = 0.06) or underbody (0.44) and the electric heating blanket to the lower body (0.02) or the whole body (0.07) significantly reduced the risk of shivering.

CONCLUSIONS

The results of this NMA revealed that forced-air warming with an underbody blanket effectively elevates core body temperatures in 60 and 120 min after induction of anesthesia and prevents shivering in patients recovering from abdominal surgery.

Association of triglyceride-glucose index with myocardial injury post-stroke in older patients with first-ever ischemic stroke

BACKGROUND

Myocardial injury post-stroke is a common sequela of acute stroke. Triglyceride-glucose index (TyG index), a valuable surrogate indicator of insulin resistance, has been suggested to be closely related to cardiovascular outcomes. However, it is unknown whether the TyG index is independently associated with a higher risk of myocardial injury post-stroke. We therefore investigated the longitudinal association between TyG index and risk of myocardial injury post-stroke in older patients with first-ever ischemic stroke and no prior cardiovascular comorbidities.

METHODS

We included older patients with first-ever ischemic stroke and no prior cardiovascular comorbidities between January 2021 to December 2021. The individuals were stratified into low and high TyG index groups according to the optimal cutoff value with TyG index. We performed logistic regression analysis, propensity score matching (PSM) analysis, restricted cubic spline analysis, and subgroup analyses to explore the longitudinal association between TyG index and risk of myocardial injury post-stroke.

RESULTS

We included 386 individuals with a median age of 69.8 years (interquartile range: 66.6, 75.3). The optimal TyG index cut-off for predicting myocardial injury post-stroke was 8.9 (sensitivity 67.8%; specificity 75.5%; area under curve 0.701). Multivariate logistic regression analysis revealed that the risk of genesis of myocardial injury post-stroke increased with elevated TyG index (odds ratio [OR], 2.333; 95% confidence interval [CI], 1.201-4.585; P = 0.013). Furthermore, all covariates were well balanced between the two groups. The longitudinal association between TyG index and myocardial injury post-stroke remained significantly robust (OR: 2.196; 95% CI: 1.416-3.478; P < 0.001) after PSM adjustment.

CONCLUSION

Individuals with an elevated TyG index were more susceptible to having an increased risk of myocardial injury post-stroke. TyG index thus might be served as a complementary approach for optimized-for-risk stratification in older patients with first-ever ischemic stroke and no prior cardiovascular comorbidities.

Effect of active warming on perioperative cardiovascular outcomes: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

The objective of this study was to provide an updated review on the active warming effects on major adverse cardiac events, 30-day all-cause mortality, and myocardial injury after noncardiac surgery.

METHOD

We systematically searched MEDLINE, EMBASE, CINAHL, Cochrane CENTRAL, Web of Science, and Chinese BioMedical Literature Database. We included randomized controlled trials of adult population undergoing noncardiac surgeries that concentrate on the comparison of active warming methods and passive thermal management. Cochrane Collaboration's tool was applied for risk-of-bias assessment. We used trial sequential analysis to evaluate the possibility of false positive or negative results.

RESULTS

A total of 13,316 unique records were identified, of which only 19 with reported perioperative cardiovascular outcomes were included in the systematic review and nine of them were included in final meta-analysis. No statistically significant difference between active warming methods and routine care was found in major adverse cardiac events (RR 0.56, 95% confidence interval (CI) 0.14-2.21, I² = 71%, number of events 59 vs. 70), 30-day all-cause mortality (RR 0.81, 95% CI 0.43-1.54, I² = 0%, number of events 17 vs. 21), and myocardial injury after noncardiac surgery (RR 0.61, 95% CI 0.17-2.22, I² = 79%, number of events 236 vs. 234). Trial sequential analysis suggests that current trials did not reach the minimum information size regarding the major cardiovascular events.

CONCLUSIONS

Compared to routine perioperative care, we found that active warming methods are not necessary for cardiovascular prevention in patients undergoing noncardiac surgery.

Perioperative temperature monitoring for patient safety: A period prevalence study of five hospitals

BACKGROUND

Monitoring body temperature is essential for safe perioperative care. Without patient monitoring during each surgical phase, alterations in core body temperature will not be recognised, prevented, or treated. Safe use of warming interventions also depends on monitoring. Yet there has been limited evaluation of temperature monitoring practices as the primary endpoint.

OBJECTIVE

To investigate temperature monitoring practices during all stages of perioperative care. We examined what patient characteristics are associated with the rate of temperature monitoring, along with clinical variables such as warming intervention or exposure to hypothermia.

DESIGN

An observational period-prevalence study over seven days across five Australian hospitals.

SETTINGS

Four metropolitan, tertiary hospitals and one regional hospital.

PARTICIPANTS

We selected all adult patients (N = 1690) undergoing any surgical procedure and any mode of anaesthesia during the study period.

METHODS

Patient characteristics, perioperative temperature data, warming interventions and exposure to hypothermia were retrospectively collected from patient charts. We describe the frequencies and distribution of temperature data at each perioperative stage, including adherence to minimum temperature monitoring based on clinical guidelines. To examine associations with clinical variables, we also modelled the rate of temperature monitoring using each patient's count of recorded temperature measurements within their calculated time interval from anaesthetic induction to postanaesthetic care unit discharge. All analyses adjusted 95% confidence intervals (CI) for patient clustering by hospital.

RESULTS

There were low levels of temperature monitoring, with most temperature data clustered around admission to postanaesthetic care. Over half of patients (51.8%) had two or less temperatures recorded during perioperative care and one-third (32.7%) had no temperature data at all prior to admission to postanaesthetic care. Of all patients that received active warming intervention during surgery, over two-thirds (68.5%) had no temperature monitoring recorded. In our adjusted model, associations between clinical variables and the rate of temperature monitoring often did not reflect clinical risk or need: rates were decreased for those with greatest operative risk (American Society of Anesthesiologists Classification IV: rate ratio (RR) 0.78, 95% CI 0.68-0.89; emergency surgery: RR 0.89, 0.80-0.98), and neither warming interventions (intraoperative warming: RR 1.01, 0.93-1.10; postanaesthetic care unit warming: RR 1.02, 0.98-1.07) nor hypothermia at postanaesthetic care unit admission (RR 1.12, 0.98-1.28) were associated with monitoring rate.

CONCLUSIONS

Our findings point to the need for systems-level change to enable proactive temperature monitoring over all phases of perioperative care to enhance patient safety outcomes.

REGISTRATION

Not a clinical trial.

Quantifying and Interpreting Inequality in Surgical Site Infections per Quarter Among Anesthetizing Locations and Specialties

Background Earlier studies have shown that prevention of surgical site infection can achieve net cost savings when targeted to operating rooms with the most surgical site infections. Methodology This retrospective cohort study included all 231,057 anesthetics between May 2017 and June 2022 at a large teaching hospital. The anesthetics were administered in operating rooms, procedure rooms, radiology, and other sites. The 8,941 postoperative infections were identified from International Classification of Diseases diagnosis codes relevant to surgical site infections documented during all follow-up encounters over 90 days postoperatively. To quantify the inequality in the counts of infections among anesthetizing locations, the Gini index was used, with the Gini index being proportional to the sum of the absolute pairwise differences among anesthetizing locations in the counts of infections. Results The Gini index for infections among the 112 anesthetizing locations at the hospital was 0.64 (99% confidence interval = 0.56 to 0.71). The value of 0.64 is so large that, for comparison, it exceeds nearly all countries' Gini index for income inequality. The 50% of locations with the fewest infections accounted for 5% of infections. The 10% of locations with the most infections accounted for 40% of infections and 15% of anesthetics. Among the 57 operating room locations, there was no association between counts of cases and infections (Spearman correlation coefficient r = 0.01). Among the non-operating room locations (e.g., interventional radiology), there was a significant association (Spearman r = 0.79). Conclusions Targeting specific anesthetizing locations is important for the multiple interventions to reduce surgical site infections that represent fixed costs irrespective of the number of patients (e.g., specialized ventilatory systems and nightly ultraviolet-C disinfection).

Hypothermia is an independent risk factor for prolonged ICU stay in coronary artery bypass surgery: an observational study

Maintenance of normothermia is a critical perioperative issue. The warming process after hypothermia tends to increase oxygen demand, which may lead to myocardial ischemia. This study explored whether hypothermia was an independent risk factor for increased morbidity and mortality in patients receiving CABG. We conducted a retrospective observational study of CABG surgeries performed from January 2018 to June 2019. The outcomes of interest were mortality, surgical site infection rate, ventilator dependent time, intensive care unit (ICU) stay, and hospitalization duration. Data from 206 patients were analysed. Hypothermic patients were taller (p = 0.012), had lower left ventricular ejection fraction (p = 0.016), and had off-pump CABG more frequently (p = 0.04). Our analysis noted no incidence of mortality within 30 days. Hypothermia was not associated with higher surgical site infection rate or longer intubation time. After adjusting for sex, age, cardiopulmonary bypass duration, left ventricular ejection fraction, and EuroSCORE II, higher EuroSCORE II (p < 0.001; odds ratio 1.2) and hypothermia upon ICU admission (p = 0.04; odds ratio 3.8) were independent risk factors for prolonged ICU stay. In addition to EuroSCORE II, hypothermia upon ICU admission was an independent risk factor for prolonged ICU stay in patients receiving elective CABG.

Perioperative strategies to reduce risk of myocardial injury after non-cardiac surgery (MINS): A narrative review

Myocardial injury is a frequent complication of surgical patients after having non-cardiac surgery that is strongly associated with perioperative mortality. While intraoperative anesthesia-related deaths are exceedingly rare, about 1% of patients undergoing non-cardiac surgery die within the first 30 postoperative days. Given the number of surgeries performed annually, death following surgery is the second leading cause of death in the United States. Myocardial injury after non-cardiac surgery (MINS) is defined as an elevation in troponin concentrations within 30 days postoperatively. Although typically asymptomatic, patients with MINS suffer myocardial damage and have a 10% risk of death within 30 days after surgery and excess risks of mortality that persist during the first postoperative year. Many factors for the development of MINS are non-modifiable, such as preexistent coronary artery disease. Preventive measures, systematic approaches to surveillance and treatment standards are still lacking, however many factors are modifiable and should be considered in clinical practice: the importance of hemodynamic control, adequate oxygen supply, metabolic homeostasis, the use of perioperative medications such as statins, anti-thrombotic agents, beta-blockers, or anti-inflammatory agents, as well as some evidence regarding the choice of sedative and analgesic for anesthesia are discussed. Also, as age and complexity in comorbidities of the surgical patient population increase, there is an urgent need to identify patients at risk for MINS and develop prevention and treatment strategies. In this review, we provide an overview of current screening standards and promising preventive options in the perioperative setting and address knowledge gaps requiring further investigation.

Association between intraoperative body temperature and postoperative delirium: A retrospective observational study

STUDY OBJECTIVE

The effect of perioperative body temperature derangement on postoperative delirium remains unclear. This study aimed to evaluate the association between intraoperative body temperature and postoperative delirium in patients having noncardiac surgery.

DESIGN

Single-center retrospective observational study.

SETTING

Tertiary university hospital.

PATIENT

Adult patients who had major noncardiac surgery under general anesthesia for at least two hours between 2019 and 2021.

INTERVENTIONS

Patients were classified into three groups according to their intraoperative time-weighted average body temperature: severe hypothermia (<35.0 °C), mild hypothermia (35.0 °C-36.0 °C), and normothermia (≥36.0 °C) groups.

MEASUREMENTS

The primary outcome was the risk of delirium occurring within seven days after surgery, which was compared using logistic regression analysis. A multivariable procedure was performed adjusting for potential confounders including demographics, history of hypertension, diabetes, atrial fibrillation or flutter, myocardial infarction, congestive heart failure, and stroke or transient ischemic attack, preoperative use of antidepressants and statins, preoperative sodium imbalance, high-risk surgery, emergency surgery, duration of surgery, and red blood cell transfusion. Cox regression analysis was also performed using the same covariates.

MAIN RESULTS

Among 27,674 patients analyzed, 5.5% experienced postoperative delirium. The incidence rates of delirium were 6.2% (63/388) in the severe hypothermia group, 6.4% (756/11779) in the mild hypothermia group, and 4.6% (712/15507) in the normothermia group. Compared with the normothermia group, the risk of delirium was significantly higher in the severe hypothermia (adjusted odds ratio, 1.43; 95% confidence interval, 1.04-1.97) and mild hypothermia (1.15; 1.02-1.28) groups. The mild hypothermia group also had a significantly increased risk of cumulative development of delirium than the normothermia group (adjusted hazard ratio 1.14; 95% confidence interval, 1.03-1.26).

CONCLUSIONS

Intraoperative hypothermia (even mild hypothermia) was significantly associated with an increased risk of postoperative delirium.

Modeling iatrogenic intraoperative hyperthermia from external warming in children: A pooled analysis from two prospective observational studies

BACKGROUND

Maintenance of normothermia is an important quality metric in pediatric anesthesia. While inadvertent hypothermia is effectively prevented by forced-air warming, this therapeutic approach can lead to iatrogenic hyperthermia in young children.

AIMS

To estimate the influence of external warming by forced air on the development of intraoperative hyperthermia in anesthetized children aged 6 years or younger.

METHODS

We pooled data from two previous clinical studies. Primary outcome was the course of core temperature over time analyzed by a quadratic regression model. Secondary outcomes were the incidence of hyperthermia (body core temperature >38°C), the probability of hyperthermia over the duration of warming in relation to age and surface-area-to-weight ratio, respectively, analyzed by multiple logistic regression models. The influence of baseline temperature on hyperthermia was estimated using a Cox proportional hazards model.

RESULTS

Two hundred children (55 female) with a median age of 2.1 [1^st -3^rd quartile 1-4.2] years were analyzed. Mean temperature increased by 0.43°C after 1 h, 0.64°C after 2 h, and reached a peak of 0.66°C at 147 min. Overall, 33 children were hyperthermic at at least one measurement point. The odds ratios of hyperthermia were 1.14 (95%-CI: 1.07-1.22) or 1.13 (95%-CI: 1.06-1.21) for every 10 min of warming therapy in a model with age or surface-area-to weight ratio (ceteris paribus), respectively. Odds ratio was 1.33 (95%-CI: 1.07-1.71) for a decrease of 1 year in age and 1.63 (95%-CI: 0.93-2.83) for an increase of 0.01 in the surface-to-weight-area ratio (ceteris paribus). An increase of 0.1°C in baseline temperature increased the hazard of becoming hyperthermic by a factor of 1.33 (95%-CI: 1.23-1.43).

CONCLUSIONS

In children, external warming by forced-air needs to be closely monitored and adjusted in a timely manner to avoid iatrogenic hyperthermia especially during long procedures, in young age, higher surface-area-to-weight ratio, and higher baseline temperature.

Perioperative troponin surveillance in major noncardiac surgery: a narrative review

Myocardial injury is now an acknowledged complication in patients undergoing noncardiac surgery. Heterogeneity in the definitions of myocardial injury contributes to difficulty in evaluating the value of cardiac troponins (cTns) measurement in perioperative care. Pre-, post-, and peri-operatively increased cTns are encompassed by the umbrella term 'myocardial injury' and are likely to reflect different pathophysiological mechanisms. Increased cTns are independently associated with cardiovascular and non-cardiovascular complications, poor short-term and long-term cardiovascular outcomes, and increased mortality. Preoperative measurement of cTns aids preoperative risk stratification beyond the Revised Cardiac Risk Index. Systematic measurement detects acute perioperative increases and allows early identification of acute myocardial injury. Common definitions and standards for reporting are a prerequisite for designing impactful future trials and perioperative management strategies.

Hypothermia and Prolonged Time From Procedure End to Extubation After Endovascular Thoracic Aortic Surgery

OBJECTIVE

Perioperative hypothermia (core temperature <36°C) occurs in 50%-to-80% of patients recovering from thoracic aortic surgery, though its effects have not been described fully in this context. The authors, therefore, sought to characterize the incidence of perioperative hypothermia and its association with time from procedure end to extubation in endovascular aortic surgical patients.

DESIGN

A retrospective cohort study.

SETTING

At a single academic tertiary center.

PARTICIPANTS

Patients recovering from thoracic aortic surgery with lumbar drains.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

A total of 196 patients were included in this study, 55 of whom were hypothermic with temperatures <35.0°C at the end of surgery. Though the unadjusted time to extubation was not statistically different in the hypothermic group (median 8 minutes, IQR 5-13.5 minutes) compared to the normothermic group (median 7 minutes, IQR 4-12 minutes; p = 0.062), multivariate predictors of increased time from procedure end to extubation included hypothermia (p = 0.011), age (p = 0.009), diabetes (p = 0.015), history of carotid disease (p = 0.040), and crystalloid volume (p = 0.019).

CONCLUSIONS

Hypothermia in patients recovering from endovascular aortic surgery was associated with prolonged time from procedure end to extubation. Because of the retrospective observational nature of the authors' analysis, it was not possible to determine the extent to which prolonged mechanical ventilation was influenced by low temperature.

Platform trials for anaesthesia and perioperative medicine: a narrative review

Large randomised trials provide the most reliable evidence of effectiveness of new treatments in clinical practice. However, the time and resources required to complete such trials can be daunting. An overarching clinical trial platform focused on a single condition or type of surgery, aiming to compare several treatments, with an option to stop any or add in new treatment options, can provide greater efficiency. This has the potential to accelerate knowledge acquisition and identify effective, ineffective, or harmful treatments faster. The master protocol of the platform defines the study population(s) and standardised procedures. Ineffective or harmful treatments can be discarded or study drug dose modified during the life cycle of the trial. Other adaptive elements that can be modified include eligibility criteria, required sample size for any comparison(s), randomisation assignment ratio, and the addition of other promising treatment options. There are excellent opportunities for anaesthetists to establish platform trials in perioperative medicine. Platform trials are highly efficient, with the potential to provide quicker answers to important clinical questions that lead to improved patient care.

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

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

A comparison of the warming capabilities of two Baragwanath rewarming appliances with the Hotline fluid warming device

Background

Accidental intraoperative hypothermia is a common and avoidable adverse event of the perioperative period and is associated with detrimental effects on multiple organ systems and postoperative patient outcomes. In a resource-limited environment, prevention of intraoperative hypothermia is often challenging. Resourceful clinicians overcome these challenges through creative devices and frugal innovations.

Objectives

To investigate the thermal performance of two Baragwanath Rewarming Appliances (BaRA) against that of the Hotline device to describe an optimal setup for these devices.

Methods

This was a quasi-experimental laboratory study that measured the thermal performance of two BaRA devices and the Hotline device under a number of scenarios. Independent variables including fluid type, flow rate, warming temperature and warming transit distance were sequentially altered and temperatures measured along the fluid stream. Change in temperature (ΔT) was calculated as the difference between entry and exit temperature for each combination of variables for each warming device.

Results

A total of 219 experiments were performed. At a temperature of 43.0°C and a transit distance of 200 cm, the BaRA A configuration either matched or exceeded the ΔT of the Hotline over all fluid type and flowrate combinations. The BaRA B configuration does not provide comparable thermal performance to the Hotline. Measured flowrates were noticeably slower than manufacturer-quoted values for all intravenous (IV) cannulae used.

Conclusion

A warm-water bath at 43.0°C with 200 cm of submerged IV tubing provides thermal performance comparable to the Hotline device, with all fluid type and flowrate combinations.

Contributions of the study

The present study provides an evidence-based method for warming intravenous fluid in resource-limited scenarios.