Survey on intraoperative temperature management in Europe

Perioperative Health Care Professionals' Knowledge of Evidence-Based Inadvertent Perioperative Hypothermia Management

PURPOSE

To evaluate the perioperative health care professionals' knowledge of evidence-based inadvertent perioperative hypothermia management.

DESIGN

A descriptive, cross-sectional study.

METHODS

The research sample consisted of 219 perioperative nurses and anesthesia technicians working in the university hospital and participating in perioperative care. Data were collected by the researchers using a questionnaire that included descriptive characteristics of health care professionals and inadvertent perioperative hypothermia management between March and April 2021. Descriptive statistics, Shapiro-Wilk normality, Kruskal Wallis, Mann Whitney U, and Spearman correlation test were used to analyze the data.

FINDINGS

In this study, only 29.2% of the health care professionals knew that the threshold value for inadvertent perioperative hypothermia was <36 °C. The mean knowledge score of health care professionals on the management of inadvertent perioperative hypothermia was 13.78 ± 3.47. The knowledge score of 79.5% of health care professionals was moderate level. A significant correlation was determined between inadvertent perioperative hypothermia management knowledge score and education status (P = .032), task (P < .001), and mean years in the profession (P = .02).

CONCLUSIONS

The knowledge of the health care professionals working in the perioperative process about evidence-based practices related to inadvertent perioperative hypothermia management was determined to be moderate. We recommend increasing the level of knowledge of health care professionals by providing education on guidelines regarding inadvertent perioperative hypothermia management.

Effects of Perioperative Hypothermia on Extubation, Recovery Time, and Postoperative Shivering in Breast Surgery

Women undergoing breast surgery seem to be under the risk for hypothermia (central body temperature <36°) due to the uncertainty caused by the preoperative preparation time and the variety of operations, leading to neglect of warming precautions. The study examines the perioperative hypothermia (PH) in breast surgery and the relationships between the depth of decrease in body temperature and individual or clinical variables. This prospective, cross-sectional, observational study includes 120 female patients 18-65 years of age who were given general anesthesia for breast surgery. The incidence of hypothermia was 68.1%. The given patients were discriminated as body temperature <36°, hypothermia was significantly related with lower weight, body mass index, American Society of Anesthesiology (ASA) score, baseline body temperatures, higher extubation, and recovery times. When patients' temperature decreases by >1 or 1.5°, lower age and longer durations of operation and anesthesia were also significant variables. The incidence of shivering is quite high at temperatures below 36°C or at 1 and 1.5°C reductions from baseline (72.7%, 84%, 94.1%, respectively). Body temperature changes of the patients had no effect on nausea-vomiting and pain scores. It turned out that the incidence of PH and shivering is high in women who underwent breast surgery. We think that the depth of decrease in body temperature should be taken into account when evaluating the predictors or clinical consequences of hypothermia, except for the 36°C limit for body temperature.

Perioperative hypothermia in robotic-assisted thoracic surgery: Incidence, risk factors, and associations with postoperative outcomes

OBJECTIVE

Inadvertent perioperative hypothermia has been associated with poor surgical outcomes. The purpose of this study was to evaluate the incidence and associated postoperative complications of inadvertent perioperative hypothermia in patients undergoing robotic-assisted thoracic surgery lung resections.

METHODS

This was a single-center, retrospective cohort study evaluating all consecutive patients who underwent robotic-assisted thoracic surgery lung resection between January 1, 2021, and November 30, 2022. Temperatures were measured at 5 time points: preprocedure unit, anesthesia induction, 30 minutes postinduction, extubation, and recovery room arrival. Temperature changes were calculated at each interval. Adjusted and unadjusted comparison was performed between those who experienced varying levels of inadvertent perioperative hypothermia (Hypothermia I: <36 °C, Hypothermia II: <35.5 °C, and Hypothermia III: <35 °C) and those who did not.

RESULTS

A total of 313 patients were included, and 201 (64.2%) lobectomies, 50 (16.0%) segmentectomies, and 62 (19.8%) wedge resections were performed. Across all patients, 291 (93.0%) had a temperature less than 36 °C, 195 (62.3%) had a temperature less than 35.5 °C, and 100 (31.9%) had a temperature less than 35.0 °C. Patients experienced significant temperature change at all intervals (P < .001), with the greatest loss occurring during the preprocedure interval (between leaving preprocedure unit and anesthesia induction). On adjusted analysis, patients who experienced inadvertent perioperative hypothermia less than 35.5 °C were older (odds ratio, 1.03; 95% CI, 1.01-1.05), had lower body mass index (odds ratio, 0.95; 95% CI, 0.87-0.98), and had increasing operative time (odds ratio, 1.00; 95% CI, 1.00-1.01). Patients who experienced inadvertent perioperative hypothermia had higher risk-adjusted rates of overall morbidity and infectious postoperative complications.

CONCLUSIONS

The majority of patients undergoing robotic-assisted thoracic surgery lung resections experience some degree of inadvertent perioperative hypothermia and have associated increased rates of 30-day morbidity. Structured and interval-specific interventions should be implemented to decrease rates of inadvertent perioperative hypothermia and subsequent complications.

Effect of Aggressive Warming versus Routine Thermal Management on the Incidence of Perioperative Hypothermia in Patients Undergoing Thyroid Surgery: A Prospective, Randomized, Double-Blind Controlled Trial

Purpose

Despite the implementation of various insulation measures, the incidence of hypothermia during thyroid surgery remains high. This randomized controlled study aimed to evaluate the effects of aggressive thermal management combined with resistive heating mattresses to prevent perioperative hypothermia in patients undergoing thyroid surgery.

Patients and Methods

142 consecutive patients scheduled for elective thyroid surgery were enrolled in the study. They were randomly and equally allocated to the aggressive warming or routine care groups (n = 71). The patients' body temperature was monitored before the induction of anesthesia until they returned to the ward. The primary outcome was the incidence of perioperative hypothermia. Secondary outcomes included postoperative complications, such as mortality, cardiovascular complications, wound infection, shivering, postoperative nausea and vomiting (PONV), visual analog scale (VAS) pain scores, fever, headache and hospital length of stay (LOS).

Results

In our study, the results showed that a significantly higher rate of hypothermia was observed in the routine care group compared with the aggressive warming group. The incidence of perioperative hypothermia was 19.72% (14/71) in the aggressive warming group and 35.21% (25/71) in the routine care group (P < 0.05). The incidence of shivering in the aggressive warming group (1.41%) was significantly lower than that in the routine care group (11.27%) (P < 0.05), and a one-day reduction in hospital length of stay was observed in the aggressive warming group (P < 0.05). There was no significant difference in mortality or other postoperative complications, such as cardiovascular complications, wound infection, PONV, pain, fever or headache, between the two groups (P > 0.05).

Conclusion

Our results suggest that aggressive thermal management combined with resistive heating mattresses provided improved perioperative body temperature and reduced the incidence of perioperative hypothermia and shivering compared to routine thermal management.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

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

Applying Adult Learning Theory in Improving Knowledge, Attitude, and Practice of Inadvertent Perioperative Hypothermia in Operating Room Nurses: Single-Group "Before and After Study"

The study aimed to explore the effect of the training scheme guided by Knowles' adult learning theory model on perioperative hypothermia prevention-related knowledge, practice, and behavior in operating room nurses. Operating room nurses of a teaching hospital were included from February to May 2023. Under the guideline of the adult learning theory, we accessed the score of the knowledge, attitude, and practice in operating room nurses about the prevention of the inadvertent perioperative hypothermia (IPH) before and after trainings through qualitative interviews and questionnaire surveys. There were statistically significant differences in scores of knowledge, attitude, and practice of IPH prevention in operating room nurses before and after training. The training program guided by adult learning theory could significantly increase the scores of IPH prevention-related knowledge of operating room nurses, improve the attitude of perioperative hypothermia prevention, and advance the compliance with IPH prevention interventions. Clinical Trial Registration number: 2023IIT109.

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.

Incidence and associated factors of perioperative hypothermia in adult patients at a university-based, tertiary care hospital in Thailand

BACKGROUND

Inadvertent perioperative hypothermia is an unintentional drop in core body temperature to less than 36 °C perioperatively and is associated with many negative outcomes such as infection, a prolonged stay in a recovery room, and decreased patient comfort.

OBJECTIVE

To determine the incidence of postoperative hypothermia and to identify the associated factors with postoperative hypothermia in patients undergoing head, neck, breast, general, urology, and vascular surgery. The incidences of pre- and intraoperative hypothermia were examined as the intermediate outcomes.

MATERIALS AND METHODS

A retrospective chart review was conducted in adult patients undergoing surgery at a university hospital in a developing country for two months (October to November 2019). Temperatures below 36 °C were defined as hypothermia. Univariate and multivariate analyses were used to identify factors associated with postoperative hypothermia.

RESULTS

A total of 742 patients were analyzed, the incidence of postoperative hypothermia was 11.9% (95% CI 9.7%-14.3%), and preoperative hypothermia was 0.4% (95% CI 0.08%-1.2%). Of the 117 patients with intraoperative core temperature monitoring, the incidence of intraoperative hypothermia was 73.5% (95% CI 58.8-90.8%), and hypothermia occurred most commonly after anesthesia induction. Associated factors of postoperative hypothermia were ASA physical status III-IV (OR = 1.78, 95%CI 1.08-2.93, p = 0.023) and preoperative hypothermia (OR = 17.99, 95%CI = 1.57-206.89, p = 0.020). Patients with postoperative hypothermia had a significantly longer stay in the PACU (100 min vs. 90 min, p = 0.047) and a lower temperature when discharged from PACU (36.2 °C vs. 36.5 °C, p < 0.001) than those without hypothermia.

CONCLUSION

This study confirms that perioperative hypothermia remains a common problem, especially in the intraoperative and postoperative periods. High ASA physical status and preoperative hypothermia were associated factors of postoperative hypothermia. In order to minimize the incidence of perioperative hypothermia and enhance patient outcomes, appropriate temperature management should be emphasized in patients at high risk.

REGISTRATION

Clinical Trials.gov (NCT04307095) (13/03/2020).

Health Technology Assessment for the Prevention of Peri-Operative Hypothermia: Evaluation of the Correct Use of Forced-Air Warming Systems in an Italian Hospital

This study investigates the implications of using a system for the maintenance of normothermia in the treatment of patients undergoing surgery, determining whether the FAW (Forced-Air Warming) systems are more effective and efficient than the non-application of appropriate protocols (No Technology). We conducted Health Technology Assessment (HTA) analysis, using both real-world data and the data derived from literature, assuming the point of view of a medium-large hospital. The literature demonstrated that Inadvertent Perioperative Hypothermia (IPH) determines adverse events, such as surgical site infection (FAW: 3% vs. No Technology: 12%), cardiac events (FAW: 3.5% vs. No Technology: 7.6%) or the need for blood transfusions (FAW: 6.2% vs. No Technology: 7.4%). The correct use of FAW allows a medium saving of 16% per patient to be achieved, compared to the non-use of devices. The Cost Effectiveness Value (CEV) is lower in the hypothesis of FAW: it enables a higher efficacy level with a contextual optimization of patients' path costs. The social cost is reduced by around 30% and the overall hospital days are reduced by between 15% and 26%. The qualitative analyses confirmed the results. In conclusion, the evidence-based information underlines the advantages of the proper use of FAW systems in the prevention of accidental peri-operative hypothermia for patients undergoing surgery.

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 warm and humidified gas insufflation in gynecological laparoscopy on maintenance of body temperature: a prospective randomized controlled multi-arm trial

Background

Hypothermia is defined as a decrease in body core temperature to below 36 °C. If intraoperative heat-preserving measures are omitted, a patient’s temperature will fall by 1 – 2 °C. Even mild forms of intraoperative hypothermia can lead to a marked increase in morbidity and mortality. Using warm and humidified gas insufflation in laparoscopy may help in the maintenance of intraoperative body temperature.

Methods

In this prospective randomized controlled study, we investigated effects of temperature and humidity of the insufflation gas on intra- and postoperative temperature management. 150 patients undergoing gynecologic laparoscopic surgery were randomly assigned to either insufflation with non-warmed, non-humidified CO₂ with forced air warming blanket (AIR), humidified warm gas without forced air warming blanket (HUMI) or humidified warm gas combined with forced air warming blanket (HUMI+). We hypothesized that the use of warmed laparoscopic gas would have benefits in the maintenance of body temperature and reduce the occurrence of hypothermia.

Results

The use of warm and humidified gas insufflation alone led to more hypothermia episodes with longer duration and longer recovery times as well as significantly lower core body temperature compared to the other two groups. In the comparison of the AIR group and HUMI + group, HUMI + patients had a significantly higher body temperature at arrival at the PACU (Post Anaesthesia Care Unit), had the least occurrence of hypothermia and suffered from less shivering.

Conclusion

The use of warm and humidified gas insufflation alone does not sufficiently warm the patients. The optimal temperature management is achieved in the combination of external forced air warming and insufflation of warm and humidified laparoscopy gas.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-022-06499-z.

Comparison of zero heat flux and double sensor thermometers during spinal anaesthesia: a prospective observational study

Because of the difficulties involved in the invasive monitoring of conscious patients, core temperature monitoring is frequently neglected during neuraxial anaesthesia. Zero heat flux (ZHF) and double sensor (DS) are non-invasive methods that measure core temperature from the forehead skin. Here, we compare these methods in patients under spinal anaesthesia. Sixty patients scheduled for elective unilateral knee arthroplasty were recruited and divided into two groups. Of these, thirty patients were fitted with bilateral ZHF sensors (ZHF group), and thirty patients were fitted with both a ZHF sensor and a DS sensor (DS group). Temperatures were saved at 5-min intervals from the beginning of prewarming up to one hour postoperatively. Bland–Altman analysis for repeated measurements was performed and a proportion of differences within 0.5 °C was calculated as well as Lin`s concordance correlation coefficient (LCCC). A total of 1261 and 1129 measurement pairs were obtained. The mean difference between ZHF sensors was 0.05 °C with 95% limits of agreement − 0.36 to 0.47 °C, 99% of the readings were within 0.5 °C and LCCC was 0.88. The mean difference between ZHF and DS sensors was 0.33 °C with 95% limits of agreement − 0.55 to 1.21 °C, 66% of readings were within 0.5 °C and LCCC was 0.59. Bilaterally measured ZHF temperatures were almost identical. DS temperatures were mostly lower than ZHF temperatures. The mean difference between ZHF and DS temperatures increased when the core temperature decreased.

Trial registration: The study was registered in ClinicalTrials.gov on 13th May 2019, Code NCT03408197.

Underbody blankets have a higher heating effect than overbody blankets in lithotomy position endoscopic surgery under general anesthesia: a randomized trial

BACKGROUND

Surgery under general anesthesia results in temperature decrease due to the effect of anesthetics and peripheral vasodilation on thermoregulatory centers. Perioperative temperature control is therefore an issue of high importance. In this study, we aimed to compare the warming effect of underbody and overbody blankets in patients undergoing surgery in the lithotomy position under general anesthesia.

METHODS

From September 2018 to October 2019, 99 patients undergoing surgery for colorectal cancer in the lithotomy position were included in this randomized controlled trial and assigned to the intervention group (underbody blanket) or control group (overbody blanket).

RESULTS

The central temperature was significantly higher in the underbody blanket group than in the overbody blanket group at 90 min after the beginning of the surgery (p = 0.02); also in this group, the peripheral temperature was significantly higher 60 min after the beginning of the surgery (p = 0.02). Regarding postoperative factors, the underbody blanket group had a significantly lower frequency of postoperative shivering (p < 0.01) and a significantly shorter postoperative hospital stay (p = 0.04) than the overbody blanket group.

CONCLUSIONS

We recommend the use of underbody blankets for intraoperative temperature control in patients undergoing surgery in the lithotomy position under general anesthesia. Underbody blankets showed improved rise and maintenance of central and peripheral temperature, decreased the incidence of postoperative shivering, and shortened the postoperative length of hospital stay.

Clinical evaluation of a cutaneous zero-heat-flux thermometer during cardiac surgery

We evaluated the disposable non-invasive SpotOn™ thermometer relying on the zero-heat-flux technology. We tested the hypothesis that this technology may accurately estimate the core temperature. The primary objective was to compare cutaneous temperature measurements from this device with blood temperatures measured with the pulmonary artery catheter. Secondary objective was to compare measurements from the zero-heat-flux thermometer indirectly with other routinely used thermometers (nasopharyngeal, bladder, rectal). We included 40 patients electively scheduled for either off-pump coronary artery bypass surgery or pulmonary thromboendarterectomy. Temperatures were measured using zero-heat-flux (SpotOn™), pulmonary artery catheter, nasopharyngeal, rectal, and bladder thermometers. Agreement was assessed using the Bland and Altman random effects method for repeated measures data, and Lin's concordance correlation coefficient. Accuracy was estimated (defined as <0.5° difference with the gold standard), with a 95% confidence interval considering the multiple pairs of measurements per patient. 17 850 sets of temperature measurements were analyzed from 40 patients. The mean overall difference between zero-heat-flux and pulmonary artery catheter thermometer was -0.06 °C (95% limits of agreement of ± 0.89 °C). In addition, 14 968 sets of temperature measurements were analyzed from 34 patients with all thermometers in situ. Results from the zero-heat-flux thermometer showed better agreement with the pulmonary artery catheter than the other secondary core thermometers assessed. In conclusion, the SpotOn™ thermometer reliably assessed core temperature during cardiac surgery. It could be considered an alternative for other secondary thermometers in the assessment of core temperature during general anesthesia.

Coagulation under Mild Hypothermia Assessed by Thromboelastometry

Introduction

While previous studies have shown a significant impact of extreme hypo- and hyperthermia on coagulation, effects of much more frequently occurring perioperative mild hypothermia are largely unknown. This study therefore aimed to analyze the effects of mild hypothermia using rotational thromboelastometry in vitro.

Materials and Methods

Twelve healthy volunteers were included in this study. Standard thromboelastometric tests (EXTEM, INTEM, FIBTEM) were used to evaluate coagulation in vitro at 39, 37, 35.5, 35, and 33°C. Beyond standard thromboelastometric tests, we also evaluated the effects of mild hypothermia on the TPA-test (ClotPro, Enicor GmbH, Munich, Germany), a new test which aims to detect fibrinolytic capacity by adding tissue plasminogen activator to the sample. Data are presented as the median with 25/75th percentiles.

Results

Extrinsically activated coagulation (measured by EXTEM) showed a significant increase in clot formation time (CFT; 37°C: 90 s [81/105] vs. 35°C: 109 s [99/126]; p = 0.0002), while maximum clot firmness (MCF) was not significantly reduced. Intrinsically activated coagulation (measured by INTEM) also showed a significant increase in CFT (37°C: 80 s [72/88] vs. 35°C: 94 s [86/109]; p = 0.0002) without significant effects on MCF. Mild hypothermia significantly increased both the lysis onset time (136 s [132/151; 37°C] vs. 162 s [141/228; 35°C], p = 0.0223) and lysis time (208 s [184/297; 37°C] vs. 249 s [215/358; 35°C]; p = 0.0259).

Conclusion

This demonstrates that even under mild hypothermia coagulation is significantly altered in vitro. Perioperative temperature monitoring and management are greatly important and can help to prevent mild hypothermia and its adverse effects. Further investigation and in vivo testing of coagulation under mild hypothermia is needed.

Perioperative temperature management: a survey of 6 Asia-Pacific countries

BACKGROUND

Anesthesia leads to impairments in central and peripheral thermoregulatory responses. Inadvertent perioperative hypothermia is hence a common perioperative complication, and is associated with coagulopathy, increased surgical site infection, delayed drug metabolism, prolonged recovery, and shivering. However, surveys across the world have shown poor compliance to perioperative temperature management guidelines. Therefore, we evaluated the prevalent practices and attitudes to perioperative temperature management in the Asia-Pacific region, and determined the individual and institutional factors that lead to noncompliance.

METHODS

A 40-question anonymous online questionnaire was distributed to anesthesiologists and anesthesia trainees in six countries in the Asia-Pacific (Singapore, Malaysia, Philippines, Thailand, India and South Korea). Participants were polled about their current practices in patient warming and temperature measurement across the preoperative, intraoperative and postoperative periods. Questions were also asked regarding various individual and environmental barriers to compliance.

RESULTS

In total, 1154 valid survey responses were obtained and analyzed. 279 (24.2%) of respondents prewarm, 508 (44.0%) perform intraoperative active warming, and 486 (42.1%) perform postoperative active warming in the majority of patients. Additionally, 531 (46.0%) measure temperature preoperatively, 767 (67.5%) measure temperature intraoperatively during general anesthesia, and 953 (82.6%) measure temperature postoperatively in the majority of patients. The availability of active warming devices in the operating room (p < 0.001, OR 10.040), absence of financial restriction (p < 0.001, OR 2.817), presence of hospital training courses (p = 0.011, OR 1.428), and presence of a hospital SOP (p < 0.001, OR 1.926) were significantly associated with compliance to intraoperative active warming.

CONCLUSIONS

Compliance to international perioperative temperature management guidelines in Asia-Pacific remains poor, especially in small hospitals. Barriers to compliance were limited temperature management equipment, lack of locally-relevant standard operating procedures and training. This may inform international guideline committees on the needs of developing countries, or spur local anesthesiology societies to publish their own national guidelines.

Effects of different thermal insulation methods on the nasopharyngeal temperature in patients undergoing laparoscopic hysterectomy: a prospective randomized controlled trial

Background

This study explored the comparison of the thermal insulation effect of incubator to infusion thermometer in laparoscopic hysterectomy.

Methods

We assigned 75 patients enrolled in the study randomly to three groups: Group A: Used warming blanket; group B: Used warming blanket and infusion thermometer; group C: Used warming blanket and incubator. The nasopharyngeal temperature at different time points during the operation served as the primary outcome.

Results

The nasopharyngeal temperature of the infusion heating group was significantly higher than that of the incubator group 60 min from the beginning of surgery (T3): 36.10 ± 0.20 vs 35.81 ± 0.20 (P<0.001)90 min from the beginning of surgery (T4): 36.35 ± 0.20 vs 35.85 ± 0.17 (P<0.001). Besides, the nasopharyngeal temperature of the incubator group was significantly higher compared to that of the control group 60 min from the beginning of surgery (T3): 35.81 ± 0.20 vs 35.62 ± 0.18 (P<0.001); 90 min from the beginning of surgery (T4): 35.85 ± 0.17 vs 35.60 ± 0.17 (P<0.001). Regarding the wake-up time, that of the control group was significantly higher compared to the infusion heating group: 24 ± 4 vs 21 ± 4 (P = 0.004) and the incubator group: 24 ± 4 vs 22 ± 4 (P = 0.035).

Conclusion

Warming blanket (38 °C) combined infusion thermometer (37 °C) provides better perioperative thermal insulation. Hospitals without an infusion thermometer can opt for an incubator as a substitute.

Trial registration

This trial was registered with ChiCTR2000039162, 20 October 2020.

Incidence of postoperative hypothermia and its risk factors in adults undergoing orthopedic surgery under brachial plexus block: A retrospective cohort study

Postoperative hypothermia increases patient mortality and morbidity. However, the incidence of, and risk factors for, postoperative hypothermia in patients undergoing surgery under brachial plexus block (BPB) as the primary method of anesthesia remain unclear. This study aimed to determine the incidence of, and risk factors for, postoperative hypothermia in patients undergoing surgery under BPB. We retrospectively analyzed 660 patients aged ≥ 19 years who underwent orthopedic surgery under BPB in our hospital between October 2014 and October 2019. Postoperative hypothermia was defined as a tympanic membrane temperature < 36 °C when the patient arrived in the post-anesthesia care unit. Multivariate logistic regression analysis was performed to identify the independent risk factors for postoperative hypothermia. Postoperative hypothermia was observed in 40.6% (268/660) of patients. Independent risk factors for postoperative hypothermia were lower baseline core temperature before anesthesia (odds ratio [OR] 0.355; 95% confidence interval [CI] 0.185-0.682), alcohol abuse (OR 2.658; 95% CI 1.105-6.398), arthroscopic shoulder surgery (OR 2.007; 95% CI 1.428-2.820), use of fentanyl (OR 1.486; 95% CI 1.059-2.087), combined use of midazolam and dexmedetomidine (OR 1.816; 95% CI 1.268-2.599), a larger volume of intravenous fluid (OR 1.001; 95% CI 1.000-1.002), and longer duration of surgery (OR 1.010; 95% CI 1.004-1.017). Postoperative hypothermia is common in adult patients undergoing orthopedic surgery under BPB. The risk factors identified in this study should be considered to avoid postoperative hypothermia in these patients.

Influence of insufflated carbon dioxide on abdominal temperature compared to oesophageal temperature during laparoscopic surgery

BACKGROUND

Body core temperature is an important vital parameter during surgery and anaesthesia. It is influenced by several patient-related and surgery-related factors. Laparoscopy is considered beneficial in terms of a variety of parameters, for example, postoperative pain and length of hospital stay. Non-humidified, non-warmed insufflated CO₂ applied during laparoscopy is standard of care. This prospective observational trial therefore evaluates the impact of non-humidified CO₂ at room temperature on abdominal temperature and its correlation to body core temperature.

METHODS

Seventy patients undergoing laparoscopic surgery were included in this prospective observational study. Temperature was measured oesophageal and abdominal before induction of anaesthesia (T1), right before skin incision (T2), 15 min, 30 min and 60 min after skin incision. All patients were treated according to actual guidelines for perioperative temperature measurement.

RESULTS

Body core temperature and abdominal temperature correlated moderately (r = 0.6123; p < 0.0001). Bland-Altman plot for comparison of methods showed an average difference of 0.4 °C (bias - 0.3955; 95% agreement of bias from - 2.365 to 1.574). Abdominal temperature further decreased after establishing pneumoperitoneum (T2: 36.2 °C (35.9/36.4) to T5: 36.1 °C (35.6/36.4); p < 0.0001), whereas oesophageal temperature increased (T2: 36.2 °C (35.9/36.4) to 36.4 °C (36.0/36.7); p = 0.0296). Values of oesophageal and abdominal measurement points differed at T4 (36.3 °C (36.0/36.6) vs. 36.1 °C (35.4/36.6); p < 0.0001) and T5 (36.4 °C (36.0/36.7) vs. 36.1 °C (35.6/36.4) p = 0.0003).

CONCLUSION

This prospective observational trial shows the influence of insufflated, non-humidified carbon dioxide at room temperature on abdominal temperature during laparoscopic surgery. We show that carbon dioxide applied at these conditions decreases abdominal temperature and therefore might be a risk factor for perioperative hypothermia.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Protocol Implementation for Normothermia in Surgery Settings in Italy: Budget-Impact Analysis

Introduction

Hypothermia is a well-known risk of the perioperative period and considered a preventable effect of anesthesia care. Nevertheless, it is not fully controlled, causing a number of adverse outcomes following surgical operations and thus increasing length of stay in hospital and treatment costs. The aim of this study was to assess the budget impact (BI) of the implementation of proactive strategies to prevent inadvertent perioperative hypothermia (IPH) in surgical patients in Italy, as recommended by international guidelines and by a good clinical practice (GCP) guideline of the Italian Society of Anesthesia, Analgesia, Reanimation, and Intensive Care.

Methods

BI was calculated over a 3-year period from the perspective of the Italian National Health Service (NHS). Model inputs were extracted from national literature when available and otherwise from international sources. The reference analytic model was based on the cost-effectiveness analysis of the National Institute for Health and Care Excellence clinical guidance 65. Estimates were based on assessments made about current malpractice in Italy and on a hypothesis of how future practice might change by implementing the GCP. Model output included overall BI results, variations in the number of warmed patients, medical-device average costs and use of mix.

Results

The base-case estimate quantified a decrease of 35% in extra days of hospital stay due to IPH and a net BI of –€60.92 million.

Conclusion

Increasing protocol adoption for preventing IPH would lead to both clinical advantages and significant savings for the NHS. Its large diffusion in Italian hospitals is thus desirable.

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

PURPOSE

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

DESIGN

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

METHODS

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

FINDINGS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Association Between Postoperative Body Temperature and All-Cause Mortality After Off-Pump Coronary Artery Bypass Graft Surgery: A Retrospective Observational Study

BACKGROUND

Inadvertent perioperative hypothermia is common in patients undergoing off-pump coronary artery bypass grafting (OPCAB). We investigated the association between early postoperative body temperature and all-cause mortality in patients undergoing OPCAB.

METHODS

We reviewed the electronic medical records of 1714 patients who underwent OPCAB (median duration of follow-up, 47 months). Patients were divided into 4 groups based on body temperature at the time of intensive care unit admission after surgery (moderate-to-severe hypothermia, <35.5°C; mild hypothermia, 35.5°C-36.5°C; normothermia, 36.5°C-37.5°C; and hyperthermia, ≥37.5°C). Cox proportional hazards models were used to assess the association between body temperature and all-cause mortality. The association between early postoperative changes in body temperature and all-cause mortality was also assessed by dividing the patients into 4 categories according to the body temperature measured at postoperative intensive care unit admission and the average body temperature during the first 3 postoperative days.

RESULTS

Compared to the normothermia group, the adjusted hazard ratios of all-cause mortality were 2.030 (95% confidence interval, 1.407-2.930) in the moderate-to-severe hypothermia group and 1.445 (95% confidence interval, 1.113-1.874) in the mild hypothermia group. Patients who were hypothermic at postoperative intensive care unit admission but attained normothermia thereafter were at a lower risk of all-cause mortality compared to patients who did not regain normothermia (adjusted hazard ratio, 0.631; 95% confidence interval, 0.453-0.878), while they were still at a higher risk of all-cause mortality than those who were consistently normothermic (adjusted hazard ratio, 1.435; 95% confidence interval, 1.090-1.890).

CONCLUSIONS

Even mild early postoperative hypothermia was associated with all-cause mortality after OPCAB. Patients who regained normothermia postoperatively were at lower risk of all-cause mortality compared to those who did not.

Effects of Inadvertent Perioperative Hypothermia on Metabolic and Inflammatory Mediators

Objective

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

Methods

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

Results

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

Conclusion

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

Barriers and enablers to the implementation of perioperative hypothermia prevention practices from the perspectives of the multidisciplinary team: a qualitative study using the Theoretical Domains Framework

Purpose: Inadvertent perioperative hypothermia is a significant problem for surgical patients globally, and is associated with many detrimental side-effects. Despite the availability of rigorously developed international evidence-based guidelines for prevention, a high incidence of this complication persists. This qualitative study aims to identify and examine the domains which act as barriers and enablers to perioperative hypothermia prevention practices, from the perspectives of the key healthcare professionals involved with perioperative temperature management. Methods: A qualitative study employing semi-structured interviews was utilized. A purposive sample of key stakeholders involved in perioperative temperature management, including perioperative nurses, anesthetists, surgeons, and perioperative managers, were recruited via email. The interview guide was developed in reference to the Theoretical Domains Framework. All interviews were recorded, de-identified, transcribed, and coded. Belief statements were generated within each domain, and a frequency score generated for each belief. Finally, the domains were mapped to the COM-B model of the Behavior Change Wheel to develop recommendations for future interventions. Results: Twelve participants were included including eight nurses, two surgeons, and two anesthetists. Eleven key theoretical domains that influence the uptake of perioperative hypothermia practices were identified: knowledge; skills; social/professional role and identity; beliefs about capabilities; optimism; beliefs about consequences; reinforcement; goals; memory, attention, and decision processes; environmental context and resources; social influence. Suggested intervention strategies include training, reminder systems, audit, and feedback, organizational support to resolve lack of control of ambient temperature, as well as provision of accurate temperature measurement devices. Conclusion: Future interventions to address the key behavioral domains and improve perioperative hypothermia prevention need to be evaluated in the context of feasibility, effectiveness, safety, acceptability, and cost by the target users. All suggested intervention strategies need to take a team-based, multi-modal approach, as this is most likely to facilitate improvements in perioperative hypothermia prevention.

The influence of body mass index on temperature management during general anaesthesia-A prospective observational study

RATIONALE, AIMS, AND OBJECTIVES

During general anaesthesia, body core temperature is influenced by several factors that are either anaesthesia-related (type and duration of anaesthesia and fluid management), surgery-related (type of surgery and extent of the surgical procedure), or patient-related (age, gender, body weight, and preoperative body core temperature). Interestingly, data concerning body mass index (BMI) and its influence on patients' temperature are sparse. The aim of this study was to evaluate the impact of BMI on body core temperature under general anaesthesia.

METHODS

A single centre, prospective, observational study was conducted at a university hospital. Two cohorts (lower limb surgery and abdominal surgery) were evaluated. Patients were treated according to actual German guidelines for the prevention of hypothermia. Temperature was measured sublingually prior to anaesthesia and during the first 60 minutes of anaesthesia. Each cohort was divided in three subgroups (BMI < 24 kg m^-2 , BMI 25-34.9 kg m^-2 , and BMI > 35 kg m^-2 ) according to body weight.

RESULTS

A total of 206 patients were evaluated. One hundred four underwent lower limb surgery; 102 underwent abdominal surgery. After induction of anaesthesia, temperature dropped in all subgroups, but this decline was more pronounced in patients with lower BMI. Significant differences concerning temperature changes were observed in abdominal surgery between low and high BMI groups. After 60 minutes of anaesthesia, group-dependent temperature differences had levelled out, and relevant differences compared with preoperative temperatures could no longer be observed in any of the groups.

CONCLUSION

Current guidelines provide effective protection against perioperative hypothermia. In the current study, this was true for obese as well as normal weight patients.

Clinical practice guideline. Unintentional perioperative hypothermia

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

Comparative Study of the Effect of Warming at Various Temperatures on Biochemical, Hematologic, and Hemodynamic Parameters During Spinal Fusion Surgery Under Intravenous Anesthesia

BACKGROUND

Perioperative inadvertent hypothermia (PIH) commonly occurs after major surgical procedures under local or general anesthesia and increases the risk of complications such as organ failure, hypoperfusion, and peripheral vasoconstriction, as well as adverse postoperative outcomes, such as wound infection and increased surgical bleeding.

OBJECTIVES

We hypothesized that the intra-operative warming may affect these complications and thus, we aimed to compare the most appropriate temperature of the warmer to decrease patients' complications.

METHODS

The present randomized clinical trial investigated 90 patients undergoing total intravenous anesthesia in posterior spinal fusion surgery, randomly divided into two groups of 45. The warmer was set at 38°C for group "A" during surgery and at 40°C for group "B." Patient's demographic characteristics, the serum level of hemoglobin, hematocrit, and platelet counts, mean core temperature, systolic blood pressure (BP), heart rate, and respiratory rate were recorded before and after the surgery. Variables were compared between the two groups at three time intervals (during induction, during operation, and during recovery).

RESULTS

The mean temperature was not different between the two groups at the three time intervals. Other laboratory serum tests, vital signs, and oxygen consumption were maintained within the normal range although they did not improve significantly in two groups at the three time intervals.

CONCLUSIONS

There was no significant difference in warming of the patients during operation at 38 or 40°C to prevent hypothermia-induced complications during induction, operation, and recovery.

Automated closed-loop management of body temperature using forced-air blankets: preliminary feasibility study in a porcine model

Background

Management of a patient’s body temperature is an important aspect of care that should be addressed by targeted temperature management (TTM). Often, non-invasive methods like forced-air blankets are used. Especially in the operating room this management may be a subsidiary and repetitive task requiring constant observation of the patient’s body temperature and adaption using the limited set of available settings. Thus, automation of TTM is a feasible target to improve patient outcome and reduce caregiver workload.

Methods

A Philips IntelliVue MP 50 patient monitor with an arterial PiCCO catheter system was used to measure patient blood temperature. Thermal management was performed with a 3M Bair Hugger 755 warming unit with forced air blankets. The warming unit was extended by a computer interface to allow for remote and automated control. A proposed closed-loop algorithm reads the measured temperature and performs automated control of the 3M Bair Hugger. Evaluation was performed in an experimental intensive care setting for animal studies. Two fully automated trials are compared with two manual and two uncontrolled trials in the same study setting using six female pigs for prolonged observation times of up to 90 hours in each trial.

Results

The developed system and proposed algorithm allow more precise temperature management by keeping a set target temperature within a range of ± 0.5 °C in 88% of the observation time and within a range of ± 1.0 °C at all times. The proposed algorithm yielded better performance than did manual control or uncontrolled trials. It was able to adapt to individual patient needs as it is more dynamic than look-up table approaches with fixed settings for various temperatures.

Conclusions

Closed-loop TTM using non-invasive forced-air warming blankets was successfully tested in a porcine study with the proposed hardware interface and control algorithm. This automation can be beneficial for patient outcome and can reduce caregiver workload and patient risk in clinical settings. As temperature readings are most often available, existing devices like the 3M Bair Hugger can easily be expanded. However, even if clinical application is feasible, open questions regarding approval and certification of such automated systems within the current legal situation still need to be answered.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0542-4) contains supplementary material, which is available to authorized users.

The Effect of Operating Room Temperature on the Performance of Clinical and Cognitive Tasks

Introduction:

Operating room (OR) temperature may impact the performance of health care providers. This study assesses whether hot or cold room temperature diminishes the performance of OR personnel measured by psychomotor vigilance testing (PVT) and self-report scales.

Methods:

This prospective observational study enrolled surgical/anesthesia trainees, student registered nurse anesthetists, and certified registered nurse anesthetists. Each provider participated in a test of psychomotor function and a questionnaire using a self-report scale of personal comfort and well-being. The PVT and questionnaires were completed after 30 minutes of exposure to 3 different conditions (temperature of 21°C, 23°C, and 26°C).

Results:

The cohort of 22 personnel included 9 certified registered nurse anesthetists, 7 anesthesia/surgical trainees, and 6 student registered nurse anesthetists. Mean reaction time on the PVT was comparable among baseline (280 ± 47 ms), hot (286 ± 55 ms; P = 0.171), and cold (303 ± 114 ms; P = 0.378) conditions. On the self-report score (range, 1–21), there was no difference in the self-rated subjective performance between baseline and cold conditions. However, the self-rated subjective performance scale was lower (12 ± 6, P = 0.003) during hot conditions.

Discussion:

No difference was noted in reaction time depending on the temperature; however, excessive heat in the OR environment was associated with worse self-rated subjective performance among health care providers. Particularly, self-rated subjective physical demand and frustration were greater under hot condition.

Temperature management under general anesthesia: Compulsion or option

Administration of general anesthesia requires continuous monitoring of vital parameters of the body including body temperature. However, temperature continues to be one of the least seriously monitored parameters perioperatively. Inadvertent perioperative hypothermia is a relatively common occurrence with both general and regional anesthesia and can have significant adverse impact on patients' outcome. While guidelines for perioperative temperature management have been proposed, there are no specific guidelines regarding the best site or best modality of temperature monitoring and management intraoperatively. Various warming and cooling devices are available which help maintain perioperative normothermia. This article discusses the physiology of thermoregulation, effects of anesthesia on thermoregulation, various temperature monitoring sites and methods, perioperative warming devices, guidelines for perioperative temperature management and inadvertent temperature complications (hypothermia/hyperthermia) and measures to control it in the operating room.

Approach to Perioperative Hypothermia by Anaesthesiology and Reanimation Specialist in Turkey: A Survey Investigation

OBJECTIVE

The aim is to investigate the attitudes of anaesthesiologists working in Turkey on perioperative temperature monitoring.

METHODS

The questionnaire comprised 25 questions. Data were obtained through the completion of the questionnaire by hand or via the web.

RESULTS

Two hundred and four questionnaires were evaluated. Most physicians were working in government hospitals. We determined that 26% of physicians often use temperature monitoring and that physicians who works in university hospitals are significantly more common monitor the body temperature. There are different approachs on core temperature. The skin/axilla was the most preferred monitoring site; forced-air warming devices were the most common preferred heating systems. New-borns were the most commonly monitored group, and the Turkish Anaesthesiology and Reanimation Society guideline was the most commonly used reference. Physicians working in university or private hospitals were significantly more able to adjust the operating room temperature on demand.

CONCLUSION

There are different applications to prevent perioperative hypothermia. Although physicians are aware of the effects of anaesthesia on hypothermia and the contribution of hypothermia to complications, this awareness was not enough for them to make temperature monitoring a routine practice. To make temperature monitoring a standard practice, we believe that more studies should be conducted and that this issue needs to be more frequently addressed in congresses, anaesthesia conferences and particularly in residency training clinics.

Efficacy of Prewarming With a Self-Warming Blanket for the Prevention of Unintended Perioperative Hypothermia in Patients Undergoing Hip or Knee Arthroplasty

PURPOSE

Unintended perioperative hypothermia (UPH) is a common and serious complication for patients undergoing anesthesia. The purpose of this study was to identify the incidence of UPH and evaluate the efficacy of a self-warming blanket on the drop in core temperature and risk of UPH in patients undergoing hip or knee arthroplasty.

DESIGN

A case-control study was used.

METHODS

Sixty patients were included. Thirty patients received prewarming with a self-warming blanket and forced-air warming intraoperatively; thirty patients received only forced-air warming intraoperatively.

FINDING

The incidence of UPH (<36°C) was identified in 13% of the patients in the prewarmed group and 43% of the patients in the control group. Mean core temperature in the prewarmed group was significantly higher and remained above 36°C in the perioperative period.

CONCLUSIONS

The study suggests that preoperative warming with a self-warming blanket reduces the incidence of UPH and decreases the drop in core temperature.

Comparison of Conventional Mercury Thermometer and Continuous TherCom® Temperature Recording in Hospitalized Patients

INTRODUCTION

Detection of accurate body temperature fluctu-ations in hospitalized patients is crucial for appropriate clinical decision-making. The accuracy and reliability of body temperature assessment may significantly affect the proper treatment.

AIM

To compare the conventional and continuous body temperature recordings in hospitalized patients.

MATERIALS AND METHODS

This cross-sectional study was carried out at a tertiary care centre and study included 55 patients aged between 18-65 years with a history of fever admitted to a tertiary care hospital. A noninvasive continuous temperature recording was done using TherCom^® device through tympanic temperature probe at tympanic site at one-minute intervals for 24 hours. The conventional temperatures were recorded in the axilla using mercury thermometer at specific time intervals at 12:00 noon, 8:00 PM and 5:00 AM. Peak temperature differences between continuous and conventional methods were compared by applying Independent sample t-test. Intra class Correlation Coefficient (ICC) test was performed to assess the reliability between two temperature-monitoring methods. A p<0.05 was considered as significant.

RESULTS

The average peak temperature by non-invasive continuous recording method was 39.07°C ±0.76°C while it was 37.55°C ±0.62°C by the conventional method. A significant temperature difference of 1.52°C [p<0.001;95% CI(1.26-1.78)] was observed between continuous and conventional temperature methods. Intra class Correlation Coefficient (ICC) between continuous and conventional temperature readings at 12:00 noon was α= 0.540, which had moderate reliability. The corresponding coefficients at 8:00 PM and 5:00 AM were α=0.425 and 0.435, respectively, which had poor reliability.

CONCLUSION

The conventional recording of temperature is routinely practiced and does not reflect the true temperature fluctuations. However, the continuous non-invasive temperature recording is simple, inexpensive and a better tool for recording the actual temperature changes.

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

STUDY OBJECTIVE

Incidence of inadvertent perioperative hypothermia is still high; therefore, present guidelines advocate "prewarming" for its prevention. Prewarming means preoperative patient skin warming, which minimizes redistribution hypothermia caused by induction of anesthesia. In this study, we compared the new self-warming BARRIER EasyWarm blanket with passive thermal insulation regarding mean perioperative patient core body temperature.

DESIGN

Multinational, multicenter randomized prospective open-label controlled trial.

SETTING

Surgical ward, operation room, postanesthesia care unit at 4 European hospitals.

PATIENTS

A total of 246 adult patients, American Society of Anesthesiologists class I to III undergoing elective orthopedic; gynecologic; or ear, nose, and throat surgery scheduled for 30 to 120 minutes under general anesthesia.

INTERVENTIONS

Patients received warmed hospital cotton blankets (passive thermal insulation, control group) or BARRIER EasyWarm blanket at least 30 minutes before induction of general anesthesia and throughout the perioperative period (intervention group).

MEASUREMENTS

The primary efficacy outcome was the perioperative mean core body temperature measured by a tympanic infrared thermometer. Secondary outcomes were hypothermia incidence, change in core body temperature, length of stay in postanesthesia care unit, thermal comfort, patient satisfaction, ease of use, and adverse events related to the BARRIER EasyWarm blanket.

MAIN RESULTS

The BARRIER EasyWarm blanket significantly improved perioperative core body temperature compared with standard hospital blankets (36.5°C, SD 0.4°C, vs 36.3, SD 0.3°C; P<.001). Intraoperatively, in the intervention group, hypothermia incidence was 38% compared with 60% in the control group (P=.001). Postoperatively, the figures were 24% vs 49%, respectively (P=.001). Patients in the intervention group had significantly higher thermal comfort scores, preoperatively and postoperatively. No serious adverse effects were observed in either group.

CONCLUSIONS

Perioperative use of the new self-warming blanket improves mean perioperative core body temperature, reduces the incidence of inadvertent perioperative hypothermia, and improves patients' thermal comfort during elective adult surgery.

A comparison of the temperature difference according to the placement of a nasopharyngeal temperature probe

BACKGROUND

The purpose of this study was to compare temperatures measured at three different sites where a nasopharyngeal temperature probe is commonly placed.

METHODS

Eighty elective abdominal surgical patients were enrolled. After anesthesia induction, four temperature probes were placed at the nasal cavity, upper portion of the nasopharynx, oropharynx, and the esophagus. The placement of the nasopharyngeal temperature probes was evaluated using a flexible nasendoscope, and the depth from the nares was measured. The four temperatures were simultaneously recorded at 10-minute intervals for 60 minutes.

RESULTS

The average depths of the probes that were placed in the nasal cavity, upper nasopharynx, and the oropharynx were respectively 5.7 ± 0.9 cm, 9.9 ± 0.7 cm, and 13.6 ± 1.7 cm from the nares. In the baseline temperatures, the temperature differences were significantly greater in the nasal cavity 0.32 (95% CI; 0.27-0.37)℃ than in the nasopharynx 0.02 (0.01-0.04)℃, and oropharynx 0.02 (-0.01 to 0.05)℃ compared with the esophagus (P < 0.001). These differences were maintained for 60 minutes. Twenty patients showed a 0.5℃ or greater temperature difference between the nasal cavity and the esophagus, but no patient showed such a difference at the nasopharynx and oropharynx.

CONCLUSIONS

During general anesthesia, the temperatures measured at the upper nasopharynx and the oropharynx, but not the nasal cavity, reflected the core temperature. Therefore, the authors recommend that a probe should be placed at the nasopharynx (≈ 10 cm) or oropharynx (≈ 14 cm) with mucosal attachment for accurate core temperature measurement.