Temperature monitoring and perioperative thermoregulation

Survival at 30 days in elderly patients with hip fracture surgery who were exposed to hypothermia: Survival study

The effect of hypothermia as a mortality risk factor at 30 days in the elderly who had hip fracture (HF) surgery is still controversial because it may be due to a set of poorly identified factors. In this study, we aim to determine if exposure to intra and immediate postoperative hypothermia increases the incidence of mortality at 30 days in elderly patients who had HF surgery.Survival study in the elderly who had HF surgery with and without exposure to hypothermia. Sociodemographic, anesthetic and surgical factors were collected. The temperature of the rectum was measured at the end of the surgery and in the recovery room. The effect of hypothermia was analyzed by the incidence of mortality at 30 days. Other results were considered, such as, surgical site infection (SSI), blood transfusions, and influence of implants used in the 30-day mortality.Three hundred eighty five subjects were eligible, to include 300. Inadvertent hypothermia was 12%, the 30-day overall mortality was 9% and in subjects with hypothermia it was 25% (P = .002). Subjects with hypothermia had a higher risk of SSI (relative risk 4.2, 95% confidence interval 1.3-13.6, P = .03) and receive more transfusions (relative risk 3.6, 95% confidence interval 2.0-6.5, P < .001).Elderly subjects with HF exposed to hypothermia who undergo hip hemiarthroplasty and who receive 2 or more blood transfusions during their treatment, are at greater risk of dying after 30 days of the surgery. Hypothermia, as a possible causative factor of mortality, should continue to be studied.

Risk factors for inadvertent intraoperative hypothermia in patients undergoing laparoscopic surgery: A prospective cohort study

Background

Inadvertent intraoperative hypothermia is frequent during open surgeries; however, few studies on hypothermia during laparoscopic abdominal surgery have been reported. We aimed to investigate the incidence and risk factors for hypothermia in patients undergoing laparoscopic abdominal surgery.

Methods

This single-center prospective cohort observational study involved patients undergoing laparoscopic surgery between October 2018 and June 2019. Data on core body temperature and potential variables were collected. A multivariate logistic regression analysis was performed to identify the risk factors associated with hypothermia. A Cox regression analysis was used to verify the sensitivity of the results.

Results

In total, 690 patients were included in the analysis, of whom 200 (29.0%, 95% CI: 26%−32%) had a core temperature < 36°C. The core temperature decreased over time, and the incident hypothermia increased gradually. In the multivariate logistic regression analysis, age (OR = 1.017, 95% CI: 1.000–1.034, P = 0.050), BMI (OR = 0.938, 95% CI: 0.880–1.000; P = 0.049), baseline body temperature (OR = 0.025, 95% CI: 0.010–0.060; P < 0.001), volume of irrigation fluids (OR = 1.001, 95% CI: 1.000–1.001, P = 0.001), volume of urine (OR = 1.001, 95% CI: 1.000–1.003, P = 0.070), and duration of surgery (OR = 1.010, 95% CI: 1.006–1.015, P < 0.001) were significantly associated with hypothermia. In the Cox analysis, variables in the final model were age, BMI, baseline body temperature, volume of irrigation fluids, blood loss, and duration of surgery.

Conclusions

Inadvertent intraoperative hypothermia is evident in patients undergoing laparoscopic surgeries. Age, BMI, baseline body temperature, volume of irrigation fluids, and duration of surgery are significantly associated with intraoperative hypothermia.

Accuracy of non-invasive body temperature measurement methods in critically ill patients: a prospective, bicentric, observational study

Objective: The accuracy of different non-invasive body temperature measurement methods in intensive care unit (ICU) patients is uncertain. We aimed to study the accuracy of three commonly used methods. Design: Prospective observational study. Setting: ICUs of two tertiary Australian hospitals. Participants: Critically ill patients admitted to the ICU. Interventions: Invasive (intravascular and intra-urinary bladder catheter) and non-invasive (axillary chemical dot, tympanic infrared, and temporal scanner) body temperature measurements were taken at study inclusion and every 4 hours for the following 72 hours. Main outcome measures: Accuracy of non-invasive body temperature measurement methods was assessed by the Bland-Altman approach, accounting for repeated measurements and significant explanatory variables that were identified by regression analysis. Clinical adequacy was set at limits of agreement (LoA) of 1°C compared with core temperature. Results: We studied 50 consecutive critically ill patients who were mainly admitted to the ICU after cardiac surgery. From over 375 observations, invasive core temperature (mostly pulmonary artery catheter) ranged from 33.9°C to 39°C. On average, the LoA between invasive and non-invasive measurements methods were about 3°C. The temporal scanner showed the worst performance in estimating core temperature (bias, 0.66°C; LoA, -1.23°C, +2.55°C), followed by tympanic infrared (bias, 0.44°C; LoA, -1.73°C, +2.61°C) and axillary chemical dot methods (bias, 0.32°C; LoA, -1.64°C, +2.28°C). No methods achieved clinical adequacy even accounting for significant explanatory variables. Conclusions: The axillary chemical dot, tympanic infrared and temporal scanner methods are inaccurate measures of core temperature in ICU patients. These non-invasive methods appeared unreliable for use in ICU patients.

Incidence of Severe Hypothermia and Its Impact on Postoperative Surgical Complications and Time Delay to Adjunct Treatments in Breast Surgery Cancer Patients: A Case-Controlled Study

Introduction: Unintended postoperative hypothermia frequently occurs upon arrival in the post anesthesia care unit (PACU). As part of our quality assurance program in anesthesia, we regularly monitor the incidence of this complication through our anesthesia information management system (AIMS). In this case-controlled retrospective study, our goal was to detect the incidence of unintended severe hypothermia in our breast surgery cancer patients, and subsequently to analyze the consequence of this complication in terms postoperative cutaneous infection, as well as its impact on further complementary treatment, such as radiotherapy and chemotherapy. Methods: This study was a retrospective analysis conducted through our AIMS system from 2015 through 2019, with extraction criteria based on year, type of surgery (breast), and temperature upon arrival in PACU. A tympanic temperature of less than 36 °C was considered to indicate hypothermia. Severe hypothermia was considered for patients having a temperature lower than 35.2 °C (hypothermic) (n = 80), who were paired using a propensity score analysis with a control group (normothermic) (n = 80) of other breast cancer surgery patients. Extracted data included time of surgery, sex, age, ASA status, and type and duration of the intervention. Results: The mean incidence of hypothermia was 21% from 2015 through 2019. The body mass index (BMI) was significantly lower in the hypothermia group before matching, 23.5 ± 4.1 vs. 26.4 ± 6.1 kg/m² in normothermic patients (p < 0.05). The hypothermia group also had significantly fewer monitoring and active warming devices. No difference was noted for wound complications. Time to complementary chemotherapy and or radiotherapy did not differ between groups (52 ± 21 days in group hypothermia vs 49 ± 22 days in the control group). Conclusion: Severe intraoperative hypothermia remains an important quality assurance issue in our breast surgery cancer patients, but we could not detect any long-term effect of hypothermia.

The Effect of Intraoperative Body Temperature on Postoperative Nausea and Vomiting in Pediatric Patients

PURPOSE

Pediatric patients are at greater risk for both perioperative hypothermia and postoperative nausea and vomiting (PONV). The primary aim of this study was to investigate whether there is a relationship between intraoperative body temperature and PONV in children undergoing anesthesia. The secondary aim was to investigate the relationship between PONV and intraoperative fentanyl use, age and duration of operation.

DESIGN

A prospective cohort study METHODS: The study included 80 children who were undergoing lower abdominal surgery. Body temperature was monitored after routine preoperative preparation and standard induction. Analgesic and antiemetic requirements and the presence of nausea and vomiting were assessed postoperatively on the 30th minute and the 6th, 12th and 24th hour.

FINDINGS

The children with or without PONV were compared. At the postoperative 6th hour, the incidence of nausea was statistically significant in the children with a mean body temperature below 36°C (P = 0.044; P < 0.05). The mean duration of the surgery was statistically significant longer in the children with PONV (P = 0.001; P = 0.004; P <0.05). Mean body temperature was not statistically significant when comparing children with and without vomiting(P > 0.05).

CONCLUSION

While a body temperature below 36°C increases the incidence of postoperative nausea, it does not cause an increase in the incidence of vomiting. A long operation time in pediatric patients causes an increase in the incidence of PONV. Although not statistically significant, PONV is encountered more than twice as much in patients receiving intraoperative fentanyl administration.

The Role of Perioperative Hypothermia in the Development of Surgical Site Infection: A Systematic Review

Surgical patients may experience inadvertent perioperative hypothermia, a condition that can cause a variety of complications, including surgical site infection (SSI). The authors of this systematic review used the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines to examine the role of perioperative hypothermia in the development of SSI. The authors searched the PubMed, Cumulative Index Nursing and Allied Health Literature, Cochrane, and ScienceDirect databases for eligible articles published between January 2008 and November 2018 and identified seven studies that met the inclusion criteria. The results of this review indicate that the relationship between hypothermia and SSI is closely related to the type of the surgical intervention performed (eg, emergent, colorectal), and that severe hypothermia (eg, <35.0° C [95.0° F]) can increase the risk of developing an SSI. Perioperative nurses should monitor patients for inadvertent hypothermia and prevent its occurrence when possible.

Clinical accuracy of non-contact forehead infrared thermometer and infrared tympanic thermometer in postoperative adult patients: A comparative study

Core temperature monitoring is important for the assessment and prevention of possible postoperative complications. The aim of the present study was to examine the agreement between the core temperature values and the forehead, tympanic membrane and axillary values in postoperative adult patients in clinical practice. The study measured the core temperature of 65 patients undergoing scheduled abdominal surgery using SpotOn™ and compared these with those obtained using non-contact forehead infrared, infrared tympanic and axillary thermometers. Correlation and Bland-Altman analyses were conducted for these comparisons. All temperatures were recorded at 4h intervals after postoperative arrival to the ward. Forehead temperature recordings showed a good correlation with the core temperature with excellent accuracy and was comparable to the tympanic temperature. Both forehead and tympanic thermometers can rapidly and effectively measure the core temperature during early postoperative period. Considering patients' safety, non-contact forehead infrared thermometers may be useful for postoperative monitoring.

Perioperative Hypothermia in Children

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

Zero-Heat-Flux and Esophageal Temperature Monitoring in Orthopedic Surgery: An Observational Study

Purpose

Perioperative hypothermia prevention requires regular, accurate, and consistent temperature monitoring. Zero-heat-flux (ZHF) thermometry offers a non-invasive, measurement method that can be applied across all surgical phases. The purpose of this study was to measure agreement between the zero-heat-flux device and esophageal monitoring, sensitivity, and specificity to detect hypothermia and patient acceptability amongst patients undergoing upper and lower limb orthopedic surgery.

Patients and Methods

This prospective, observational study utilized Bland–Altman analysis and Lin’s concordance coefficient to measure agreement between devices, sensitivity and specificity to detect hypothermia and assessed patient acceptability amongst 30 patients between December 2018 and June 2019.

Results

Bias was observed between devices via Bland Altman, with bias dependent on actual temperature. The mean difference ranged from −0.16°C at 34.9°C (where the mean of ZHF was lower than the esophageal device) to 0.46°C at 37.25°C (where the mean of ZHF was higher than esophageal device), with 95% limits of agreement (max) upper LOA = 0.80 to 1.41, lower LOA = −1.12 to −0.50. Seventy-five percentage of zero-heat-flux measurements were within 0.5°C of esophageal readings. Patient acceptability was high; 96% (n=27) stated that the device was comfortable.

Conclusion

ZHF device achieved lesser measurement accuracy with core (esophageal) temperature compared to earlier findings. Nonetheless, due to continuous capability, non-invasiveness and patient reported acceptability, the device warrants further evaluation.

Title Registration

The study was registered at www.ANZCTR.org.au (reference: ACTRN12619000842167).

Evaluation of dexmedetomidine anesthesia-related temperature changes: preliminary retrospective observational study

INTRODUCTION AND OBJECTIVE

Dexmedetomidine is a potent adrenergic alpha-2 agonist, and analgesic, sedative, anxiolytic and sympatholytic. Given there have been reports of dexmedetomidine associated temperature changes, in which these events have been associated with complications, our objective was to describe both temperature increase and decrease, during the intra and postoperative period (initial 24 hours), and factors associated, in patients who received dexmedetomidine for anesthesia/sedation in the surgical suite.

METHOD

Retrospective observational study, analyzing charts of patients ≥ 18 years submitted to anesthesia/sedation with dexmedetomidine, between 1/1/2017 and 31/12/2017. Upper temperature threshold was considered ≥ 37.8 °C, and lower, < 35 °C. The association with dexmedetomidine was assessed by the OMS/UMC causality system and by the Naranjo algorithm.

RESULTS

The sample included 42 patients who received dexmedetomidine and whose temperature data were available, with predominance of men 26 (62%), 49.4/16.5 years old (mean/standard deviation), and weight 65/35.8 kg. None of the patients presented intraoperative temperature equal to or above 37.8 °C or below 35 °C. During the postoperative period, one patient presented an increase ≥ 37.8 °C (2.4%) and three, temperature decrease < 35 °C (7%). Surgery/anesthesia time and exposure time to dexmedetomidine were not appropriate linear predictors of maximum temperature. Older age (p < 0.01), longer exposure to dexmedetomidine (p < 0.05) and shorter surgery time (p < 0.01) were significant linear predictors for lower minimum temperature.

CONCLUSIONS

Increase ≥ 37.8 °C/decrease < 35 °C of temperature possibly associated with dexmedetomidine did not occur in the intraoperative period and had a low frequency during the postoperative period.

Heated Humidified Breathing Circuit Rewarming in Hypothermic Patients Post-Cardiopulmonary Bypass-Pilot Study

OBJECTIVES

Hypothermia on intensive care unit (ICU) admission after cardiac surgery and cardiopulmonary bypass is common. It contributes to postoperative complications including shivering, coagulopathy, increased blood loss and transfusion requirements, morbid cardiac events, metabolic acidosis, increased wound infections, and prolonged hospital length of stay. The current standard of care for rewarming ICU patients is forced air warming blankets. However, high-quality evidence on additional benefit rendered by other warming methods, such as heated humidified breathing circuits (HHBC), is lacking. Therefore, the authors conducted a pilot study to examine whether the addition of HHBC to standard forced air warming blankets in hypothermic patients (≤35°C) admitted to the ICU after cardiac surgery using cardiopulmonary bypass reduced time to normothermia.

DESIGN

Prospective study conducted at a single large academic medical center.

PARTICIPANTS

The study group was composed of 14 patients who were enrolled prospectively between April 1 and June 14, 2019. The study group was compared with a 2:1 matched retrospective control group. The matched group consisted of 28 patients from a 12-month period from July 1, 2018 June 30, 2019.

INTERVENTIONS

Study patients received warming via forced air warming blankets and HHBC and were compared with patients in a control group who received only warming blankets. Time to normothermia, time to extubation, time to normal pH, blood loss, blood transfusions, and coagulation profile laboratory values were compared between the study and control groups.

MEASUREMENTS AND MAIN RESULTS

The present study found no statistical difference in time to normothermia, for which the standard-of-care retrospective group achieved normothermia after a median (Q1-Q3) 4.8 (4.0-6.0) hours compared with 4.4 (3.5-5.5) hours in the prospective group receiving HHBC. All secondary outcomes, including time to extubation, time to normal pH, ICU blood product transfusion, chest tube output, and coagulation profile, were similar.

CONCLUSIONS

The present pilot study detected a similar time to normothermia, extubation, and normal pH when HHBC were added to standard forced air warming blankets in hypothermic patients (≤35°C) admitted to the ICU after cardiac surgery using cardiopulmonary bypass. A future larger prospective study designed to detect smaller, but clinically meaningful, reductions in the time to key clinical events for patients treated with HHBC is feasible and warranted.

Recommendations for standards of monitoring during anaesthesia and recovery 2021: Guideline from the Association of Anaesthetists

This guideline updates and replaces the 5th edition of the Standards of Monitoring published in 2015. The aim of this document is to provide guidance on the minimum standards for monitoring of any patient undergoing anaesthesia or sedation under the care of an anaesthetist. The recommendations are primarily aimed at anaesthetists practising in the UK and Ireland, but it is recognised that these guidelines may also be of use in other areas of the world. Minimum standards for monitoring patients during anaesthesia and in the recovery phase are included. There is also guidance on monitoring patients undergoing sedation and during transfer. There are new sections specifically discussing capnography, sedation and regional anaesthesia. In addition, the indications for processed electroencephalogram and neuromuscular monitoring have been updated.

Cardiac arrest caused by accidental severe hypothermia and myocardial infarction during general anesthesia

Therapeutic hypothermia is often used for traumatic brain injury because of its neuroprotective effect and decreased secondary brain injury. However, this procedure lacks clinical evidence supporting its efficacy, and adverse outcomes have been reported during general anesthesia. A 61-year-old man with a history of percutaneous coronary intervention (PCI) was admitted with traumatic brain injury. Immediately after admission, he underwent mild therapeutic hypothermia with a target temperature of 33.0°C for neuroprotection. During general anesthesia for emergency surgery because he developed a mass effect, hypothermic cardiac arrest occurred following an additional decrease in the core body temperature. Moreover, myocardial infarction caused by restenosis of the previous PCI lesion also contributed to the cardiac arrest. Although the patient recovered spontaneous circulation after an hour-long cardiopulmonary resuscitation with rewarming, he eventually died of subsequent repetitive cardiac arrests. When anesthetizing patients undergoing therapeutic hypothermia, caution is required to prevent adverse outcomes that can be caused by unintentional severe hypothermia and exacerbation of underlying heart disease.

Measuring Core Body Temperature Using a Non-invasive, Disposable Double-Sensor During Targeted Temperature Management in Post-cardiac Arrest Patients

Background: Precisely measuring the core body temperature during targeted temperature management after return of spontaneous circulation is mandatory, as deviations from the recommended temperature might result in side effects such as electrolyte imbalances or infections. However, previous methods are invasive and lack easy handling. A disposable, non-invasive temperature sensor using the heat flux approach (Double Sensor), was tested against the standard method: an esophagus thermometer.

Methods: The sensor was placed on the forehead of adult patients (n = 25, M/F, median age 61 years) with return of spontaneous circulation after cardiac arrest undergoing targeted temperature management. The recorded temperatures were compared to the established measurement method of an esophageal thermometer. A paired t-test was performed to examine differences between methods. A Bland-Altman-Plot and the intraclass correlation coefficient were used to assess agreement and reliability. To rule out possible influence on measurements, the patients' medication was recorded as well.

Results: Over the span of 1 year and 3 months, data from 25 patients were recorded. The t-test showed no significant difference between the two measuring methods (t = 1.47, p = 0.14, n = 1,319). Bland-Altman results showed a mean bias of 0.02°C (95% confidence interval 0.00–0.04) and 95% limits of agreement of −1.023°C and 1.066°C. The intraclass correlation coefficient was 0.94. No skin irritation or allergic reaction was observed where the sensor was placed. In six patients the bias differed noticeably from the rest of the participants, but no sex-based or ethnicity-based differences could be identified. Influences on the measurements of the Double Sensor by drugs administered could also be ruled out.

Conclusions: This study could demonstrate that measuring the core body temperature with the non-invasive, disposable sensor shows excellent reliability during targeted temperature management after survived cardiac arrest. Nonetheless, clinical research concerning the implementation of the sensor in other fields of application should be supported, as well as verifying our results by a larger patient cohort to possibly improve the limits of agreement.

Application of a sub-0.1-mm3 implantable mote for in vivo real-time wireless temperature sensing

There has been increasing interest in wireless, miniaturized implantable medical devices for in vivo and in situ physiological monitoring. Here, we present such an implant that uses a conventional ultrasound imager for wireless powering and data communication and acts as a probe for real-time temperature sensing, including the monitoring of body temperature and temperature changes resulting from therapeutic application of ultrasound. The sub-0.1-mm³, sub-1-nW device, referred to as a mote, achieves aggressive miniaturization through the monolithic integration of a custom low-power temperature sensor chip with a microscale piezoelectric transducer fabricated on top of the chip. The small displaced volume of these motes allows them to be implanted or injected using minimally invasive techniques with improved biocompatibility. We demonstrate their sensing functionality in vivo for an ultrasound neurostimulation procedure in mice. Our motes have the potential to be adapted to the distributed and localized sensing of other clinically relevant physiological parameters.

Use of high-resolution thermography as a validation measure to confirm epidural anesthesia in mice: a cross-over study

BACKGROUND

Effective epidural anesthesia is confirmed in humans by sensory assessments but these tests are not feasible in mice. We hypothesized that, in mice, infrared thermography would demonstrate selective segmental warming of lower extremities following epidural anesthesia.

METHODS

We anesthetized 10 C57BL/6 mice with isoflurane and then inserted a PU-10 epidural catheter under direct surgical microscopy at T11-12. A thermal camera (thermal sensitivity ±0.05°C, pixel resolution 320x240 pixels, and spatial resolution 200 μm) recorded baseline temperature of front and rear paws, tail and ears. Thermography was assessed at baseline and 2, 5, 10, and 15 min after an epidural bolus dose of 50 μL bupivacaine 0.25% or 50 μL saline (control) using a cross-over design with dose order randomized and investigators blinded to study drug. Thermal images were recorded from video and analyzed using FLIR software. Effect over time and maximal effect (E_max) were assessed by repeated measures ANOVA and paired t-tests. Comparisons were between bupivacaine and control, and between lower vs upper extremities.

RESULTS

Epidural bupivacaine caused progressive warming of lower compared with upper extremities (P <0.001), typically returning to baseline by 15 min after administration. Mean (±SD) E_max was +3.73 (±1.56) °C for lower extremities compared with 0.56 (±0.68) °C (P=0.03) for upper extremities. Following epidural saline, there was no effect over time (E_max for lower extremities -0.88 (±0.28) °C compared with the upper extremities -0.88 (±0.19) °C (P >0.99).

CONCLUSIONS

Thermography is a useful tool to confirm epidural catheter placement in animals for which subjective, non-noxious, sensory measures are impossible.

Accuracy of non-invasive body temperature measurement methods in adult patients admitted to the intensive care unit: a systematic review and meta-analysis

Objective: Non-invasive thermometers are widely used in both clinical practice and trials to estimate core temperature. We aimed to investigate their accuracy and precision in patients admitted to the intensive care unit (ICU). Study design: Systematic review and meta-analysis. Data sources: We searched MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials to identify all relevant studies from 1966 to 2017. We selected published trials that reported the accuracy and precision of non-invasive peripheral thermometers (index test) in ICU patients compared with intravascular temperature measurement (reference test). The extracted data included the study design and setting, authors, study population, devices, and body temperature measurements. Methods: Two reviewers performed the initial search, selected studies, and extracted data. Study quality was assessed using the QUADAS-2 tool. Pooled estimates of the mean bias between index and reference tests and the standard deviation of mean bias were synthesised using DerSimonian and Laird random effects meta-analyses. Results: We included 13 cohort studies (632 patients, 105 375 measurements). Axillary, tympanic infrared and zero heat flux thermometers all underestimated intravascular temperature. Only oesophageal measurements showed clinically acceptable accuracy. We found an insufficient number of studies to assess precision for any technique. Study heterogeneity was high (99-100%). Risk of bias for the index test was unclear, mostly because of no device calibration or control for confounders. Conclusions: Compared with the gold standard of intravascular temperature measurement, non-invasive peripheral thermometers have low accuracy. This makes their clinical and trial-related use in ICU patients unreliable and potentially misleading.

Central Neural Circuits Orchestrating Thermogenesis, Sleep-Wakefulness States and General Anesthesia States

Great progress has been made in specifically identifying the central neural circuits (CNCs) of the core body temperature (Tcore), sleep-wakefulness states (SWs), and general anesthesia states (GAs), mainly utilizing optogenetic or chemogenetic manipulations. We summarize the neuronal populations and neural pathways of these three CNCs, which gives evidence for the orchestration within these three CNCs, and the integrative regulation of these three CNCs by different environmental light signals. We also outline some transient receptor potential (TRP) channels that function in the CNCs-Tcore and are modulated by some general anesthetics, which makes TRP channels possible targets for addressing the general-anesthetics-induced-hypothermia (GAIH). We suggest this review will provide new orientations for further consummating these CNCs and elucidating the central mechanisms of GAIH.

Does the Laminar Airflow System Affect the Development of Perioperative Hypothermia? A Randomized Clinical Trial

OBJECTIVES

We aimed to compare tympanic membrane temperature changes and the incidence of inadvertent perioperative hypothermia (IPH) in patients undergoing laparoscopic cholecystectomy under general anesthesia in laminar airflow systems (LAS-OR) and conventional turbulent airflow systems (CAS-OR).

BACKGROUND

Different heating, ventilation, and air-conditioning (HVAC) systems are used in the operating room (OR), such as LAS and CAS. Laminar airflow is directed directly to the patient in LAS-OR. Does laminar airflow in ORs cause faster heat loss by convection?

METHODS

This is a prospective, randomized study. We divided 200 patients with simple randomization (1:1), as group LAS and group CAS, and took the patients into the LAS-OR or CAS-OR for the operation. Clinical trial number: IRCT20180324039145N3. The tympanic membrane temperatures of patients were measured (°C) before anesthesia induction (T ₀) and then every 15 min during surgery (T_n). Changes (Δ_n) between T ₀ and T_n were measured.

RESULTS

In the first 30 min, there was a temperature decrease of approximately 0.8 °C (1.44 °F) in both groups. Temperature decreases at 45 min were higher in group LAS than in group CAS but not statistically significant, Δ₄₅, respectively, 0.89 (95% confidence interval [CI] [0.77, 1.02]) versus 0.77 (95% CI [0.69, 0.84]; p = .09). IPH occurred in a total of 60.9% (112 of 184) of patients in the entire surgical evaluation period in group LAS and group CAS (58.9% vs. 62.8%, p = . 59).

CONCLUSIONS

IPH is seen frequently in both HVAC systems. Clinically, the advantage of HVAC systems relative to each other has not been demonstrated during laparoscopic cholecystectomy.

Development of a Nomogram to Predict Postoperative Transfusion in the Elderly After Intramedullary Nail Fixation of Femoral Intertrochanteric Fractures

Purpose

The aim of our study was to explore the risk factors related to blood transfusion after intramedullary nail fixation of elderly femoral intertrochanteric fracture (FTF) and establish a nomogram prediction model.

Patients and Methods

We conducted a retrospective study including elderly FTF patients treated by intramedullary nail between January 2017 and December 2019. Perioperative information was obtained retrospectively, uni- and multivariate regression analyses were performed to determine risk factors for blood transfusion. A nomogram model was established to predict the risk of blood transfusion, and consistency coefficient (C-index) and correction curve were used to evaluate the prediction performance and consistency of the model.

Results

Of 148 patients, 119 were finally enrolled in the study and and 46 patients (38.7%) received a blood transfusion after the operation. Logistic regression analysis the female, lower preoperative Hb, ASA score >2, general anesthesia, and higher intraoperative blood loss were independently associated with the blood transfusion. The accuracy of the contour map for predicting transfusion risk was 0.910.

Conclusion

These risk factors are shown on the nomogram and verified. Through the assessment of the risk of blood transfusion and the intervention of modifiable risk factors, we may be able to reduce the blood transfusion rate to a certain extent, so as to further guarantee the safety of the elderly patients during the perioperative period.

Influence of flow rate, fluid temperature, and extension line on Hotline and S-line heating capability: an in vitro study

Background

A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation.

Methods

We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr).

Results

At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using room-temperature or cold fluid. Administering of the warm fluid at the same flow rate significantly increased the TProx and TDistal values in S-line more than the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature.

Conclusions

Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. Administering warm fluid in S-line prevented a decrease in the fluid temperature at a high flow rate. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

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.

Too Cool? Hip Fracture Care and Maintaining Body Temperature

Introduction:

Patients with hip fractures can become cold during the perioperative period despite measures applied to maintain warmth. Poor temperature control is linked with increasing complications and poorer functional outcomes. There is generic evidence for the benefits of maintaining normothermia, however this is sparse where specifically concerning hip fracture. We provide the first comprehensive review in this population.

Significance:

Large studies have revealed dramatic impact on wound infection, transfusion rates, increased morbidity and mortality. With very few studies relating to hip fracture patients, this review aimed to capture an overview of available literature regarding hypothermia and its impact on outcomes.

Results:

Increased mortality, readmission rates and surgical site infections are all associated with poor temperature control. This is more profound, and more common, in older frail patients. Increasing age and lower BMI were recognized as demographic factors that increase risk of hypothermia, which was routinely identified within modern day practice despite the use of active warming.

Conclusion:

There is a gap in research related to fragility fractures and how hypothermia impacts outcomes. Inadvertent intraoperative hypothermia still occurs routinely, even when active warming and cotton blankets are applied. No studies documented temperature readings postoperatively once patients had been returned to the ward. This is a point in the timeline where patients could be hypothermic. More studies need to be performed relating to this area of surgery.

Accuracy of zero-heat-flux thermometry and bladder temperature measurement in critically ill patients

Core temperature (T_Core) monitoring is essential in intensive care medicine. Bladder temperature is the standard of care in many institutions, but not possible in all patients. We therefore compared core temperature measured with a zero-heat flux thermometer (T_ZHF) and with a bladder catheter (T_Bladder) against blood temperature (T_Blood) as a gold standard in 50 critically ill patients in a prospective, observational study. Every 30 min T_Blood, T_Bladder and T_ZHF were documented simultaneously. Bland–Altman statistics were used for interpretation. 7018 pairs of measurements for the comparison of T_Blood with T_ZHF and 7265 pairs of measurements for the comparison of T_Blood with T_Bladder could be used. T_Bladder represented T_Blood more accurate than T_ZHF. In the Bland Altman analyses the bias was smaller (0.05 °C vs. − 0.12 °C) and limits of agreement were narrower (0.64 °C to − 0.54 °C vs. 0.51 °C to – 0.76 °C), but not in clinically meaningful amounts. In conclusion the results for zero-heat-flux and bladder temperatures were virtually identical within about a tenth of a degree, although T_ZHF tended to underestimate T_Blood. Therefore, either is suitable for clinical use.

German Clinical Trials Register, DRKS00015482, Registered on 20th September 2018, http://apps.who.int/trialsearch/Trial2.aspx?TrialID=DRKS00015482.

Effects of hyperthermia on the effective concentration of rocuronium and sugammadex-mediated reversal in isolated phrenic nerve hemidiaphragm preparations of rats

Background

Hyperthermia is relatively rare during general anesthesia; however, a few studies have been conducted on hyperthermia and the neuromuscular blockade (NMB) induced by rocuronium, and the reversal of NMB by sugammadex. We investigated the effect of hyperthermia status on the NMB induced by rocuronium, and its reversal by sugammadex, in isolated phrenic nerve hemidiaphragm (PNHD) preparations of the rat.

Methods

Thirty-three male Sprague-Dawley rat PNHD preparations were randomly assigned to three groups at different temperatures (36 °C, 38 °C, and 40 °C; each group, n = 11, in Krebs solution). The train-of-four (TOF) and twitch height responses were checked mechanomyographically. The PNHD were treated with progressively increasing doses of rocuronium and three effective concentrations (ECs), EC50, EC90, and EC95, of rocuronium were analyzed in each group via nonlinear regression analysis. Then, sugammadex was administered in doses equimolar to rocuronium. Thereafter, the T1 height (%), TOFR (%) and the duration index were measured.

Results

The EC of rocuronium (EC50, EC90, and EC95) decreased significantly in accordance with increasing temperature. The groups at 36 °C and 40 °C showed clear differences in all areas (all P < 0.001). Moreover, the T1 height (%) and the duration index upon sugammadex administration showed faster recovery results in the36 °C than the 38 °C and 40 °C groups.

Conclusion

A rise of temperature from 38 °C to 40 °C in rat PNHD preparations proportionally enhanced the NMB induced by rocuronium. In addition, equimolar doses of sugammadex to the administered rocuronium showed a slower recovery time as the temperature rises.

Thermoregulation: A journey from physiology to computational models and the intensive care unit

Thermoregulation plays a vital role in homeostasis. Many species of animals as well as humans have evolved various physiological mechanisms for body temperature control, which are characteristically flexible and enable a fine-tuned spatial and temporal regulation of body temperature in different environmental conditions and circumstances. Human beings normally maintain a core body temperature at around 37°C, and maintenance of this relatively high temperature is critical for survival. Therefore, principles of thermoregulatory control have also important clinical implications. Infections can cause the body temperature to rise internally and several diseases can cause a dysfunction of thermoregulatory mechanisms. Moreover, the utilization of thermotherapies in treating various diseases has been known for thousands of years with a recent resurgence of interest. An increasing amount of research suggests that targeted temperature management is of paramount importance to patient outcomes in certain clinical scenarios. We provide a concise summary of the basic concepts of thermoregulation. Emphasis is given to the principles of thermoregulation in humans in basic pathological states and to targeted temperature management strategies in the clinical environment, with special attention on therapeutic hypothermia in postcardiac arrest patients. Finally, the discussion is focused on the potential offered by computational thermophysiological models for predicting thermal responses of patients in various clinical circumstances, for proposing new perspectives in the design of novel thermal therapies, and to optimize targeted temperature management strategies. This article is categorized under: Cardiovascular Diseases > Cardiovascular Diseases>Computational Models Cardiovascular Diseases > Cardiovascular Diseases>Environmental Factors Cardiovascular Diseases > Cardiovascular Diseases>Biomedical Engineering.

Intraoperative zero-heat-flux thermometry overestimates esophageal temperature by 0.26 °C: an observational study in 100 infants and young children

In pediatric anesthesia, deviations from normothermia can lead to many complications, with infants and young children at the highest risk. A measurement method for core temperature must be clinically accurate, precise and should be minimally invasive. Zero-heat-flux (ZHF) temperature measurements have been evaluated in several studies in adults. We assessed the agreement between the 3M Bair Hugger^™ temperature measurement sensor (T_ZHF) and esophageal temperature (T_Eso) in children up to and including 6 years undergoing surgery with general anesthesia. Data were recorded in 5 min-intervals. We investigated the accuracy of the ZHF sensor overall and in subgroups of different age, ASA classification, and temperature ranges by Bland–Altman comparisons of differences with multiple measurements. Change over time was assessed by a linear mixed model regression. Data were collected in 100 children with a median (1st–3rd quartile) age of 1.7 (1–3.9) years resulting in 1254 data pairs. Compared to T_Eso (range from 35.3 to 39.3 °C; median 37.2 °C), T_ZHF resulted in a mean bias of +0.26 °C (95% confidence interval +0.22 to +0.29 °C; 95% limits of agreement −0.11 to +0.62 °C). Lin’s concordance correlation coefficient was 0.89. There was no significant or relevant change of temperature over time (0.006 °C per hour measurement interval, p = 0.199) and no relevant differences in the subgroups. Due to the mean bias of +0.26 °C in T_ZHF, the risk of hypothermia may be underestimated, while the risk of hyperthermia may be overestimated. Nevertheless, because of its high precision, we consider ZHF valuable for intraoperative temperature monitoring in children and infants.

Perioperative Hypothermia after Transurethral Surgeries: Is it Necessary to Heat the Irrigation Fluids?

Objective

To investigate the role of heated irrigation fluids in the risk of hypothermia and related complications in patients undergoing transurethral procedures.

Methods

The medical records of all patients who underwent transurethral procedures between 2000 and 2016 at the VA Hospital were reviewed. Irrigation fluids have been heated to 42°C since 2013, as per the institutional policy (Group II). Prior to this date, room temperature solutions were used (Group I). The perioperative body temperature, use of warming devices, procedure length, and anaesthesia type were extracted from records and compared for both groups. In addition, demographic and anthropometric data, preoperative comorbidities, laboratory data, admission information and postoperative complications were obtained from the quality improvement database.

Results

There were 1,363 patients in Group I and 269 patients in Group II. Perioperative temperature was decreased by 0.10°C in Group I compared to a temperature gain of 0.32°C in Group II (p<0.001). Three hundred and forty-eight (21%) patients undergoing transurethral procedures developed hypothermia <36°C. There was no difference in the incidence of postoperative mortality or complications between the normothermic and hypothermic patients.

Conclusion

The replacement of room temperature solutions with warmed solutions for irrigation during transurethral procedures reduced the risk of temperature loss and hypothermia following these procedures. Available heating strategies effectively prevented the perioperative heat loss; however, such strategies did not affect the incidence of postoperative complications.

Institution of Monthly Anesthesia Quality Reports Does Not Reduce Postoperative Complications despite Improved Metric Compliance

While quality programs have been shown to improve provider compliance, few have demonstrated conclusive improvements in patient outcomes. We hypothesized that there would be increased metric compliance and decreased postoperative complications after initiation of an anesthesiology quality improvement program at our institution. We performed a retrospective study of all adult inpatients having anesthesia for a twelve-month period that spanned six months before and after program implementation. The primary outcome was the rate of complications in the post-implementation period. Secondary outcomes included the change in proportion of complications and compliance with quality metrics. We studied a total of 9620 adult inpatient cases, subdivided into pre- and post-implementation groups (4832 vs 4788.) After multivariate model adjustment, the rate of any complication (our primary outcome) was not significantly changed (32% to 31%; adjusted P = 0.410.) Of the individual complications, only wound infection (2.0% to 1.5%; adjusted P = 0.020) showed a statistically significant decrease. Statistically and clinically significant increases in compliance were seen for the BP-02 Avoiding Monitoring Gaps metric (81% to 93%, P < 0.001), both neuromuscular blockade metrics (NMB-01 76% to 91%, P < 0.001; NMB-02 95% to 97%, P = 0.006), both tidal volume metrics (PUL-01 84% to 93%, P < 0.001; PUL-02 30% to 45%, P < 0.001), and the TEMP-02 Core Temperature Measurement metric (88% to 94%, P < 0.001). Implementation of a comprehensive quality feedback program improved metric compliance but was not associated with a change in postoperative complications.

Undesirable Postoperative Anesthesia Outcomes at Two National Referral Hospitals: A Cross-Sectional Study in Eritrea

Background

Postoperative undesirable anesthesia outcomes are common among patients undergoing surgery. They may affect body systems and lead into more serious postoperative problems. This research is conducted in the Eritrean National Referral Hospitals with the aim of assessing the prevalence of undesirable anesthesia outcomes during the postoperative period.

Method

A cross-sectional study design was applied on 470 patients who underwent different types of surgeries within a three-month period. Patients were interviewed 24 hours after operation (POD 1) using the Leiden Perioperative care Patient Satisfaction questionnaire (LPPSq). This study reports one component of a large study conducted. The dimension "Discomfort and needs" of the LPPSq was considered, and the measurements of that dimension are presented in this report. Items of the dimension were standardized and measured using a five-point Likert scale from "Not at all" to "Extremely." Multivariable logistic regression was used to look for the association of the outcomes with the types of surgery and types of anesthesia using SPSS (Version 22).

Results

The prevalence were computed in two manners, prevalence of those with 'at least a little bit' outcomes, which was computed to see the total occurrence of these outcomes, and prevalence of those having 'more than moderate' outcomes to see the severe experience of these outcomes. Prevalence of the predominant undesirable outcome, postoperative pain, for 'at least a little bit' and 'more than moderate' were 82.6% and 43.6%, respectively. The rest of the postoperative undesirable outcomes were less frequently reported.

Conclusion

Postoperative pain was found to be the most prevalent undesirable outcome. Enhancement of proper assessment and management of postoperative pain through the development and implementation of specific pain management modalities is needed.

Effect of intrathecal lipophilic opioids on the incidence of shivering in women undergoing cesarean delivery after spinal anesthesia: a systematic review and bayesian network meta- analysis of randomized controlled trials

Background

Shivering is a common side effect in women having cesarean delivery (CD) under spinal anesthesia, which can be bothersome to the patient, and it can also interfere with perioperative monitoring. In several studies, the intrathecal (IT) addition of a lipophilic opioid to local anesthetics has been shown to decrease the incidence of shivering.

Objective

We performed this network meta-analysis to evaluate the effects of intrathecal lipophilic opioids in preventing the incidence of shivering in patients undergoing CD.

Methods

This review was planned according to the PRISMA for Network Meta-Analysis (PRISMA-NMA) guidelines. An English literature search of multiple electronic databases was conducted. We included randomized controlled trials (RCTs) that reported on the incidence of shivering, with study groups receiving either IT fentanyl, sufentanil, or meperidine in women undergoing CD under spinal anesthesia. Quality of the studies was assessed using the modified Oxford scoring system. Using random-effects modeling, dichotomous data were extracted and summarized using odds ratio (OR) with a 95% credible interval (CrI). Statistical analysis was conducted using R studio version 1.0.153 - Inc.

Results

Twenty-one studies consisting of 1433 patients (Control group: 590 patients in twenty-one studies; Fentanyl group:199 patients in seven studies; Sufentanil group: 156 patients in five studies; Meperidine group: 488 patients in ten studies) met the inclusion criteria for this systematic review investigating the effect of intrathecal lipophilic opioids in preventing the incidence of shivering in women undergoing cesarean delivery under spinal anesthesia. Methodological validity scores ranged from 3 to 7. The Bayesian mixed network estimate showed the incidence of shivering was significantly lower with IT fentanyl (pooled odds ratio (OR): 0.13; 95% credible interval (CrI): 0.04 to 0.35; P = 0.0004) and IT meperidine (OR: 0.12; 95% CrI: 0.05 to 0.29; P < 0.00001), but not with IT sufentanil (OR: 0.37; 95% CrI: 0.11 to 1.22; P = 0.23). The IT fentanyl group had a significantly lower incidence of intraoperative discomfort [Risk Ratio (RR): 0.19; 95% CI: 0.10–0.35; P < 0.00001], the IT sufentanil group had a significantly higher incidence of pruritus (RR: 6.18; 95% CI: 1.18–32.46; P = 0.03) The IT meperidine group had a significantly lower incidence of intraoperative discomfort (2.7% vs. 13.6%; RR: 0.22; 95% CI: 0.09–0.55; P = 0.001), but there was a significant increase in nausea and vomiting (IT meperidine group vs. Control group: 42.7% vs. 19.4%; RR: 2.56; 95% CI: 1.14–5.75; P = 0.02). Meta-regression analysis based on the opioid dose and quality of the study did not impact the final inference of our result.

Conclusion

IT fentanyl significantly decreased the incidence of shivering in women undergoing CD under spinal anesthesia without increasing maternal adverse events, confirming that routine use in this patient population is a good choice. IT sufentanil did not decrease the incidence of shivering. IT meperidine decreased the incidence and severity of shivering, but its use was also associated with significant nausea and vomiting.

Infrared thermal imaging associated with pain in laboratory animals

The science of animal welfare has evolved over the years, and recent scientific advances have enhanced our comprehension of the neurological, physiological, and ethological mechanisms of diverse animal species. Currently, the study of the affective states (emotions) of nonhuman animals is attracting great scientific interest focused primarily on negative experiences such as pain, fear, and suffering, which animals experience in different stages of their lives or during scientific research. Studies underway today seek to establish methods of evaluation that can accurately measure pain and then develop effective treatments for it, because the techniques available up to now are not sufficiently precise. One innovative technology that has recently been incorporated into veterinary medicine for the specific purpose of studying pain in animals is called infrared thermography (IRT), a technique that works by detecting and measuring levels of thermal radiation at different points on the body’s surface with high sensitivity. Changes in IRT images are associated mainly with blood perfusion, which is modulated by the mechanisms of vasodilatation and vasoconstriction. IRT is an efficient, noninvasive method for evaluating and controlling pain, two critical aspects of animal welfare in biomedical research. The aim of the present review is to compile and analyze studies of infrared thermographic changes associated with pain in laboratory research involving animals.

Use of Different Cooling Methods in Pig Facilities to Alleviate the Effects of Heat Stress-A Review

An increase in the frequency of hot periods, which has been observed over the past decades, determines the novel approach to livestock facilities improvement. The effects of heat stress are revealed in disorders in physiological processes, impaired immunity, changes in behaviour and decreases in animal production, thus implementation of cooling technologies is a key factor for alleviating these negative consequences. In pig facilities, various cooling methods have been implemented. Air temperature may be decreased by using adiabatic cooling technology such as a high-pressure fogging system or evaporative pads. In modern-type buildings large-surface evaporative pads may support a tunnel ventilation system. Currently a lot of attention has also been paid to developing energy- and water-saving cooling methods, using for example an earth-air or earth-to-water heat exchanger. The pigs' skin surface may be cooled by using sprinkling nozzles, high-velocity air stream or conductive cooling pads. The effectiveness of these technologies is discussed in this article, taking into consideration the indicators of animal welfare such as respiratory rate, skin surface and body core temperature, performance parameters and behavioural changes.

Immunological and behavioral responses to in vivo lipopolysaccharide administration in young and healthy obese and normal-weight humans

Obesity is associated with an increase prevalence of neuropsychiatric symptoms and diseases, such as depression. Based on the facts that pro-inflammatory cytokines are able to modulate behavior, and that obesity is characterized by a chronic low-grade inflammatory state, inflammation has been hypothesized to contribute to the neuropsychiatric comorbidity in obese individuals. However, a causal link between inflammation and the development of neuropsychiatric symptoms is hard to establish in humans. Here, we used an inflammatory stimulus, i.e. the intravenous injection of lipopolysaccharide (LPS), in a double-blind placebo-controlled design, to determine the vulnerability of obese individuals to inflammation-induced behavioral changes. The hypothesis was that obese individuals would show heightened behavioral response compared to normal-weight subjects for the same inflammatory stimulus, reflecting an increased sensitivity to the behavioral effects of pro-inflammatory cytokines. LPS (dose 0.8 ng/kg body weight, adjusted for estimated blood volume in obese subjects) and placebo (saline) were intravenously injected in 14 obese healthy subjects and 23 normal-weight healthy subjects in a within-subject, randomized, crossover design. LPS administration induced, in both groups, an acute increase in blood concentrations of cytokines (interleukin-6, tumor necrosis factor-α, and IL-10), as well as in body temperature, cortisol, norepinephrine, sickness symptoms, fatigue, negative mood, and state anxiety. There were little differences in the immune and behavioral responses to LPS between obese and normal-weight subjects, but the cortisol response to LPS was strongly attenuated in obese individuals. Higher percentage of body fat was related to a lower cortisol response to LPS. Taken together, the population of young and healthy obese individuals in this study did not exhibit an increased behavioral sensitivity to cytokines, but an attenuated cortisol response to the immune challenge. Future studies will need to determine whether additional physiological and psychological factors interact with the state of obesity to increase the risk for inflammation-induced neuropsychiatric symptoms.

Cryotherapy Improves Limb Use But Delays Normothermia Early After Stifle Joint Surgery in Dogs

Objective: To evaluate the short-term efficacy and safety of cold compression therapy (CCT) relative to a soft padded bandage (SPB) in dogs undergoing surgery to manage cranial cruciate ligament injury. Methods:Dogs were randomized into groups that received CCT or SPB after surgery. Weight bearing was measured using a weight distribution platform before and the day after surgery. Stifle joint flexion and extension were measured using a goniometer before and the day after surgery. Rectal temperatures were measured every 15 min for 2 h after surgery and the morning after surgery. Mechanical nociceptive thresholds (MNT) were measured using an algometer the day after surgery. Findings in both groups were compared using a mixed model ANOVA. Results:20 dogs were enrolled: 10 in the CCT and 10 in the SPB group. Dogs undergoing CCT had more stifle joint flexion (P = 0.008) and weight bearing (P < 0.001) after surgery than dogs with SPB. MNT after surgery correlated statistically with stifle joint flexion after surgery (r = -0.315, P = 0.014), extension after surgery (r = 0.310, P = 0.016), and weight bearing after surgery (r = 0.314, P = 0.003). Return to normothermia was delayed in the CCT group, with temperatures ~0.5°C (1.0°F) lower 105 (P = 0.018) and 120 min (P = 0.013) after surgery. Conclusion:Relative to bandaging, CCT had a positive short-term impact on stifle flexion and weight bearing. CCT delayed warming after surgery but dogs were only mildly hypothermic [0.5°C [1.0°F]].

Analysis of the Gearbox Oil Maintenance Procedures in Wind Energy

This work analyzes the impact of the operation and maintenance procedure on the condition of gearbox oil. The analytical results reveals how different scenarios modify them. The analysis is based on key operational data collected from 30 different multi-megawatt wind turbines at different locations in Spain with a variety of technologies from different top-tier manufacturers. The study includes various situations and decisions, such as leakage and replacement of oil, offline filter installation, oil brand change, substitution of valves, and even the position where the sample is taken and how these situations can provoke false warnings that trigger modifications in the operation and maintenance of wind farms with new unnecessary tasks and costs. The experimental results conclude that complete and reliable information is crucial when warning about risk situations. It is not possible to take appropriate actions without accurate information and consequently the spread of the problem cannot be stopped.

Altered Thermoregulatory Responses Following Spinal Morphine for Caesarean Delivery: a Case Report

OBJECTIVE

Spinal anaesthesia interferes with physiological thermoregulatory responses, potentially leading to peri-operative hypothermia. Spinal morphine can further compound this by a paradoxical clinical presentation leading to poor patient outcome.

CASE REPORT

Following an uneventful caesarean delivery (CD) under spinal anaesthesia with intrathecal morphine for post-operative analgesia, a parturient presented in the recovery room with increasing somnolence, excessive sweating and a sensation of feeling hot. She was haemodynamically stable, but her temperature was 34.5°C. Active warming measures were implemented, and normothermia was achieved in 3 hours.

CONCLUSION

Spinal morphine can alter the clinical presentation of hypothermia by manifesting as excessive sweating and subjective sensation of warmth. Teams involved in the perioperative care of parturients should be aware of (a) the possibility of spinal anaesthesia causing perioperative hypothermia, (b) intrathecal morphine masking the clinical presentation of hypothermia and (c) the importance of monitoring temperature of patients who have received spinal anaesthesia with added morphine.

Accuracy and precision of zero-heat-flux temperature measurements with the 3M™ Bair Hugger™ Temperature Monitoring System: a systematic review and meta-analysis

Zero-heat-flux thermometers provide clinicians with the ability to continuously and non-invasively monitor body temperature. These devices are increasingly being used to substitute for more invasive core temperature measurements during surgery and in critical care. The aim of this review was to determine the accuracy and precision of zero-heat-flux temperature measurements from the 3M™ Bair Hugger™ Temperature Monitoring System. Medline and EMBASE were searched for studies that reported on a measurement of core or peripheral temperature that coincided with a measurement from the zero-heat-flux device. Study selection and quality assessment was performed independently using the Revised Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2). The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach was used to summarize the strength of the evidence. Pooled estimates of the mean bias and limits of agreement with outer 95% confidence intervals (population limits of agreement) were calculated. Sixteen studies were included. The primary meta-analysis of zero-heat-flux versus core temperature consisted of 22 comparisons from 16 individual studies. Data from 952 participants with 314,137 paired measurements were included. The pooled estimate for the mean bias was 0.03 °C. Population limits of agreement, which take into consideration the between-study heterogeneity and sampling error, were wide, spanning from - 0.93 to 0.98 °C. The GRADE evidence quality rating was downgraded to moderate due to concerns about study limitations. Population limits of agreement for the sensitivity analysis restricted to studies rated as having low risk of bias across all the domains of the QUADAS-2 were similar to the primary analysis. The range of uncertainty in the accuracy of a thermometer should be taken into account when using this device to inform clinical decision-making. Clinicians should therefore consider the potential that a temperature measurement from a 3M™ Bair Hugger™ Temperature Monitoring System could be as much as 1 °C higher or lower than core temperature. Use of this device may not be appropriate in situations where a difference in temperature of less than 1 °C is important to detect.

A 0.065-mm3 Monolithically-Integrated Ultrasonic Wireless Sensing Mote for Real-Time Physiological Temperature Monitoring

Accurate monitoring of physiological temperature is important for many biomedical applications, including monitoring of core body temperature, detecting tissue pathologies, and evaluating surgical procedures involving thermal treatment such as hyperthermia therapy and tissue ablation. Many of these applications can benefit from replacing external temperature probes with injectable wireless devices. Here we present such a device for real-time in vivo temperature monitoring that relies on "chip-as-system" integration. With an on-chip piezoelectric transducer and measuring only 380 μm × 300 μm × 570 μm, the 0.065-mm³ monolithic device, in the form of a mote, harvests ultrasound energy for power and transmits temperature data through acoustic backscattering. Containing a low-power temperature sensor implemented with a subthreshold oscillator and consuming 0.813 nW at 37 °C, the mote achieves line sensitivity of 0.088 °C/V, temperature error of +0.22/-0.28 °C, and a resolution of 0.0078 °C rms. A long-term measurement with the mote reveals an Allan deviation floor of <138.6 ppm, indicating the feasibility of using the mote for continuous physiological temperature monitoring.

Improving intraoperative temperature management in elective repeat cesarean deliveries: a retrospective observational cohort study

Background

Inadvertent perioperative hypothermia (< 36 °C) occurs frequently during elective cesarean delivery and most institutions do employ perioperative active warming. The purpose of this retrospective observational cohort study was to determine if the addition of preoperative forced air warming in conjunction with intraoperative underbody forced air warming improved core temperature and reducing inadvertent perioperative hypothermia during elective repeat elective cesarean delivery with neuraxial anesthesia.

Methods

We evaluated the addition of perioperative active warming to standard passive warming methods (preheated intravenous/irrigation fluids and cotton blankets) in 120 parturients scheduled for repeat elective cesarean delivery (passive warming, n = 60 vs. active + passive warming, n = 60) in a retrospective observational cohort study. The primary outcomes of interest were core temperature at the end of the procedure and a decrease in inadvertent perioperative hypothermia (< 36 °C). Secondary outcomes were surgical site infections and adverse markers of neonatal outcome.

Results

The mean temperature at the end of surgery after instituting the active warming protocol was 36.0 ± 0.5 °C (mean ± SD, 95% CI 35.9–36.1) vs. 35.4 ± 0.5 °C (mean ± SD, 95% CI 35.3–35.5) compared to passive warming techniques (p <  0.001) and the incidence of inadvertent perioperative hypothermia at the end of the procedure was less in the active warming group - 68% versus 92% in the control group (p <  0.001). There was no difference in surgical site infections or neonatal outcomes.

Conclusions

Perioperative active warming in combination with passive warming techniques was associated with a higher maternal temperature and lower incidence of inadvertent perioperative hypothermia with no detectable differences in surgical site infections or indicators of adverse neonatal outcomes.

Perioperative temperature monitoring in general and neuraxial anesthesia: a survey study

Background

Perioperative hypothermia is an unintended decrease in the core temperature of patients. Hypothermia has many proven complications. The aim of this study is to investigate the perioperative temperature monitoring rates and the difficulties encountered during monitoring, particularly in patients undergoing neuraxial anesthesia.

Methods

Two hundred anesthesiologists were included in the study who work in Turkey and actively work in an operating room. A questionnaire was applied to the participants via printed form or e-mail.

Results

In Turkey, the overall temperature monitoring ratio was measured as 5.5%. Temperature monitoring was the most frequently used for cardiovascular surgery patients group. In neuraxial anesthesia, temperature monitoring was only 1.5%. The most common reason for not using a temperature monitor was the lack of appropriate equipment (45%). The most common temperature monitoring area was the axillary zone (48%).

Conclusion

Participants were aware of the importance of temperature monitoring but concluded that it was not sufficient in practice. Where and how to measure core temperature in awake patients is a controversial issue. Furthermore, the accuracy of measurements in neuraxial anesthesia should be discussed. Interestingly, raising awareness about this issue was not effective in the resolution of the problem. Still, in order to keep this issue up to date, the importance of perioperative temperature monitoring should be emphasized more frequently in anesthesia meetings and education programs.

Intravascular Cooling Device Versus Esophageal Heat Exchanger for Mild Therapeutic Hypothermia in an Experimental Setting

BACKGROUND

Targeted temperature management is a standard therapy for unconscious survivors of cardiac arrest. To date, multiple cooling methods are available including invasive intravascular cooling devices (IVDs), which are widely used in the clinical setting. Recently, esophageal heat exchangers (EHEs) have been developed providing cooling via the esophagus that is located close to the aorta and inferior vena cava. The objective was to compare mean cooling rates, as well as differences, to target temperature during maintenance and the rewarming period of IVD and EHE.

METHODS

The study was conducted in 16 female domestic pigs. After randomization to either IVD or EHE (n = 8/group), core body temperature was reduced to 33°C. After 24 hours of maintenance (33°C), animals were rewarmed using a target rate of 0.25°C/h for 10 hours. All cooling phases were steered by a closed-loop feedback system between the internal jugular vein and the chiller. After euthanasia, laryngeal and esophageal tissue was harvested for histopathological examination.

RESULTS

Mean cooling rates (4.0°C/h ± 0.4°C/h for IVD and 2.4°C/h ± 0.3°C/h for EHE; P < .0008) and time to target temperature (85.1 ± 9.2 minutes for IVD and 142.0 ± 21.2 minutes for EHE; P = .0008) were different. Mean difference to target temperature during maintenance (0.07°C ± 0.05°C for IVD and 0.08°C ± 0.10°C for EHE; P = .496) and mean rewarming rates (0.2°C/h ± 0.1°C/h for IVD and 0.3°C/h ± 0.2°C/h for EHE; P = .226) were similar. Relevant laryngeal or esophageal tissue damage could not be detected. There were no significant differences in undesired side effects (eg, bradycardia or tachycardia, hypokalemia or hyperkalemia, hypoglycemia or hyperglycemia, hypotension, overcooling, or shivering).

CONCLUSIONS

After insertion, target temperatures could be reached faster by IVD compared to EHE. Cooling performance of IVD and EHE did not significantly differ in maintaining target temperature during a targeted temperature management process and in active rewarming protocols according to intensive care unit guidelines in this experimental setting.

Effects of postoperative active warming and early exercise on postoperative body temperature distribution: Non-blinded and randomized controlled trial

AIM

We tested a hypothesis that postoperative active warming and/or arm leg stretches reduce the difference between core and skin temperatures (primary variable) improving the peripheral circulation immediately after major abdominal surgery.

METHODS

Fifty-one patients undergoing major abdominal surgeries were randomly assigned to receive one of three interventions immediately after surgery; routine care (control group), mild intermittent exercise on the bed (exercise group), and forced-air warming (warming group). Core and skin temperatures and perfusion index were continuously measured from anesthesia induction to 12 h after arrival at the ward.

RESULTS

Core body temperature was maintained over 37°C with a relatively greater gap between core and skin temperatures over 1°C and reduced perfusion index in the early postoperative period in the control group. In the warming group, the reduced skin temperature at arrival at the ward approximated to the core temperature leading to significant reduction of the temperature gap and increasing the perfusion index to the preoperative level. Although less evident, both the temperature gap and peripheral perfusion significantly improved in the exercise group after 6 and 8 h after arrival at the ward, respectively.

CONCLUSIONS

Vasoconstriction in response to cessation after anesthesia and surgery serves to maintain core temperature, but impairs peripheral circulation. Active warming and intermittent mild exercise immediately after arrival at the ward reduces the temperature gap and improves peripheral circulation during the early postoperative period. While cost-effectiveness needs to be considered before clinical application of the intervention, the cost-free mild exercise may be a feasible option for improving postoperative patient care.

Simple calculation of the optimal insertion depth of esophageal temperature probes in children

Placing an esophageal temperature probe (ETP) in the optimal esophageal site is important in various anesthetic and critical care settings to accurately monitor the core temperature of a pediatric patient. However, no reported study has provided a formula to calculate the optimal insertion depth of ETP placement in children based on direct measurement of the optimal depth. The aim of this study was to develop a simple and reliable method to determine the optimal depth of ETP placement in children via their mouth. Using preoperative chest computed tomography scans, intraoperative chest X-rays, and the actual depth of ETP insertion, we measured the optimal depth of ETP placement retrospectively in 181 children aged 3-13 years who underwent minimally invasive repairs of the pectus excavatum and removal of a pectus bar. A linear regression analysis was performed to assess the correlation of the optimal depth of ETP placement with the children's age, weight, and height. The optimal depth of ETP placement had a greater correlation with height than with age or weight, and the best-fit equation was '0.180 × height + 6.749 (cm) (R² = 0.920).' We obtained three simplified formulae, which showed no statistically significant difference in predicting the optimal depth of ETP placement: height/6 + 8 (cm), height/5 + 4 (cm), and height/5 + 5 (cm). The optimal depth of ETP via children's mouths has a close correlation with height and can be calculated with a simple formula 'height/5 + 5 (cm)'.

A mechanistic study of the tremor associated with epidural anaesthesia for intrapartum caesarean delivery

BACKGROUND

It is not known if the tremor associated with an epidural top-up dose for intrapartum caesarean delivery is thermoregulatory shivering. A tremor is only shivering if it has the same frequency profile as cold stress-induced shivering. Thermoregulatory shivering is a response to a reduction in actual body temperature, whereas non-thermoregulatory shivering may be triggered by a reduction in sensed body temperature. This mechanistic study aimed to compare: 1. the frequency profiles of epidural top-up tremor and cold stress-induced shivering; and 2. body temperature (actual and sensed) before epidural top-up and at the onset of tremor.

METHODS

Twenty obstetric patients received an epidural top-up for intrapartum caesarean delivery and 20 non-pregnant female volunteers underwent a cold stress. Tremor, surface electromyography, core temperature, skin temperature (seven sites) and temperature sensation votes (a bipolar visual analog score ranging from -50 to +50 mm) were recorded.

RESULTS

The mean (SD) primary oscillation (9.9 (1.9) Hz) frequency of epidural top-up tremor did not differ from that of cold stress-induced shivering (9.0 (1.6) Hz; P=0.194), but the mean (SD) burst frequency was slower (6.1 (1.2) × 10^-2 Hz vs 6.9 (0.7) × 10^-2 Hz, respectively; P=0.046). Before the epidural top-up dose, the mean (SD) core temperature was 37.6 (0.6) °C. Between the epidural top-up dose and the onset of tremor the mean (SD) core temperature did not change (-0.1 (0.1) °C; P=0.126), the mean (SD) skin temperature increased (+0.4 (0.4) °C; P=0.002) and the mean (SD) temperature sensation votes decreased (-12 (16) mm; P=0.012).

CONCLUSION

These results suggest that epidural top-up tremor is a form of non-thermoregulatory shivering triggered by a reduction in sensed body temperature.