Perioperative Core Temperature Research Articles

The Effect of Temperature Chain Management Scheme During Robot-Assisted Radical Prostatectomy.

The study aimed to explore the effect of the temperature chain management scheme on preventing hypothermia in patients undergoing robot-assisted radical prostatectomy (RARP). The patients were randomized to receive either intraoperative warming only (control group, Group C) or the temperature chain management (experimental group, Group T). We compared the core temperature, inadvertent perioperative hypothermia (IPH) rates, the incidence of shivering, and thermal comfort between the two groups. The perioperative core temperature of the Group T was higher than that of the Group C, and the incidence of IPH, the incidence of shivering in the postanesthesia care unit (PACU), and the length of stay in PACU were lower than those of the control group. The thermal comfort of Group T scored higher than that of Group C when leaving the PACU, all above have a statistically significant difference (p < 0.05). The temperature chain management scheme could decrease the IPH rates and reduce postoperative complications in RARP patients. The Clinical Trials Registration number is 2023IIT034.

The Effect of Temperature Chain Management Scheme During da Vinci Robot-Assisted Radical Resection of Urological Tumor.

To explore the effect of the temperature chain management scheme on inadvertent perioperative hypothermia (IPH) during robot-assisted radical resection of urological tumors. Fifty male patients who underwent elective robot-assisted radical prostatectomy (RARP) or robot-assisted radical cystectomy (RARC) surgery from February 2022 to March 2023 in a teaching hospital were enrolled and randomized to receive either intraoperative warming, including forced-air warming blanket and prewarming fluid (group C) or the temperature chain management involving an active warming bunch covering the whole perioperative period (group T). Comparing the core temperature, IPH rates, the incidence of shivering, recovery from anesthesia, and thermal between the two groups. Perioperative core temperature of group T was higher compared with group C (p < 0.05); IPH rates and the incidence of shivering in postanesthesia care unit (PACU) of group T were lower compared with group C (p < 0.05); group T scored higher in thermal comfort compared with group C after PACU 15 minutes, after PACU 30 minutes, and when leaving the PACU (p < 0.05); group T took shorter time on recovering from anesthesia (p < 0.05). Temperature chain management could reduce IPH and postoperative complications during RARP and RARC.

Validation of a Prediction Model for Intraoperative Hypothermia in Patients Receiving General Anesthesia.

Objectives There have been no fully validated tools for the rapid identification of surgical patients at risk of intraoperative hypothermia. The objective of this study was to validate the performance of a previously established prediction model in estimating the risk of intraoperative hypothermia in a prospective cohort. Methods In this observational study, consecutive adults scheduled for elective surgery under general anesthesia were enrolled prospectively at a tertiary hospital between September 4, 2020, and December 28, 2020. An intraoperative hypothermia risk score was calculated by a mobile application of the prediction model. A wireless axillary thermometer was used to continuously measure perioperative core temperature as the reference standard. The discrimination and calibration of the model were assessed, using the area under the receiver operating characteristic curve (AUC), Hosmer–Lemeshow goodness-of-fit test, and Brier score. Results Among 227 participants, 99 (43.6%) developed intraoperative hypothermia, and 10 (4.6%) received intraoperative active warming with forced-air warming. The model had an AUC of 0.700 (95% confidence interval [CI], 0.632–0.768) in the overall cohort with adequate calibration (Hosmer–Lemeshow χ2 = 13.8, P=0.087; Brier score = 0.33 [95% CI, 0.29–0.37]). We categorized the risk scores into low-risk, moderate-risk, and high-risk groups, in which the incidence of intraoperative hypothermia was 23.0% (95% CI, 12.4–33.5), 43.4% (95% CI, 33.7–53.2), and 62.7% (95% CI, 51.5–74.3), respectively (P for trend <0.001). Conclusions The intraoperative hypothermia prediction model demonstrated possibly helpful discrimination and adequate calibration in our prospective validation. These findings suggest that the risk screening model could facilitate future perioperative temperature management.

The Effect of Sevoflurane Low-Flow Anesthesia on Preserving Patient Core Temperature

Introduction: Low-flow anesthesia (LFA) reduces the fresh gas flow (FGF) entering the anesthesia circuit and saves on the volatile agent used. In this study, the effect of LFA with sevoflurane on core temperature and the incidence of perioperative hypothermia were investigated. Methods: According to the FGF applied, patients were classified into three groups: LFA (1 L/min), medium-flow anesthesia (MFA = 2 L/min), and high-flow anesthesia (HFA = 4 L/min). Patients’ demographic data and the initial (T1) and final (T2) core temperatures during the operation were compared. Results: A total of 160 patients were included in the study. The T2 value of the HFA group was significantly lower than the LFA group (p = 0.028). Different flow values were found to have a significant effect on temperature change (F = 21.630, p < 0.001, partial eta squared = 0.216). There was a significant difference between the mean temperatures measured at two different times (F = 301.064, p < 0.001, partial eta squared = 0.657). The overall incidence of hypothermia was 32.5%, with 52 patients. Hypothermia (T²<36°C) incidences were not different between the LFA group and the MFA and HFA groups (p = 0.682). However, perioperative core temperature loss was significantly lower in the LFA group (p = 0.001). Conclusions: LFA using sevoflurane was not sufficient alone to significantly reduce the incidence of hypothermia. However, we have demonstrated that it may also have a beneficial effect on reducing perioperative temperature loss.

Association between preoperative toe perfusion index and maternal core temperature decrease during cesarean delivery under spinal anesthesia: a prospective cohort study

BackgroundThe main mechanism of body temperature decrease during cesarean delivery under spinal anesthesia is core-to-peripheral redistribution of body heat, attributable to vasodilation. Perfusion index (PI) obtained with a pulse oximeter helps to assess peripheral perfusion dynamics by detecting the change in peripheral vascular tone. This study aimed to examine whether preoperative toe PI could predict the decrease in core temperature induced by spinal anesthesia during cesarean delivery.MethodsParturients undergoing scheduled cesarean delivery under combined spinal-epidural anesthesia from September 2019 to March 2020 were enrolled in this single-center prospective cohort study. All parturients received 0.5% hyperbaric bupivacaine (10 mg) with fentanyl (15 μg) intrathecally. A pulse oximeter probe was placed on the left second toe for continuous PI measurement. The 3 M™ Bair Hugger™ Temperature Monitoring System placed over the right temporal region was used to record core temperature over time. We evaluated the association between the maximum core temperature decrease, which is the primary outcome, and the preoperative toe PI at operating room (OR) admission using a segmented regression model (SRM) and a generalized additive model (GAM). The maximum core temperature decrease was defined as the difference between core temperature at OR admission and minimum intraoperative core temperature.ResultsForty-eight patients were evaluated. In the SRM, the slope for the association between the maximum core temperature decrease and the preoperative toe PI changed from 0.031 to 0.124 after PI = 2.4%. Likewise, with the GAM, there was a small core temperature decrease when preoperative toe PI was greater than 2.0 to 3.0%.ConclusionsLow preoperative toe PI was associated with maternal core temperature decrease during cesarean delivery under spinal anesthesia. Preoperative toe PI is a simple, non-invasive, and effective tool for the early prediction of perioperative core temperature decrease during cesarean delivery.Trial registrationUMIN Clinical Trials Registry (registry number: UMIN000037965).

The Accuracy of a Wireless Axillary Thermometer for Core Temperature Monitoring in Pediatric Patients Having Noncardiac Surgery: An Observational Study

PurposeA wireless and wearable axillary thermometer (iThermonitor) has been validated for perioperative core temperature monitoring in adults. The purpose of this study was to evaluate its accuracy in pediatrics having non–cardiac surgery. DesignProspective observational study. MethodsFrom January 2019 to December 2019, 70 children aged younger than 14 years undergoing surgery in a tertiary hospital were selected. Pairs of esophageal temperatures (TEso), rectal temperatures (TRec), and axillary temperatures monitored by the iThermonitor (TiTh) were collected every 5 min during surgery. Taking TEso as reference, the bias between TEso and TiTh and the proportion of bias within ±0.5°C were calculated. Bland-Altman method was used to analyze the 95% of limits of agreement (LOA) between TiTh and TEso. The same analyses were done for TRec. FindingsA total of 2232 pairs of temperatures were collected. The bias (mean ± SD) between TiTh and TEso was -0.07 °C ± 0.25°C, and 95% LOA was -0.07°C ± 0.50°C. The proportion of bias within ±0.5°C accounted for 96% (95% Confidence Interval [CI], 92-98%). Higher bias and 95% LOA, and lower proportion of bias within ± 0.5°C were found between TRec and TEso than those between TiTh and TEso. ConclusionDuring pediatric non–cardiac surgery, axillary temperature derived from iThermonitor is in good agreement with esophageal temperature and can be used as an alternative to core temperature.

Effectiveness of prewarming in prevention of inadvertent intraoperative hypothermia

Background: Inadvertent perioperative hypothermia (IPH), defined as a perioperative core temperature < 36 °C is attributable to redistribution of body heat from the core to peripheries during the initial phase of anaesthesia and is difficult to treat. We conducted this study to find the effectiveness of pre-warming in preventing the occurrence of hypothermia intraoperatively in adult patients undergoing elective laparotomy under general anaesthesia. Material and Methods: Forty-four adult patients undergoing elective laparotomy were randomized into two groups of 22 each. Patients in Group P were prewarmed for 60 minutes prior to induction and those in Group C did not receive prewarming. Results: Patients in Group P had a significantly higher peripheral temperature at induction compared to those in Group C (p = 0.025), whereas the core temperature at induction was found to be comparable between the 2 groups. The core to peripheral temperature gradient was found to be lower in group P when compared to group C and the difference was statistically significant (p = 0.042). The core temperature dropped to less than 35 °C in the first two hours following induction in 2 patients in Group P and in 14 patients in group C (p < 0.001). The rate of drop in the core temperature was higher in group C compared to group P (p=0.002).The mean peripheral temperature as well as the core temperature in group P was significantly higher than in group C from induction to 60th minute, and it was statistically significant. Conclusion: In the first 2 hours post induction, prewarming is effective in preventing the drop in core temperature and reduces the rate of drop in core temperature. Prewarming is effective in reducing the core to peripheral temperature gradient at induction.

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.

A Comparison of the Effects of Lung Protective Ventilation and Conventional Ventilation on Thermoregulation During Anaesthesia.

During prolonged surgery, hypothermia is an unwanted condition that frequently develops and increases complication rates. It has been shown that positive end-expiratory pressure (PEEP) during mechanical ventilation reduces hypothermia development by providing earlier peripheral vasoconstriction. In the present study, an investigation was made of the effect of two different ventilation models on perioperative hypothermia development. A total of 40 patients undergoing elective lumbar disc surgery were randomised to either the conventional group (Group C, n=20, tidal volume=10 mL kg-1, PEEP=0 cm H2O) or the lung protective ventilation group (Group P, n=20, tidal volume=6 mL kg-1, PEEP=5 cm H2O). Demographic data on gender, age, weight, height, preoperative-postoperative temperatures and haemodynamic values were recorded. The point where the forearm to fingertip skin temperature difference reached 0°C was determined as the peripheral vasoconstriction development. At this point, the core temperature was recorded as the thermoregulatory vasoconstriction threshold. Demographic characteristics of the patients and haemodynamic variables were similar between the groups. Preoperative and postoperative temperature gradients were not significantly different between the two groups (p=0.827). There was also no significant difference between the two groups in respect of the vasoconstriction threshold of the patients (p=0.432). The study results showed that lung protective ventilation has no advantage in preserving the perioperative core temperature compared to conventional ventilation.

Determining the accuracy of zero-flux and ingestible thermometers in the peri-operative setting.

Accurately monitoring peri-operative core temperature is a cornerstone of good practice. Relatively invasive devices such as oesophageal temperature probes and pulmonary artery catheters facilitate this, but are inappropriate for many patients. There remains a need for accurate monitors of core temperature that can be used in awake patients. This study compared the accuracy of two core temperature thermometers that can be used for this purpose: the 3M Bair Hugger™ Temperature Monitoring System Zero Flux Thermometer and the CorTempR™ Wireless Ingestible Temperature Sensor. Readings were compared with the oesophageal probe, the current intraoperative standard. Thirty patients undergoing elective surgical procedures under general anaesthesia were recruited. The ingestible sensor was ingested prior to induction of anaethesia, and post induction, the zero-flux electrode attached above the right eyebrow and oesophageal probe inserted. During surgery, the temperature on each device was recorded every minute. Measurements were compared using Bland-Altman analysis. The ingestible sensor experienced interference from use of diathermy and fluoroscopy in the operating theatre, rendering 39% of its readings unusable. These were removed from analysis. With remaining readings the bias compared with oesophageal probe was + 0.42°C, with 95% limits of agreement - 2.4°C to 3.2°C. 75.4% of readings were within ± 0.5°C of the OTP reading. The bias for the zero flux electrode compared to oesophageal probe was + 0.02°C with 95% limits of agreement - 0.5°C to 0.5°C. 97.7% of readings were within ± 0.5°C of the oesophageal probe. The study findings suggest the zero-flux thermometer is sufficiently accurate for clinical use, whereas the ingestible sensor is not.Trial registration The study was registered at http://www.clinicaltrials.gov , NCT Number: NCT02121574.

A prospective comparative study between prewarming and cowarming to prevent intraoperative hypothermia.

Background and Aims:Inadvertent perioperative hypothermia defined as the perioperative core temperature of <36°C is a common problem in day-to-day anesthesia practice. It is not clear from the literature whether prewarming, that is, initiation of convective warming of the patient at a time point prior to induction of anesthesia is superior or comparable to cowarming, that is, initiation of convective warming simultaneously with induction of anesthesia. We conducted this study to find whether cowarming is as good as prewarming in preventing the occurrence of intraoperative hypothermia.Material and Methods:Sixty-two adult patients undergoing major abdominal surgery under general anesthesia were randomized to receive either prewarming for 60 min at 40° C or cowarming using the Level 1® Equator ® body warmer. All patients who were prewarmed also received cowarming during induction of anesthesia. In both the groups, convective warming was continued during intraoperative period. Incidence of intraoperative hypothermia, core, and peripheral body temperatures were compared between the two groups.Results:Among 27 patients in each group who completed the study core temperature decreased to <35° C toward the end of surgery in 17 patients in group prewarming [mean (SD) 34.59 (1.17° C)] and 18 patients in group cowarming [mean (SD) 34.31 (1.34° C)]. The incidence of intraoperative hypothermia and the core temperature at the end of surgery were comparable (P = 0.42).Conclusion:Cowarming is as effective as prewarming to prevent intraoperative hypothermia.

Effects of perioperative warm socks-wearing in maintaining core body temperature of patients undergoing spinal surgery.

To investigate whether warming the feet with socks would prevent hypothermia among patients undergoing spinal surgery. Perioperative hypothermia is a common health problem among spinal surgery patients. This study used a quasi-experimental design. Seventy-two patients were assigned to two groups. The control group (n=36) received usual care without the warmed socks. The intervention group (n=36) received usual care plus warmed socks during operation and recovery period. Data were collected during (180min) and after the surgery (30min) during the period of 7 February-10 April 2015. Core body temperature, shivering response and subjective thermal comfort of the two groups were compared over time using the repeated-measures ANOVA. The oesophageal temperature of the socks-wearing group was maintained between 36.36-36.45°C during surgery (mean=36.41±0.03, 95% CI=36.34-36.47), whereas that of the control was between 35.75-35.97°C (mean=35.98±0.03, 95% CI=35.92-36.04). The tympanic temperature in the recovery room of the socks-wearing group was between 36.28-36.38°C (mean=36.37±0.04, 95% CI=36.29-36.45) and that of the control group was 35.90-36.04°C (mean=35.95±0.04, 95% CI=35.88-36.05). Shivering response of the intervention group (mean=0.04±0.08, 95% CI=-0.13 to 0.21) was significantly lower than that of the control group (mean=0.47±0.08, 95% CI=0.30-0.64) in the recovery room (F=4.28, p<.001). As for subjective thermal comfort, the intervention group (mean=4.86±0.13, 95% CI=4.62-5.13) was significantly lower than that of the control group (mean=3.08±0.13, 95% CI=2.82-3.33) in the recovery room (F=98.13, p<.001). As for the frequency of pethidine medication, the intervention group was significantly lower than that of the control (χ2 =5.14, p=.023). The use of perioperative warmed socks for spinal surgery patients was effective in maintaining perioperative core temperature, preventing shivering and maintaining subjective thermal comfort. Considering cost-effectiveness of warmed socks, it might be worth trying option for the maintenance of core temperature in spinal surgery patients.

A randomized trial of prewarming on patient satisfaction and thermal comfort in outpatient surgery

Study objectiveTo test the primary hypothesis that forced-air prewarming improves patient satisfaction after outpatient surgery and to evaluate the effect on core temperature and thermal comfort. DesignProspective randomized controlled trial. SettingPreoperative area, operating room, and postanesthesia care unit. PatientsA total of 115 patients aged 18 to 75 years with American Society of Anesthesiologists status <4 and body mass index of 15 to 36kg/m2 who were undergoing outpatient surgery (duration <4 hours). InterventionsPatients were randomized to active prewarming with a Mistral-Air warming system initially set to 43°C or no active prewarming. All patients were warmed intraoperatively. MeasurementsDemographic and morphometric characteristics, perioperative core temperature, ambient temperature, EVAN-G satisfaction score, thermal comfort via visual analog scales. Main ResultsData from 102 patients were included in the final analysis. Prewarming did not significantly reduce redistribution hypothermia, with prewarmed minus not prewarmed core temperature differing by only 0.18°C (95% confidence interval [CI], −0.001 to 0.37) during the initial hour of anesthesia (P=.052). Prewarming increased the mean EVAN-G satisfaction score, although not significantly, with an overall difference (prewarmed minus not prewarmed) of 5.6 (95% CI, −0.9 to 12.2; P=.09). Prewarming increased thermal comfort, with an overall difference of 6.6 mm (95% CI, 1.0-12.9; P=.02). ConclusionActive prewarming increased thermal comfort but did not significantly reduce redistribution hypothermia or improve postoperative patient satisfaction.

Use of an Esophageal Heat Exchanger to Maintain Core Temperature during Burn Excisions and to Attenuate Pyrexia on the Burns Intensive Care Unit.

Introduction. Burns patients are vulnerable to hyperthermia due to sepsis and SIRS and to hypothermia due to heat loss during excision surgery. Both states are associated with increased morbidity and mortality. We describe the first use of a novel esophageal heat exchange device in combination with a heater/cooler unit to manage perioperative hypothermia and postoperative pyrexia. Material and Methods. The device was used in three patients with full thickness burns of 51%, 49%, and 45% body surface area to reduce perioperative hypothermia during surgeries of >6 h duration and subsequently to control hyperthermia in one of the patients who developed pyrexia of 40°C on the 22nd postoperative day due to E. coli/Candida septicaemia which was unresponsive to conventional cooling strategies. Results. Perioperative core temperature was maintained at 37°C for all three patients, and it was possible to reduce ambient temperature to 26°C to increase comfort levels for the operating team. The core temperature of the pyrexial patient was reduced to 38.5°C within 2.5 h of instituting the device and maintained around this value thereafter. Conclusion. The device was easy to use with no adverse incidents and helped maintain normothermia in all cases.

Evaluation of a novel noninvasive continuous core temperature measurement system with a zero heat flux sensor using a manikin of the human body.

Reliable continuous perioperative core temperature measurement is of major importance. The pulmonary artery catheter is currently the gold standard for measuring core temperature but is invasive and expensive. Using a manikin, we evaluated the new, noninvasive SpotOn™ temperature monitoring system (SOT). With a sensor placed on the lateral forehead, SOT uses zero heat flux technology to noninvasively measure core temperature; and because the forehead is devoid of thermoregulatory arteriovenous shunts, a piece of bone cement served as a model of the frontal bone in this study. Bias, limits of agreements, long-term measurement stability, and the lowest measurable temperature of the device were investigated. Bias and limits of agreement of the temperature data of two SOTs and of the thermistor placed on the manikin's surface were calculated. Measurements obtained from SOTs were similar to thermistor values. The bias and limits of agreement lay within a predefined clinically acceptable range. Repeat measurements differed only slightly, and stayed stable for hours. Because of its temperature range, the SOT cannot be used to monitor temperatures below 28°C. In conclusion, the new SOT could provide a reliable, less invasive and cheaper alternative for measuring perioperative core temperature in routine clinical practice. Further clinical trials are needed to evaluate these results.

Comparison of peri‐operative core temperature in obese and non‐obese patients*

Our aim was to compare peri-operative core temperatures and the incidence of hypothermia in obese and non-obese women with active forced-air warming. Twenty female patients scheduled for abdominal surgery were allocated to two groups according to body mass index. Ten obese (30.0-34.9 kg.m(-2) ) and 10 non-obese (18.5-24.9 kg.m(-2) ) women received forced-air warming on their lower limbs. At the end of surgery, the mean (SD) core temperatures were 36.7 (0.5) °C in the obese group and 36.0 (0.6) °C in the non-obese group (p < 0.001). Only in the non-obese group was there a significant decrease in the intra-operative core temperature values (p < 0.001). The incidences of intra-operative hypothermia were lower in the obese group (10%) compared with non-obese group (60%; p = 0.019). In the postoperative recovery phase, the mean (SD) core temperature data were higher in the obese group than in the non-obese group (36.2 (0.4) vs 35.6 (0.5) °C, respectively (p < 0.001)). In conclusion, obese female patients have higher peri-operative core temperature and a lower incidence of hypothermia compared with non-obese female patients during abdominal surgery with active forced-air warming.

Research News: Perioperative Normothermia

ASPAN published the Evidence-Based Clinical Practice Guideline for the Promotion of Perioperative Normothermia in late 2009. In that document, the authors described key terms, risk factors for perioperative hypothermia, core versus near-core temperature measurements, and patient assessment and management guidelines. Notably, interventions include both passive and active warming measures. Active warming measures are defined as the ‘‘application of a forced-air convection warming system and circulating-water mattresses, resistive heating blankets, radiant warmers, negative-pressure warming systems, and warmed, humidified, inspired oxygen,’’ (p. 274). Passive warming measures refer to ‘‘the application of warmed cotton blankets, reflective blankets, socks, and head covering, as well as limiting skin exposure to lower ambient room temperature,’’ (p. 274). The following two studies were identified in the medical literature as recent research involving warming devices in the perioperative period, specifically the efficacy of active warming measures on thermoregulation.

Temporal Artery Versus Bladder Thermometry During Perioperative and Intensive Care Unit Monitoring

Core temperature measurements are an important component of perioperative patient monitoring. It is fairly easy to obtain core temperature measurements invasively in anesthetized patients. However, such measurements are more difficult to obtain noninvasively in awake patients. Recently, a new version of a temporal artery thermometer for noninvasive core temperature measurements (TemporalScanner TAT-5000) was introduced with accuracy and precision advertised as being comparable to invasive core temperature measurements. In this study, we sought to determine if this new thermometer is an acceptable substitute for invasive bladder temperature measurement. In 35 patients undergoing neurosurgical interventions and 35 patients in the neurosurgical intensive care unit, measurements from the temporal artery thermometer were compared with those from a bladder thermometer. Four measurements were obtained from each patient. Overall 280 measurement pairs were obtained. The mean bias between the methods was 0.07 degrees C +/- 0.79 degrees C; the limits of agreement were approximately 3 times greater than the a priori defined limit of +/-0.5 degrees C (-1.48 to 1.62). The sensitivity for detecting fever (core temperature >37.8 degrees C) using the temporal artery thermometer was 0.72, and the specificity was 0.97. The positive predictive value for fever was 0.89; the negative predictive value was 0.94. The sensitivity for detecting hypothermia (core temperature <35.5 degrees C) was 0.29, and the specificity was 0.95. The positive predictive value for hypothermia was 0.31, and the negative predictive value was 0.95. The results of this study do not support the use of temporal artery thermometry for perioperative core temperature monitoring; the temporal artery thermometer does not provide information that is an adequate substitute for core temperature measurement by a bladder thermometer.

Troponin T elevation after coronary bypass surgery: clinical relevance and correlation with perioperative variables

Elevation in markers of myocardial necrosis is a common feature following coronary artery bypass surgery, but its relevance is unclear. The objective of this study was to evaluate the association between postoperative troponin T elevation, perioperative variables and clinical outcomes. We evaluated 100 low-risk patients undergoing first-time elective on-pump coronary artery bypass surgery. The mean age was 62 +/- 9.8 years and 83% were male; patients with diabetes mellitus, renal failure and impaired left ventricular function (ejection fraction < 40%) were excluded. Troponin levels were measured at baseline and 12 and 24 h following the onset of cardiopulmonary bypass. Predefined clinical endpoints included death, new Q waves on 12-lead electrocardiogram and inotropic requirement. Postoperative troponin elevation occurred in 95%. Troponin T elevation was related to the duration of cardiopulmonary bypass (P = 0.0001) and aortic cross-clamp time (P = 0.0003). There was also an inverse relationship with perioperative core temperature (P = 0.0001). There was no association between postoperative troponin elevation and clinical outcomes. Postoperative troponin T elevation occurs in the majority of patients undergoing elective on-pump coronary artery bypass surgery. In this low-risk cohort, troponin T elevation was associated with procedural duration but not with clinical outcome.

Intravenous or caudal clonidine does not influence core temperature in children

Clonidine is known to impair cold defence mechanisms by decreasing thermoregulatory thresholds. Thus, clonidine might contribute to perioperative hypothermia during minor paediatric surgery. This study was designed to investigate the influence of intravenous or epidural clonidine on perioperative core temperature in children. A total of 23 children undergoing minor inguinal or genital surgery under combined general and caudal anaesthesia were randomly assigned to 3 groups: caudal clonidine (1–3 μg kg −1), intravenous clonidine (3 μg kg −1) and a control group without clonidine. Neither caudal nor intravenous application of clonidine significantly affected core temperature.