Prewarming Parturients for Cesarean Section Does Not Raise Wound Temperature But Body Heat and Level of Comfort: A Randomized Trial.

PURPOSE: Prewarming before cesarean section lowers the rates of surgical site infections (SSIs). We hypothesized that this effect is explained due to a higher core temperature resulting in a higher wound temperature. DESIGN: We conducted an open-labeled randomized study with on-term parturients scheduled for elective cesarean section under spinal anesthesia. Participants were randomized into an intervention group (prewarming) and a control group. METHODS: Core and wound temperature, comfort level, and examination results were taken at defined times until discharge from the postanesthesia care unit (PACU). There was a follow-up visit and interview 1 day after the procedure. The primary outcome was a difference in wound temperature. The secondary outcomes were differences in core temperature, patient comfort, blood loss, SSI, and neonatal outcome. FINDINGS: We randomized a total of 60 patients, 30 per group. Prewarming lead to a significantly higher core temperature. Additionally, patient comfort was significantly higher in the prewarming group even after discharge from PACU. We did not find a difference in wound temperature, SSI, neonatal outcome, or blood loss. CONCLUSIONS: Prewarming before cesarean section under spinal anesthesia maintains core temperature and improves patient comfort but does not affect wound temperature.

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

BACKGROUND: Maintenance of normothermia is an important quality metric in pediatric anesthesia. While inadvertent hypothermia is effectively prevented by forced-air warming, this therapeutic approach can lead to iatrogenic hyperthermia in young children. AIMS: To estimate the influence of external warming by forced air on the development of intraoperative hyperthermia in anesthetized children aged 6 years or younger. METHODS: We pooled data from two previous clinical studies. Primary outcome was the course of core temperature over time analyzed by a quadratic regression model. Secondary outcomes were the incidence of hyperthermia (body core temperature >38°C), the probability of hyperthermia over the duration of warming in relation to age and surface-area-to-weight ratio, respectively, analyzed by multiple logistic regression models. The influence of baseline temperature on hyperthermia was estimated using a Cox proportional hazards model. RESULTS: Two hundred children (55 female) with a median age of 2.1 [1st -3rd quartile 1-4.2] years were analyzed. Mean temperature increased by 0.43°C after 1 h, 0.64°C after 2 h, and reached a peak of 0.66°C at 147 min. Overall, 33 children were hyperthermic at at least one measurement point. The odds ratios of hyperthermia were 1.14 (95%-CI: 1.07-1.22) or 1.13 (95%-CI: 1.06-1.21) for every 10 min of warming therapy in a model with age or surface-area-to weight ratio (ceteris paribus), respectively. Odds ratio was 1.33 (95%-CI: 1.07-1.71) for a decrease of 1 year in age and 1.63 (95%-CI: 0.93-2.83) for an increase of 0.01 in the surface-to-weight-area ratio (ceteris paribus). An increase of 0.1°C in baseline temperature increased the hazard of becoming hyperthermic by a factor of 1.33 (95%-CI: 1.23-1.43). CONCLUSIONS: In children, external warming by forced-air needs to be closely monitored and adjusted in a timely manner to avoid iatrogenic hyperthermia especially during long procedures, in young age, higher surface-area-to-weight ratio, and higher baseline temperature.

Evaluation of the non-invasive Temple Touch Pro temperature monitoring system compared with oesophageal temperature in paediatric anaesthesia (PETER PAN): A prospective observational study.

BACKGROUND: Monitoring peri-operative body temperature in children is currently mainly achieved through invasive devices. The Temple Touch Pro Temperature Monitoring System estimates core temperature noninvasively based on heat flux thermometry. OBJECTIVE: To investigate the agreement of this noninvasive sensor against standard oesophageal core temperature. DESIGN: A prospective observational study. SETTING: University hospital recruiting between April and July 2021. PATIENTS: One hundred children (32 girls) aged 6 years or younger scheduled for noncardiac surgery, resulting in 6766 data pairs. Exclusion criteria were contraindication for the insertion of an oesophageal temperature probe, and procedures in which one of the measurement methods would interfere with the surgical field. MAIN OUTCOME MEASURES: Primary outcome was the agreement analysis by a Bland-Altman comparison with multiple measurements. Posthoc, we performed another agreement analysis after exclusion of a statistically determined equilibration time. Secondary outcomes were the temperature differences over time and subgroup analysis of hypothermic, normothermic and hyperthermic temperature ranges, age, sex and sensor's side by type III analysis of variance. Further, we correlated the sonographically determined depth of the artery with trueness. RESULTS: The mean difference was -0.07°C (95% CI -0.15 to +0.05) with limits of agreement of -1.00 and +0.85°C. After adjusting for an equilibration time of 13 min, the mean difference improved to -0.04°C (95% CI -0.08 to +0.01) with limits of agreement of -0.68 and +0.60°C. Concordance correlation coefficient was 0.83 (95% CI 0.82 to 0.84). Differences between the skin sensor and oesophageal reference increased over time by -0.05°C per hour. Subgroup analysis showed no clinically relevant differences. Depth of artery negatively correlated with trueness by 0.03°C per millimetre. CONCLUSIONS: Although the Temple Touch Pro sensor showed acceptable accuracy after allowing for an equilibration time, it still needs further investigation for routine use in children. This particularly affects accuracy in hypothermic ranges, imprecise positioning and applicability in children with immature or vulnerable skin. TRIAL REGISTRATION: German Clinical Trials Register, identifier: DRKS00024703.

Evaluation of the Temple Touch Pro™ noninvasive core-temperature monitoring system in 100 adults under general anesthesia: a prospective comparison with esophageal temperature.

Perioperative hypothermia is still common and has relevant complication for the patient. An effective perioperative thermal management requires essentially an accurate method to measure core temperature. So far, only one study has investigated the new Temple Touch Pro™ (Medisim Ltd., Beit-Shemesh, Israel). during anesthesia Therefore, we assessed the agreement between the Temple Touch Pro™ thermometer (TTP) and distal esophageal temperature (TEso) in a second study. After approval by the local ethics committee we studied 100 adult patients undergoing surgery with general anesthesia. Before induction of anesthesia the TTP sensor unit was attached to the skin above the temporal artery. After induction of anesthesia an esophageal temperature probe was placed in the distal esophagus. Recordings started 10 min after placement of the esophageal temperature probe to allow adequate warming of the probes. Pairs of temperature values were documented in five-minute intervals until emergence of anesthesia. Accuracy of the two methods was assessed by Bland-Altman comparisons of differences with multiple measurements. Core temperatures obtained with the TTP in adults showed a mean bias of -0.04 °C with 95% limits of agreement within - 0.99 °C to + 0.91 °C compared to an esophageal temperature probe. We consider the TTP as a reasonable tool for perioperative temperature monitoring. It is not accurate enough to be used as a reference method in scientific studies, but may be a useful tool especially for conscious patients undergoing neuraxial anesthesia or regional anesthesia with sedation. Trial registration This study was registered in the German Clinical Trials Register (DRKS-ID: 00024050), day of registration 12/01/2021.

What is the best way to keep the patient warm during technical rescue? Results from two prospective randomised controlled studies with healthy volunteers.

BACKGROUND: Accidental hypothermia is a manifest problem during the rescue of entrapped victims and results in different subsequent problems as coagulopathy and wound infection. Different warming methods are available for the preclinicial use. However, their effectiveness has hardly been evaluated. METHODS: In a first step a survey among German fire brigades was performed with questions about the most used warming methods. In a second step two crossover studies were conducted. In each study two different warming method were compared with forced air warming - which is the most frequently used and highly effective warming method in operation rooms (Study A: halogen floodlight vs. forced air warming; Study B: forced air warming vs. fleece blanket). In both studies healthy volunteers (Study A: 30 volunteers, Study B: 32 volunteers) were sitting 60 min in a cold store. In the first 21 min there was no subject warming. Afterwards the different warming methods were initiated. Every 3 min parameters like skin temperature, core body temperature and cold perception on a 10-point numeric rating scale were recorded. Linear mixed models were fitted for each parameter to check for differences in temperature trajectories and cold perception with regard to the different warming methods. RESULTS: One hundred fifty-one German fire brigades responded to the survey. The most frequently used warming methods were different rescue blankets (gold/silver, wool) and work light (halogen floodlights). Both studies (A and B) showed significantly (p < 0.05) higher values in mean skin temperature, mean body temperature and total body heat for the forced air warming methods compared to halogen floodlight respectively fleece blanket shortly after warming initiation. In contrast, values for the cold perception were significantly lower (less unpleasant cold perception) during the phase the forced air warming methods were used, compared to the fleece blanket or the halogen floodlight was used. CONCLUSION: Forced air warming methods used under the standardised experimental setting are an effective method to keep patients warm during technical rescue. Halogen floodlight has an insufficient effect on the patient's heat preservation. In healthy subjects, fleece blankets will stop heat loss but will not correct heat that has already been lost. TRIAL REGISTRATION: The studies were registered retrospectively on 14/02/2022 on the German Clinical Trials registry (DRKS) with the number DRKS00028079.

Target insertion depth of nasopharyngeal temperature probes in children: A prospective observational study analyzing magnetic resonance images.

BACKGROUND: Core temperature monitoring is indispensable to prevent children from perioperative thermal perturbations. Although nasopharyngeal measurements are commonly used in anesthesia and considered to reflect core temperature accurately, standardized target depths for probe insertion are unknown in children. AIMS: Our primary goal was to determine a target depth of nasopharyngeal temperature probe insertion in children by measuring distances on magnetic resonance imaging (MRI). Secondary aims were to correlate these measurements with biometric variables and facial landmark-distances to derive formulas estimating target depth. METHODS: We conducted a prospective observational study in children ≤12 years undergoing cranial MRI with anesthesia. We documented patient characteristics and measured the landmark-distances nostril-mandible, nostril-tragus, and philtrum-tragus on patient's faces. On MRI, the target point for the probe tip was considered to be the site of the nasopharyngeal mucosa with the closest proximity to the internal carotid artery. After its determination in the transverse axis and triangulation to the sagittal axis, we measured the distance to the nostril. This distance, defined as target insertion depth, was correlated with the patient characteristics and used for univariate and multiple linear regression analysis. RESULTS: One hundred twenty children with a mean age of 4.5 years were included. The target insertion depth ranged from 61.8 mm in infants to 89.8 mm in 12-year-old children. Height correlated best (ρ = 0.685, 95%-CI: [0.57-0.77]). The best-fit estimation in millimeters, "40.8 + height [cm] × 0.32,″ would lead to a placement in the target position in 67% of cases. A simplified approach by categories of 50-80, 80-110, 110-130, and >130 cm height with target insertion depths of 60, 70, 80, and 85 mm, respectively, achieved similar probabilities. CONCLUSIONS: Height-based formulas could be a valuable proxy for the insertion depth of nasopharyngeal temperature probes. Further clinical trials are necessary to investigate their measurement accuracy.

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

BACKGROUND: Anesthesia leads to impairments in central and peripheral thermoregulatory responses. Inadvertent perioperative hypothermia is hence a common perioperative complication, and is associated with coagulopathy, increased surgical site infection, delayed drug metabolism, prolonged recovery, and shivering. However, surveys across the world have shown poor compliance to perioperative temperature management guidelines. Therefore, we evaluated the prevalent practices and attitudes to perioperative temperature management in the Asia-Pacific region, and determined the individual and institutional factors that lead to noncompliance. METHODS: A 40-question anonymous online questionnaire was distributed to anesthesiologists and anesthesia trainees in six countries in the Asia-Pacific (Singapore, Malaysia, Philippines, Thailand, India and South Korea). Participants were polled about their current practices in patient warming and temperature measurement across the preoperative, intraoperative and postoperative periods. Questions were also asked regarding various individual and environmental barriers to compliance. RESULTS: In total, 1154 valid survey responses were obtained and analyzed. 279 (24.2%) of respondents prewarm, 508 (44.0%) perform intraoperative active warming, and 486 (42.1%) perform postoperative active warming in the majority of patients. Additionally, 531 (46.0%) measure temperature preoperatively, 767 (67.5%) measure temperature intraoperatively during general anesthesia, and 953 (82.6%) measure temperature postoperatively in the majority of patients. The availability of active warming devices in the operating room (p < 0.001, OR 10.040), absence of financial restriction (p < 0.001, OR 2.817), presence of hospital training courses (p = 0.011, OR 1.428), and presence of a hospital SOP (p < 0.001, OR 1.926) were significantly associated with compliance to intraoperative active warming. CONCLUSIONS: Compliance to international perioperative temperature management guidelines in Asia-Pacific remains poor, especially in small hospitals. Barriers to compliance were limited temperature management equipment, lack of locally-relevant standard operating procedures and training. This may inform international guideline committees on the needs of developing countries, or spur local anesthesiology societies to publish their own national guidelines.

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 (TZHF) and esophageal temperature (TEso) 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 TEso (range from 35.3 to 39.3 °C; median 37.2 °C), TZHF 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 TZHF, 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.

Short interruptions between pre-warming and intraoperative warming are associated with low intraoperative hypothermia rates.

BACKGROUND: Prevention of inadvertent hypothermia is recommended for procedures >30 minutes because hypothermia increases the risk of myocardial ischemia, intraoperative blood loss, transfusion and wound complications. Therefore, short warming interruptions between pre-warming and intraoperative warming might result in lower hypothermia rates. The aim of this retrospective investigation was to determine whether the incidence of inadvertent intraoperative hypothermia was affected by the warming interruption. METHODS: The lowest intraoperative body core temperature value and the warming interruption time were taken from anaesthesia records. Body core temperature was recorded continuously, and a patient was classified to be hypothermic if the lowest recorded temperature value was <36°C. Hypothermia rates and the correlation between warming interruption times and intraoperative hypothermia rates were calculated. RESULTS: Five thousand eighty-four patients were analysed. The intraoperative hypothermia rate was 15.3%. Nineteen patients (0.4%) had a recorded temperature of <35.0°C. An increase in forced-air warming interruption time was significantly associated with an increase in intraoperative hypothermia rates (P < .0001). Patients with interruptions in forced-air warming >20 minutes showed significantly higher hypothermia rates than those with interruptions of ≤20 minutes (P < .0001). CONCLUSION: Intraoperative hypothermia rates increased significantly with longer forced-air warming interruptions between pre-warming and intraoperative warming. Short warming interruptions can preserve the effect of pre-warming and are associated with low intraoperative hypothermia rates.

Influence of oral premedication and prewarming on core temperature of cardiac surgical patients: a prospective, randomized, controlled trial.

BACKGROUND: Perioperative hypothermia is still very common and associated with numerous adverse effects. The effects of benzodiazepines, administered as premedication, on thermoregulation have been studied with conflicting results. We investigated the hypotheses that premedication with flunitrazepam would lower the preoperative core temperature and that prewarming could attenuate this effect. METHODS: After approval by the local research ethics committee 50 adult cardiac surgical patients were included in this prospective, randomized, controlled, single-centre study with two parallel groups in a university hospital setting. Core temperature was measured using a continuous, non-invasive zero-heat flux thermometer from 30 min before administration of the oral premedication until beginning of surgery. An equal number of patients was randomly allocated via a computer-generated list assigning them to either prewarming or control group using the sealed envelope method for blinding. The intervention itself could not be blinded. In the prewarming group patients received active prewarming using an underbody forced-air warming blanket. The data were analysed using Student's t-test, Mann-Whitney U-test and Fisher's exact test. RESULTS: Of the randomized 25 patients per group 24 patients per group could be analysed. Initial core temperature was 36.7 ± 0.2 °C and dropped significantly after oral premedication to 36.5 ± 0.3 °C when the patients were leaving the ward and to 36.4 ± 0.3 °C before induction of anaesthesia. The patients of the prewarming group had a significantly higher core temperature at the beginning of surgery (35.8 ± 0.4 °C vs. 35.5 ± 0.5 °C, p = 0.027), although core temperature at induction of anaesthesia was comparable. Despite prewarming, core temperature did not reach baseline level prior to premedication (36.7 ± 0.2 °C). CONCLUSIONS: Oral premedication with benzodiazepines on the ward lowered core temperature significantly at arrival in the operating room. This drop in core temperature cannot be offset by a short period of active prewarming. TRIAL REGISTRATION: This trial was prospectively registered with the German registry of clinical trials under the trial number DRKS00005790 on 20th February 2014.

Comparison of Conductive and Convective Warming in Patients Undergoing Video-Assisted Thoracic Surgery: A Prospective Randomized Clinical Trial.

Background Perioperative hypothermia is frequent during thoracic surgery. After approval by the local ethics committee and written informed consent from patients, we examined the efficiency of prewarming and intraoperative warming with a convective warming system and conductive warming system to prevent perioperative hypothermia during video-assisted thoracic surgery (VATS). Methods We randomized 60 patients with indication for VATS in two groups (convective warming with an underbody blanket vs. conductive warming with an underbody mattress and additional warming of the legs). All patients were prewarmed before induction of anesthesia with the corresponding system. Core temperature was measured sublingual and in the nasopharynx. Results Both groups were not significantly different in regard to clinical parameter, prewarming, and initial core temperature. The patients in conduction group had lower intraoperative core temperatures and a higher incidence of intraoperative (73.9 vs. 24%) and postoperative hypothermia (56.5 vs. 8%) compared with convective warming. Conclusions Pre- and intraoperative convective warming with an underbody blanket prevents perioperative hypothermia during VATS better than conductive warming. The inferior prevention in conductive warming group may be caused by reduced body contact to the warming mattresses in lateral position.

Does sodium bicarbonate infusion really have no effect on the incidence of acute kidney injury after cardiac surgery? A prospective observational trial.

INTRODUCTION: Postoperative acute kidney injury (AKI) is a frequently observed phenomenon after cardiac surgery with cardio-pulmonary bypass (CPB); this severe complication is associated with adverse patient outcomes. There are multiple mechanisms involved in AKI during cardiac surgery, including CPB-dependent hemolysis. An IV infusion of sodium bicarbonate, which leads to urine alkalization, may play a role in preventing AKI. Recently, several trials have investigated the effect of sodium bicarbonate and reported controversial results. The purpose of this investigation was to investigate the following question. Under what circumstances can sodium bicarbonate prevent postoperative AKI? METHODS: We analyzed data from 342 patients undergoing CPB surgery at the University Hospital Goettingen, Germany. A total of 174 patients received a preemptive dose of sodium bicarbonate. Directly after the induction of anesthesia, the continuous infusion of 0.15 mmol/kg body weight/h was started and continued until 2 pm on the first postoperative day. Patients who were not treated with sodium bicarbonate formed the control group (n = 168). To verify the AKI risk configuration of each group, we surveyed risk factors and determined the commonly used clinical predictive score according to Thakar and colleagues. We recorded the concentration of free hemoglobin (fhb) to estimate the amount of CPB-dependent hemolysis. The definition of AKI was acquired by applying the AKI-network (AKIN) classification over the course of five postoperative days. RESULTS: Patients who received the sodium bicarbonate infusion showed a significantly lower incidence (35.6 vs. 50%) of AKI than that of patients who did not receive the infusion (p = 0.01). AKIN levels 2 and 3 were also more frequent when sodium bicarbonate was not administered. Particularly, in the low-risk cohort (<3 Thakar points), the incidence of AKI was significantly reduced (26 vs. 46%) when patients received sodium bicarbonate (p = 0.01), whereas in the high-risk patients, no significant reduction was observed. CONCLUSION: In this study, we observed that low-risk patients particularly benefited from the preventive treatment with sodium bicarbonate. The incidence of AKI was significantly reduced in low-risk patients while there was no statistically significant difference in the high-risk patient cohort. TRIAL REGISTRATION: DRKS00007616, Registered 12 December 2014.

Quantification of urinary TIMP-2 and IGFBP-7: an adequate diagnostic test to predict acute kidney injury after cardiac surgery?

INTRODUCTION: Postoperative acute kidney injury (AKI) is a frequently observed complication after on-pump cardiac surgery (CS) and is associated with adverse patient outcomes. Early identification of patients at risk is essential for the prevention of AKI after CS. In this study, we analysed whether urinary tissue inhibitor of metalloproteinase 2 (TIMP-2) combined with urine insulin-like growth factor binding protein 7 (IGFBP-7) ([TIMP-2] × [IGFBP-7]) is an adequate diagnostic test to identify early AKI after on-pump CS. METHODS: In 42 patients undergoing coronary artery bypass graft surgery, we surveyed individual risk factors for AKI and defined AKI by applying the Kidney Disease: Improving Global Outcomes (KDIGO) classification during the day of surgery and the following 2 days after surgery. Concentrations of urinary TIMP-2 multiplied by IGFBP-7 were recorded at four time points: at baseline pre-surgery, at the end of surgery, 4 hours after cardiopulmonary bypass (CPB) and at 8:00 AM on the first postoperative day. RESULTS: In total, 38% of the patients experienced AKI. The results showed a median baseline [TIMP-2] × [IGFBP-7] concentration of 0.3 (ng/ml)(2)/1,000, decreasing at the end of surgery and then increasing at the next measurement point 4 hours after CPB and further on the first postoperative day. On the first postoperative day, patients with AKI had significantly higher concentrations of [TIMP-2] × [IGFBP-7]. On the day of surgery, the concentration did not significantly differ between patients classified as KDIGO 0 or KDIGO 1 or 2. Previously published cutoff points of 0.3 and 2 were not confirmed in our study cohort. CONCLUSION: [TIMP-2] × [IGFBP-7] concentration can be used as a diagnostic test to identify patients at increased risk of AKI after CS on the first postoperative day. At earlier time points, no significant difference in [TIMP-2] × [IGFBP-7] concentration was found between patients classified as KDIGO 0 or KDIGO 1 or 2. TRIAL REGISTRATION: German Clinical Trials Register (DRKS) DRKS00005457. Registered 26 November 2013.

Remifentanil added to sufentanil-sevoflurane anesthesia suppresses hemodynamic and metabolic stress responses to intense surgical stimuli more effectively than high-dose sufentanil-sevoflurane alone.

BACKGROUND: Even extremely high-doses of the potent opioid, sufentanil, cannot reliably suppress stress responses to intense surgical stimuli such as sternotomy. The chemically related opioid remifentanil with its different pharmacokinetics and binding affinities for delta- and kappa-opioid receptors might be more effective in attenuating these responses. METHODS: ASA I-III patients scheduled for a surgical procedure with sternotomy under balanced anesthesia (sevoflurane and sufentanil 3 µg.kg(-1) bolus, 0.017 µg.kg(-1).min(-1) infusion) were randomized into two groups. Patients in the study group were supplemented with remifentanil (2 µg.kg(-1) bolus, 2-7 µg.kg(-1).min(-1) infusion) starting ten minutes before sternotomy. Heart rate, arterial blood pressures, cardiac index, ejection fraction, systemic vascular resistance index (SVRI), total body oxygen uptake (VO2) and electric dermal response were measured and compared between the groups. RESULTS: 62 patients were studied (study group 32, control group 30). Systolic and mean arterial blood pressures, SVRI, VO2 and skin conductance increased during sternotomy and sternal spread in the control group but not in the study group. Systolic blood pressure increase: 7.5 ± 19 mmHg vs. -3.4 ± 8.9 (p = 0.005); VO2 increase: 31 ± 46% vs. -0.4 ± 32%; incidence of systolic blood pressure increase greater than 15 percent: 20% vs. 3% (p = 0.035) (control vs. study group). CONCLUSION: High-dose remifentanil added to sevoflurane-sufentanil anesthesia suppresses the sympathoadrenergic response to sternotomy and sternal spread better than high-dose sufentanil alone. CLINICAL TRIAL NUMBER: DRKS00004327, August 31, 2012.

Accuracy of a zero-heat-flux thermometer in cardiac surgery, a prospective, multicentre, method comparison study.

Accurate measurement of core temperature is of utmost importance during on-pump cardiac surgery, for detection of hypothermia before cardiopulmonary bypass (CPB), guidance of temperature management on CPB, active rewarming on CPB and guidance of warming therapy after CPB. Most temperature measurement methods are known to become inaccurate during rapid changes in core temperature and suffer from delayed detection of temperature changes. Zero-heat-flux temperature (ZHF) measurement from the lateral forehead may be an alternative, non-invasive method quantifying the core temperature. A prospective, observational, multicentre study was conducted in one hundred patients scheduled for on-pump coronary artery bypass grafting. Core temperatures were measured every minute by two zero-heat-flux thermometer (SpotOn™) and a bladder thermometer and a pulmonary artery catheter (PAC) in the period after induction of anesthesia until CPB. Accuracy and precision of both methods were compared against core temperature measured in the pulmonary artery using the method of Bland and Altman. A high accuracy (around 0.1 °C) and a very good precision (Limits of agreement (LoA) - 0.6; 0.4 °C) were found between zero-heat-flux thermometer and core temperature measured by PAC. Among the two ZHF thermometers the bias was negligible (- 0.003 °C) with narrow LoA of - 0.42 °C and 0.41 °C. In contrast, bias between bladder temperature and PAC temperature was large (0.51 °C) with corresponding LoA of - 0.06 °C and 1.1 °C. ZHF thermometers are in contrast to bladder temperature a reliable core temperature monitor in cardiac surgery during the period after induction of anestesia until CPB. The zero-heat-flux method can provide clinicians reliably with continuous and non-invasive measurements of core temperature in normothermic and mild hypothermic temperature ranges and therefore can be helpful to guide temperature management.

Prevention of intraoperative hypothermia in neonates and infants: results of a prospective multicenter observational study with a new forced-air warming system with increased warm air flow.

OBJECTIVES: Neonates and infants are at the highest risk of developing perioperative hypothermia. A number of methods to prevent hypothermia during pediatric anesthesia are in use, and despite the fact that conventional forced-air warmers are the most effective devices, they are not always sufficient enough to maintain body temperature. Therefore, recently a new forced-air warming system with an increased warm air flow was introduced to the market. AIM: The aim of this study was to evaluate this new forced-air warming system in neonates and infants during pediatric anesthesia. We hypothesized that the new blanket alone is sufficient enough to prevent neonates and infants from intraoperative hypothermia. METHODS: Neonates and infants (body weight <10 kg) were enrolled in this prospective multicenter observational study. After admission to the operating room, the children were placed on the new forced-air warming blanket. Body temperature was measured continuously until admission to the recovery room or pediatric intensive care unit (PICU). RESULTS: Hundred and nineteen children with a median body weight of 4.1 kg (range: 0.7-9.8) were enrolled and received their intended treatment. Median body temperature at the induction of anesthesia was 36.5 °C (range: 35.3-38.2 °C) and increased with the length of the operation up to 37.8 °C (37.1-38.2 °C) after 180 min. Median body temperature after admission to the recovery room or PICU was 37.2 °C (36.0-38.6 °C) and remained significantly above baseline (P < 0.05). CONCLUSIONS: The new forced-air warming system as a sole warming device is effective in preventing perioperative hypothermia during pediatric anesthesia in neonates and infants.

Randomized comparison of the i-gel™, the LMA Supreme™, and the Laryngeal Tube Suction-D using clinical and fibreoptic assessments in elective patients.

BACKGROUND: The i-gel™, LMA-Supreme (LMA-S) and Laryngeal Tube Suction-D (LTS-D) are single-use supraglottic airway devices with an inbuilt drainage channel. We compared them with regard to their position in situ as well as to clinical performance data during elective surgery. METHODS: Prospective, randomized, comparative study of three groups of 40 elective surgical patients each. Speed of insertion and success rates, leak pressures (LP) at different cuff pressures, dynamic airway compliance, and signs of postoperative airway morbidity were recorded. Fibreoptic evaluation was used to determine the devices' position in situ. RESULTS: Leak pressures were similar (i-gel™ 25.9, LMA-S 27.1, LTS-D 24.0 cmH2O; the latter two at 60 cmH2O cuff pressure) as were insertion times (i-gel™ 10, LMA-S 11, LTS-D 14 sec). LP of the LMA-S was higher than that of the LTS-D at lower cuff pressures (p <0.05). Insertion success rates differed significantly: i-gel™ 95%, LMA-S 95%, LTS-D 70% (p <0.05). The fibreoptically assessed position was more frequently suboptimal with the LTS-D but this was not associated with impaired ventilation. Dynamic airway compliance was highest with the i-gel™ and lowest with the LTS-D (p <0.05). Airway morbidity was more pronounced with the LTS-D (p <0.01). CONCLUSION: All devices were suitable for ventilating the patients' lungs during elective surgery. TRIAL REGISTRATION: German Clinical Trial Register DRKS00000760.

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.

Perioperative Hypothermia-A Narrative Review.

Unintentional hypothermia (core temperature < 36 °C) is a common side effect in patients undergoing surgery. Several patient-centred and external factors, e.g., drugs, comorbidities, trauma, environmental temperature, type of anaesthesia, as well as extent and duration of surgery, influence core temperature. Perioperative hypothermia has negative effects on coagulation, blood loss and transfusion requirements, metabolization of drugs, surgical site infections, and discharge from the post-anaesthesia care unit. Therefore, active temperature management is required in the pre-, intra-, and postoperative period to diminish the risks of perioperative hypothermia. Temperature measurement should be done with accurate and continuous probes. Perioperative temperature management includes a bundle of warming tools adapted to individual needs and local circumstances. Warming blankets and mattresses as well as the administration of properly warmed infusions via dedicated devices are important for this purpose. Temperature management should follow checklists and be individualized to the patient's requirements and the local possibilities.