When cooling of the skin is perceived as warmth: Enhanced paradoxical heat sensation by pre-cooling of the skin in healthy individuals.

A paradoxical heat sensation (PHS) is the misperception of warmth when the skin is cooled. PHS is uncommon in healthy individuals but common in patients with neuropathy and is associated with reduced thermal sensitivity. Identifying conditions that contribute to PHS may indirectly help us understand why some patients experience PHS. We hypothesized that pre-warming increased the number of PHS and that pre-cooling had minimal effect on PHS. We tested 100 healthy participants' thermal sensitivity on the dorsum of their feet by measuring detection and pain thresholds to cold and warm stimuli and PHS. PHS was measured using the thermal sensory limen (TSL) procedure from the quantitative sensory testing protocol of the German Research Network on Neuropathic Pain and by using a modified TSL protocol (mTSL). In the mTSL we examined the participants' thermal detection and PHS after pre-warming of 38°C and 44°C and pre-cooling of 26°C and 20°C. Compared to a baseline condition, the number of PHS responders was significantly increased after pre-cooling (20°C: RR = 1.9 (1.1; 3.3), p = 0.023 and 26°C: RR = 1.9 (1.2; 3.2), p = 0.017), but not significantly after pre-warming (38°C: RR = 1.5 (0.86; 2.8), p = 0.21 and 44°C: RR = 1.7 (.995; 2.9), p = 0.078). Pre-warming and pre-cooling increased the detection threshold of both cold and warm temperatures. We discussed these findings in relation to thermal sensory mechanisms and possible PHS mechanisms. In conclusion, PHS and thermosensation are closely related and pre-cooling can induce PHS responses in healthy individuals.

Risk factors and outcomes of intraoperative hypothermia in neonatal and infant patients undergoing general anesthesia and surgery.

Objective: The incidence of intraoperative hypothermia remains high in pediatric patients during anesthesia and surgery even though core body temperature monitoring and warming systems have been greatly improved in recent years. We analyzed the risk factors and outcomes of intraoperative hypothermia in neonates and infants undergoing general anesthesia and surgery. Methods: The data on the incidence of intraoperative hypothermia, other clinical characteristics, and outcomes from electronic records of 1,091 patients (501 neonates and 590 infants between 28 days and 1 year old), who received general anesthesia and surgery, were harvested and analyzed. Intraoperative hypothermia was defined as a core temperature below 36°C during surgery. Results: The incidence of intraoperative hypothermia in neonates was 82.83%, which was extremely higher than in infants (38.31%, p < 0.001)-the same as the lowest body temperature (35.05 ± 0.69°C vs. 35.40 ± 0.68°C, p < 0.001) and the hypothermia duration (86.6 ± 44.5 min vs. 75.0 ± 52.4 min, p < 0.001). Intraoperative hypothermia was associated with prolonged PACU, ICU, hospital stay, postoperative bleeding, and transfusion in either age group. Intraoperative hypothermia in infants was also related to prolonged postoperative extubation time and surgical site infection. After univariate and multivariate analyses, the age (OR = 0.902, p < 0.001), weight (OR = 0.480, p = 0.013), prematurity (OR = 2.793, p = 0.036), surgery time of more than 60 min (OR = 3.743, p < 0.001), prewarming (OR = 0.081, p < 0.001), received >20 mL/kg fluid (OR = 2.938, p = 0.004), and emergency surgery (OR = 2.142, p = 0.019) were associated with hypothermia in neonates. Similar to neonates, age (OR = 0.991, p < 0.001), weight (OR = 0.783, p = 0.019), surgery time >60 min (OR = 2.140, p = 0.017), pre-warming (OR = 0.017, p < 0.001), and receive >20 mL/kg fluid (OR = 3.074, p = 0.001) were relevant factors to intraoperative hypothermia in infants along with the ASA grade (OR = 4.135, p < 0.001). Conclusion: The incidence of intraoperative hypothermia was still high, especially in neonates, with a few detrimental complications. Neonates and infants each have their different risk factors associated with intraoperative hypothermia, but younger age, lower weight, longer surgery time, received more fluid, and no prewarming management were the common risk factors.

Spatiotemporal Thermal Control Effects on Thermal Grill Illusion.

The thermal grill illusion induces a pain sensation under a spatial display of warmth and coolness of approximately 40 °C; and 20 °C. To realize virtual pain display more universally during the virtual reality experience, we proposed a spatiotemporal control method to realize a variable thermal grill illusion and evaluated the effect of the method. First, we examined whether there was a change in the period until pain occurred due to the spatial temperature distribution of pre-warming and pre-cooling and verified whether the period until pain occurred became shorter as the temperature difference between pre-warming and pre-cooling increased. Next, we examined the effect of the number of grids on the illusion and verified the following facts. In terms of the pain area, the larger the thermal area, the larger the pain area. In terms of the magnitude of the pain, the larger the thermal area, the greater the magnitude of the sensation of pain.

Short-Periods of Pre-Warming in Laparoscopic Surgery. A Non-Randomized Clinical Trial Evaluating Current Clinical Practice.

BACKGROUND: Pre-warming prevents perioperative hypothermia. We evaluated the current clinical practice of pre-warming and its effects on temperature drop and postoperative complications; Methods: This prospective, observational pilot study examines clinical practice in a tertiary hospital on 99 patients undergoing laparoscopic urological surgery. Pre-warming was performed in the pre-anesthesia room. Patients were classified into three groups: P 0 (non-prewarmed), P 5-15 (pre-warming 5-15 min) and P > 15 (pre-warming 15-30 min). Tympanic temperature was recorded in the pre-anesthesia room, prior to anesthesia induction, and in the PACU. Esophageal temperature was recorded intraoperatively. The occurrence of shivering, pain intensity, length of stay in PACU, and postoperative complications during hospital stay were also recorded; Results: After pre-warming, between-group difference in body temperature was higher in P > 15 than in P 0 (0.4 °C, 95% CI 0.14-0.69, p = 0.004). Between P 5-15 and P 0 difference was 0.2 °C (95% CI 0.04-0.55, p = 0.093). Temperature at the end of surgery was higher in pre-warmed groups [mean between-group difference 0.5 °C (95% CI 0.13-0.81, p = 0.007) for P 5-15; 0.9 °C (95% CI 0.55-1.19, p < 0.001) for P > 15]. Pain and shivering was less common in pre-warmed groups. Postoperative transfusions and surgical site infections were lower in P > 15; Conclusion: Short-term pre-warming prior to laparoscopic urological surgery decreased temperature perioperative drop and postoperative complications.

Intraoperative thermal insulation in off-pump coronary artery bypass grafting surgery: a prospective, double blind, randomized controlled, single-center study.

BACKGROUND: About 50% patients who underwent off-pump coronary artery bypass grafting (OPCAB) experienced perioperative hypothermia. Pre-warming and intraoperative infusion of amino acid injection are the most popular perioperative insulation measures in recent years, but neither of them can completely prevent intraoperative hypothermia. The objective is to investigate the effect of preoperative warming and/or intraoperative infusion of amino acid injection on body temperature in patients undergoing OPCAB. METHODS: A prospective, double blind, randomized controlled, single-center study. Seventy-two patients were randomly divided into 4 groups: control group, pre-warming group, amino-acid group and multi-mode group. Pre-warming and multi-mode group were pre-heated with warming blankets and forced-air warming system before induction. After that, amino-acid and multi-mode group were infused with 18-amino acid solution. The perioperative temperature and complications were monitored. RESULTS: The temperature of control and amino-acid group decreased significantly, but amino-acid group recovered to preoperative level faster. The temperature of pre-warming group was stable, and that in multi-mode group increased at 60 min after the start of surgery. There was a significant difference in temperature at each time, and no difference in the incidence of complications between the groups. CONCLUSIONS: Preoperative warming and/or intraoperative infusion of amino acid injection can effectively reduce hypothermia in OPCAB surgery. Pre-warming before anesthesia is more effective, and the combination of the two methods has the best effect.

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.

Prevention of inadvertent perioperative hypothermia - Guideline compliance in German hospitals.

Patients undergoing elective surgery are at risk for inadvertent postoperative hypothermia, defined as a core body temperature below 36°C. This study was conducted to investigate the acceptance of the recommendations of the German S3 Guideline, in particular with respect to the concept of pre-warming and sublingual temperature measurement. The main focus was to gather data concerning the postoperative core temperature and the frequency of perioperative hypothermia in patients receiving a pre-warming regime and those without. The study team investigated the local concept and measures employed to avoid inadvertent perioperative hypothermia with respect to defined outcome parameters following a specific protocol. In summary, the study hospitals vary greatly in their perioperative processes to prevent postoperative hypothermia. However, each hospital has a strategy to prevent hypothermia and was more or less successful in keeping its patients normothermic during the perioperative process. Our data could not demonstrate major differences between hospitals in the implementation strategy to prevent perioperative hypothermia in regard to the hospital size. The results of our study suggest a wide-spread acceptance, as no postoperative hypothermia was detected in a cohort of 431 patients.

Detection of Listeria spp. and L. monocytogenes in pooled test portion samples of processed dairy products.

Listeria monocytogenes is a major foodborne pathogen. Testing multiple portions of the same final product is often required to verify the effectiveness of a food safety management system. Therefore, it will be advantageous to the laboratories to combine these test portions and process as one sample. However, combining samples for analysis, i.e., pooling, can be done only if there is no negative impact on the result. The objective of this study was to validate pooling of test portions for the detection of L. monocytogenes and Listeria spp. in dairy products as no scientific evidence currently exists to support this practice. Six representative matrices, namely, pudding, yogurt, brie cheese, 2% milk, ice cream and infant formula were spiked separately with stressed L. monocytogenes and Listeria spp. in 25 g and pooled test portions (375 g/250 g/125 g). Two methods, namely, ISO-11290-1:1996 Amd1:2004 and a validated alternative method Rapid'L.Mono were used for sample testing. Performance of a method in pooled test portions was considered to be satisfactory if the relative limit of detection (RLOD50; LOD50 [pooled test portion]/LOD50 [25 g test portion]) and limit of detection (LOD50) obtained was ≤2.5 and 1 CFU or MPN, respectively. Results obtained from L. monocytogenes and Listeria spp. trials were given equal weightage to decide on the impact of pooling. Acceptable RLOD50 and LOD50 values were consistently obtained in L. monocytogenes and Listeria spp. inoculation experiments when test portions were pooled up to 125 g for all matrices tested with both methods. While there was a slight delay for the primary enrichment of the pooled test portions to reach the desired incubation temperature when compared to the 25 g test portions, it did not negatively impact the outcome when samples were pooled up to 125 g. Background organisms were in general present at low concentrations and did not seem to adversely impact the recovery of the target organism in 125 g samples. Thus, pooling of test portions to up to 125 g for the detection of L. monocytogenes and Listeria spp. by two culture methods in processed dairy products has been validated.

Effect of pre-warming on perioperative hypothermia during holmium laser enucleation of the prostate under spinal anesthesia: a prospective randomized controlled trial.

BACKGROUND: The purpose of this study is to assess whether the application of preoperative forced air warming set to high temperature (> 43 °C) for brief period can increase temperature on admission to the postanesthesia care unit (PACU) and prevent hypothermia or shivering during holmium laser enucleation of the prostate performed under spinal anesthesia. METHODS: Fifty patients were enrolled were assigned randomly to receive passive insulation (control group, n = 25) or forced-air skin surface warming for 20 min before spinal anesthesia (pre-warming group, n = 25). The primary outcome was temperature at PACU admission. RESULTS: The pre-warming group had a significantly higher temperature on admission to the PACU than the control group (35.9 °C [0.1] vs 35.6 °C [0.1], P = 0.023; 95% confidence interval of mean difference, 0.1 °C-0.5 °C). The trend of decreasing core temperature intraoperatively was not different between groups (P = 0.237), but intraoperative core temperature remained approximately 0.2 °C higher in the pre-warming group (P = 0.005). The incidence of hypothermia on admission to the PACU was significantly lower in the pre-warming group (56% vs 88%, P = 0.025). Shivering occurred in 14 patients in the control group, and 4 patients in the pre-warming group (P = 0.007). CONCLUSION: Brief pre-warming at 45 °C increased perioperative temperature and decreased the incidence of hypothermia and shivering. However, it was not sufficient to modify the decline of intraoperative core temperature or completely prevent hypothermia and shivering. Continuing pre-warming to immediately before induction of spinal anesthesia or combining pre-warming with intraoperative active warming may be necessary to produce clearer thermal benefits in this surgical population. TRIAL REGISTRATION: This trial was registered with Clinicaltrials.gov, NCT03184506 , 5th June 2017.

Multimodal temperature management during donor hepatectomy under combined general anaesthesia and neuraxial analgesia: Retrospective analysis.

BACKGROUND AND AIMS: Unintended hypothermia (UIH) during surgery under general anaesthesia has adverse implications. A retrospective analysis of the perioperative temperature records of healthy voluntary liver donors was done to evaluate the efficacy of a multimodal protocol for temperature management. METHODS: Records of 50 American Society of Anesthesiologists physical status Class 1 patients operated for Donor Hepatectomy lasting >2 h under combined general and epidural anaesthesia were analysed. Ambient temperature was maintained 24°C-27°C before induction of GA and during insertion of epidural catheter. Active warming was done using warming mattress set to temperature 38°C, hot air blanket with temperature set to 38°C and fluid warming device (Hotline™) with preset temperature of 41°C. Nasopharyngeal temperature was continuously monitored. After induction of GA and draping of the patient, ambient temperature was decreased and maintained at 21°C-24°C and was again increased to 24°C-27°C at the conclusion of surgery. During surgery, for every 0.1°C above 37°C, one heating device was switched off such that at 37.3°C all the 3 devices were switched off. Irrigation fluid was pre-warmed to 39°C. RESULTS: Baseline temperature was 35.9°C ± 0.4°C. Minimum temperature recorded was 35.7°C ± 0.4°C. Mean decrease in temperature below the baseline temperature was 0.2°C ± 0.2°C. Temperature at the end of surgery was 37.4°C ± 0.5°C. CONCLUSION: Protocol-based temperature management with simultaneous use of resistive heating mattress, forced-air warming blanket, and fluid warmer along with ambient temperature management is an effective method to prevent unintended perioperative variation in body temperature.

Preventive effect of pre-warming, hot compress, and pH adjustment in oxaliplatin-induced venous pain.

Background Venous pain induced by peripheral intravenous administration of oxaliplatin remains clinically unresolved. Objective The aim of this study was to determine the efficacy of comprehensive intervention care for venous pain in colorectal cancer patients receiving oxaliplatin. Setting A Japanese tertiary hospital. Method We treated all outpatients after April 2012 with comprehensive intervention care including pre-warming of the oxaliplatin solution, use of a hot compress, and pH adjustment by combination with dexamethasone. We retrospectively reviewed the electronic medical records from colorectal cancer patients who had received oxaliplatin via a peripheral vein between December 2009 and June 2014. Main outcome measures The primary endpoint of this study was the incidence of venous pain at the administration site during oxaliplatin infusion, according to injection site reaction grade ≥ 2. Results We evaluated 271 treatment courses in 59 patients. Venous pain occurred in 42 courses (15.5%) among 26 patients. Multivariate logistic regression analysis revealed that female gender and body mass index ≥ 25 kg/m2 were significantly associated with an increased risk of venous pain during all courses (adjusted odds ratio [OR]: 3.18, 95% confidence interval [CI] 1.35-7.92; P < 0.01; and adjusted OR: 3.37, 95% CI 1.26-9.40; P = 0.02, respectively), whereas comprehensive intervention care were significantly associated with reduced risk of venous pain during all courses (adjusted OR: 0.10, 95% CI 0.02-0.44; P < 0.01). Conclusion Comprehensive intervention care is a clinical treatment option for oxaliplatin-induced peripheral venous pain in patients with colorectal cancer, especially females with obesity.

Validation of test portion pooling for Salmonella spp. detection in foods.

Pathogen monitoring programs play a crucial role in the verification of the effectiveness of implemented hygiene control measures. Sampling and testing procedures included in pathogen monitoring involve the analysis of multiple test portions where all samples must be negative for the presence of pathogens for a certain test portion size. Many food safety programs require increased testing due to the risks that a pathogen may be present. Analyzing more than one test portion could prove to be expensive and labor intensive. When more than one test portion for a specified food item is to be tested, the test portions could be combined to form a pooled test portion to reduce laboratory workload, costs of reagents and further confirmatory steps, but only when evidence is available that pooling does not affect on the number of false negative results for different matrices. This study has been performed to demonstrate the equivalence of test portion pooling for Salmonella detection with five different methods using cultural, ELISA and Real Time PCR technologies. Twenty-three (23) different food items including confectionary products, meal components, infant formula, pet food and powdered beverages were validated. Other complementary parameters like impact of minimum and maximum incubation time for pre-enrichment, temperature profile, pH and Salmonella concentration after the pre-enrichment and background flora have also been considered in the study. The results showed that pooling test portions up to 375g for Salmonella detection is valid for the methods that were tested. Relative level of detection (RLOD50) values for 22 of the food items tested were acceptable (i.e. lower than 2.5) when comparing the reference sample size (25g) against the alternative pooled sample size (375g), provided the enrichment broth was pre-warmed and maximum incubation time is respected.

The efficacy of pre-warming on reducing intraprocedural hypothermia in endovascular coiling of cerebral aneurysms.

BACKGROUND: The anesthetic management of patients undergoing endovascular treatment of cerebral aneurysms in the interventional neuroradiology suite can be challenged by hypothermia because of low ambient temperature for operating and maintaining its equipments. We evaluated the efficacy of skin surface warming prior to induction of anesthesia to prevent the decrease in core temperature and reduce the incidence of hypothermia. METHODS: Seventy-two patients were randomized to pre-warmed and control group. The patients in pre-warmed group were warmed 30 minutes before induction with a forced-air warming blanket set at 38°C. Pre-induction tympanic temperature (Tpre) was measured using an infrared tympanic thermometer and core temperature was measured at the esophagus immediately after intubation (T0) and recorded at 20 minutes intervals (T20, T40, T60, T80, T100, and T120). The number of patients who became hypothermic at each time was recorded. RESULTS: Tpre in the control and pre-warmed group were 36.4 ± 0.4°C and 36.6 ± 0.3°C, whereas T0 were 36.5 ± 0.4°C and 36.6 ± 0.2°C. Core temperatures in the pre-warmed group were significantly higher than the control group at T20, T40, T60, T80, T100, and T120 (P < 0.001). Compared to T0, core temperatures at each time were significantly lower in both two groups (P = 0.007 at T20 in pre-warmed group, P < 0.001 at the other times in both groups). The incidence of hypothermia was significantly lower in the pre-warmed group than the control group from T20 to T120 (P = 0.002 at T20, P < 0.001 at the other times). CONCLUSION: Pre-warming for 30 minutes at 38°C did not modify the trends of the temperature decrease seen in the INR suite. It just slightly elevated the beginning post intubation base temperature. The rate of decrease was similar from T20 to T120. However, pre-warming considerably reduced the risk of intraprocedural hypothermia. TRIAL REGISTRATION: Clinical Research Information Service (CRiS) Identifier: KCT0001320. Registered December 19th, 2014.

Effect of Resin Cement Pre-heating on the Push-out Bond Strength of Fiber Post to Root Canal Dentin.

Background and aims. Various factors influence the interfacial bond between the fiber posts and root canal dentin. The aim of the present study was to evaluate the effect of pre-warming of resin cement on the push-out bond strength of fiber posts to various segments of root canal dentin. Materials and methods . In this in vitro study, 40 single-rooted human premolars were decoronated and underwent root canal treatment along with post space preparation. The samples were randomly divided into two groups: In group 1, Panavia F 2.0 cement was used at room temperature; in group 2, the same cement was warmed to 55‒60°C before mixing. After fiber posts were placed and cemented in the root canals, 3 dentin/post sections (coronal, middle and apical) with a thickness of 3 mm were prepared. A universal testing machine was used to measure push-out bond strength in MPa. Data was analyzed using two-factor ANOVA and a post hoc Tukey test at α=0.05. Results. The mean value of push-out bond strength was high at room temperature, and the differences in the means of push-out bond strength values between the resin cement temperatures and between different root segments in each temperature were significant (P<0.05). Conclusion. Pre-warming of Panavia F 2.0 resin cement up to 55-60°C reduced push-out bond strength to root canal dentin. In addition, in each temperature group bond strengths decreased from coronal to apical segments.

Prewarming of the i-gel facilitates successful insertion and ventilation efficacy with muscle relaxation: a randomized study.

STUDY OBJECTIVE: To determine if prewarming of the i-gel (Intersurgical, Wokingham, United Kingdom) improves insertion and ventilation efficacy with muscle relaxation in patients undergoing elective surgery. DESIGN: Clinical randomized study. SETTING: Operating room. PATIENTS: Sixty-eight adult patients scheduled for elective surgery under general anesthesia with American Society of Anesthesiologists physical status 1-3. INTERVENTIONS: The i-gel was warmed to 42°C for 30 minutes before insertion (W group; 34 patients) or kept at room temperature (approximately 23°C) (C group; 34 patients). MEASUREMENTS: The number of attempts for a successful insertion and the sealing pressure and leak volume 30 seconds and 30 minutes after initiating mechanical ventilation. MAIN RESULTS: The total insertion attempts were 1 (W group, 31 cases; C group, 24 cases) and 2 (W group, 3 cases; C group, 10 cases), which was significant (P = .001). Sealing pressure was significantly higher in the W group than the C group (W group, 21.8 ± 3.7 cm H2O; C group, 18.5 ± 3.4 cm H2O; P = .001). Leak volume was significantly smaller after 30 seconds in the W group than the C group (P = .002), but not after 30 minutes (P = .69). CONCLUSIONS: Prewarming the i-gel to 42°C demonstrated a higher successful ventilation initiation.