Assessment of skin temperature during regional anaesthesia-What the anaesthesiologist should know

The Effects of Actively Warming the Patient on Maternal and Infant Well-Being in a Cesarean Section Operation

PURPOSE

Intraoperative warming is recommended for surgical patients under anesthesia, but there are insufficient studies on this topic in cesarean delivery patients under spinal anesthesia. The purpose of this study was to determine the effects of active warming on the mother and newborn during elective cesarean section.

DESIGN

This research was carried out in an experimental design with a pretest-posttest randomized intervention and control group.

METHODS

The research was conducted with 34 women (17 intervention and 17 control), who gave birth by cesarean section. The study examined outcomes for both mother and newborn. Women in the intervention group were heated by both active (warmed with carbon fiber resistive underbody heaters during surgery) and passive heating (preoperative- socks, nonelectrified wool blankets, etc). Only passive heating methods were applied to the women in the control group (preoperative). Neonatal Activity - Pulse - Grimace - Appearence - Respiration (APGAR) score, body temperature, cortisol, and blood glucose levels in the intervention and control groups were evaluated, while body temperature and shivering conditions were evaluated in the mother.

FINDINGS

Body temperature and first minute APGAR score of the infants in the intervention and control groups after cesarean section were 36.88 ± 0.27, 36.52 ± 0.32 (P = .002); 7.00 ± 0.36, 7.47 ± 0.64 (P = .009), respectively. Cortisol and blood glucose levels in the intervention and control groups were 3.55 ± 1.09, 4.51 ± 0.70 (P = .010), 77.94 ± 7.07, 72.47 ± 10.24 (P > .05), respectively. The body temperatures of the women in the intervention and control groups at 15, 30, and 45 minutes were significantly different (P < .05), while they were similar (P > .05) at 60 minutes. Oxygen saturation measured at 30 minutes during the operation was 97.10 ± 1.41 in the intervention group and 95.20 ± 1.78 in the control group (P < .05).

CONCLUSIONS

Active warming before, during, and after cesarean section affected body temperature, pulse, respiration, blood pressure, and oxygen saturation of women, and while it increased the body temperature and APGAR score of newborns, it decreased cortisol level.

Effect of Prewarming on Skin Temperature Changes After Spinal Anesthesia in Transurethral Resection of the Bladder

PURPOSE

Monitoring of peripheral skin temperature changes is an objective and rapid method to evaluate the success of neuraxial block after spinal anesthesia. The aim of this study is to investigate the effect of prewarming on peripheral temperature changes after the administration of spinal anesthesia.

DESIGN

Randomized, prospective, single-blind study.

METHODS

In this study, patients scheduled for transurethral resection of the bladder surgery under spinal anesthesia were divided into two groups: those with active prewarming and those without active prewarming. The groups were compared in core and skin temperature changes after administration of spinal anesthesia, length of stay in the postanesthesia care unit, shivering score, and the thermal comfort scale.

FINDINGS

A statistically significant difference was found between the groups on time for a 1 °C increase in ankle and toe skin temperatures (P < .001). There was a statistically significant difference between the groups in core temperature measurements (P < .001). When thermal comfort was compared between the groups, a statistically significant difference was found (P < .001). Patients' shivering score (P = .704), and length of stay in the postanesthesia care unit (P = .059) between the groups were similar.

CONCLUSIONS

Skin temperature changes in the prewarming group were lower, and this group had a lower rate of increase than the nonprewarming group. Therefore, skin temperature changes in the lower extremity can be used to determine the success of spinal anesthesia in patients who are prewarmed, with the awareness of these differences.

Efficacy of the intertransverse process block: single or multiple injection? A randomized, non-inferiority, blinded, cross-over trial in healthy volunteers

INTRODUCTION

The intertransverse process block is increasingly used to ameliorate postoperative pain following a plethora of surgical procedures involving the thoracic wall. Nevertheless, the optimal approach and cutaneous extent of the sensory block are currently unknown. We aimed to further describe the intertransverse process block, single injection versus multiple injection, and we hypothesized that the single-injection intertransverse process block is a non-inferior technique.

METHODS

Twelve healthy male volunteers were cross-over randomized to receive either single-injection intertransverse process block with 21 mL ropivacaine 7.5 mg/mL, including two sham injections, at the thoracic level T4/T5 or multiple-injection intertransverse process block with three injections of 7 mL ropivacaine 7.5 mg/mL at the thoracic levels T2/T3, T4/T5 and T6/T7 at the first visit. At the second visit, the other technique was applied on the contralateral hemithorax. A non-inferiority margin of 1.5 anesthetized thoracic dermatomes was chosen.

RESULTS

The mean difference (95% CI) in the number of anesthetized thoracic dermatomes was 0.82 (-0.41 to 2.05) pnon-inf<0.01 indicating non-inferiority favoring the single-injection technique.Both techniques anesthetized the ipsilateral thoracic wall and demonstrated contralateral cutaneous involvement to a variable extent. The multiple-injection intertransverse process block anesthetized a significantly larger cutaneous area on the posterior hemithorax and decreased mean arterial pressure at 30 and 60 min postblock application. Thoracic thermography showed no intermodality temperature differences yet compared with baseline temperatures both techniques showed significant differences.

CONCLUSIONS

Single-injection intertransverse process block is non-inferior to multiple injection in terms of anesthetized thoracic dermatomes. Both techniques generally anesthetize the hemithoracic wall to a variable extent.

EU CLINICAL TRIALS REGISTER

2022-501312-34-01.

Fabrication of Temperature Sensors with High-Performance Uniformity through Thermal Annealing

It is considered to be of great significance to monitor human health and track the effect of drugs by measuring human temperature mapping through flexible temperature sensors. In this work, we found that the thermal annealing of flexible temperature sensors based on graphite-acrylate copolymer composites can not only improve the temperature coefficient of resistance (TCR) values of the devices, but also greatly improve the uniformity of the performance of the devices prepared in parallel. The best results were obtained when the devices were annealed at 100 °C, which is believed to be due to the rearrangement of graphite particles to generate more uniform and numerous conductive channels within the conductive composite. We believe this finding might promote the practical development of flexible temperature sensors in body temperature sensing for health maintenance and medical applications.

Regional haemodynamic variables and perfusion index in the evaluation of sciatic nerve block: a prospective observational trial

OBJECTIVE

We determined whether regional haemodynamics and perfusion index (PI) could be reliable indicators of a successful sciatic nerve block (SNB).

DESIGN

Prospective observational trial.

SETTING

A tertiary teaching hospital in China from April 2020 to August 2020.

PARTICIPANTS

We assessed 79 patients for eligibility to participate in this study. Nine patients were excluded for not meeting our inclusion criteria, and three patients were excluded due to missing measurements at all time points.

INTERVENTIONS

The patients underwent SNB. Pulsed-wave Doppler and PI measurements were performed.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the diagnostic power of regional haemodynamic change and PI to predict successful SNB. The secondary outcome measure was the effect of SNB on the regional haemodynamics and PI in the lower extremity.

RESULTS

We assessed 79 patients in this study and 67 patients available for the final analysis. The SNB was successful in 59 patients and failed in eight patients. There were no significant differences in demographic characteristics between the patients with successful and failed SNB. Starting from 10 min after SNB, the peak systolic velocity (PSV), end-diastolic velocity, time-averaged maximum velocity and time-averaged mean velocity of the anterior tibial artery and posterior tibial artery of patients in the successful SNB group were significantly higher than those in the failed SNB group (p<0.05). The PSV percentage increase at 10 min after SNB has great potential to predict the block success. The area under the receiver operating characteristic curve (AUC) values were 0.893 (95% CI 0.7809 to 1.000) and 0.880 (95% CI 0.7901 to 0.9699). The corresponding cut-off values were 19.22 and 35.88, respectively. The PI increased during 5-45 min intervals in patients with successful SNB. The AUC for the PI percentage increases at 10 min after SNB was 0.853 (95% CI 0.7035 to 1.000), with a cut-off value of 93.09.

CONCLUSION

The regional haemodynamic variables, PSV and PI in particular, can be used as alternative indicators for clinicians to evaluate the success of SNB objectively and early.

TRIAL REGISTRATION NUMBER

ChiCTR2000030772.

Pulse perfusion index for predicting intrapartum fever during epidural analgesia

STUDY OBJECTIVE

To assess whether pulse perfusion index (PI) values could be employed to predict intrapartum fever and to provide a cut-off PI value for predicting intrapartum fever occurrence.

DESIGN

We conducted a single-center, prospective, observational study.

SETTING

Delivery room at the Department of Obstetrics, Affiliated Hospital of Jiangsu University.

PATIENTS

117 parturients who intended to have a vaginal delivery.

INTERVENTIONS

Each parturient received epidural analgesia.

MEASUREMENTS

We checked each parturient's tympanic temperature before analgesia (T₀), at 1 h (T₁) and 2 h (T₂) after analgesia, immediately at the end of the second (T₃) and third (T₄) stages of labor, and at 1 h postpartum (T₅). A temperature of ≥38°C was defined as fever. PI, measured on the right second toe, was recorded before analgesia (PI₀) and at 10 min (PI₁₀), 20 min (PI₂₀), and 30 min (PI₃₀) after analgesia. The PI change rate was calculated as the incremental change in PI₃₀ from PI₀, divided by the PI₀. Receiver operating characteristic (ROC) curves were used to verify the utility of the PI₃₀ and PI change rate values for predicting intrapartum fever.

MAIN RESULTS

We found that peak temperature (T_P) occurred at the end of the second or the third stage of labor. Within 30 min after analgesia, the PI showed a significant increase over time and there was a linear correlation between PI₃₀ and T_P values (P < 0.001, r = 0.544). The PI₁₀, PI₂₀, PI₃₀ and PI change rate in febrile parturients were higher than those in afebrile parturients (P < 0.001). The area under the ROC (AUROC) for PI₃₀ was 0.818 (P < 0.001) with a cut-off of 9.30. The AUROC of the PI change rate was 0.738 (P < 0.001) with a cut-off of 3.45.

CONCLUSIONS

PI₃₀ and PI change rate values could be used to predict intrapartum fever in parturients after epidural analgesia.

Infrared thermography for assessment of thoracic paravertebral block: a prospective observational study

Background

There was no “gold standard” to assess the success or failure of thoracic paravertebral block (TPVB). Measurement of skin temperature with infrared thermography (IT) would be a reliable method to evaluate the effectiveness of regional blocks. This study aimed to explore the feasibility of using skin temperature difference (Td) determined by IT between the blocked and unblocked side to predict the spread of TPVB.

Methods

Sixty-one patients undergoing elective unilateral breast or thoracoscopic surgery were enrolled in this prospective observational study. TPVB was performed at T4 and T5 under real-time ultrasound guidance with 10 mL of 0.4% ropivacaine for each patient, respectively. Td between the blocked and unblocked side were measured with IT from T2 to T10 at the anterior chest wall before TPVB and 5 min, 10 min, 15 min and 20 min after TPVB. Pinprick test was performed at 20 min after TPVB. Successful TPVB was defined as no sensation to pinprick in 3 or more adjacent dermatomes corresponding to the site of injection at 20 min after TPVB. Td was compared to pinprick test for evaluating its effectiveness in predicting the success of TPVB. The sensitivity, specificity, and cut-off value of Td for predicting successful TPVB were determined by receiver operator characteristic (ROC) curve analysis.

Results

Compared with the baseline value before block, Td from T2 to T10 were significantly increased at each time point in successful blocks. In failed blocks, Td was not increased in any dermatome. The increase of Td at T4-T7 was more than 1 °C 20 min after successful TPVB. Fifteen minutes after block, Td increase at T4 had the greatest potential to predict block success. The area under the ROC curve was 0.960 at a cut-off value of 0.63 °C with a sensitivity of 83.3% and a specificity of 100.0%.

Conclusions

This study suggested that the increase of Td at T4 dermatome determined by IT between the blocked and unblocked side is an early, quantitative, and reliable predictor of successful TPVB.

Trial registration

Clinical trial registration: NCT04078347.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01389-4.

Quantitative Analysis of Real-Time Infrared Thermography for the Assessment of Lumbar Sympathetic Blocks: A Preliminary Study

Lumbar sympathetic blocks (LSBs) are commonly performed to treat pain ailments in the lower limbs. LSBs involve injecting local anesthetic around the nerves. The injection is guided by fluoroscopy which is sometimes considered to be insufficiently accurate. The main aim was to analyze the plantar foot skin temperature data acquired while performing LSBs in patients with complex regional pain syndrome (CRPS) affecting the lower limbs. Forty-four LSBs for treating lower limb CRPS in 13 patients were assessed. Pain medicine physicians visualized the infrared thermography (IRT) video in real time and classified the performance depending on the observed thermal changes within the first 4 min. Thirty-two percent of the cases did not register temperature variations after lidocaine was injected, requiring the needle to be relocated. Differences between moments are indicated using the 95% confidence intervals of the differences (CI 95%), the Cohen effect size (ES) and the significance (p value). In successful cases, after injecting lidocaine, increases at minute 7 for the mean (CI 95% (1.4, 2.1 °C), p < 0.001 and ES = 0.5), at minute 5 for maximum temperature (CI 95% (2.3, 3.3 °C), p < 0.001 and ES = 0.6) and at minute 6 for SD (CI 95% (0.2, 0.3 °C), p < 0.001 and ES = 0.5) were observed. The results of our preliminary study showed that the measurement of skin temperature in real time by infrared thermography is valuable for assessing the success of lumbar sympathetic blocks.

Skin temperature changes after ultrasound-guided supra-inguinal fascia iliaca block: a prospective observational study

PURPOSE

Ultrasound-guided supra-inguinal fascia iliaca block (SFIB) is widely used as regional anesthesia of the hip and thigh. It is difficult to judge the blocking effect and the spreading local anesthesia. We hypothesize that the effect and spread of the block could be proven objectively by a rise in the temperature. In this prospective observational study, the broad regional rise in skin temperature of twenty patients who were scheduled for hip surgery was measured using an infrared thermographic camera at multiple intervals following ultrasound-guided SFIB.

METHODS

Infrared thermographic imaging of skin temperature at the femoral, obturator, and lateral femoral cutaneous nerve sites was performed before and at 5-min intervals after ultrasound-guided SFIB for up to 15-min post-injection. The primary outcomes are skin surface temperature. Sensory block was assessed immediately after the final infrared thermographic image acquisition using the cold test.

RESULTS

Compared to pre-injection baseline, temperature increased by 1.2 °C [95% confidence interval (CI) 0.4-2.0 °C] after 5 min, 1.2 °C (95% CI 0.4-2.0 °C) after 10 min, and 0.9 °C (95% CI 0.4-2.1°C) after 15 min. The cold test response was reduced in all cases at the femoral and lateral femoral cutaneous nerve sites and in 13 cases at the obturator nerve site. The sensitivity and specificity of the temperature increase to cold loss were 96% and 63%, respectively when we defined >0°C as the clinical threshold.

CONCLUSIONS

Successful SFIB significantly enhanced skin temperature at the hip and thigh in all cases, suggesting that infrared surface thermography can be used as an objective assessment tool for adequate analgesia.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trials Registry ( UMIN 000037866 ). Registered 31 August 2019.

Short-Term Effect of Different Taping Methods on Local Skin Temperature in Healthy Adults

BACKGROUND

There were limited studies on the effect of skin temperature and local blood flow using kinesio tape (KT) adhered to the skin in different taping methods. This study aimed to determine the short-term effect of KT and athletic tape (AT) on skin temperature in the lower back and explore the possible effect of different taping methods (Y-strip and fan-strip taping) on local microcirculation.

MATERIALS AND METHODS

Twenty-six healthy participants completed the test-retest reliability measurement of the infrared thermography (IRT), intraclass correlation coefficient (ICC), and standard error of measurement (SEM) were calculated to evaluate the reliability. Then, 21 healthy participants received different taping condition randomly for 5 times, including Y-strip of kinesio taping (KY), fan-strip of kinesio taping (Kfan), Y-strip of athletic taping (AY), fan-strip of athletic taping (Afan), and no taping (NT). Above taping methods were applied to the participants' erector spinae muscles on the same side. Skin temperature of range of interest (ROI) was measured in the taping area through IRT at pre taping and 10 min after taping. Additionally, participants completed self-perceived temperature evaluation for different taping methods through visual analog scaling. One-way repeated-measured analysis of variance was used to compare the temperature difference among different taping methods. Bonferroni test was used for post hoc analysis.

RESULTS

There was a good test-retest reliability (ICC = 0.82, 95% CI = 0.60-0.92; SEM = 0.33; and MD = 0.91) of the IRT. Significant differences were observed in the short-term effect on skin temperature among all different taping methods (p = 0.012, F = 3.435, and ηp 2 = 0.147), post hoc test showed a higher significantly skin temperature difference in Kfan taping compared to no taping (p = 0.026, 95% CI = 0.051-1.206); However, no significant differences were observed among self-perceived temperature (p = 0.055, F = 2.428, and ηp 2 = 0.108).

CONCLUSION

This study showed that the fan-strip of KT increased significantly the skin temperature of the waist after taping for 10 min. The application of KT may modify the skin temperature of the human body and promote local microcirculation, although it remained unclear for the real application.

Thermochromic nail polish as a novel indicator to predict infraclavicular brachial plexus block success: A prospective cohort study

BACKGROUND

Skin temperature measurements after peripheral nerve block can be used as an easy and objective method to help predict block success. Thermochromic nail polishes are popular cosmetic products especially among young women. The colour change of nail polish is based on a thermochromic reaction as the temperature changes.

OBJECTIVE

The aim of this study was to test the hypothesis that the success of infraclavicular brachial plexus blocks (IBPBs) can be predicted by the colour change in thermochromic nail polish, which depends on skin temperature changes.

DESIGN

A prospective cohort study.

SETTING

Training and research hospital from December 2018 to March 2019.

PATIENTS

A total of 50 patients who received IBPB for forearm, wrist or hand surgery were included.

MAIN OUTCOME MEASURES

Thermochromic nail polish was applied to the nails of both hands of all patients before the block. Reaction of the nail polish in both hands was photographed immediately after application of nail polish and at 30 min after performing the block. The digital photographs of each patient were evaluated by observers. To evaluate the validity of the colour change in nail polish in predicting a successful IBPB, sensitivity, specificity, positive and negative predictive values and positive and negative likelihood ratios were estimated.

RESULTS

The positive predictive value for colour change in thermochromic nail polish predicting a successful IBPB was 96% [95% confidence interval (CI) 90 to 98] and sensitivity was 94% (95% CI 87 to 97). Fleiss kappa value showed substantial agreement (0.76; 95% CI 0.59 to 0.93) in the assessment of interobserver agreement.

CONCLUSION

The current study demonstrates that the colour change in thermochromic nail polish is a valid and reliable indicator for the prediction of block success.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03767868.

Microcirculation and haemodynamics after infraclavicular brachial plexus block using adrenaline as an adjuvant to lidocaine: a randomised, double-blind, crossover study in healthy volunteers

We evaluated the effect of adrenaline on human skin microcirculation (nutritive and sub-papillary) and systemic cardiovascular variables after it was added to lidocaine in infraclavicular brachial plexus blocks. Twelve healthy, non-smoking male volunteers were included, each attending two study sessions 2 weeks apart, and they were studied using a crossover design. In both sessions, they received an ultrasound-guided infraclavicular brachial plexus block in the non-dominant arm with 0.4 ml.kg^-1 lidocaine, 15 mg.ml^-1 with or without adrenaline 5 μg.ml^-1 . Microcirculation was assessed by laser Doppler fluxmetry (sub-papillary blood flow), capillary video microscopy (nutritive blood flow) and continuous temperature measurements. Heart rate and arterial pressure were recorded continuously and non-invasively. Median (IQR [range]) sub-papillary blood flow increased substantially 30 min after the brachial plexus block, from 8.5 (4.4-13.5 [2.9-28.2]) to 162.7 (111.0-197.8 [9.5-206.7]) arbitrary units with adrenaline (p = 0.017), and from 6.9 (5.3-28.5 [1.8-42.1] to 133.7 (16.5-216.7 [1.0-445.0] arbitrary units without adrenaline (p = 0.036). Nutritive blood flow (functional capillary density, capillaries.mm^-2 , measured at the dorsal side of the hand) decreased in the blocked extremity when adrenaline was used as adjuvant, from median (IQR [range]) 45 (36-52 [26-59]) to 38 (29-41 [26-42]), p = 0.028, whereas no significant change occurred without adrenaline. Median finger skin temperature (°C) increased by 44% (data pooled) with no significant differences between the groups. No significant changes were found in the systemic cardiovascular variables with or without adrenaline. We conclude that lidocaine infraclavicular brachial plexus blocks caused an increase in skin sub-papillary blood flow. The addition of adrenaline produced stronger and longer lasting blocks, but decreased the nutritive blood flow.

A retrospective evaluation of the risk of bias in perioperative temperature metrics

The prevention and treatment of hypothermia is an important part of routine anesthesia care. Avoidance of perioperative hypothermia was introduced as a quality metric in 2010. We sought to assess the integrity of the perioperative hypothermia metric in routine care at a single large center. Perioperative temperatures from all anesthetics of at least 60 min duration between January 2012 and 2017 were eligible for inclusion in analysis. Temperatures were displayed graphically, assessed for normality, and analyzed using paired comparisons. Automatically-recorded temperatures were obtained from several monitoring sites. Provider-entered temperatures were non-normally distributed, exhibiting peaks at temperatures at multiples of 0.5 °C. Automatically-acquired temperatures, on the other hand, were more normally distributed, demonstrating smoother curves without peaks at multiples of 0.5 °C. Automatically-acquired median temperature was highest, 36.8 °C (SD = 0.8 °C), followed by the three manually acquired temperatures (nurse-documented postoperative temperature, 36.5 °C [SD = 0.6 °C]; intraoperative manual temperature, 36.5 °C [SD = 0.6 °C]; provider-documented postoperative temperature, 36.1 °C [SD = 0.6 °C]). Provider-entered temperatures exhibit values that are unlikely to represent a normal probability distribution around a central physiologic value. Manually-entered perioperative temperatures appear to cluster around salient anchoring values, either deliberately, or as an unintended result driven by cognitive bias. Automatically-acquired temperatures may be superior for quality metric purposes.