Forced-Air Warming During Pediatric Surgery

Comparison between upper body and full underbody forced-air warming blanket in pediatric patients undergoing cardiovascular interventions under general anesthesia: a randomized controlled trial

BACKGROUND

Pediatric patients undergoing cardiovascular interventions outside the operating room are at high risk of perioperative hypothermia. We aimed to compare the effects of upper body and full underbody forced-air warming blankets on the time-weighted deviation of esophageal temperature outside the target range (36.5-37.5 °C) during general anesthesia.

METHODS

In this randomized controlled study, 88 children (age < 15 years) scheduled for elective cardiovascular interventions under general anesthesia were randomly assigned to the upper body (n = 44) or full underbody (n = 44) group. After the induction of anesthesia, warming blankets were applied and heated using a forced-air warmer to maintain an esophageal temperature of 36.5-37.5 °C. The primary outcome was the time-weighted average deviation of esophageal temperature outside the desired range, defined as the total deviation in temperature divided by the duration spent outside the target range. Secondary outcomes included use of additional warming or cooling methods, temperature trends, thermal comfort, and adverse events. Statistical comparisons were performed using t-tests or chi-square tests, with p < 0.05 considered significant.

RESULTS

The time-weighted averages of periods out of the desired temperature range were comparable between the two groups (upper body vs. full underbody, 0.213 ± 0.212 °C vs. 0.265 ± 0.277 °C; mean difference, 0.053; 95% confidence interval [CI], - 0.052 to 0.157; p = 0.318). The incidence of hyperthermia (> 37.5 °C) was 9.09% (upper body) and 0% (full underbody, p = 0.125). The duration of hypothermia (< 36.5 °C) was 58.82 ± 48.83 min (upper body) and 70.03 ± 53.20 min (full underbody; mean difference, 11.20 min; 95% CI, - 10.44 to 32.85; p = 0.318). The incidence rates of adverse events were 4.55% (upper body) and 15.91% (full underbody, p = 0.159).

CONCLUSIONS

Both warming methods showed comparable time-weighted averages of temperatures outside the desired range, suggesting similar effectiveness. However, careful monitoring is essential to mitigate the risks of hyperthermia and skin-related complications and ensure patient safety during pediatric cardiovascular interventions.

TRIAL REGISTRATION NUMBER

NCT05349734 (registered at clinicaltrials, principal investigator: Hee-Soo Kim, registration date: April 26,2022).

What is the minimum time interval for reporting of intraoperative core body temperature measurements in pediatric anesthesia? A secondary analysis

Given that perioperative normothermia represents a quality parameter in pediatric anesthesia, numerous studies have been conducted on temperature measurement, albeit with heterogeneous measurement intervals, ranging from 30 s to fifteen minutes. We aimed to determine the minimum time interval for reporting of intraoperative core body temperature across commonly used measurement intervals in children. Data were extracted from the records of 65 children who had participated in another clinical study and analyzed using a quasibinomial mixed linear model. Documented artifacts, like probe dislocations or at the end of anesthesia, were removed. Primary outcome was the respective probability of failing to detect a temperature change of 0.2 °C or more at any one measurement point at 30 s, one minute, two minutes, five minutes, ten minutes, and fifteen minutes, considering an expected probability of less than 5% to be acceptable. Secondary outcomes included the probabilities of failing to detect hypothermia (< 36.0 °C) and hyperthermia (> 38.0 °C). Following the removal of 4,909 exclusions, the remaining 222,366 timestamped measurements (representing just over 60 h of monitoring) were analyzed. The median measurement time was 45 min. The expected probabilities of failing to detect a temperature change of 0.2 °C or more were 0.2% [95%-CI 0.0-0.7], 0.5% [95%-CI 0.0-1.2], 1.5% [95%-CI 0.2-2.6], 4.8% [95%-CI 2.7-6.9], 22.4% [95%-CI 18.3-26.4], and 31.9% [95%-CI 27.3-36.4], respectively. Probabilities for the detection of hyperthermia (n = 9) were lower and omitted for hypothermia due to low prevalence (n = 1). In conclusion, the core body temperature should be reported at intervals of no more than five minutes to ensure the detection of any temperature change in normothermic ranges. Further studies should focus on hypothermic and hyperthermic ranges.

Head cooling wrap could suppress the elevation of core temperature after cardiac surgery during forced-air warming in a pediatric intensive care unit: a randomized clinical trial

PURPOSE

The main aim of the current trial was to explore our hypothesis that cooling head wraps lower the core temperature more effectively than ice packs on the head during forced-air warming after pediatric cardiac surgeries.

METHODS

This study was a single-center Randomized Controlled Trial. Participants were children with a weight ≤ 10 kg and hyperthermia during forced-air warming after cardiac surgeries. When the core temperature reached 37.5 °C, ice packs on the head (group C) or a cooling head wrap (group H) were used as cooling devices to decrease the core temperature. The primary outcome was the core temperature. The secondary outcomes were the foot surface temperature and heart rate. We measured all outcomes every 30 min for 240 min after the patient developed hyperthermia. We conducted two-way ANOVA as a pre-planned analysis and also the Bonferroni test as a post hoc analysis.

RESULTS

Twenty patients were randomly assigned to groups C and H. The series of core temperatures in group H were significantly lower than those in group C (p < 0.0001), and post hoc analysis showed that there was no significant difference in core temperatures at T0 between the two groups and statistically significant differences in all core temperatures at T30-240 between the two groups. There was no difference between the two groups' surface temperatures and heart rates.

CONCLUSIONS

Compared to ice packs on the head, head cooling wraps more effectively suppress core temperature elevation during forced-air warming after pediatric cardiac surgery.

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.

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.

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.

New-onset intra-operative hyperthermia in a large surgical patient population: A retrospective observational study

BACKGROUND

Intra-operative hypothermia has been extensively investigated. However, the incidence of intra-operative hyperthermia has not been investigated in detail.

OBJECTIVE

The main objective of this study was to assess the incidence and risk factors of new-onset intra-operative hyperthermia in a large surgical patient population.

DESIGN

Retrospective database review.

SETTING

Tertiary-care teaching hospital.

PATIENTS

Patients undergoing surgery with general anaesthesia between 1 January 2002 and 31 December 2017 were included.

MAIN OUTCOME MEASURES

The primary outcome measurement was new-onset intra-operative hyperthermia (>37.5 °C). A logistic regression model was fitted to identify risk factors for intra-operative hyperthermia.

RESULTS

A total of 103 648 patients were included in the final analyses. The incidence of new-onset hyperthermia in the overall patient cohort was 6.45%, reaching 20 to 30% after prolonged (>8 h) surgery, and was up to 26.5% in paediatric patients. The use of forced air active patient warming, larger amounts of fluid administration, longer surgery, younger age and smaller body size were all independently associated with intra-operative hyperthermia. The adoption of the Surgical Care Improvement Project (SCIP) temperature measures was associated with an increased incidence of intra-operative hyperthermia.

CONCLUSION

Mild intra-operative hyperthermia is not uncommon particularly in longer procedures and small children.

Effects of different thermal insulation methods on the nasopharyngeal temperature in patients undergoing laparoscopic hysterectomy: a prospective randomized controlled trial

Background

This study explored the comparison of the thermal insulation effect of incubator to infusion thermometer in laparoscopic hysterectomy.

Methods

We assigned 75 patients enrolled in the study randomly to three groups: Group A: Used warming blanket; group B: Used warming blanket and infusion thermometer; group C: Used warming blanket and incubator. The nasopharyngeal temperature at different time points during the operation served as the primary outcome.

Results

The nasopharyngeal temperature of the infusion heating group was significantly higher than that of the incubator group 60 min from the beginning of surgery (T3): 36.10 ± 0.20 vs 35.81 ± 0.20 (P<0.001)90 min from the beginning of surgery (T4): 36.35 ± 0.20 vs 35.85 ± 0.17 (P<0.001). Besides, the nasopharyngeal temperature of the incubator group was significantly higher compared to that of the control group 60 min from the beginning of surgery (T3): 35.81 ± 0.20 vs 35.62 ± 0.18 (P<0.001); 90 min from the beginning of surgery (T4): 35.85 ± 0.17 vs 35.60 ± 0.17 (P<0.001). Regarding the wake-up time, that of the control group was significantly higher compared to the infusion heating group: 24 ± 4 vs 21 ± 4 (P = 0.004) and the incubator group: 24 ± 4 vs 22 ± 4 (P = 0.035).

Conclusion

Warming blanket (38 °C) combined infusion thermometer (37 °C) provides better perioperative thermal insulation. Hospitals without an infusion thermometer can opt for an incubator as a substitute.

Trial registration

This trial was registered with ChiCTR2000039162, 20 October 2020.

Comparative evaluation of forced air warming and infusion of amino acid-enriched solution on intraoperative hypothermia in patients undergoing head and neck cancer surgeries: A prospective randomised study

BACKGROUND

Inadvertent core hypothermia is a common occurrence during general anaesthesia. Forced air warming (FAW) is the most effective perianaesthetic warming system, but it may lead to thermal discomfort. Amino acids (AAs) have been used to prevent hypothermia, but no study has compared the effect of AA infusion with FAW systems. We have conducted this study to compare the effects of external heating (FAW system) and internal heat generation (AA infusion) in preventing hypothermia during anaesthesia.

METHODS

After institutional review board approval, 80 American Society of Anesthesiologists Grade I/II adult patients admitted for head and neck cancer surgeries lasting more than 2 h under general anaesthesia were included. The patients were randomly divided into two groups using computer-generated codes to receive AA infusion at 3 mL/kg/h, Group AA (N = 40), or normal saline at 3 mL/kg/h with FAW, Group FA (N = 40) till the end of surgery. Standard anaesthetic technique and monitoring was used in all the patients.

RESULTS

The baseline mean temperature in both the groups was comparable. The core temperature was similar in the two groups at 30 min (35.6 ± 0.54 vs 35.5 ± 0.54), 60 min (35.5 ± 0.63 vs 35.3 ± 0.60), 90 min (35.5 ± 0.79 vs 35.2 ± 0.66), 120 min (35.6 ± 0.93 vs 35.2 ± 0.78), 150 min (35.7 ± 0.88 vs 35.3 ± 0.89) and 180 min (35.8 ± 1.01 vs 35.3 ± 0.95) in Groups FA and AA, respectively (P > 0.05). However, the core temperature was significantly higher in Group FA at 210 min (35.8 ± 1.0 vs 35.3 ± 0.85; P = 0.01), 240 min (35.9 ± 1.0 vs 35.4 ± 0.90; (P = 0.001), 270 min (35.9 ± 1.12 vs 35.6 ± 0.97; P = 0.002) and 300 min (36.0 ± 1.12 vs 35.6 ± 1.02; P = 0.002), respectively. Clinically relevant hypothermia (at least one measurement <35.5°C) was comparable between the two groups.

CONCLUSION

The AA infusion can be used as an alternative to FAW in preventing intraoperative hypothermia under general anaesthesia especially in places where FAW system is unavailable.

Engineering Graphene Flakes for Wearable Textile Sensors via Highly Scalable and Ultrafast Yarn Dyeing Technique

Multifunctional wearable e-textiles have been a focus of much attention due to their great potential for healthcare, sportswear, fitness, space, and military applications. Among them, electroconductive textile yarn shows great promise for use as next-generation flexible sensors without compromising the properties and comfort of usual textiles. However, the current manufacturing process of metal-based electroconductive textile yarn is expensive, unscalable, and environmentally unfriendly. Here we report a highly scalable and ultrafast production of graphene-based flexible, washable, and bendable wearable textile sensors. We engineer graphene flakes and their dispersions in order to select the best formulation for wearable textile application. We then use a high-speed yarn dyeing technique to dye (coat) textile yarn with graphene-based inks. Such graphene-based yarns are then integrated into a knitted structure as a flexible sensor and could send data wirelessly to a device via a self-powered RFID or a low-powered Bluetooth. The graphene textile sensor thus produced shows excellent temperature sensitivity, very good washability, and extremely high flexibility. Such a process could potentially be scaled up in a high-speed industrial setup to produce tonnes (∼1000 kg/h) of electroconductive textile yarns for next-generation wearable electronics applications.