Thermal burn injury associated with a forced-air warming device

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 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.

Increase in body temperature in pediatric patients after costal cartilage harvest in microtia reconstruction: A retrospective observational study

BACKGROUND

Previous evidence has clearly shown that maintaining normothermia in children undergoing surgery is difficult and is associated with adverse outcomes. Therefore, this study aimed to retrospectively analyze the changes in body temperature over time in 2 different types of microtia reconstruction surgeries, namely, embedding, and elevation surgeries.

METHODS

We performed a retrospective chart review of patients who underwent microtia reconstruction (embedding and elevation) between July 2012 and February 2015 (n = 38). The changes in body temperature between the 2 types of surgeries were compared.

RESULTS

During microtia reconstruction, the body temperature in the embedding surgery group was significantly higher than that in the elevation surgery group from 1 hour after the start of surgery to 1 day after the surgery (P < .001). Time, group, and time-group interaction were associated with an increase in body temperature (P < .001) but not the warming method.

CONCLUSION

We found an increase in body temperature in patients with microtia who underwent embedding surgery (autologous costal cartilage harvest surgery), and this was related to the type of surgery and not to the warming method. Therefore, further research is warranted to determine the cause of the increase in body temperature during this surgery.

Thermal injury from forced-air warmer device precipitated by massive extravasation from peripheral venous cannula

Extravasation injury (EVI) is an iatrogenic complication of venous cannulation. Usually innocuous but occasionally it engenders sequelae. Its severity is determined by various physicochemical properties of infusate. A 50-year-old patient developed leg EVI from crystalloids infused through a pressurized digital infuser (PDI), likely from cannula tip displacement during positioning for craniotomy. We ignored checking gravity-aided free-fluids flow before switching on PDI. Following surgery, the patient had an edematous leg with bullae and epidermal peelings from severe extravasation and burns, respectively. Doppler revealed patent leg arteries. Therefore, EVI was conservatively managed, with complete recovery. Apparently, increased local tissue pressure from extravasation produced conditions of peripheral circulation sufficiency predisposing the leg to thermal injury from the forced-air warmer. On inspecting PDI postoperatively, its upper-pressure alarm limit was 300 mmHg, which prevented it from sounding alarm during extravasation.

Acute vesicular eruption postoperatively after use of a forced-air warming device

Thermal burn injuries are a known complication of forced-air warming devices but rarely occur when the device is used in accordance with the manufacturer's instructions. Here we present a case of a 3-year-old girl who in the immediate postoperative period was found to have prominent linear, evenly spaced vesicles and bullae in a pattern that distinctly matched the air-exit perforations of the Bair Hugger device. Clinicians should be aware of potential complications arising from even proper use of a medical device and take all necessary precautions to prevent such incidents.

The Effect of Active Warming on Postoperative Hypothermia on Body Temperature and Thermal Comfort: A Randomized Controlled Trial

PURPOSE

The purpose of this study was to determine the effect of active warming method in temperature control and thermal comfort in hypothermia after surgery.

DESIGN

A randomized controlled trial.

METHODS

The study sample consisted of 64 male and female postanesthesia care unit and intensive care unit neurosurgery postoperative inpatients. The experimental group was warmed using the active warming method, and the control group's routine care was continued via a cotton blanket. Patients were warmed until their tympanic body temperature reached 37°C.

FINDINGS

The time needed to adequately warm patients was approximately twice as short in those who received active warming as compared with the control group. The perception of thermal comfort was significantly higher in the first hour in patients who received the active warming method (P < .05).

CONCLUSIONS

The active warming method resulted in a shorter time to warming in hypothermia after surgery and an increase in the perception of thermal comfort and body temperature.

Significant factors influencing inadvertent hypothermia in pediatric anesthesia

Thermal imbalances are very common during surgery. Hypothermia exposes the patient to post-operative shivering, cardiac dysfunction, coagulopathy, bleeding, wound infection, delayed anesthesia recovery, prolonged hospital stay and increased hospitalization cost. There are many factors contributing to intraoperative hypothermia. This is a prospective cohort study conducted through observation and measurement of pediatric surgical patients' temperature. Convenience sampling methods were used in this study. Initial skin temperature and core temperature at 10 min, 30 min,1 h, 2 h, 3 h, 4 h, 5 h, 6 h and at the end of surgery were recorded. Body temperature was monitored from time of transfer to the operating table until recovery and discharge to the respective pediatric ward. The overall incidence of intraoperative hypothermia was still very high at about 46.6% even though active and passive temperature management were carried out during surgery. Patient's age, body weight, duration of surgery, type of surgery, intraoperative blood loss, type of anesthesia and operating room temperature were factors that contributed to intraoperative hypothermia. Hypothermia is common in surgery, especially in major and long duration surgery. Intraoperative hypothermia can be life threatening if it is not handled carefully. Various methods are used before, during and after surgery to maintain a patient's body temperature within the normothermia range. The use of an active warming device like the Bair Hugger® air-forced warming system seems to be a good method for reducing the risk of intraoperative hypothermia and effectively maintaining body temperature for all major and minor surgeries.

Forced-Air Warming and Resistive Heating Devices. Updated Perspectives on Safety and Surgical Site Infections

Introduction: Perioperative hypothermia is one of the most common phenomena seen among surgical patients, leading to numerous adverse outcomes such as intraoperative blood loss, cardiac events, coagulopathy, increased hospital stay and associated costs. Forced air warming (FAW) and resistive heating (RH) are the two most commonly used and widely studied devices to prevent perioperative hypothermia. The effect of FAW on operating room laminar flow and surgical site infection is unclear and we initiated an extensive literature search in order to get a scientific insight of this aspect.

Material and Methods: The literature search was conducted using the Medline search engine, PubMed, Cochrane review, google scholar, and OSU library.

Results: Out of 92 Articles considered initially for review we selected a total of 73 relevant references. Currently there is no robust evidence to support that FAW can increase SSIs. In addition, both of the two warming devices present safety problems.

Conclusion: As unbiased independent reviewers, we advise clinicians to weigh the risks and benefits when using either one of these devices; no change in the current practice is necessary until further data emerges.

The serotonin 2C receptor agonist WAY-163909 attenuates ketamine-induced hypothermia in mice

Anesthesia-Induced Hypothermia (AIH) has been reported to be the cause of many postoperative adverse effects, including increased mortality, decreased immune responses, cardiac events, and a greater prevalence of postoperative surgical wound infections. AIH can in some cases be minimized with pre-warming fluids and gases and forced-air heating systems, but such techniques are not always effective and can result in patient burns or other adverse effects. Stimulation of 5-HT₂ receptors has been reported to increase body temperature through a variety of mechanisms, and as such, may be a viable target for pharmacologically minimizing AIH. In the present study, we examined the effects of 5-HT₂ receptor stimulation on hypothermia induced by the injectable anesthetic ketamine in Swiss-Webster mice using rectal thermometry. We report that ketamine dose-dependently induced hypothermia, and mice did not become tolerant to this effect of ketamine over the course of three injections spaced at once per week. Ketamine-induced hypothermia was significantly attenuated by pretreatment with the selective 5-HT_2C receptor agonist WAY-163909 but not by pretreatment with the mixed 5-HT_2A/2C receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI). Moreover, the blockade of ketamine-induced hypothermia by WAY-163909 was reversed by pretreatment with the selective 5-HT_2C receptor antagonist SB-242084. These findings demonstrate that stimulation of 5-HT_2C receptors can reduce AIH, at least for ketamine-induced hypothermia. They warrant further study of the pharmacological and neurobiological mechanisms underlying this interaction and its extension to other anesthetics. Furthermore, these findings suggest that the maintenance of body temperature during surgery may be a new clinical use for 5-HT_2C receptor agonists.

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.

Inadvertent thermal injury following knee arthroscopic surgery in a pediatric patient

Inadvertent thermal injury can occur in pediatric patients under general anesthesia during knee arthroscopic surgery. Here, we report the case of a 10-year-old boy who underwent knee arthroscopic surgery under general anesthesia. After the surgery, he complained of pain in the left lower part of his chin and was diagnosed as having a thermal burn. At three-month follow-up, he recovered without any abnormalities except mild hypertrophy of the wound area. Although rare, arthroscopic surgery has the potential to cause thermal injury from the light source. We recommend that the light source should be connected to the arthroscope before switching the power on and disconnected after a considerable time of switching the power off when not in use.

Normothermia in Arthroplasty

BACKGROUND

Since the initial design of surgical theatres, the thermal environment of the operating suite itself has been an area of concern and robust discussion. In the 1950s, correspondence in the British Medical Journal discussed the most suitable design for a surgeon's cap to prevent sweat from dripping onto the surgical field. These deliberations stimulated questions about the effects of sweat-provoking environments on the efficiency of the surgical team, not to mention the effects on the patient. Although these benefits translate to implant-based orthopedic surgery, they remain poorly understood and, at times, ignored.

METHODS

A review and synthesis of the body of literature on the topic of maintenance of normothermia was performed.

RESULTS

Maintenance of normothermia in orthopedic surgery has been proven to have broad implications from bench top to bedside. Normothermia has been shown to impact everything from nitrogen loss and catabolism after hip fracture surgery to infection rates after elective arthroplasty.

CONCLUSION

Given both the physiologic impact this has on patients, as well as a change in the medicolegal environment around this topic, a general understanding of these concepts should be invaluable to all surgeons.

Guideline Implementation: Preventing Hypothermia

The updated AORN "Guideline for prevention of unplanned patient hypothermia" provides guidance for identifying factors associated with intraoperative hypothermia, preventing hypothermia, educating perioperative personnel on this topic, and developing relevant policies and procedures. This article focuses on key points of the guideline, which addresses performing a preoperative assessment for factors that may contribute to hypothermia, measuring and monitoring the patient's temperature in all phases of perioperative care, and implementing interventions to prevent hypothermia. Perioperative RNs should review the complete guideline for additional information and for guidance when writing and updating policies and procedures.

Thermal burn associated with intraoperative convective forced-air warming blanket (bair paws™ flex gown system)

A 44-year-old man undergoing ambulatory surgery sustained a 5% total body surface first-degree burn on his lower and lateral torso and upper thigh during routine use of a new forced-air warming Bair Paws™ flex gown system. We describe the likely mechanism of injury, intraoperative events suggesting special variation in the warming process, and a brief review of adverse events associated with forced-air warming systems.

Peri-operative warming devices: performance and clinical application

Since the adverse consequences of accidental peri-operative hypothermia have been recognised, there has been a rapid expansion in the development of new warming equipment designed to prevent it. This is a review of peri-operative warming devices and a critique of the evidence assessing their performance. Forced-air warming is a common and extensively tested warming modality that outperforms passive insulation and water mattresses, and is at least as effective as resistive heating. More recently developed devices include circulating water garments, which have shown promising results due to their ability to cover large surface areas, and negative pressure devices aimed at improving subcutaneous perfusion for warming. We also discuss the challenge of fluid warming, looking particularly at how devices' performance varies according to flow rate. Our ultimate aim is to provide a guide through the bewildering array of devices on the market so that clinicians can make informed and accurate choices for their particular hospital environment.