Construction and validation of a risk prediction model for soldiers with frostbite in northeast China: a cross-sectional study.

BACKGROUND: One of the challenges of physical training in extreme condition is frostbite, especially in Northeast China. In this study, we aimed to construct a risk prediction model for frostbite among soldiers in Northeast China, and verify its effect. METHODS: 698 participants were selected via convenience sampling from Northeast China from December 2021 to January 2022 (winter). They were randomly divided into a training set (N = 479) and a testing set (N = 202) in a ratio of 7:3. All participants completed a researcher-made questionnaire on frostbite. The prediction model was constructed through the use of Logistic regression analysis, which was used to predict the independent risk factors for frostbite formation and screen significant indicators. The model's performance was assessed using the receiver operating characteristic (ROC) curve and decision curve analysis (DCA) to evaluate the prediction efficiency and goodness of fit. RESULTS: The incidence of frostbite in the training set was 19.83% (95 people), all of which were first-degree frostbite. Among them, frostbite in multiple parts was the most common (58.95%), followed by singular body parts like hands (24.21%), ears (11.58%) and feet (5.26%). Single factor logistic regression analyses showed that ambient temperature, ambient wind speed, outdoor stationary time, stationary status, and history of frostbite are independent risk factors that affect the occurrence of frostbite. Furthermore, we constructed the frostbite risk prediction model for soldiers in the northeastern region of China. The area under the receiver operating characteristic curve (AUC) for the risk of frostbite in the training set and testing set was 0.816 (95% CI, 0.770 ~ 0.862) and 0.787 (95% CI, 0.713 ~ 0.860), respectively. The Hosmer-Lemeshow test of the model showed χ2 = 11.328 and P = 0.184 (> 0.05). The DCA curve indicated that most of the clinical net benefits of the model are greater than 0, demonstrating good clinical usefulness. CONCLUSION: The constructed frostbite prediction model can effectively identify soldiers with a higher risk of frostbite. It provided theoretical support for commanders to take preventive measures to reduce the incidence of frostbite among soldiers and was of great clinical guiding significance.

Cold-induced vasodilation during sequential immersions of the hand.

A common practice for those operating in cold environments includes repetitive glove doffing and donning to perform specific tasks, which creates a repetitive cycle of hand cooling and rewarming. This study aimed to determine the influence of intraday repeated hand cooling on cold-induced vasodilation (CIVD), sympathetic activation, and finger/hand temperature recovery. Eight males and two females (mean ± SD age: 28 ± 5 year; height: 181 ± 9 cm; weight: 79.9 ± 10.4 kg) performed two 30-min hand immersions in cold (4.3 ± 0.92 °C) water in an indoor environment (18 °C). Both immersions (Imm1; Imm2) were performed on the same day and both allowed for a 10-min recovery. CIVD components were calculated for each finger (index, middle, ring) during each immersion. CIVD onset time (index, p = 0.546; middle, p = 0.727; ring, p = 0.873), minimum finger temperature (index, p = 0.634; middle, p = 0.493; ring, p = 0.575), and mean finger temperature (index, p = 0.986; middle, p = 0.953; ring, p = 0.637) were all similar between immersions. Recovery rates generally demonstrated similar responses as well. Findings suggest that two sequential CIVD tests analyzing the effect of prior cold exposure of the hand does not impair the CIVD response or recovery. Such findings appear promising for those venturing into cold environments where hands are likely to be repeatedly exposed to cold temperatures.

Accuracy of infrared thermography evaluation in burn wound healing: a systematic review and meta-analysis.

OBJECTIVE: Accurate assessment of burn depth and burn wound healing potential is essential to determine early treatments. Infrared thermography (IRT) is a non-invasive and objective tool to do this. This systematic review evaluated the accuracy of IRT to determine burn wound healing potential. METHOD: This systematic review and meta-analysis used MEDLINE, EMBASE, CINAHL, PEDro, DiTA and CENTRAL databases. IRT data were extracted from primary studies and categorised into four cells (i.e., true positives, false positives, true negatives and false negatives). Subgroup analysis was performed according to methods used to capture thermal images. RESULTS: The search strategy identified 2727 publications; however, 15 articles were selected for review and 11 for meta-analysis. In our meta-analysis, the accuracy of IRT was 84.8% (63% sensitivity and 81.9% specificity). CONCLUSION: IRT is a moderately accurate tool to identify burn depth and healing potential. Thus, IRT should be used carefully for evaluating burn wounds.

Oropharyngeal Swelling and Airway Obstruction from Environmental Cold Exposure: A Case Report.

A 19-year-old male presented with facial frostbite and severe oropharyngeal edema after prolonged riding of a snowmobile without any facial covering. The diffuse swelling eventually progressed to airway obstruction, requiring a surgical airway. No alternative explanation was found for his presentation, making this the first case found in the literature of airway obstruction secondary to environmental cold exposure.

Keep Cool but Don't Freeze: The Influence of William J. Mills Jr. on the Treatment of Frostbite.

Dr William J. Mills Jr., an Alaskan orthopedic surgeon, helped establish the current protocols for frostbite treatment and changed a dogma used for more than 140 years that was established by Napoleon's surgeon general of the army, Baron Dominique-Jean Larrey. During Napoleon's 1812 siege of Moscow, Larrey noticed the destructive effects of using open fire heat for warming frozen body parts, so he suggested rubbing snow or immersion in cold water. Dr Mills treated many cold injuries during his medical career. After setting up his medical practice in Anchorage, Alaska, he realized the inefficiency of the established protocols and started researching new treatments for frostbite. Dr Mills followed Meryman's method of rapidly thawing frozen red blood cells in warm water. Mills and his colleagues established a treatment protocol for freezing cold injury that included rapid warming in warm water. These studies resulted in the publication of three key papers in 1960 and 1961. These papers were the first clinical studies that described rapid warming as a treatment. Subsequently, rapid warming, with some variation in water temperatures, has been accepted as the standard of treatment. Due to his outstanding contribution to the treatment of frostbite, he has been referred to as "the nation's leading authority on cold injury." Mills and his colleagues created a new classification system that divided frostbite into two levels, superficial and deep, which was more applicable in clinics than the traditional 4-tier classification. The 2-tier classification is still useful outside of the hospital setting.

Cold-Induced Vasodilation, Rewarming, and Dexterity Impairment Following Second-Degree Frostbite.

Frostbite, a severe cold injury resulting from exposure to subfreezing temperatures, damages the skin and underlying tissues of the affected area and ranges in severity from first to fourth degree. This case report investigates the impact of second-degree frostbite suffered by a marine during winter training on cold-induced vasodilation (CIVD). Comparisons of CIVD before and after the injury revealed significant alterations in CIVD responses. CIVD, a physiological mechanism characterized by blood vessel dilation in response to cold exposure, plays a crucial role in operating in cold-weather environments and enhancing dexterity. The marine exhibited prolonged CIVD onset time, lower finger temperatures, increased pain sensations, and diminished dexterity after the frostbite injury during follow-up CIVD testing. The findings suggest that the frostbite-induced damage possibly compromised the microvascular function, contributing to the observed changes in CIVD. The marine reported persistent cold sensitivity and difficulty in maintaining hand warmth when assessed postinjury. This case underscores the potential long-term consequences of frostbite on CIVD and manual dexterity, emphasizing the importance of understanding these physiological changes for individuals engaged in cold-weather activities, particularly for military and occupational personnel.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2024 Update.

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for the prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the guidelines published in 2019.

Convolutional neural network models for automatic diagnosis and graduation in skin frostbite.

The study aimed to develop and validate a convolutional neural network (CNN)-based deep learning method for automatic diagnosis and graduation of skin frostbite. A dataset of 71 annotated images was used for the training, the validation, and the testing based on ResNet-50 model. The performances were evaluated with the test set. The diagnosis and graduation performance of our approach was compared with two residents from burns department. The approach correctly identified all the frostbite of IV (18/18, 100%), but with respectively 1 mistake in the diagnosis of degree I (29/30, 96.67%), II (28/29, 96.55%) and III (37/38, 97.37%). The accuracy of the approach on the whole test set was 97.39% (112/115). The accuracy of the two residents were respectively 77.39% and 73.04%. Weighted Kappa of 0.583 indicates good reliability between the two residents (P = .445). Kendall's coefficient of concordance is 0.326 (P = .548), indicating differences in accuracy between the approach and the two residents. Our approach based on CNNs demonstrated an encouraging performance for the automatic diagnosis and graduation of skin frostbite, with higher accuracy and efficiency.

Clinical utilization of a sous vide device in the acute rewarming of frostbitten extremities.

The current standard of care for acute frostbite rewarming is the use of a circulating warm water bath at a temperature of 37 °C to 39 °C. There is no standardized method to achieve this. Manual management of a warm water bath can be inefficient and time consuming. This case describes the clinical use of a sous vide cooking device to create and maintain a circulating warm water bath to rewarm acute frostbite. A 34 year-old male presented to the emergency department with acute frostbite. Each of the patient's feet were placed in a water bath with a sous vide device attached to the side of the basin and set to 38 °C. Temperatures were recorded every 2 m from 2 thermometers. Once target temperature was achieved, the extremities were rewarmed for 30 m. The water baths required an average of 25 m to reach target temperature and maintained the target temperature within ±1 °C for the duration of the rewarming. The extremities were clinically thawed in one session and there were no adverse events. The patient was seen by plastic and vascular surgery and admitted to the hospital for conservative management. He was discharged on hospital day 3 and did not require any amputations. A sous vide device can be used clinically to heat and maintain a water bath and successfully rewarm frostbitten extremities in one 30 m cycle. No adverse events were reported and providers rated this as a convenient method of water bath management.

Extracellular vesicles from human hepatic progenitor cells accelerate deep frostbite wound healing by promoting fibroblasts proliferation and inhibiting apoptosis.

Frostbites are cold tissue damages frequently observed at high altitudes and under extremely cold conditions. Though their incidence rate is low, the resulting impact in affected patients can be very serious, often leading to amputations. Clinical management and the prediction of outcome can be of utmost importance to frostbite patients. A possible use of stem cell-derived extracellular vesicles (EVs) has been suggested for cutaneous wound healing and we, therefore, tested their use for the treatment of deep frostbite wound. To this end, the impacts of hHPC-derived EVs were evaluated in an in vivo animal model comprising of Kunming female mice as well as studied in vitro for the mechanism. We first characterized the EVs and these hHPC-derived EVs, when applied to treat frostbite wounds, accelerated wound healing in the in vivo animal model, as assessed by wound closure, re-epithelization thickness, collagen density and the expression of Collagen I and α-SMA. The proliferation and migration of human skin fibroblasts was also found to be increased by EVs in the in vitro experiments. The H2O2-induced apoptosis cell model, established to simulate the post-frostbite injury, was inhibited by EVs, with concomitant increase in the expression of Bcl-2 and decreased expression of Bax, further confirming the findings. Our novel results indicate that the application of EVs might be a promising strategy for deep frostbite wound healing.

Frostbite injury: an unknown risk when using nitrous oxide as a party drug.

In recent years nitrous oxide has become a popular party drug. Large cylinders filled with nitrous oxide are used to fill balloons for recreational use. We present two patients with severe third-degree cold burns on their thighs after clamping a large cylinder between their legs while filling balloons. During filling, large amounts of nitrous oxide are inhaled, which causes the pain to be numbed. As nitrous oxide is discharged from the cylinder, the cylinder becomes ice cold. Due to direct contact with the icecold cylinder and numbness, third-degree frostbite wounds occur. In both cases presented, the burn wounds had to be debrided and treated with split-thickness skin transplants. Awareness is needed as at first presentation as the burns look superficial, but can rapidly develop into third-degree burn wounds. Close follow-up and aggressive treatment is necessary to prevent infections and to regain a good functional outcome of the affected limb.

A Tibetan adolescent girl suffered frostbite on the journey of pilgrimage: A case report.

Frostbite in Southwestern China has been overlooked due to its low incidence, relatively mild temperature and lack of literature published before. However, it needs to be further studied for religious diversity and distinct geomorphology. In this article, we reported an 18-year-old Tibetan girl who suffered from blizzard attack during pilgrimage. Her feet and several fingers showed mummified gangrene upon physical examination with poor movement. She was diagnosed with 3rd to 4th degree of frostbite. The girl was given oral ibuprofen, debridement and other regular treatment daily, but she was eventually amputated due to insufficient thrombolytic management in primary hospital, delayed informing consent in the referral hospital and ethnic conflict between religion and guidelines. This case enriched the experience of managing complex frostbite in Tibetan population and alarms that efforts should be integrated to protect pilgrims and mountaineers in the Tibetan region.

Effects of 7 Consecutive Systematic Applications of Cryotherapy With Compression.

CONTEXT: Postsurgical and acute orthopedic patients are frequently treated with consecutive systematic cryotherapy despite the void of data to support treatment safety or effectiveness. The purpose of this study was to examine the occurrence of frostbite and measure skin temperatures during the systematic application of 2 cryocompression protocols. DESIGN: A repeated-measures design guided this study. METHODS: Nine healthy, college-aged participants (4 men and 5 women; age = 20.7 [1.2] y; height = 174 [11.01] cm; mass = 74 [14] kg) received both cryocompression protocols separated by ≥ 1 week. The static cryocompression protocol consisted of seven 40-minute "on" cycles of cryotherapy (4.4°C) with 45 mm Hg of compression, each followed by a 30-minute "off" cycle (no cryotherapy, compression set at 5 mm Hg). The intermittent cryocompression protocol consisted of seven 40-minute "on" cycles of cryotherapy (4.4°C) with compression alternating between 5 and 45 mm Hg, each followed by a 30-minute "off" cycle (no cryotherapy, compression set at 5 mmHg). At the end of each "on" and "off" cycle, we used a checklist to assess for frostbite, a PT-6 thermocouple to measure skin temperature (in degrees Celsius), and a 10-cm Likert scale to assess comfort. RESULTS: None of the participants experienced any signs or symptoms of frostbite. There were no differences in skin temperature between the compression conditions over time (F14,112 = 1.43; P = .149) nor were there any differences between the 2 compression conditions (F1,8 = 3.75; P = .087; 1-ß = 0.40). The skin temperatures were statistically different over the course of all 7 "on" and "off" cycles (F14,112 = 95.12; P < .001). There was no difference between the skin temperatures produced at the end of each "on" cycle. CONCLUSIONS: The application of 7 consecutive cryotherapy treatments with compression did not result in any signs or symptoms of frostbite and produced similar skin temperatures with each "on" cycle.

A digital tool for prevention and management of cold weather injuries-Cold Weather Ensemble Decision Aid (CoWEDA).

This paper describes a Cold Weather Ensemble Decision Aid (CoWEDA) that provides guidance for cold weather injury prevention, mission planning, and clothing selection. CoWEDA incorporates current science from the disciplines of physiology, meteorology, clothing, and computer modeling. The thermal performance of a cold weather ensemble is defined by endurance times, which are the time intervals from initial exposure until the safety limits are reached. These safety limits correspond to conservative temperature thresholds that provide a warning of the approaching onset of frostbite and/or hypothermia. A validated six-cylinder thermoregulatory model is used to predict human thermal responses to cold while wearing different ensembles. The performance metrics, model, and a database of clothing properties were integrated into a user-friendly software application. CoWEDA is the first tool that allows users to build their own ensembles from the clothing menu (i.e., jackets, footwear, and accessories) for each body region (i.e., head, torso, lower body, hands, feet) and view their selections in the context of physiological strain and the operational consequences. Comparison of predicted values to skin and core temperatures, measured during 17 cold exposures ranging from 0 to -40°C, indicated that the accuracy of CoWEDA prediction is acceptable, and most predictions are within measured mean ± SD. CoWEDA predicts the risk of frostbite and hypothermia and ensures that a selected clothing ensemble is appropriate for expected weather conditions and activities. CoWEDA represents a significant enhancement of required clothing insulation (IREQ, ISO 11079) and wind chill index-based guidance for cold weather safety and survival.

Exploring the frostbite healing potential of hyaluronic acid based hydrogel of Manuka honey through in-silico antithrombotic and anti-platelet studies of major phytoconstituents and in-vivo evaluation in Wistar rat model.

OBJECTIVE: Development of Frostbite healing hydrogel of Manuka honey and hyaluronic acid. SIGNIFICANCE: Frostbite is a cold-induced ischemic vascular injury non-responsive to most of the wound healing products. Thrombus-induced ischemia is the main cause of frostbite-related necrosis. Hyaluronic acid is known to possess significant antithrombotic and wound healing activity. Moreover, Manuka Honey is also rich in flavonoids and polyphenols with potential antithrombotic activity. These two agents were together utilized to develop a frostbite healing formulation. METHODS: In-silico antithrombotic efficacy of major phytoconstituents of Manuka honey was evaluated using in-silico-docking studies against Tissue plasminogen activator and Cyclooxygenase-1 protein. Further in-vivo frostbite healing evaluation was carried out in Wistar rats, by inducing frostbite with a supercooled rod. RESULTS: The results indicate that major leptosin and other major phytoconstituent of Manuka honey has significant antithrombotic property. The hydrogel formulation of HA and MH possess significant antimicrobial efficacy. The wound contraction studies and histopathological evaluation reveals that the hydrogel also has a good frostbite healing activity showing complete wound healing within an 18-day period. The findings of the western blotting studies suggest that the hydrogel acts by VEGF- NRF-2 pathway. CONCLUSION: This result implies that the prepared hydrogel can serve as an effective frostbite healing formulation.

The Wind-Chill Index.

This Lessons from History article about the wind-chill index (WCI) explores the historical polar and meteorologic literature relevant to the topic and presents unpublished work from 1939. Geographer Paul Siple (1908-1968) was a 6-time Antarctic explorer and scientist who invented and named the WCI in his doctoral dissertation at Clark University. Siple and Charles Passel (1915-2002) performed studies in Antarctica in 1940 that led to publication in 1945. This paper is often credited as the beginning of the WCI. Through years of critiques and revisions by others, these efforts evolved into the wind-chill equivalent temperatures (WCTs) used today. This essay explores the history, the science, and the overlooked originality, simplicity, and details of Siple's unpublished work. The remarkable similarity of the original chart to a current chart is shown by adapting and overlaying the 1939 WCI onto a current WCT chart with its times-to-frostbite data. The writings of Siple, Passel, and others provide an evocative supporting narrative to illustrate some of the problems of living in cold environmental conditions.

Frostbite and Cold Agglutinin Disease: Coexistence of Two Entities Leading to Poor Clinical Outcomes.

An 83-year-old woman was admitted to the emergency department for a 7-day history of fatigue and progressive cyanosis in the feet and hands after cold exposure despite physical protective measures. Upon arrival, the patient presented with necrotic cutaneous lesions in both hands and distal lower extremities. Upon admission, hemoglobin was 7.6 g/dL and laboratory tests were consistent with cold agglutinin disease (CAD), the presence of monoclonal IgM, and flow cytometry consistent with lymphoplasmacytic lymphoma, but MYD88 L265P mutation was negative. The patient required blood transfusion, resulting in stabilized hemoglobin and a decrease in markers of hemolysis. Treatment with aspirin 250 mg daily and intravenous iloprost 0.5 mL/h was initiated with a poor clinical response at day 4. Amputation was required. Plasma exchange was performed and chemotherapy with rituximab and bendamustine was initiated. The clinical course was marked by further necrosis, prompting discussions regarding an additional amputation that was not performed considering the high surgical risk and refusal by the patient. Supportive treatment was initiated, and the patient expired one month after hospital admission.

Hyperbaric Oxygen Therapy with Iloprost Improves Digit Salvage in Severe Frostbite Compared to Iloprost Alone.

Background and Objectives: Frostbite is a freezing injury that can lead to amputation. Current treatments include tissue rewarming followed by thrombolytic or vasodilators. Hyperbaric oxygen (HBO) therapy might decrease the rate of amputation by increasing cellular oxygen availability to the damaged tissues. The SOS-Frostbite study was implemented in a cross-border program among the hyperbaric centers of Geneva, Lyon, and the Mont-Blanc hospitals. The objective was to assess the efficacy of HBO + iloprost among patients with severe frostbite. Materials and Methods: We conducted a multicenter prospective single-arm study from 2013 to 2019. All patients received early HBO in addition to standard care with iloprost. Outcomes were compared to a historical cohort in which all patients received iloprost alone between 2000 and 2012. Inclusion criteria were stage 3 or 4 frostbite and initiation of medical care <72 h from frostbite injury. Outcomes were the number of preserved segments and the rate of amputated segments. Results: Thirty patients from the historical cohort were eligible and satisfied the inclusion criteria, and 28 patients were prospectively included. The number of preserved segments per patient was significantly higher in the prospective cohort (mean 13 ± SD, 10) compared to the historical group (6 ± 5, p = 0.006); the odds ratio was significantly higher by 45-fold (95%CI: 6-335, p < 0.001) in the prospective cohort compared to the historical cohort after adjustment for age and delay between signs of freezing and treatment start. Conclusions: This study demonstrates that the combination of HBO and iloprost was associated with higher benefit in patients with severe frostbite. The number of preserved segments was two-fold higher in the prospective cohort compared to the historical group (mean of 13 preserved segments vs. 6), and the reduction of amputation was greater in patients treated by HBO + iloprost compared with the iloprost only.

What Interventional Radiologists Need to Know About Managing Severe Frostbite: A Meta-Analysis of Thrombolytic Therapy.

OBJECTIVE. The purpose of this study is to review the various techniques and clinical management paradigms using tissue plasminogen activator (tPA) to treat severe frostbite injuries, which are relevant to the interventional radiologist. MATERIALS AND METHODS. A literature search yielded 157 citations, which were manually screened for inclusion criteria of case reports, case series, cohort studies, and randomized prospective studies that reported the use of tPA to treat severe frostbite injuries, of which 16 qualified for review. Data extracted from the studies included authors, journal, year of publication, initial assessment and management of severe frostbite injuries, inclusion and exclusion criteria for tPA therapy, treatment and control group size, different imaging modalities used in evaluation of severe frostbite injuries, tPA treatment protocols, outcomes, and side effects or complications. RESULTS. The analyzed series included 209 patients with 1109 digits at risk of amputation who were treated with intraarterial (IA) or IV tPA (116 and 77 patients, respectively). A total of 926 digits at risk were treated with IA tPA and resulted in amputation of 222 digits, for a salvage rate of 76%. Twenty-four of 63 patients underwent amputation after IV tPA, resulting in a salvage rate of 62%. Both digital subtraction angiography and triple-phase bone scan were used for initial imaging evaluation. Additional concurrent treatment included therapeutic heparin, warfarin, nonsteroidal antiinflammatory drugs, pain management, and light dressings with topical antimicrobial agents. CONCLUSION. Severe frostbite injuries can lead to devastating outcomes with loss of limbs and digits, yet clinical management continues to consist primarily of tissue rewarming, prolonged watchful waiting, and often delayed amputation. Recent studies have shown promising results using both IA and IV tPA to reduce amputation after severe frostbite injuries. Through a meta-analysis of thrombolytic therapy in the management of severe frostbite, this article provides a useful guideline for interventional radiologists including a suggested protocol, inclusion and exclusion criteria, and potential complications.

A novel approach to rapid rewarming of a frostbitten extremity: The sous vide method.

BACKGROUND: Rapid rewarming of an acutely frostbitten extremity has been the standard treatment for nearly 60 years, however, there are no existing practical recommendations to create a warm water bath. Our study describes a novel approach to rapid rewarming using a sous vide cooking device to create and maintain a circulating warm water bath at a desired set temperature. METHODS: A series of in vitro experiments were performed to assess the efficacy of different methods of maintaining constant water temperature while rapidly rewarming a simulated frostbitten extremity (frozen pig's foot). An Anova Sous Vide Precision Cooker® was attached to a 5 gallon bucket and used to circulate and maintain the water at 104 °F while rewarming a frozen pig's foot. This method was compared to manual exchange of water to maintain the temperature at 104 °F and to a control with no water exchanged. During each experiment, the temperature of the water was recorded every 2 min and the pliability of the pig's foot was assessed after 30 min. RESULTS: The sous vide method maintained circulating water at a constant temperature of 104 °F for 30 min. At 30 min the frozen pig's foot was warm, soft, and pliable. The manual method resulted in temperature fluctuations requiring frequent large volume water exchanges. When no water was exchanged, the water cooled quickly and the pig's foot remained partially frozen. CONCLUSION: Sous vide rewarming is a novel method that easily creates and maintains a warm water bath ideal for rapid rewarming of a frostbitten extremity.