Frostbite

Frostbite in the Pediatric Population: A Comprehensive Review and a Prospective Canadian Survey

INTRODUCTION

Frostbite in the pediatric population, where skeletal maturity has not been achieved, can have important repercussions on subsequent growth. Yet, the optimal management of frostbite injuries in children remains vague. This review aims to summarize the current evidence for frostbite management in children and understand Canadian practice trends on this topic.

METHODS

A review using Medline, Scopus, Web of Science, and gray literature was performed to identify relevant literature on the clinical manifestations, diagnostic methods, and treatment options in pediatric frostbite. An online survey was sent to plastic surgeons through the Canadian Society of Plastic Surgeons (CSPS) mailing list to further identify national practices and trends for pediatric frostbite management.

RESULTS

A total of 109 articles were reviewed. No article provided a specific algorithm for pediatric frostbite, with existing recommendations suggesting the use of adult guidelines for treating children. Our survey yielded 9 responses and highlighted the rarity of pediatric frostbite cases, with no responder treating more than 10 cases per year. Most (55.6%) do not use a pediatric-specific treatment algorithm, whereas 30% apply adult guidelines. A conservative approach focusing on rewarming (55.6%), limb elevation (50%), and tetanus status verification (66.7%) was predominant. Imaging and surgical interventions seem to be reserved for severe cases.

CONCLUSIONS

The current literature for pediatric frostbite management lacks specificity. Canadian practices vary, with a trend toward a conservative approach. The limited evidence and rarity of experience highlight the need for further research, ideally in a collaborative multicentric manner, to create a consensus for pediatric frostbite care.

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.

American Burn Association Clinical Practice Guidelines on the Treatment of Severe Frostbite

This Clinical Practice Guideline addresses severe frostbite treatment. We defined severe frostbite as atmospheric cooling that results in a perfusion deficit to the extremities. We limited our review to adults and excluded cold contact or rapid freeze injuries that resulted in isolated devitalized tissue. After developing population, intervention, comparator, outcomes (PICO) questions, a comprehensive literature search was conducted with the help of a professional medical librarian. Available literature was reviewed and systematically evaluated. Recommendations based on the available scientific evidence were formulated through consensus of a multidisciplinary committee. We conditionally recommend the use of rapid rewarming in a 38 to 42°C water bath and the use of thrombolytics for fewer amputations and/or a more distal level of amputation. We conditionally recommend the use of "early" administration of thrombolytics (≤12 hours from rewarming) compared to "later" administration of thrombolytics for fewer amputations and/or a more distal level of amputation. No recommendation could be formed on the use of vascular imaging studies to determine the use of and/or the time to initiate thrombolytic therapy. No recommendation could be formed on the use of intravenous thrombolytics compared to the use of intra-arterial thrombolytics on fewer amputations and/or a more distal level of amputation. No recommendation could be formed on the use of iloprost resulting in fewer amputations and/or more distal levels of amputation. No recommendation could be formed on the use of diagnostic imaging modalities for surgical planning on fewer amputations, a more distal level of amputation, or earlier timing of amputation.

Feet Salvage Using Anterolateral Thigh Flaps after Severe Frostbite Injury: A Case Report

BACKGROUND

Frostbite is a severe injury characterized by tissue damage due to exposure to freezing temperatures. It often necessitates prompt medical intervention to prevent further complications such as necrosis and amputation. This case report explores the successful use of bilateral anterolateral thigh (ALT) free flaps for feet salvage in a 19-year-old male refugee from Gambia who suffered severe frostbite injuries.

CASE REPORT

The patient, found after six days in freezing conditions, exhibited necrosis on multiple toes. Initial management included stabilization, intravenous fluids, and rewarming. Subsequent necrectomy and amputation revealed exposed metatarsal bones, necessitating a meticulous reconstructive strategy. Bilateral ALT flaps were chosen to preserve walking function, with a staged reconstruction involving multiple operations. The patient's progress, from inpatient care to outpatient follow-ups, is detailed, emphasizing the challenges and decisions in managing severe frostbite injuries.

RESULTS

The surgical intervention utilizing bilateral ALT flaps successfully salvaged the patient's feet. Throughout the postoperative period, wound care, rehabilitation, and outpatient monitoring contributed to positive outcomes. Despite challenges associated with the patient's ethnic background and nutritional status, the staged reconstruction facilitated effective healing and functional recovery. The use of ALT flaps provided a reliable solution with minimal donor site morbidity.

CONCLUSION

This case highlights the efficacy of bilateral ALT flap reconstruction in salvaging feet following severe frostbite injury. The successful restoration of foot function underscores the importance of early intervention and tailored reconstructive approaches in frostbite management. Despite patient-specific challenges, including nutritional status and limited healthcare resources, the use of ALT flaps facilitated optimal recovery and functional outcomes. Importantly, this report is unique as it describes a novel case of feet salvage using bilateral ALT flaps in severe frostbite injury, with only one similar case previously reported in the literature. This emphasizes the rarity and significance of this specific surgical approach in frostbite management.

Update on Cold-Induced Injuries

Cold-induced injuries are a major challenge for burn surgeons, leading to significant sequelae for the patients including amputations, long-term disability, and death. Rapid assessment and diagnosis are essential for optimal outcomes. Various therapies have emerged to improve outcomes. Topical, oral, and intravenous agents have shown to minimize the impact of cold-induced injuries. Thrombolytics have shown the greatest promise in improving tissue perfusion outcomes in cold-induced injuries. This article provides an update on the evidence-based assessment and management of cold-induced injuries, as well as reviews outcomes and future directions of this challenging pathology.

Surgery under siege: A case study of leg amputation in 18th century Louisbourg, Nova Scotia, Canada

OBJECTIVE

Paleopathological analysis of a below-knee amputation was conducted to explore the sociocultural reasons why the amputation took place.

MATERIALS

Older adolescent male (18-21 years) from the New Englander mass burial at the 18th century Fortress of Louisbourg.

METHODS

Macroscopic assessment and archival data.

RESULTS

A surgical amputation of the right tibia and fibula, distal to the knee was identified. The cross-sectional diaphysis of the leg has kerf marks and a splinter (breakaway point) at the posterior-lateral border of the tibia suggesting the leg gave way from its own weight or was manually removed once most of the sawing was complete.

CONCLUSIONS

Archival records suggest frostbite from prolonged exposure to freezing temperatures and trauma from unsafe working conditions at the Fortress were the main causes that led to amputation.

SIGNIFICANCE

This case study highlights the importance of contextualizing cases of amputation to understand factors leading to the amputation procedure and techniques used in the past, and the social and living conditions of the individual.

LIMITATIONS

Observations were restricted to skeletal material as soft tissue decomposed and there was no material evidence suggestive of amputation associated with this individual in their grave.

SUGGESTIONS FOR FUTURE RESEARCH

Full trauma assessment of the Fortress of Louisbourg skeletal collection to provide additional insight into injury sustained at Louisbourg and 18th century surgical practices.

Acupuncture and herbal medicine in preventing amputation and promoting tissue regeneration in severe frostbite: A case series

BACKGROUND

Frostbite is a medically significant form of tissue injury that can lead to the potential need for amputation or necessitate tissue regeneration. It occurs most frequently at cryogenic temperatures in extreme altitude climbing, winter sports, and military activities. While acupuncture and herbal medicine have been reported to possess tissue regeneration effectiveness, there is currently no clinical evidence supporting their use in treating grade 3 frostbite cases at risk of amputation.

CASE PRESENTATION

Three patients were diagnosed with grade 3 frostbite based on the extent and severity of tissue damage after alpine climbing in the Himalayas. After an urgent treatment, partial body amputation was advised. In order to seek any complementary treatment options and avoid amputation, they were referred to a frostbite expert in traditional Korean medicine. They received a comprehensive treatment consisting of acupuncture, bloodletting, direct moxibustion, and herbal medicine. All the patients showed notable healing of the damaged tissue, which prevented the need for amputation. No adverse effects or other sequelae were observed.

CONCLUSION

This case series suggests that complementary medicine, primarily acupuncture and herbal medicine, could be effective for severe frostbite. Further studies with larger sample sizes and control groups are needed to determine the efficacy and safety of this treatment modality for frostbite management.

Comprehensive treatment of deep frostbite of multiple fingers after trauma: A case report

BACKGROUND

Frostbite is becoming increasingly common in urban environments, and severe cases can lead to tissue loss. The treatment goal is to preserve tissue and function; the sooner appropriate treatment is administered, the more tissue can be saved. However, not every patient with deep frostbite seeks medical care promptly.

CASE SUMMARY

We report the case of a 73-year-old male patient who was lost in the wilderness for 2 d due to trauma and confusion. He experienced deep frostbite on multiple fingers. Treatment should not be discontinued for patients with deep frostbite who present after the optimum treatment timing. Bullae that no longer form (bloody) blisters within 24 h of aspiration should be removed. Mucopolysaccharide polysulfate cream has clinical value in frostbite treatment. The patient was transferred to Chinese Academy of Medical Sciences and Peking Union Medical College Hospital 12 h after being rescued. The patient had contraindications for thrombolysis, the most effective treatment, due to intracranial hemorrhage and presenting past the optimum treatment timing. We devised a comprehensive treatment plan, which involved delayed use vasodilators and high-pressure oxygen therapy at day 49 post-injury. We experimented with mucopolysaccharide polysulfate cream to treat the frostbite. The aim of the treatment was to safeguard as much tissue as possible. In the end, the fingers that suffered from frostbite were able to be partially preserved.

CONCLUSION

The case indicated that patients with severe frostbite who missed the optimal treatment time and had contraindications for thrombolysis could still partially preserve the affected limbs through comprehensive treatment.

Can iloprost be used for treatment of cold weather injury at the point of wounding in a forward operating environment? A literature review

INTRODUCTION

Cold Weather Injury (CWI) represents a spectrum of pathology, the two main divisions being Freezing Cold Injury (FCI) and Non-Freezing Cold Injury (NFCI). Both are disabling conditions associated with microvascular and nerve injury often treated hours after initial insult when presenting to a healthcarestablishment. Given that iloprost is used for the treatment of FCI, could it be used in a forward operating environment to mitigate treatment delay? Is there a role for its use in the forward treatment of NFCI? This review sought to evaluate the strength of evidence for the potential use of iloprost in a forward operating environment.

METHODS

Literature searches were undertaken using the following question for both FCI and NFCI: in [patients with FCI/NFCI] does [the use of iloprost] compared to [standard care] reduce the incidence of [long-term complications]. Medline, CINAHL and EMBASE databases were searched using the above question and relevant alternative terminology. Abstracts were reviewed before full articles were requested.

RESULTS

The FCI search yielded 17 articles that were found to refer to the use of iloprost and FCI. Of the 17, one referred to pre-hospital treatment of frostbite at K2 base camp; however, this was utilising tPA. No articles referred to pre-hospital use in either FCI or NFCI.

DISCUSSION

Although evidence exists to support the use of iloprost in the treatment of FCI, its use to date has been in hospital. A common theme is delayed treatment due to the challenges of evacuating casualties from a remote location. There may be a role for iloprost in the treatment of FCI; however, further study is required to better understand the risk of its use.

Iloprost for the treatment of frostbite: a scoping review

We performed a scoping review to identify the extent of the literature describing the use of iloprost in the treatment of frostbite. Iloprost is a stable synthetic analog of prostaglandin I₂. As a potent inhibitor of platelet aggregation and vasodilator, it has been used to address the post-rewarming reperfusion injury in frostbite. The search using iloprost and frostbite as key words and MeSH terms yielded 200 articles. We included in our review the literature examining iloprost for the treatment of frostbite in humans in the form of primary research, conference proceedings and abstracts. Twenty studies published from 1994 to 2022 were selected for analysis. The majority were retrospective case series consisting of a homogeneous population of mountain sport enthusiasts. A total of 254 patients and over 1000 frostbitten digits were included among the 20 studies. The larger case series demonstrated a decrease in amputation rates relative to untreated patients. Primary gaps in the literature include a paucity of randomised trials and relatively limited study populations to date. While the case evidence is promising, a multi-centre collaboration would be crucial to adequately power prospective randomised studies to definitively determine if iloprost has a role in the treatment of frostbite.

Exploring the Development of a Canadian Frostbite Care Network and the Future of Frostbite Care in Canada Using a Qualitative Approach

INTRODUCTION

The Canadian Frostbite Collaborative project is exploring frostbite patient care needs and current practices in Canada to inform the development of a Canadian frostbite care network (CFCN) as a national quality improvement initiative.

METHODS

Using a quantitative and qualitative approach, this study aimed to define the landscape of current frostbite practices, challenges, and interest in future work.

RESULTS

Current frostbite care practices were initially assessed through semistructured phone interviews of Canadian healthcare providers. Canadian healthcare providers managing frostbite in a range of health disciplines and contexts then participated in focus group sessions discussing the potential roles and opportunities as well as potential challenges in developing a CFCN. Roles and opportunities for a network in advancing frostbite care included facilitating research, educating stakeholders, facilitating collaboration, standardizing care, and advocating for frostbite care. Challenges identified in frostbite care and network development included managing resources, navigating the Canadian healthcare system, overcoming low numbers, and communicating with policymakers and frontline providers.

CONCLUSIONS

Formalizing a CFCN may provide important opportunities and support in overcoming critical barriers to providing high-quality frostbite care across Canada.

Frostbite: a treatment guideline for prehospital treatment in a military environment

Frostbite remains a severe medical condition that causes long-lasting sequelae and can threaten military operations. Information on prehospital treatment of frostbite is scarce and existing guidelines are aimed at the general population.This paper provides a guideline on prehospital emergency care of frostbite in the (Netherlands) Armed Forces. The insights gained from studies reporting on frostbite treatment in the prehospital setting were combined with the expert opinions of the authors and applied to the military context. The resulting guideline consists of two stages: (prolonged) field care and care at a Medical Treatment Facility. The cornerstones are rewarming in warm water and evacuation to a medical facility. Additional aspects of prehospital treatment are rehydration, proper analgesia, non-steroidal anti-inflammatory drugs and wound care.We suggest further collaboration among North Atlantic Treaty Organization partners and other affiliated nations, focusing on the full spectrum of military injury management including state-of-the-art aftercare, long-lasting sequelae and return to duty after frostbite.

Experiences of frostbite injury from recreational use of nitrous oxide canisters in a UK burns center: Not a laughing matter

Nitrous oxide is used as a recreational drug. Contact frostbite injury from compressed gas canisters has previously been described in the literature, but an increased number of such cases has been noted in our busy regional burns center in the UK. A single-center prospective case series of all patients referred and treated for frostbite injury secondary to misuse of nitrous oxide compressed gas canisters between January and December 2022 is presented. Data collection was performed through a referral database and patient case notes. Sixteen patients, of which 7 were male and 9 were female, satisfied the inclusion criteria. Mean patient age was 22.5 years. The median TBSA was 1%. In total, 50% of patients in the cohort had a delayed initial presentation to A&E of greater than 5 days. Eleven patients were reviewed at our burns center for further assessment and management. In total, 11 patients had bilateral inner thigh frostbite injuries, of which 8 had necrotic full-thickness injury, including subcutaneous fat. Seven patients were reviewed at our burns center and offered excision and split-thickness skin graft. Four patients presented with contact frostbite injury to the hand and one patient to the lower lip. This subgroup was managed successfully with conservative management alone. The reproducible pattern of frostbite injury secondary to the abuse of nitrous oxide compressed gas canisters is demonstrated in our case series. The distinct pattern of injury, patient cohort, and anatomical area affected presents an opportunity for targeted public health intervention in this group.

The Effects of Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor Gel on Third-Degree Frostbite Wounds in Northeastern China: A Randomized Controlled Trial

The aim of the study was to investigate the effects of the rhGM-CSF gel on third-degree frostbite wounds. Sixty-two patients who had suffered third-degree frostbite on their hand or foot (91 wounds in total) were selected using a convenience sampling method and randomly allocated to two groups: the rhGM-CSF group(31patients,45 frostbite wounds) received the rhGM-CSF gel when wound dressing change daily; however, the control group (31patients, 46 frostbite wounds) received aloe glue. The wound healing time, the score of inflammation about the wound and the positive bacterial culture of wound secretions were used to measure outcomes, respectively. Data were analyzed using SPSS (25.0), Student's t test or Mann-Whitney U test and chi-square test or Fisher exact test were selected, as appropriate. The healing time of the rhGM-CSF group was (12.2 ± 5.0) days, which was significantly shorter than that of the control group (15.5 ± 4.7) days (P < .0001). The rhGM-CSF group's wound inflammation scores on the 7th and 14th day of treatment were (0.96 ± 0.21) and (1.88 ± 0.29), respectively, which were better than those of the control group (1.12 ± 0.24) and (1.38 ± 0.15) (both P < .0001). The positive bacterial culture of wound secretions in the rhGM-CSF group was also better than that in the control group on the 3rd, 7th, and 14th day after treatment (P = .027, .004, .030, respectively). According to the results, using rhGM-CSF gel considerably increases the speed of frostbite wounds healing, and have an effect on protecting third-degree frostbite wounds regarding the positive effects. Trial Registration: This trial was registered in the Chinese Clinical Trial Register, ChiCTR1900021299.

Frostbite: a systematic review on freezing cold injuries in a military environment

BACKGROUND

Military practice or deployment in extreme conditions includes risks, dangers and rare disorders. One of the challenges is frostbite; however, current literature does not provide an overview of this condition in a military context. This review aims to map the incidence, risk factors and outcome of frostbite in military casualties in the armed forces.

METHODS

A systematic literature search on frostbite (freezing cold injuries) in military settings from 1995 to the present was performed. A critical appraisal of the included articles was conducted. Data on incidence, risk factors, treatment and outcome were extracted.

RESULTS

Fourteen studies were included in our systematic review. Most studies of frostbite in a military setting were published nearly half a century ago. Frostbite incidence has declined from 7% to around 1% in armed forces in arctic regions but could be as high as 20% in small-scale arctic manoeuvres. Overall and military-specific risk factors for contracting frostbite were identified.

CONCLUSION

During inevitable arctic manoeuvres, frostbite is a frequently diagnosed injury in service members. Postfreezing symptoms often persist after severe frostbite injury, which decreases employability within the service. Over time, military practice has changed considerably, and modern protective materials have been introduced; therefore, re-evaluation and future study in the military field are appropriate, preferably with other North Atlantic Treaty Organization partners.

A prospective study on local cold injuries in northern Sweden

The study aimed to determine the prevalence and incidence proportion of local cold injuries in northern Sweden, and identify associated factors. It was based on prospective data from surveys in 2015 and 2021 sent to a population-based sample in northern Sweden. Multiple binary logistic regression was performed. The study included 5,017 subjects (response rate 44.4%). The prevalence of cold injuries in the hands was 11.4%, feet 12.6%, and face 19.9%, while the incidence proportion was 1.0%, 1.0%, and 0.9%, respectively. Male gender was associated with incident cold injuries in the hands (OR 1.69; 95% CI 1.31-1.28), feet (OR 1.34; 95% CI 1.04-1.73), and face (OR 1.53; 95% CI 1.15-2.03); mental stress with cold injuries in the hands (OR 1.55; 95% CI 1.16-2.05) and feet (OR 1.39; 95% CI 1.04-1.88); previous stroke with cold injuries in the hands (OR 2.64; 95% CI 1.09-6.40) and face (OR 3.09; 95% CI 1.26-7.56); and Raynaud's phenomenon with cold injuries in the hands (OR 2.48; 95% CI 1.80-3.41) and feet (OR 2.07; 95% CI 1.50-2.87). We conclude that male gender, mental stress, previous stroke, and Raynaud's phenomenon increased the probability of contracting local cold injuries.

Practical management of Raynaud's phenomenon - a primer for practicing physicians

PURPOSE OF REVIEW

Raynaud's phenomenon (RP) is a common vasospastic condition that results in digital hypoperfusion in response to cold and/or emotional stress and is associated with significant pain and disability. The aim of our review is to provide a practical approach for clinicians to inform assessment and management of patients with RP.

RECENT FINDINGS

Autoantibodies and nailfold capillaroscopy are key investigations to stratify the risk of progression to systemic sclerosis (SSc) in patients RP, which was recently confirmed in the multicenter, very early diagnosis of systemic sclerosis (VEDOSS) project. Research has explored the complex lived-patient experience of RP including digital vasculopathy in SSc and has highlighted the need for outcome measure development to facilitate research in the field. Pharmacological treatment strategies vary significantly internationally and there is continued interest in developing surgical approaches.

SUMMARY

We provide a practical and up-to-date approach to inform the assessment and management of patients with RP including guidance on drug initiation and escalation. Calcium channel blockers are first-line treatment and can be initiated by primary care physicians. We also highlight second-line drug therapies used for refractory RP and the potential role for surgical intervention.

The Intersection of Telemedicine and Wilderness Care: Past, Present, and Future

Wilderness medicine and telemedicine seemingly exist at opposite ends of the clinical continuum. However, these 2 specialties share a common history and the literature abounds with examples of successful deployment of telemedicine to resource limited settings. The recent widespread adoption of telemedicine has important ramifications for wilderness providers. Telemedicine is inherently reliant on some sort of technology. There is a wide spectrum of complexity involved, but in general these systems rely on a hardware component, a software component, and a network system to transmit information from place to place. Today, connectivity is nearly ubiquitous through access to cellular networks, Wi-Fi, or communication satellites. However, bandwidth, defined as the amount of data which can be transmitted through a given connection over time, remains a limiting factor for many austere settings. Telemedicine services are typically organized into 4 categories: 1) live/interactive; 2) store and forward; 3) remote patient monitoring; and 4) mHealth. Each of these categories has an applicable wilderness medicine use case which will be reviewed in this paper. Though the regulatory environment remains complex, there is enormous potential for telemedicine to enhance the practice of wilderness medicine. Drones are likely to transform wilderness medicine supply chains by facilitating delivery of food, shelter, and medicines and are able to enhance search and rescue efforts. Remote consultations can be paired with remote patient monitoring technology to deliver highly specialized care to austere environments. Early feasibility studies are promising, but further prospective data will be required to define future best practices for wilderness telemedicine.

Human vulnerability and variability in the cold: Establishing individual risks for cold weather injuries

Human tolerance to cold environments is extremely limited and responses between individuals is highly variable. Such physiological and morphological predispositions place them at high risk of developing cold weather injuries [CWI; including hypothermia and/or non-freezing (NFCI) and freezing cold injuries (FCI)]. The present manuscript highlights current knowledge on the vulnerability and variability of human cold responses and associated risks of developing CWI. This review 1) defines and categorizes cold stress and CWI, 2) presents cold defense mechanisms including biological adaptations, acute responses and acclimatization/acclimation and, 3) proposes mitigation strategies for CWI. This body of evidence clearly indicates that all humans are at risk of developing CWI without adequate knowledge and protective equipment. In addition, we show that while body mass plays a key role in mitigating risks of hypothermia between individuals and populations, NFCI and FCI depend mainly on changes in peripheral blood flow and associated decrease in skin temperature. Clearly, understanding the large interindividual variability in morphology, insulation, and metabolism is essential to reduce potential risks for CWI between and within populations.

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.

Study on the experimental verification and regulatory mechanism of Rougui-Ganjiang herb-pair for the actions of thermogenesis in brown adipose tissue based on network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Cinnamomum cassia Presl (Rougui) has character of xin、gan、wen, belongs to Jing of heart、lung、bladder, and has the effect of dispersing cold and relieving pain. It is widely used to resolve the exterior and dissipate cold in Treatise on Febrile Diseases (Shang Han Lun), such as Chaihu Guizhi Ganjiang Tang and Guizhi Renshen Tang. Both these two prescriptions contain Cinnamomum cassia Presl and Zingiber officinale Rosc (Ganjiang). Rougui-Ganjiang herb-pair (RGHP) can warm viscera and remove cold, which is widely used in Shang Han Lun. And in modern times, recent studies have showed that cinnamon and ginger also have the effect of thermogenesis and regulating the body temperature, respectively.

AIM OF THE STUDY

To maintain the body thermal homeostasis and prevent cold invasion of main organs, in this study, we assessed the underlying physiological changes induced by RGHP in mice exposed to -20 °C and explored the mechanisms for the thermogenic actions of RGHP in brown adipose tissue (BAT) by network pharmacology and molecular docking.

MATERIALS AND METHODS

Male Kunming (KM) mice were fed normal diet with orally administration of distilled water or ethanol RGHP extract (three doses: 375,750 and 1500 mg/kg) for 21 days, once per day and then exposed to -20 °C for 2 h. The core temperature, activity ability and the degree of frostbite in mice, morphological and ATP content of adipocytes were measured. In addition, the network pharmacology was employed to predict the targets of RGHP' s thermogenesis effect on BAT. Pathway analysis and biological process with key genes was carried out through KEGG and GO analysis, respectively. Furthermore, the core ingredients and targets obtained by network pharmacology were verified by molecular docking and Western blot assays.

RESULTS

RGHP can significantly increase the core body temperature, reduce the degree of frostbite and enhance the activity ability of mice after cold exposure. Meanwhile, it can also improve the lipid morphology and decrease ATP production in BAT. A network pharmacology-based analysis identified 246 ingredients from RGHP (two herbs), which related to 222 target genes. There were 8 common genes between 222 compounds target genes and 62 thermogenesis associated target genes, which linked to 49 potential compounds. There are 24 ingredients which degree are greater than the average. Among them, we found that oleic acid, EIC, 6-gingerol, eugenol, isohomogenol and sitogluside could be detected in mice plasma. The cAMP-PPAR signaling pathway was enriched for thermogenesis after KEGG analysis with 8 genes. Molecular docking analysis and Western blot assay further confirmed that oleic acid, 6-gingerol, eugenol and isohomogenol were potential active ingredients for RGHP's heat production effect. And UCP1, PGC-1α, PPARα and PPARγ are key thermogenesis proteins.

CONCLUSIONS

RGHP treatment can significantly maintain the rectal temperature of mice by enhancing the BAT heat production. RGHP exhibited the heat production effect, which might be mainly attributed to increasing thermogenesis through the cAMP-PPAR signaling pathway in cold exposure mice. Oleic acid, 6-gingerol, eugenol and isohomogenol might be considered the potential therapeutic ingredients which affect the key targets of thermogenesis effect.

Long-Term Sequelae of Frostbite-A Scoping Review

Frostbite is tissue damage caused by freezing temperatures and constitutes an important cause of morbidity in cold climate zones and high altitude. The direct effects of sub-zero temperatures lead to tissue freezing, electrolyte shifts and pH alterations, microvascular damage, and eventually to cell death. Upon rewarming, inflammatory reperfusion injury and thrombosis may lead to further tissue damage. Several studies and various case reports show that many patients suffer from long-term sequelae such as vasomotor disturbances (associated with susceptibility to refreezing), and neuropathic and nociceptive pain, as well as damage to skeletal structures. There are still many uncertainties regarding the pathophysiology of these sequelae. It has been shown that the transient receptor potential channel (TRP) family plays a role in cold allodynia. Botulinum Toxin type A (BTX-A) injections have been reported to be beneficial in vasomotor and neuropathic disturbances secondary to frostbite. Epidural sympathetic block has been used for short-term treatment of frostbite induced chronic pain. Furthermore, amitriptyline, gabapentinoids, and duloxetine may have some benefits. Frostbite arthritis clinically resembles regular osteoarthritis. In children there is a risk of epiphyseal cartilage damage leading to bone deformities. Despite some promising therapeutic concepts, the scarcity of data on frostbite long-term sequelae in the literature indicates the need of more in-depth studies of this pathology in all its aspects.

Comprehensive Treatment of Single Finger Frostbite: A Case Study

Third- and fourth-degree frostbites usually result in loss of skin and tissue requiring amputation, and scarring. The 3- to 6-week waiting period is often necessary to determine the severity of the lesion. This period is also a critical time for the rescue of frostbitten tissue. This patient was a 30-year-old man who developed frostbite of his right index finger. He presented to our hospital 4 hours after injury with loss of sensation on the whole index finger and early signs of necrosis. The patient received a series of comprehensive treatments, including fasciotomy, injection of papaverine hydrochloride, baking lamp irradiation, and negative pressure treatment. At the time of discharge, he had re-epithelialization of the index finger by 21 days after injury. The conclusion of this paper is that the comprehensive treatments combined with negative pressure wound treatment has certain clinical application value for the rescue of deep frostbite tissues.

Frostbite: Current status and advancements in therapeutics

Frostbite is a severe ischemic injury which occurs due to the tissue vascular damage after sub-zero temperature tissue exposure. Deep frostbite can result in necrosis and may need amputation of affected tissue. Though a serious injury, it is not very well understood, and further scientific exploration is needed. This work explores the current understanding of the pathophysiology of frostbite. We reviewed the current status of the diagnostics, the drugs, the therapies and the surgical practices for prevention and management of frostbite. Advances in nanotechnology and drug delivery had improved the therapeutic outcomes significantly. This review also explored the latest advancements and researches done for development of newer therapeutics and diagnostics for frostbite care.

Frostbite injuries: independent predictors of outcomes

Objectives

Frostbite injuries are important causes of morbidity and mortality after trauma. Epidemiology, injury patterns, and outcomes after frostbite among patients presenting to trauma centers are incompletely defined. The purpose of this study was to delineate patient demographics, clinical characteristics, and independent predictors of outcomes after frostbite.

Material and Methods

Patients with frostbite injury were identified from the National Trauma Data Bank (NTDB) (2007-2014). Demographics, clinical/injury data, and outcomes were collected. Patients were dichotomized into study groups based on intensive care unit (ICU) admission. Univariate analysis was performed with the Mann-Whitney U, Fisher's exact, or Chi-Square test as appropriate. Multivariate analysis using logistic regression determined independent predictors of outcomes.

Results

Over the study period, 241 patients were identified. Median body temperature on admission was 36.3⁰C (IQR 33.4-36.7). Mortality was 3% (n= 7). ICU admission was required in 101 (42%) patients and 48 (20%) underwent surgical intervention. On multivariate analyses, mortality was predicted by lower admission GCS (p= 0.027) and amputation by higher HR (p= 0.013). Need for ICU admission was predicted by older age (p= 0.010), male gender (p= 0.040), higher HR (p= 0.031) and ISS (p <0.001), and lower GCS (p= 0.001). Prolonged hospital LOS was predicted by higher heart rate (p <0.001) and ISS (p <0.001).

Conclusion

Frostbite injuries are uncommon but can necessitate surgical intervention and cause mortality. Lower GCS and higher heart rate, but not body temperature, portend poor outcomes. These findings can be used to triage patients appropriately upon admission and to better inform prognosis after frostbite injuries.

Increased Heat Shock Protein Expression Decreases Inflammation in Skeletal Muscle During and after Frostbite Injury

BACKGROUND

Frostbite injury results in serious skeletal muscle damage. The inflammatory response due to frostbite causes local muscle degeneration. Previous studies have shown that heat shock proteins (hsps) can protect against inflammation. In addition, our previous studies showed that increased expression of hsp70 is able to protect skeletal muscle against cryolesion.

METHODS

Therefore, our aim was to determine if the induction of the heat shock proteins are able to minimize inflammation and protect skeletal muscle against frostbite injury.

RESULTS

In the present study, we used the hsp90 inhibitor, 17-dimethylaminoethylamino- 17-demethoxygeldanamycin (17-DMAG), which was administered within 30 minutes following frostbite injury. Rat hind-limb muscles injected with 17-DMAG following frostbite injury exhibited less inflammatory cell infiltration as compared to control rat hind-limb muscles. In agreement with this observation, it has been observed that increased hsp expression resulted in decreased inflammatory cytokine expression. Additionally, we found that the administration of 17-DMAG after frostbite injury can preserve muscle tissue structure as well as function.

CONCLUSION

It has been concluded that compounds such as 17-DMAG that induce the heat shock proteins are able to preserve skeletal muscle function and structure if injected within 30 minutes after frostbite injury. Our studies provide the basis for the development of a potential therapeutic strategy to treat the injury caused by frostbite.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2019 Update

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for 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 2014.

Recognition and management of dermatologic complications from interventional radiology procedures

A variety of dermatologic complications can occur after interventional radiology procedures, including fluoroscopy-induced radiation dermatitis, thermal skin injury from tumor ablation, non-target embolization to the skin, allergic reactions related to interventional radiology procedures, and dermatitis and infections at catheter sites. Yet, interventional radiologists typically lack training in dermatology. This review focuses on recognition of dermatologic complications and introduces basic principles for management of these complications. By taking a more active role in the diagnosis, management, and follow-up of dermatologic complications, interventional radiologists can improve the care for patients suffering iatrogenic skin inury.

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.

Pediatric frostbite: A 10-year single-center retrospective study

OBJECTIVE

To describe frostbite (freezing cold injured tissue) in children and intrinsic (psychological and behavioral) and extrinsic (meteorological and safety hazard) factors related to the injury.

METHODS

Retrospective chart review of children <18 years old referred to a regional pediatric hospital for frostbite, to determine the demographics, environment, and risk factors related to injuries.

RESULTS

47 patients met the inclusion criteria. Median age was 15 years (IQR 12-16). All injuries occurred between November and March. 49% were admitted to the hospital and frostbite was associated with use of alcohol (53%), cigarettes (34%), marijuana (23%), and symptoms of depression (with and without suicidal ideation) (32%). Frostbite injury treated with conservative wound management presented at <-6°C and injury that underwent surgical procedures occurred at temperatures ≤-23°C (p=0.001). Longer exposure duration also significantly increased the likelihood of a surgical procedure (p<0.001). Intoxication and lack of supervision were two common factors, with lack of supervision at time of injury most common among patients 0-12 years (64%), and intoxication most common among patients ages 13-17 (61%).

CONCLUSION

Frostbite injuries in children begins at temperatures <-6°C; with risk of tissue loss increasing at temperatures below -23°C. Lack of supervision and intoxication are major risk factors for frostbite in children. Two-thirds of younger children were unsupervised, whereas intoxication was frequently related to frostbite in adolescents. Both of these factors can be addressed through an education-based prevention program.