Abstract
This case study describes adjunctive hyperbaric oxygen treatment (HBOT) of grade 3–4 frostbite, along with vasodilators and rheological agents. The patient in this study presented with established frostbite 3 days after an 11-day walk in cold, snowy, wet conditions in Tasmania, Australia. Hyperbaric oxygen treatment in this case seemed to reduce the penumbra of ischemia in both feet and thus possibly reduced the level of joint amputation in the toes. If available, HBOT is an adjuvant option for the treatment of frostbite, along with the more established treatments. More studies, however, are required to establish the best protocol for the use of HBOT in this circumstance, as this is currently unknown.
Introduction
Frostbite is a cold injury that leads to tissue destruction and sometimes distal joint amputation. The accepted treatments include rewarming, thrombolytics, and vasodilators. Hyperbaric oxygen therapy (HBOT) has been used in several case studies/series and in the SOS-frostbite study as an adjunct to iloprost (synthetic prostacyclin) for severe frostbite (grades 3 and 4 on the Cauchy scale). This study included 28 people and was supportive of HBOT. 1
Another series (22 cases) concluded that it was unclear whether HBOT reduced soft tissue damage or amputation rates, but a 2014 review of 17 human and 4 animal frostbite case studies showed some positive benefits.2,3
A recent systemic review and meta-analysis suggested HBOT may have a possible benefit, including reduction in amputation rates and a higher proportion of preserved tissue segments per patient, but also stated iloprost and thrombolysis “may be” beneficial and that other treatments “have not been validated.” 4 This review highlights both the lack of robust examination for any treatment and the paucity of HBOT evidence, in particular.
This case study aims to add more supportive case study evidence to bolster the use of adjunctive HBOT in managing frostbite, which can be a devastating and physically disabling condition with lifelong ramifications.
The characteristic cellular changes of frostbite are cold-induced cell death followed by reperfusion-related localized inflammatory processes and tissue ischemia. 5
Ice crystals may form either extra- or intra-cellularly, depending on the rate of freezing, rupturing membranes and causing loss of electrolytes and cell death. Inflammatory mediators such as thromboxane A2, prostaglandin F2alpha (PGF2α), bradykinins, and histamine cause increasing tissue ischemia and necrosis. Destruction of distal tissues (characteristically fingers, toes, nose, ears) ensues with gangrene and ulceration. Longer-term complications include amputation (auto or surgical), severe osteoarthritis, abnormalities in vascular tone causing vasospasm, and lifelong susceptibility to further cold injury plus chronic pain.
Because the frostbite damage proceeds from the outside in, amputation should be delayed for as long as possible to identify joint preservation levels correctly. The adage is “frostbite in January, amputate in July.”
The acute treatment of frostbite relies on rewarming alongside treating urgent issues such as trauma and hypothermia. Patients with severe frostbite grades should be administered tissue plasminogen activator (tPA) plus intravenous low molecular weight heparin within 24 h. 2 Thrombolysis has several significant contraindications such as active internal bleeding, uncontrolled hypertension, and recent head injury or hemorrhagic stroke.2,3
If there is a delay > 24 h or tPA is contraindicated, iloprost (synthetic prostacyclin) should be given (within 72 h). 6 Some protocols administer both tPA and iloprost together if the patient presents in the first 24 h 7
Surgical consultation, wound care, and control of infection/tetanus prophylaxis should all be instigated. Pentoxifylline has been used in several case studies with success, but optimal dosing is not known, and there are no controlled studies in humans.8,9
Case Report
Tasmania is the most southerly part of Australia, an island state half the size of England. The climate is temperate, with mountain and lake scenery particularly in the central and western parts of the island. Because of its rugged natural beauty, hiking and bush walking are popular, even in midwinter when temperatures can dip below freezing.
A 68-year-old male (outdoor education teacher) was kayaking and bush walking in Tasmania with his partner in April (fall, southern hemisphere autumn). He was using a home-built collapsible kayak with hand-sewn canvas skins (Figure 1). He was in the last 3 days of an 11-day trip, off track, at approximately 1000 meters above sea level. Average daytime temperatures were 1–5 °C. There were at least 5 days during the trip when the patient was exposed to deep snow with wet feet. On the return journey, a kayak trip across Lake St Clair (a 28 km2, 11 square mile lake at 2417 feet above sea level; latitude: −42.0667, longitude: 146.1667) required emergency action when his partners’ kayak sank in heavy swells and rain 2 km from the shore (water temperature was 5–6 °C). He towed his partner to shore, set up an emergency shelter and set off an emergency position indicating radio beacon (EPIRB), as his partner was hypothermic. A rotary-wing aircraft turned back due to the conditions. Small police rescue boats (zodiacs) arrived hours later; one of the boats had to be manually roped through the swell and logs to reach the hypothermic patient. She was placed in a dry suit and extracted to a local bay to be checked by paramedic rescue services. Both were considered fit to be left at their own vehicle with dry clothing and sleeping bags. Three days later, the patient noticed redness and blisters forming on the toes of both feet, with a loss of distal sensation. The distal phalanges were dusky, and there was erythema to the mid forefoot. He had mild pain (grade 4 frostbite). He presented to the local emergency department via an ambulance.
Conditions on the trip in the Lake St Clair Region of Tasmania (reproduced with kind permission). The natural beauty as well as the wintry conditions are amply illustrated.
He was admitted under the plastic surgeons from the Emergency Department, and after discussion with the hyperbaric team, HBOT was offered the next day, along with antibiotics, antibacterial dressings, and nifedipine as a vasodilator, plus pentoxifylline. There is no standard protocol at our hospital, but we have had success in the past with the rare cases of frostbite we have seen and treated in the hyperbaric chamber. We treated the patient at 240 kilopascals (kPa), 2.4 atmosphere absolute (ATA), which is a standard non-diving treatment in the chamber. This allowed us to integrate his treatment into the regular sessions offered to other patients. The duration of treatment is 90 min at depth with a subsequent 20-min ascent on oxygen. Intermittent oxygen/air periods in the chamber are performed (air breaks are to minimize the risk of oxygen toxicity at depth) Figures 2 to 4.
Appearance prior to any hyperbaric oxygen treatment. Dusky toes and discoloration extending to the mid forefoot bilaterally.
Dorsal view of the feet prior to treatment. Blisters have deflated.
The feet after the first HBOT. Pinking of the forefoot noted.
After the first treatment, clear demarcation of the ischemia was noted, along with improvement of border erythema and mottling. By day 5 of twice daily (240 kPa, 2.4 ATA, 14 meters) treatments, there was resolution of the more proximal change but progression of the necrosis at the distal tips of the toes Figure 5.
Day 5 of HBOT. Area of earlier discolouration marked by Dotted Line.
By day 10, progressive demarcation of the necrotic tips was noted, but most of the forefoot changes had resolved Figure 6.
Day 10 of treatment, continued necrosis of the distal toes.
During the next few weeks of treatment, gradual recession of the compromised areas was observed. The tips of the phalanges, however, remained dark and devitalized. The patient tolerated the treatments well with no complications such as barotrauma.
Approximately 1 month into the treatment, the patient developed wet gangrene. The patient presented to the hyperbaric department, Royal Hobart Hospital, feeling unwell with a fever and tachycardia. He was admitted under the plastics team for intravenous antibiotics. IV piperacillin/tazobactam was stepped down after 3 days to oral ciprofloxacin and metronidazole. Wound swabs grew Enterobacter faecalis and Enterobacter cloacae. He responded well to the antibiotics and was deemed fit for discharge after 4 days. On discharge, he had follow-ups with podiatry, plastic surgery, physiotherapy, and hyperbarics Figure 7.
One month post cold exposure-progressive mummification and some wet gangrene of the toes.
This admission curtailed his last HBOT treatments; he had received in total 16 HBOT at 240 kPa, initially twice a day then once daily. (See discussion for comments on treatment.)
Once discharged from the hospital, the feet continued to heal, and over the succeeding few months, the toes dried up and parts autoamputated, but the patient needed debridement and terminalization 5 months later under the plastics team (osteotomy of left second and third toes to permit soft tissue closure) Figure 8.
Four months post HBOT.
Three months after his plastic surgery, he was back doing multi-day hikes, and he continues to bushwalk in all weather. His podiatrist recommended boots with a rocking sole to minimize the impact on his toes. He continues to teach outdoor education Figure 9.
The feet four years post HBOT.
Discussion
HBOT in ischemic tissue environments is postulated to reduce reperfusion injury, which is believed to be achieved through modulation of endothelial adherence of neutrophils via β2 integrins, increased oxidative stress resistance and viability, repair of connective tissue, recruitment of stem cell lines, and enhanced microvascular repair and replacement. 6
Augmentation of the neutrophil oxidative burst also helps in the management of infected frostbite. 7
The Wilderness Medical Society published guidelines for the prevention and treatment of frostbite, which were updated in 2024. 8 The guidelines comment on the anecdotal success of HBOT in limited case series, but also on the lack of controlled studies. They also mention that time, availability, and expense may limit its use.
A guideline for thrombolytic therapy for frostbite was published in 2020 and recommended thrombolytic therapy for selected, more severe grades of frostbite injury after rewarming. 9
The American Burn Association published clinical treatment guidelines in 2024 and conditionally recommended rapid rewarming (38 to 42 °C water) and early use of thrombolytics (<12 h from rewarming) but did not comment on other adjuvant therapies due to the absence of evidence or low-quality evidence. 10
The efficacy of HBOT in digital frostbite was examined in a multi-centered retrospective cohort study in 2023, and this found no statistical difference between HBOT and non-HBOT groups for amputation characteristics but highlighted the longer hospital stay and increased cost of HBOT. 11
The optimal treatment protocol for HBOT is not known; therefore, department constraints and pragmatism governed our use of the routine 2.4 ATA (240 kPa) protocol. Because there is an absence of significant inert gas tissue super saturation, higher pressures should not offer any clinical advantage (2.8 ATA vs 2.4 ATA) but may increase the risk slightly of oxygen toxicity. 12 A “top-heavy” approach of twice-daily treatments followed by daily treatments was judged clinically to be appropriate in this case, in order to front-load tissues with oxygen, although randomised controlled trial (RCT) evidence is lacking for any protocol. The clinical evidence being mainly case reports, this makes the possible benefit and optimal treatment regime of HBOT difficult to determine. There is much variability of approaches in the case studies. The mechanism of outside-to-inside freezing, sometimes rapid, means that a penumbra of soft tissue is often partially affected. Using vasodilators and anticoagulants maximizes distal blood flow, along with the use of xanthine-derived pentoxyphylline as a rheological agent. HBOT may well not only minimize the ischemic penumbra around injured tissue but also downgrade the inflammatory response associated with tissue injury. 4 Because the most important outcome is the preservation of joint function, or minimizing tissue loss; this may well make the difference between a tip amputation and a full-digit amputation.
Delayed HBOT treatment (up to 28 days post cold exposure) has also been reported in case studies with some success.13–15 This may reflect the role of HBOT in downregulating the delayed inflammatory response, which occurs days after initial injury.
A multi-center RCT examining the role of HBOT in frostbite would be ideal. In the meantime, an International Frostbite Registry exists, based in the South Tyrol region of Italy, that collates and analyses frostbite cases to establish “the most effective current treatment strategies.” 16 During the writing of this paper, I could not establish any communication with the managers of this resource, therefore cannot comment on the content.
The aim of treatment for the best functional outcome is joint preservation and delayed amputation. Unfortunately, in this case, the complication of wet gangrene necessitated admission and intravenous antibiotics. Most of the case studies do, however, suggest joint preservation is better with adjunctive hyperbaric treatment. 5 It's difficult to assess whether the intervention of wet gangrene caused more tissue loss, but being seen daily for HBOT certainly picked up the signs of infection early. This may have reduced the tissue destruction and also reduced the risk of sepsis to the patient.
Along with other case studies, in this case, HBOT appears to be a safe and, where available, helpful adjunct to the treatment of frostbite. We hope this small case adds to the existing literature and allows or encourages further research. One issue preventing the adoption of adjunctive hyperbaric treatment would be the lack of available access to hyperbaric chambers in areas where frostbite occurs. With all hyperbaric oxygen treatments, the lack of widespread facilities creates a natural rationing of services. However, if you have the capability as we do, then perhaps the best model of care is rewarming, anticoagulation, vasodilators, infection control, and hyperbaric oxygen followed by rigorous rehabilitation.
Footnotes
Acknowledgments
We want to thank the patient and his partner, who were generous enough to consent to using these images and clinical details in this case study. Written consent was provided.
Declaration of Conflicting Interest
The author declares no potential conflict of interest with respect to the research, authorship and/or publication of this article.
Ethical Approval was not Required
Informed consent to publish was provided by the patient in written format.
Funding
The author received no financial support for the research, authorship, and/or publication of this article.
