Clinical utilization of a sous vide device in the acute rewarming of frostbitten extremities
a b s t r a c t
The current standard of care for acute frostbite rewarming is the use of a circulating Warm water bath at a tem- perature 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 extrem- ities in one 30 m cycle. No adverse events were reported and providers rated this as a convenient method of water bath management.
Frostbite is a clinical entity in which tissues undergo freezing dam- age due to prolonged exposure to cold. Once in an environment where the potential for re-freezing is minimal, the current standard of care for acute frostbite is Rapid rewarming of the affected body part using a circulating warm water bath targeted to 37-39 ?C. In both the backcountry and emergency department (ED), there is no standardized method to safely, effectively, and efficiently create and maintain a circu- lating warm water bath .
Sous vide cooking has been used for decades to precisely cook foods by maintaining consistent internal temperatures without drying or los- ing flavor. In early 2020, a study was published investigating the in vitro use of sous vide devices (SVD) to create warm water baths to rewarm frozen pigs’ feet . In this study, the SVD maintained the water bath at a constant 40 ?C for 30 m and resulted in the successful thawing of the pig foot. The sous vide rewarming (SVR) modality was compared
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against and outperformed manual water exchanges to maintain the water bath temperature. We report a case in which a SVD was used clin- ically to re-warm acute frostbite in the ED.
- Case report
In January 2021, a 34 y male presented to the ED with acute frost- bite of the bilateral fingers and toes. (Fig. 1) While hiking in the White Mountains of New Hampshire, the patient lost his shoes, socks, and gloves in a snowdrift, and had to self-extricate barefoot down a snow-covered trail for approximately 3 h. The patient was recruited and consented to have both feet re-warmed with water baths created and maintained by SVDs, using a protocol approved by the institutional review board at Dartmouth-Hitchcock Medical Center.
An Anova Precision(R) Cooker Nano SVD was clamped to a basin, which was then filled to the marked line with Room temperature water, for each extremity being rewarmed. Two thermometers were at- tached to the water basin, one (OXO Good Grips Chef’s Precision Ther- mometer) on the toe end near the SVD, and one (Vilgen Kitchen Thermometer) on the heel end closest to the frozen extremity, to
compare temperature uniformity in the water bath. The provider then placed the frozen extremity into the water bath, activated the SVD, and set it to a target temperature of 38 ?C with a 30 m run time. (Fig. 2) This temperature was chosen as mid-range of previously pub- lished guidelines for frostbite water bath temperatures . An investi- gator recorded temperatures from each thermometer every 2 m
during the warming phase until the target temperature of 38 ?C was reached. Once the target temperature was reached, the SVD automati- cally began timing with the programmed 30 m cycle. The treatment phase ran for 30 m and thermometer readings were recorded every 2 m. The starting water temperature for the two baths was 23.1 ?C. The two water baths took an average of 25 m to reach the 38 ?C target temperature. During the treatment phase the SVD maintained the water temperature within +-1 ?C of the target, with a maximum and minimum of 38.9 ?C and 37.6 ?C, respectively. (Fig. 3) The mean gradient between the proximal and distal ends of the water bath was 0.1 (+- 0.1)oC. At the end of 30 m, the tissue was fully thawed.
plastic surgery and vascular surgery were consulted and the patient was admitted with plans for conservative management. His Creatinine kinase peaked at 12,460 units/L without resultant acute kidney injury. He was discharged on hospital day 3 to follow up with plastic surgery and wound care at an outside hospital. Longitudinal follow up revealed that the patient had not required amputations and had returned to nor- mal activity.
This case demonstrated that a SVD can be used successfully in the treatment of acute frostbite to both create and maintain a circulating warm water bath. Pragmatically, it would likely be most efficient in the clinical setting to begin with warm tap water in the basin that is non-injurious to the clinician’s hand, and then use the SVD to circulate the water and maintain the temperature.
Our patient had less extensive frostbite of both hands that were si- multaneously rewarmed by nursing staff using traditional manual water bath management. While comparison between SVR and manual water bath management was not an objective in this case, this provided an opportunity for comparison between methods. Therefore, the lim- ited recorded water bath temperatures for the right hand water bath were included. (Fig. 3) These temperatures were recorded more infre- quently, displayed more variability, and were not as precisely main- tained within the target temperature range as with SVR, which was consistent with prior studies .
SVR method is much simpler and less time consuming than man- ual water exchanges for the provider managing the water bath. It may also be safer, as the Manual method may not maintain the water at the targeted temperature, or burn the frostbitten and often insensate extremity. Our case has shown the feasibility of using SVDs clinically to manage the warm water bath required to re- warm acute frostbite. We believe SVR is a safe, effective, and practi- cal tool for the treatment of acute frostbite and has potential for widespread application and improvement in the current standard of care in both high and low resource clinical settings. However, more data is needed to support the reliability and ease of use shown in this case.
This project did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Material support statement
The two SVDs were donated by Anova(R).
CRediT authorship contribution statement
Nicholas J. Daniel: Writing – review & editing, Writing – original draft, Supervision, Project administration, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization.
Fig. 3. Water bath temperatures during warming and treatment phases for proximal (heel) and distal (toe) thermometers in both enrolled feet and one hand. The power cord present in the patient’s room could not meet the output requirements for both SVDs at once. This problem was realized and an alternative power source was acquired and exchanged by the 14 m mark during the water bath warming phase. This change correlated to the upward trend in water bath temperatures 14 m into the warming phase.
Johndavid M. Storn: Formal analysis, Investigation, Writing – original draft, Writing – review & editing. James H. Elder: Writing – review & editing, Writing – original draft, Investigation, Formal analysis. Jessica
We thank Dartmouth-Hitchcock Medical Center clinical engineering for their assessment of the SVD. We would like to thank Anova(R) for the donation of the two SVDs.
- McIntosh SE, Freer L, Grissom CK, Auerbach PS, Rodway GW, Cochran A, et al. Wilder- ness medical society clinical practice guidelines for the prevention and treatment of frostbite: 2019 update. Wilderness Environ Med. 2019;30(4):S19-32.
- Fiutko A, Foreman C, Mycyk M, Weber J. A novel approach to rapid rewarming of a Frostbitten extremity: the sous vide method. Am J Emerg Med. 2020;38(3):463-5.