Just the Facts: Sympathectomy for Frostbite – A Resident Clinical Pearl

Robert J. Dunfield

PGY-3 – Integrated Family Medicine/Emergency Medicine Program

Reviewed by: Dr. Devon Webster

Copyedited by: Dr. Mandy Peach

Case:

You’re working in a rural emergency department when a 76 year old man is brought in by ambulance after being found laying in a snowbank on the side of the road, next to his parked car. The temperature outside is -20°C and it’s snowing quite heavily. As far as you can gather, the man has a history of cognitive impairment and lives alone.

You perform an appropriate initial resuscitative workup. His core temperature is warmed to 36.5°C and he is stabilized, but complains of ongoing left hand pain. You note that the man’s left hand has the following features: it is cold, throbbing, his phalanges are covered in blisters, surrounded by edema. You suspect frostbite.

Figure 1: Frostbite. [Peer-Reviewed, Web Publication] Herndon, A. Amick, A. (2021, Mar 15). Health Risks Imposed by the Beach. [NUEM Blog. Expert Commentary by Lank, P]. Retrieved from http://www.nuemblog.com/blog/health-risks-imposed-by-the-beach.

1. What features on clinical examination distinguish first, second, third, and fourth degree frostbite? ^{[1, 2]}

In the emergency department setting, distinguishing between degrees of frostbite is not accurate and not clinically useful. Similar to burns, it is more useful in the acute setting to classify frostbite as superficial or deep to help determine prognosis. Tissue involvement can change through rewarming and progress with time. All frostbite injuries are treated with a similar approach, no matter the degree of involvement.

Classically, however, frostbite injuries have been categorized as first, second, third, or fourth degree. The following table outlines the characteristics for each of these classifications.

Clinical features indicating favourable prognosis:
* Intact sensation to pinprick
* normal skin color
* large blisters with clear fluid

Clinical features indicating poor prognosis:
* Non-blanching cyanosis
* Dark fluid-filled blisters
* Hard, non-deforming skin.

2. What treatment options are available for rewarming a peripheral frostbite injury? [1, 3, 4, 5, 6]

The treatment for frostbite requires a careful approach that starts immediately during the pre-hospital stage. These patients should:

1) be removed from the cold environment,
2) have any cold and wet clothing removed,
3) begin rewarming of affected area in circulating warm water bath (37 to 39*C)

*Avoid rewarming with dry heat, vigorous rubbing, or fire.

Once these patients have arrived to your emergency department, initial resuscitation of the whole patient should be the primary focus of treatment. Follow your ABC’s and ensure their core temperature is stabilized prior to focusing on the frostbitten limb.

In terms of rewarming, the traditional approach has implicated the following interventions:

1) Analgesia: thawing can be extremely painful. Administer anti-inflammatories and/or short acting opioids as needed.

2) Warm and wet immersion: immerse the frostbitten limb in circulating water/saline warmed to 37 to 39°C.

3) Fluid resuscitation: as needed, particularly if there is concern for cold diuresis in the setting of hypothermia.

4) Movement: encourage gentle movement of the affected limb as tolerated, but ensure no rubbing/friction is applied to the frostbitten area.

5) Topical aloe vera q6h: this treatment has shown to be effective in fighting the arachidonic acid cascade that promotes inflammation and prostaglandin formation, thereby reducing tissue damage in frostbite. Can be considered when available.

6) Tetanus toxoid

7) Careful wound care: this is an important aspect of ongoing management. Prior approaches to frostbite discuss the possibility of debridement of blisters and soft tissue, but this does not need to occur in the acute setting. Incision and drainage of white, cloudy blisters remains controversial.

8) Affected limb elevation

3. What management options exist for post-rewarming pulse deficits in frostbite? [1, 5, 6, 7]

If a hand continues to demonstrate ongoing evidence of ischemia or rewarming therapy fails to achieve reperfusion, the following management strategies are suggested:

1) If not already done, emergently consult local frostbite management expertise, such as plastic or vascular surgery.

2) Consider vascular imaging of the affected area.

3) Intravenous or intraarterial thrombolytic (Tpa 0.15 mg/kg bolus then 0.15 mg/kg over 6 hours). After Tpa is administered, start IV unfractionated heparin (2 mg/kg/min) for 24 to 72 hours. This reduces the risk of digital amputation.

4) Iloprost* IV (where available) 2 mg/kg/min, 6 hours per day for 5 days.
*Iloprost is not currently available commercially in Canada, but many Canadian physicians working in northern regions of the country are currently advocating for its increased availability. Iloprost is an arterial vasodilator, often used in pulmonary arterial hypertension.

4. What role does local anaesthetic play in rewarming a frostbitten hand? [8, 9]

Studies have assessed the role of regional anesthesia to create a chemical sympathectomy for patients with frostbite. Hand surgeries performed under local anaesthetic have shown to reduce sympathetic innervation of the hand, resulting in hyperemia (increased blood flow) while simultaneously providing pain control. Hyperemia is likely a result of the sympathetic blockade that results in increased blood flow and vasodilatation peripherally. This peripheral nerve block focuses on the ulnar and median nerves.

One study looked at 39 patients undergoing carpal tunnel release. It showed that a volar nerve block resulted in 74% of patients having a temperature increase of >1°C in their distal fingers following distal forearm anaesthetic block.

Concerns about finger vasoconstriction as a result of epinephrine use in anaesthetic injected at the wrist, theoretically worsening ischemia and necrosis risk in the fingers, are currently unfounded. Local anaesthetic without epinephrine comparatively will have a shorter duration of hyperemia and analgesia.

In general, there is limited research available around the use of local anaesthetic in frostbite.
No clear guidelines outlining indications and contraindications to local anaesthetic sympathectomy in the treatment of frostbite presently exist. Currently, its use as an adjunct to other routine management of acute frostbite is recommended.

5. How is a local anaesthetic sympathectomy performed in the hand? [8]

1) Materials needed:

-Aseptic cleaning wipe/solution
-10 mL syringe
-1% lidocaine with epinephrine
-18G needle (to draw up local anaesthetic)
-27G needle (to inject local anaesthetic)
-Sterile marking pen

2) Identify your landmarks: injection of the local anaesthetic should be performed between the palmaris longus and flexor carpi ulnaris tendons, just proximal to the wrist crease. Mark the area.

3) Clean the area with an antiseptic solution.

4) Inject 10 mL of 1% lidocaine to the area landmarked, subfascially. There is no need to fan the needle during this injection.

5) Continue to monitor the temperature of the involved fingers. It is possible the area near the wrist infiltrated by the local anaesthetic will blanche, but the hand and fingers distal to this area should become warmer and hyperemic.

6. How long do the effects of local anaesthetic sympathectomy last? ^[8]

It is estimated that hyperemia will last for approximately 2 hours. Numbness may last up to 6 hours.

https://handsurgery.org/multimedia/files/preCourse/Frostbite%20treatment%20with%20blocks.pdf

SUMMARY AND KEY POINTS:

-Classifying frostbite in an acute setting is notoriously unreliable due to the ability of the insult to progress over time. Your approach to frostbitten patients should be consistent despite their initial tissue involvement.

-Initial management of the frostbite patient should focus on resuscitation and core rewarming.

-Removing the patient’s exposure to hypothermia and cause of frostbite, pain control, warm and wet rewarming, tetanus vaccination, topical aloe vera, wound care, considering thrombolysis, and consulting experts in frostbite management are core tenants of frostbite care.

-Consider local anaesthetic sympathectomy using distal volar wrist nerve block as an adjunctive therapy in patients with hand frostbite.

-Iloprost is currently unavailable commercially in Canada but advocacy is ongoing to increase its availability for treatment of frostbite, especially in northern areas of the country.

REFERENCES:

1. Tintinalli, J.E., Ma, O.J., Yealy, D.M., Meckler, G. D., Stapczynski, J.S., Cline, D., Thomas, D.M. (2016). Tintinalli’s emergency medicine: A comprehensive study guide(Ninth edition.). New York: McGraw-Hill Education. Chapter 208: Cold Injuries.
2. Comp, L. Brrr! ED Presentation, Evaluation, and Management of Cold Related Injuries. net: Practice Updates. 2018; Last updated: May 21, 2018. Accessed: June 01, 2021. Available from: http://www.emdocs.net/brrr-ed-presentation-evaluation-and-management-of-cold-related-injuries/
3. Thomas, A. CRACKCast E139 – Frostbite. org. 2017; Last updated: December 28, 2017. Accessed: June 01, 2021. Available from: https://canadiem.org/crackcast-e139-frostbite/
4. Handford, C., Buxton, P., Russell, K., Imray, C. E., McIntosh, S. E., Freer, L., Cochran, A., & Imray, C. H. 2014. Frostbite: a practical approach to hospital management. Extreme physiology & medicine, 3, 7. https://doi.org/10.1186/2046-7648-3-7
5. Basit, H., Wallen, T.J., Dudley, C. 2021. Frostbite. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nih.gov/books/NBK536914/
6. Poole, A., and Gauthier, J. 2016. Treatment of severe frostbite with iloprost in northern Canada. CMAJ, 188 (17-18): 1255-1258. https://doi.org/10.1503/cmaj.151252
7. Yun, T. 2021. ‘It’s a promising result’: Made-in-Yukon treatment reducing amputations in most severe frostbite cases. CTV News: Health News. Last updated: March 3, 2021. Accessed: June 01, 2021. Available from: https://www.ctvnews.ca/health/it-s-a-promising-result-made-in-yukon-treatment-reducing-amputations-in-most-severe-frostbite-cases-1.5331820
8. Chandran GJ, Chung B, Lalonde J, Lalonde DH. The hyperthermic effect of a distal volar forearm nerve block: a possible treatment of acute digital frostbite injuries? Plast Reconstr Surg. 2010 Sep;126(3):946-950. doi: 10.1097/PRS.0b013e3181e60400.
9. Rakower SR, Shahgoli S, Wong SL. Doppler ultrasound and digital plethysmography to determine the need for sympathetic blockade after frostbite. J Trauma. 1978 Oct;18(10):713-8. doi: 10.1097/00005373-197810000-00006.