The Iceman Cometh: Update on Hypothermia and Frostbite Management David S. Bullard, MD, MEd, FACEP,...

The Iceman Cometh: Update on Hypothermia and Frostbite Management

David S. Bullard, MD, MEd, FACEP, FAWMAssistant Professor of Emergency Medicine,

Brown University Alpert Medical SchoolMarch 6, 2012

Disclosures

• No financial conflict of interests• Always willing to obtain some

Objectives

• Review rewarming strategies• Review resuscitation and treatment considerations• Focus on treatment for the urban & suburban ED

environment NOT the backcountry• Discuss some newer treatment modalities

Accidental Hypothermia

“Urban Outdoorsman” syndrome

• October 30, 2011: Snowfall in the Northeast• 1st case of accidental hypothermia for the season• 45 year-old male (well known to the ED staff)• Rectal temperature 32⁰ C (90⁰ F)

Epidemiology

• Hypothermia occurs in various locations and in all seasons• North American survey of 428 cases of civilian accidental

hypothermia– 69 cases occurred in Florida

• Urban settings account for the majority of cases in most industrialized countries

• About 600 annual deaths attributed to accidental hypothermia in the US– About ½ of these deaths are in patients over age 65

Danzl DF, Pozos RS, Auerbach PS, et al. Annals of Emergency Medicine. 1987;16(9):1042-55.

Hypothermia

• Definition– Core body temperature below 35⁰ C (95⁰ F)

• Mild – Core temperature 32 to 35⁰ C (90 to 95⁰ F)• Moderate – Core temperature 28 to 32⁰ C (82 to 90⁰ F)• Severe – Core temperature 20 to 28⁰ C (68 to 82⁰ F)• Profound – Core temperature below 20⁰ C (68⁰ F)

Physiologic Changes of Hypothermia

• Mild– shivering, tachycardia, increased or normal blood pressure,

ataxia, poor judgment, apathy• Moderate

– shivering stops, cardiac output ⅔ of normal, a-fib, paradoxical undressing

• Severe– hypotension, bradycardia, cardiac output ½ of normal, loss of

corneal reflexes, major acid-base disturbances, v-fib • Profound

– pulse 20% of normal, EEG silent, asystole

Osborn Waves

EKG – Osborn Waves or J-waves

“No one is dead until warm and dead.”

• Dogma we all learned• Usual markers of death are unreliable with hypothermia

– Loss of brainstem reflexes– Fixed and dilated pupils– Rigor mortis– Dependent lividity

• Death declared when the patient’s core temperature has been warmed to 32⁰ C (90⁰ F) for 30 minutes

“Some people are dead when they’re cold and dead.”

Paul S. Auerbach, MD

Auerbach PS. Some people are dead when they’re cold and dead. JAMA. 1990 10;264(14):1856-7.

Potassium

• Chart review• Group A – 9 victims from snow avalanches

– Median rectal temperature 29.6° C (85.3⁰ F)– Average potassium level 14.5 mmol / L– All group A patients were in full arrest– No saves despite aggressive rewarming

• Group B – 15 patients with hypothermia following acute drug intoxication and / or cold exposure– Median rectal temperature 28.8° C (83.8⁰ F)– Average potassium level 3.5 mmol / L– All patients recovered, including 2 in full arrest

Schaller MD, Fischer AP, Perret CH. Hyperkalemia. A prognostic factor during acute severe hypothermia. JAMA. 1990 ;264(14):1842-5.

Hypothermia: Prognostic Indicators

• Retrospective Study• 22 patients rewarmed with cardiopulmonary bypass

– 10 patients with stable spontaneous circulation restored

– 2 of these patients survived long-term• Survivors

– Potassium < 9 mmol / L– pH > 6.50

Mair P, Kornberger E, Furtwaengler W, et al. Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest. Resuscitation. 1994;27(1):47-54.

Fluid Resuscitation

• Viscosity of blood increases 2% per degree Celsius drop in temperature

• Most hypothermic patients are severely dehydrated• Need for glucose as well• Consider normal saline with 5% dextrose• Ringer’s lactate should be avoided

Rewarming Strategies Summary

• Passive External Rewarming– Dry blankets & environment (0.5⁰ C – 2⁰ C per hour)

• Active External Rewarming– Bair Hugger™ (0.8⁰ C – 2.4⁰ C per hour)– Warm water immersion (2⁰ C – 4⁰ C per hour)

• Active Simple Core Rewarming– Warmed IV fluids (0⁰ C – 2⁰ C per hour)

• Active Invasive Core Rewarming– Body cavity lavage (minimal, clinically insignificant)– Cardiopulmonary Bypass (6.9⁰ C – 9.8⁰ C per hour)

Negative Pressure Rewarming

• Vital Heat®• The Thermostat®

Negative Pressure Rewarming

• 7 volunteers cooled to a temperature of 34° C (93⁰ F)• Meperidine (Demerol®) given to prevent shivering• Warmed for two hours in 3 treatment arms

– Vital Heat® and Cotton Blanket– Cotton Blanket– Forced Air Rewarming

• Vital Heat® warming (1.3 ± 0.4°C)• Cotton blanket alone (1.2 ± 0.4°C)• Core temperature increased significantly more with

forced air warming (2.6 ± 0.6°C)

Taguchi A, Arkilic CF, Ahluwalia, A, et al. Negative pressure rewarming vs. forced air warming in hypothermic postanesthetic Volunteers. Anesthesia and Analgesia. 2001;92(1):261-266.

Frostbite

Napoleon’s Retreat from Moscow

The Yeti is the exception

• Humans are better designed to be tropical beings• Basal conditions

– Total cutaneous blood flow of 200 to 500 mL/min• External heating to 41⁰ C (106⁰ F)

– Total cutaneous blood flow of 7000 to 8000 mL/min• External cooling to 14⁰ C (57⁰ F)

– Total cutaneous blood flow of 20 to 50 mL/min

Cold-Induced Vasodilatation

• “Hunting Response”• Maximal vasoconstriction at 15⁰ C• At 10⁰ C, this vasoconstriction is interrupted every

5-10 minutes by vasodilatation• Exposure to cold offers some acclimatization of this

response

Frostbite Classification

• First Degree• Numbness and

erythema without tissue loss

• May have a white or yellow plaque

• Edema common

Cauchy E, Chetaille E, Marchand V, et al. Retrospective study of 70 cases of severe frostbite lesions: A proposed new classification scheme. Wilderness & Environmental Medicine. 2001;12:248-255.


• Second Degree• Superficial skin

vesiculation• Clear or milky fluid in

blisters• Surrounding erythema

and edema



• Third Degree• Deeper hemorrhagic

blisters• Injury extends into the

reticular dermis• Beneath the dermal

vascular plexus



• Fourth Degree• Mummification• Muscle and bone

involvement


Bone Scanning


Frostbite Rewarming

• When to rewarm in the field?• Immersion in circulating water• 40 – 42° C (104 – 107.6° F)• Avoid physical trauma• Pain control

Blister Care

• Debridement of clear blisters (2nd degree frostbite)– Prevention of further contact of PGF2α and TXA2

• NO debridement of hemorrhagic blisters (3rd degree frostbite)– Prevent desiccation of the deep dermis– May be helpful to aspirate the fluid

Ibuprofen

• Inhibits the arachidonic acid cascade• Decreases prostaglandin synthesis• Decreases systemic levels of thromboxane• Ibuprofen recommendations

– Based on a single animal study showing a 23% tissue survival with aspirin vs. control

– Theoretically aspirin blocks the production of certain prostaglandins that are beneficial to wound healing

• Starting dose of 400 mg• Continue dose at 12 mg / kg / day

McIntosh SE, Hamonko M, Freer L, et al. Wilderness Medical Society practice guidelines for the prevention and treatment of frostbite. Wilderness & Environmental Medicine. 2011;22:156-166.

Aloe Vera

• Ten frostbitten rabbit ears assigned to 4 groups:– untreated controls– aloe vera cream– Pentoxifylline (Trental®)– aloe vera cream and pentoxifylline

• Results– control group – 6% tissue survival– Aloe vera cream – 24% tissue survival– Pentoxifylline – 20% tissue survival– combination therapy 30% – tissue survival

Miller MB, Koltai PJ. Treatment of experimental frostbite with pentoxifylline and aloe vera cream. Archives of Otolaryngology and Head Neck Surg. 1995;121(6):678-680.

Thrombolytics

• Retrospective, single-center review• 32 patients with digital involvement of frostbite

– All patients got digital angiography• 7 patients received tPA (6 within 24 hours of injury)• The incidence of digital amputation in patients who

did not receive tPA was 41%• In those patients who received tPA, the incidence of

amputation was reduced to 10% (P<.05)

Bruen KJ, Ballard JR, Morris SE, et al. Reduction of the incidence of amputation in frostbite injury with thrombolytic therapy. Archives of Surgery. 2007;142:546-553.

Vasodilators

• Iloprost– Prostaglandin E₁

• Reserpine– Inhibits uptake of norepinephrine

• Pentoxifylline– Phosphodiesterase inhibitor

• Buflomedil– Inhibition of α-receptors

Vasodilators / Thrombolytics

• Open-label study• Randomly assigned 47 patients with severe frostbite to

3 different treatment arms• All patients got rapid rewarming, plus aspirin and

buflomedil• Randomized to receive one of three regimens for 8

days– Group 1 – aspirin and buflomedil– Group 2– aspirin plus iloprost– Group 3 – aspirin, iloprost and rt-PA (day 1 only)

Cauchy E, Cheguillaume B, Chetaille E. A Controlled Trial of a Prostacyclin and rt-PA in the Treatment of Severe Frostbite. New England Journal of Medicine. 2011; 364:189-190.

Results

• Group 1 – aspirin and buflomedil– Risk of amputation was 60% (9 of 15 patients)

• Group 2– aspirin plus iloprost– Risk of amputation was 0% (0 of 16 patients)

• Group 3 – aspirin, iloprost and rt-PA (day 1 only)– Risk of amputation was 19% (3 of 16 patients)

• Authors maintain a role for rt-PA in select patients

Cauchy E, Cheguillaume B, Chetaille E. A Controlled Trial of a Prostacyclin and rt-PA in the Treatment of Severe Frostbite. New England Journal of Medicine. 2011; 364:189-190.

Summary

Hypothermia• Remove wet clothing• Dry environment• Accurate temperature• Hyperkalemia / Acidosis• Dehydration• Caloric needs• Rewarming

– Mild– Severe

Frostbite• Rewarming• Pain control• Ibuprofen• Blisters

– Clear– Hemorrhagic

• Aloe vera• Tetanus status• Consultants for long-term

sequelae

Prevention

The Iceman Cometh: Update on Hypothermia and Frostbite Management David S. Bullard, MD, MEd, FACEP,...

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