Hypothermia & Cold Injuries

what body temperature is indicative of hypothermia?

< 35*C

what are the 4 mechanisms of heat loss?

-radiation

-conduction

-convection

-evaporation

what is primary accidental hypothermia?

-hypothermia that results from environmental exposure in a cold climate

what are 5 risk factors for accidental hypothermia?

-extremes of age

-recreational exposure

-drug/EtOH use

-mental d/o

-inadequate clothing

what is therapeutic hypothermia?

-purposeful hypothermic drop in body temperature to decrease tissue damage during ischemic events

when is therapeutic hypothermia used?

-global cerebral ischemia

why is therapeutic hypothermia used?

-neuroprotection

when should therapeutic hypothermia be initiated for the best prognosis?

-asap

what are the 3 hallmark features of mild hypothermia?

-body temperature = 32-35*C

-conscious

-shivering

what is the Tx for mild hypothermia (2)?

-warm environment, blankets, & drinks

-attempting small active movement

what are the 3 hallmark features of moderate hypothermia?

-body temperature = 28-32*C

-impaired consciousness

-possible shivering

what is the Tx for moderate hypothermia?

-warm environment + warmed IV fluids

-monitor cardiac & core temperature

-forced-air warming using bear hugger

what severity of hypothermia is treated with a bear hugger?

-moderate

what are the 3 hallmark features of severe hypothermia?

-body temperature < 28*C

-unconscious

-present vitals

what is the Tx for severe hypothermia?

-airway management

-transfer to facility with ECMO/initiate ECMO

-thoracic, bladder, & peritoneal lavage

what severity of hypothermia requires airway management?

-severe

what severity of hypothermia may need ECMO for Tx?

-severe

what severity of hypothermia is treated with thoracic, bladder, & peritoneal lavage?

-severe

what are the 3 hallmark features of hypothermic cardiac arrest?

-body temperature < 28*C

-unconscious

-no vital signs

what is the Tx for hypothermic cardiac arrest?

-ALS = CPR + Epi x3

-transfer to facility with ECMO/initiate ECMO

when treating hypothermic cardiac arrest, what part of the body should NOT be rewarmed?

-head

pulmonary edema is present with what stage of hypothermia?

-severe

how should you measure core body temperature of a patient who is intubated?

-probe in the lower 1/3 of the esophagus

how should you measure core body temperature of a patient who is not intubated?

-rectal probe 15cm

what are the 3 common EKG findings of hypothermia?

-prolonged PR or QRS

-J wave

-arrhythmia

what is the progression of a patient’s cardiac rhythm as hypothermia worsens?

-tachycardia → bradycardia → atrial fibrillation with slow ventricular rate → ventricular fibrillation → asystole

what are the 2 possible methods of passive external rewarming?

-removal from cold environment

-insulation with blankets

what are the 3 possible methods of active external rewarming?

-heated blanket (40*C)

-radiant heat

-forced air

what are the 6 possible methods of active core rewarming?

-inhalation

-heated IV fluids

-heated gastric, colonic, & bladder lavage

-mediastinal lavage

-peritoneal lavage

-ECMO

what condition is also called immersion foot?

-trench foot

how does trench foot develop?

-prolonged exposure in wet environment at above freezing temperature causes cooling of tissue

what patient demographic most commonly presents with trench foot?

-military personnel

how does trench foot typically present initially (3)?

-subjective numbness/tingling

-pale & mottled skin

-possibly pulseless

what are the 4 phases of trench foot rewarming?

1: initial presentation

2: hyperemia after hours of rewarming with severe burning pain & return of proximal sensation

3: edema & bullae formation 2-3 days later

4: long-term hyperhidrosis & cold sensitivity

what is chilblains/pernio?

-tissue injury caused by chronic, intermittent exposure to dry nonfreezing temperatures

when do chilblains manifestations occur after the exposure?

-12-24 hours

how does chilblains typically present (4)?

-edema & erythema

-cyanosis

-nodule formation

-burning pain with rewarming

how are chilblains & trench foot treated?

-close monitoring for infection

-vasodilators

what are the 4 vasodilator agents that can be given for trench foot or chilblains?

-nifedipine

-topical corticosteroids

-prednisone

-prostaglandin E1

what is frostbite?

-freezing & crystalizing of fluids in the interstitial & cellular spaces caused by prolonged exposure to freezing temperatures

what are the 4 most common locations where frostbite occurs?

-fingers

-toes

-nose

-ears

what is the most common freezing injury?

-frostbite

what are 3 risk factors for frostbite? why do these factors increase the risk?

-Raynaud’s

-PAD

-diabetes

-cause vasoconstriction in the periphery

what is the zone of coagulation in frostbite?

-distal affected area that is the most severe & irreversible

what is the zone of stasis in frostbite?

-middle of the affected area where severe damage that may not be reversible occurs

what is the zone of hyperemia in frostbite?

-most superficial portion of the affected area that is damaged the least & is self-limiting in < 10 days

why can the severity & degree of frostbite not be determined right away?

-b/c the gangrenous tissue takes time to slough away

what are the 3 hallmark features of 1st degree frostbite?

-numbness

-central pallor + surrounding erythema & edema

-no blisters

what degree of frostbite is also called frostnip?

-1st

what are the 4 hallmark features of 2nd degree frostbite?

-blistering with erythema & edema

-sensory deficit

-progression to desquamation with black eschar

-transient cold sensitivity

when would you expect formation of blisters in 2nd degree frostbite?

-6-24 hours post-exposure

what are the 5 hallmark features of 3rd degree frostbite?

-hemorrhagic blisters

-necrosis

-blue-gray skin discoloration

-deep burning pain with warming

-thick gangrenous eschar formation in 2 weeks

what are 3 complications of 3rd degree frostbite?

-ulceration

-severe cold sensitivity

-growth plate injury

what are the 4 hallmark features of 4th degree frostbite?

-mottling of skin

-dry, black, mummified appearance of skin

-little edema

-no pain with warming

what are the 3 goals of frostbite Tx?

-salvage as much tissue as possible

-achieve maximum return to function

-prevent complications

how is frostbite diagnosed?

-clinical

what are the 4 components of frostbite Tx?

-ABCs

-correction of hypothermia to > 34*C

-rapid rewarming

-anticipation & Tx of pain

why should you not rub the area of frostbite?

-creates more tissue damage

how is rewarming performed in cases of frostbite?

-circulating 42*C H2O for 10-30 minutes

after the affected area thaws, how should you continue treating frostbite (5)?

-protection

-pain control

-topical aloe vera

-rehabilitation

-prophylactic antibiotics

what are 9 complications of frostbite?

-long-term disability

-infection

-tetanus

-tissue loss/gangrene

-septicemia

-compartment syndrome

-growth plate injuries

-reflex sympathetic dystrophy

-cold sensitivity

what are the 4 indications for a good prognosis of frostbite?

-superficial involvement

-early sensation to pinprick

-healthy appearance of skin after rewarming

-clear blisters

what are the 3 indications for a poor prognosis of frostbite?

-no edema

-hemorrhagic blisters

-mottled, cyanotic appearance of skin with continued anesthesia

what are 9 common causes of secondary accidental hypothermia?

-burns

-recent birth

-impaired shivering

-medications

-metabolic & endocrine d/o

-neuro dysfunction

-sepsis

-shock

-trauma