Cold Injury

HypothermiaHypothermiaandand

Cold Weather InjuriesCold Weather Injuries Recognizing, Preventing and TreatingRecognizing, Preventing and Treating

Shawn F. Kane, M.D.Kevin deWeber, MD, FAAFP

OutlineOutline• History

• Cold Injury v Heat Injury

• Definitions

• Physiology/Effects on Organ Systems

• Non-Freezing and Freezing cold injuries

• Treatment

• Field Management

16th Annual AMAA Sports 16th Annual AMAA Sports Medicine SymposiumMedicine Symposium

Historical PerspectiveHistorical Perspective• French invasion of Russia in 1812. Baron

de Larrey, chief surgeon, noted mental and physical hardships by Soldiers exposed to the cold– Freeze-thaw-refreeze phenomenon.

• George Washington 10% of his troops perished in the winter of 1777-78 due to cold.


Historical PerspectiveHistorical Perspective• WWII 200,000 Allied and German troops

suffer cold related injuries or deaths

• Korea 10% of all US fatalities were cold related.– 1950 Battle of Chosin Reservoir. 30K UN

troops held off and repelled 60K Chinese• UN: 2.5K KIA, 5K WIA, 7.5K Frostbite/cold weather injuries

• Chinese: 25K KIA, 12.5K WIA, 30K Frostbite/cold weather injuries

Cold Injury v Heat InjuryCold Injury v Heat Injury

• Heat Injuries: CDC 1999-2003. 3,442 deaths due to heat. Mean 688/yr

• Cold Injuries: CDC 1999-2002. 4,407 deaths due to cold. Mean 689/yr

• 60%/40% - underlying cause/contributing factor


DefinitionsDefinitions

• Accidental Hypothermia: the unintentional drop in core body temperature to <35°C (95°F)

• Intentional Hypothermia:

controlled cooling of core

body temperature for

specific medical

indications (CVA, MI, TBI)16th Annual AMAA Sports 16th Annual AMAA Sports Medicine SymposiumMedicine Symposium

DefinitionsDefinitionsTypes of Heat LossTypes of Heat Loss

• Radiation: dispersal of heat energy from uncovered skin to nearby objects– >50% of our heat loss

• Evaporation: loss of heat via the transformation of liquid water into water vapor. – 20-30% of heat loss– Insensible heat loss can lead to dehydration if

not accounted for.16th Annual AMAA Sports 16th Annual AMAA Sports Medicine SymposiumMedicine Symposium

DefinitionsDefinitionsTypes of Heat LossTypes of Heat Loss

• Conduction: transfer of heat from one object to another through physical contact– Conductivity of water is 23X that of air!! – Immersion injury reduces body temp more

rapidly than convective loss

• Convection: loss of heat to the air moving next to the body– Windy days– Cycling, running


Hypothermia Hypothermia Stages/ClassificationsStages/Classifications

ACCIDENTAL• MILD: 32°C – 35°C

90°F - 95°F

• MODERATE: 28°C – 32°C

82°F – 90°F

• SEVERE: <28°C

<82°F• 33-35(91-95), 31-32(88-90)

<31(<88)

Hypothermia of TRAUMA

• MILD: 34°C – 36°C

93°F - 97°F

• MODERATE: 32°C – 34°C

90°F - 93°F

• SEVERE: <32°C

<90°F

Jurkovich GJ. Surg Clin N AM87(2007) 247-267

Reduced shivering

Shivering

NO shivering

Human PhysiologyHuman Physiology

• Range of 34-40.5°C(95-105°F) to retain normal organ function

• Thermoregulatory drive is so important that it takes precedence over many other homeostatic functions

• Human body can compensate for hyperthermia better than hypothermia



Heat Loss Heat Gain


Physiology/Effects on Organ Physiology/Effects on Organ SystemsSystems

• Initial effects mimic those of sympathetic stimulation– Tremor– Vasoconstriction– Increased O2 consumption– Increased Heart Rate– Increased Minute Ventilation

• Continued cold exposure results in inability to compensate



• Cardiovascular:– Initial tachycardia progresses to bradycardia

starting at 34°C• CO initially increased despite a drop in BP• 50% decrease in HR

– <30°C atrial fibrillation, bradycardia and ventricular dysrhythmias

– <25°C asystole– At temperature <30°C decreased effects of

cardiac medications


• Cardiovascular:– Conduction system is VERY sensitive to

decrease temperatures.– PR interval, QRS and QT interval prolong as

temperature decreases or stays below normal– J or Osborn wave –in 80% of hypothermic

patients– Bretylium is the only CV drug that works at

decreased temperatures


Osborn or J waveOsborn or J wave

Colder the temperature the larger the J wave


• Respiratory:– Initially increased but becomes depressed at

temperature <33°C– Increased mucous production (bronchorrhea)– Left shift in oxyhemoglobin curve impairing

oxygen delivery



• GI:– Ileus, bowel wall edema, shallow gastric

ulcers (Wischnevsky’s Ulcers)– Decrease hepatic function – drug metabolism– Hemorrhagic pancreatitis, elevated amylase

• RENAL:– Initial vasoconstriction contributes to diuresis– Later loss of distal tubular water reabsorption

due to dec ADH sensitivity and inc electrolyte excretion 16th Annual AMAA Sports 16th Annual AMAA Sports

Medicine SymposiumMedicine Symposium


• HEME: – Cold platelets DO NOT work– 34°C – 40% decrease in coagulation enzyme

function– Hemoconcentration

• 1°C drop in temp 2% increase in hematocrit• Normal hematocrit in moderate to severe

hypothermia: need to be concerned about blood loss.

– Decreased WBC function, increased infection

risk 16th Annual AMAA Sports 16th Annual AMAA Sports Medicine SymposiumMedicine Symposium


• NEUROLOGICAL: – Decreased neural transmission

• Incoordination and cognition, numbness

– DTRs decrease and eventually flaccid paralysis

– <32°C = amnesia– 31°C-27°C lose consciousness– “paradoxical undressing”


HypothermiaHypothermia

• Standard clinical thermometers and a false sense of security– Only go down to 34°C(94°F) need low-reading

rectal thermometers (<32/90°C/F)– Best accuracy thermometer in place for 3

minutes at a depth of 10 cm

• Treat the patient clinically not the classification of hypothermia


NOT DEAD UNTIL THEY ARE WARM AND DEAD

(unless they are really dead)

Hypothermia Treatment

• RECOGNIZE THE CONDITION!

• Removal from nasty conditions

• Removal of wet clothing

• Handle with care (testy heart)

• Insulate and warm up

Rewarming Methods

• External – blankets– hot water bottle– heater– another body– Immersion

• Internal– Warm IV fluids– Warmed air

•Exercise is BAD

•Depletes glycogen, reduces shivering

•Increases heat loss

Hypothermia in Sport

• High risk sports– Water sports– Running, cycling– Alpine & cold weather sports

Mild Hypothermia in Sports91-95 F

• Remove from cold

• Insulate

• Warm, sweet drink– No alcohol

• Minimal to mild activity if improving

Moderate Hypothermia88-90 F

• Passive rewarming– In field, no active rewarming until rectalT >93F

• Monitor rectal temp

• Transport to ER for observation

Severe Hypothermia<88 T

• Handle with care!

• Gentle passive rewarming only

• Transport immediately, ERICU

Non-Freezing Cold InjuriesNon-Freezing Cold Injuries(NFCI)(NFCI)

• A clinical syndrome defined as:Injury to soft tissues of the extremities that result

from prolonged cooling and/or constant exposure to wet/damp conditions.

• Peripheral nerves (then muscle) are most susceptible to cold related injuries.

• Sequelae to NFCI may arise immediately after the incident or may not demonstrate themselves for up to 18 months post exposure

Non-Freezing Cold InjuriesNon-Freezing Cold Injuries

Wet

• Trenchfoot– Prolonged exposure to temps

between 0-32°C(32-60°F) for hours

to 3-4 days

• Swollen, edematous, numb foot

• Initially red then becomes pale and cyanotic

• Increased sensitivity to pain and infections

Dry

• Chilblains or Pernio– Exposure to temps <32°C(60°F)

• Bare skin exposed to dry environment

• Erythematous, tender, swollen, itchy and painful papules

• After rewarming – inflamed, red and hot to the touch for hours


Non-Freezing Cold InjuriesNon-Freezing Cold Injuries

Wet Dry


ACSM 2005ACSM 2005

Non-Freezing Cold InjuriesNon-Freezing Cold Injuries(NFCI)(NFCI)

• Transient Sequelae:– Hyperhidrosis– Hyperesthesia/Anesthesia

of digits– Dec ROM and joint

swelling– Edema– Fat pad loss, transient

muscle atrophy– Pain from injury to

peripheral nerves or small vessels as a result of ischemia

• Late Sequelae:– Hyperesthesia of distal

digits– Increased sensitivity to

heat and cold– Nail bed deformities– Hyperhidrosis,

hypohidrosis or anhidrosis– Decreased proprioception– Pain– Loss of fibrocartilage in ear– AVN, growth plate injuries

Freezing Cold Injuries (FCI)Freezing Cold Injuries (FCI)

• A clinical syndrome of temporary or permanent tissue damage that results from the formation of extra/intracellular crystals due to prolonged exposure to sub-freezing temperatures

• Extent of damage can be superficial (frostnip) to full thickness (bones and muscles)– Grade 1 through 4

• FCI composed of two parts: immediate and reperfusion

Freezing Cold Injuries (FCI)Freezing Cold Injuries (FCI)Initial Freeze Injury

• Hyperosmolarity disrupts cell function

• Rapid freezing leads to intracellular crystals and immediate cell death

• Loss of pain sensation

Reperfusion Injury• RBC, WBC and platelet

aggregation leads to patchy thrombosis in microcirculation

• Oxygen free radicals, prostaglandins and thromboxane worsen vasoconstriction and thrombosis

• MAJORITY of damage occurs during REWARMING

ACSM 2005ACSM 2005

Freezing Cold Injuries (FCI)Freezing Cold Injuries (FCI)

Cold Weather Injury TreatmentCold Weather Injury Treatment

• Low index of suspicion in an athlete who complains of being cold during or after exercise with a change in sensorium.

• ABCs

• FIRST priority is to prevent further HEAT LOSS! (shelter from wet, cold, windy environments, dry off)


16th Annual AMAA Sports Medicine 16th Annual AMAA Sports Medicine SymposiumSymposium

Cold Weather Injury TreatmentCold Weather Injury Treatment

• DO NOT thaw tissue if there is a risk of re-freezing

• DO NOT RUB the affected area• Minimize motion, move horizontally to

minimize cardiac irritability• Safety of rescuers

•

RewarmingRewarming

• PASSIVE: involves the use of blankets to cover body and head to trap heat being lost.

• ACTIVE: the application of outside heat to raise body temperature– External – heat blanket/forced hot air system – Internal – introduction of warm fluids into the

body• Warm IVF, body cavity lavage, extracorporeal



NFCI and FCI TREATMENTNFCI and FCI TREATMENT• RAPID rewarming is the goal. Trunk>Limbs

• Immersion of limb in 40-42°C (102-106°F) water bath

• 30-45 minutes – area appears flushed with good circulation when circulation is re-established

• Tetanus Toxoid• Benzyl penicillin 600mg q6 for 48-72 hours• Narcotic Pain Relief –

very painful!!!


HFCI and FCI TREATMENTHFCI and FCI TREATMENT

• Dry skin to prevent maceration.

• Prevent further injury (prostaglandins)– Serous blisters – unroof; topical aloe vera– NSAIDS

• Prevent Thrombosis – tPA – a few studies demonstrate the benefit of tPA in

preventing/minimizing amputations or the amount of amputated tissue

TREATMENT TREATMENT


Amputation should bedelayed 2-3 months

MRI/MRA Technetium 99m methylene diphosphonate bone scan (triple phase 1 minute, 2 hours and 7 hours) – as earlyas 48 hours after admission may help identify viable (hibernating) tissue


NFCI and FCI SequelaeNFCI and FCI Sequelae• Transient Sequelae:

– Hyperhidrosis– Hyperesthesia/Anesthesia

of digits– Dec ROM and joint

swelling– Edema– Fat pad loss, transient

muscle atrophy– Pain from injury to

peripheral nerves or small vessels as a result of ischemia

• Late Sequelae:– Hyperesthesia of distal

digits– Increased sensitivity to

heat and cold– Nail bed deformities– Hyperhidrosis,

hypohidrosis or anhidrosis

– Decreased proprioception

– Pain– Loss of fibrocartilage in

ear– AVN, growth plate

injuriesAMPUTATION IS THE ULTIMATE LONG-TERM SEQUELAE TO A FCI

How much do you amputate? How much do you amputate?



FIELD PASSIVE REWARMING EQPT


FIELD ACTIVE REWARMING EQPT

Prevention of Cold Injuries

• Layered clothing– Cotton BAD– Wetsuits in water sports

• Adequate nutrition & hydration

• Cancel events if too cold– ACSM: dry bulb <-4F at coldest place

Review

• Moderate hypothermia: 91-95F

• Avoid active rewarming if <93F in field

• Dry NFCI: chilblains, pernio

• Wet NFCI: trenchfoot

• Frostbite: drain SEROUS blisters; give Pcn, NSAID, Tetanus toxoid, pain meds

• Cancel events if low Temp <-4F

Questions

Documents

Cold Injury