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Sacred Heart Medical Sacred Heart Medical Center and ChildrenCenter and Children’’s s

HospitalHospital

Hypothermia & Local Cold

Injuries

Objectives

Describe mechanisms of injury for hypothermia and local cold injuries

Discuss pre-hospital and hospital treatment of hypothermia

Discuss pre-hospital and hospital treatment of local cold injuries

Types of heat loss

•• Radiation– Heat transferred from one structure to another

without heating air– Sunshine on a cold, winter day

• Convection– Heat transferred to air around body or structure– Infra-red thermogram of body heat– Significant of heat loss with air movement

Types of heat loss

•• Evaporation– Heat transferred to water molecules then

evaporate– Sweating when exercising– Significant of heat loss with air movement

• Conduction– Heat transferred directly between bodies or

structures– Patient laying on a cold, tile floor for hours– Up to 35 X greater loss in water compared to air

Thermoregulation

• “Normal” temp – 98.6°F• “Normal” range = 96.9 to 99.9 °F• “Normal” temperature required for body’s chemical

reactions to function• Core temperature variations

– Lower in the morning– Higher in the early afternoon– Higher in women during some parts of menstrual

cycle

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Thermoregulation•• Peripheral thermoreceptors– Entire outer surface of body– More in upper torso– Fewer in lower torso– Fewer still in lower limbs– Sends signals to hypothalmus

•• Central Central thermoreceptorsthermoreceptors in:in:–– Abdominal organsAbdominal organs–– Spinal cordSpinal cord–– HypothalamusHypothalamus–– All provide temperature input to hypothalamusAll provide temperature input to hypothalamus

ThermoregulationThermoregulation•• HypothalamusHypothalamus

–– Integrates input from both peripheral and central inputsIntegrates input from both peripheral and central inputs–– Maintains core temperatureMaintains core temperature

•• Core temp Core temp = sweating= sweating•• Core temp Core temp = cold response= cold response

• Vascular response– Vasoconstriction– Shunts blood from cold areas– Preserves core temperature– Ability to constrict affected by sunburn for up to one week– Drop in blood pressure with immersion rescue

Thermoregulation•• Evaporation suppressed• Metabolic response

– Increase REQUIRED to maintain core temperature– Metabolic rate will by 4% for every of 1°F in

core• Metabolic response– Glucose stores mobilized, then quickly

depleted if not replenished– Shivering may triple oxygen consumption

Thermoregulation•• Neurological response

– Enzyme function sensitive– Usually first system impaired

• Changed personality/behavior• Poor memory or judgment• Slurred speech• Decreased consciousness

– Nerve chilling shivering•• Cardiovascular response

– myocardial O2 consumption– Cardiac output will – Heart rate will and then – If patient is tachycardiac with hypothermia, look for another

cause

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Thermoregulation• Cardiovascular response

– Conduction more sensitive• PR, QRS, QT interval increased• Shivering may obscure P wave• All types of arrhythmias found• J – wave (Osburn wave)

• Cardiovascular response– J wave (Osburn wave)

• May occur in core temp 90°F• Most commonly found in II/V6• When core temps are below 77°F, may be found

in V3 & V4

J-Wave (Osburn Wave)

••

Thermoregulation• Respiratory response

– Increased rate, followed by depression– 5 – 10 breaths/minute with core temperature

86°F– Chest wall loses elasticity– Hypoxia increased by cold

• Renal response– Vasoconstriction central vascular volume– volume = diuresis– Immersion U/O by 3.5 X– Alcohol can double this!!!

Thermoregulation

• Coagulation response– Enzyme malfunction causes clotting problems– Platelets become inactive– Diuresis leads to hemoconcentration – RBCs lose ability to deform

Risk Factors• Exhaustion

– Glucose stores exhausted– No glucose for shivering– Hypoglycemia decreases temperature for shivering

threshold• Immobilization

– Unable to generate heat– Includes entrapment

• Meds affecting glucose– Beta blockers– Steroids– Oral anti-hyperglycemics

Risk Factors• Alcohol

– Affects judgment and decision making capability– May heat loss through vasodilitation, not

proven– Creates hypoglycemia

• Hypoxia – Decreases regulated core temperature• Inadequate clothing

– Simplest way to prevent– Affected by:

• Windchill• Wet clothing

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Risk Factors• Spinal cord injuries

– Acute injury may cause “spinal shock”vasodilitation

– Lack of movement decreases heat generation by movement

•• Age– Infants

• Lack of ability to shiver until about 2 years of age

• Generate heat from “brown fat”• Premature babies lack substantial “brown fat” =

greater risk for hypothermia• Large head size radiates heat

Risk Factors•• Age– Children

• Activity usually generates a substantial amount of heat

• Large head size radiates heat• Age

– Elderly• Decreased fat & insulation• Decreased muscle mass• Decreased vascular response to cold• Impaired thermal perception• Medication interactions

Risk Factors•• Medical conditions– Any condition that body reserves

• Cardiac• Respiratory• Diabetes

• Environmental acclimation– Repeated exposure = risk– Lack of acclimation = risk

• Windchill - heat loss from:– Convection – Evaporation

Windchill Chart

Risk Factors•• Dehydration– Increase risk– Better to drink cold water

• Physical condition– ability to respond to stress– Poor conditioning risk

• TRAUMA!– Often seen with hypothermia– stress response capability– May be overlooked– Caused by examination or treatment?– Causes coagulation disorders

TREAT ALL TRAUMA

PATIENTS AS IF THEY ARE

HYPOTHERMIC!

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Patient Assessment•• Thermometers

– Mercury type• More subject to error• Accurate scale?• Has it been “shaken down”?• Remain in place for 3 minutes?

– Use electronic types• Esophageal most accurate• Oral temperatures

– Mouth MUST remained closed– Affected by:

• Eating• Smoking• Fluid intake

– Axillary site as a last resort!!

Patient Assessment•• Mild hypothermia

– 96.8°F• Increased blood pressure• Increased muscle tone• Start of shivering

– 95.0°F – Maximum shivering• Mild hypothermia

– 93.2°F• Amnesia, poor judgment & maladaptive behaviors• Painful joints• Normal blood pressure• Maximum respiratory response• and then in heart rate

Patient Assessment•• Mild hypothermia

– 91.4°F• Apathy• Ataxia• & then in respiratory rate• Cold diuresis

• Moderate hypothermia– 89.6°F

• Stupor• 25% in oxygen consumption

– 87.8°F – Shivering stops– 86.0°F

• Insulin looses effectiveness• Arrhythmias begin to develop

Patient Assessment•• Moderate hypothermia– 85.2°F

• Progressive in:– Level of consciousness– Pulse– Respirations

• Pupils dilated• Paradoxical undressing

Patient Assessment

•• Severe hypothermia– 82.4°F

• Decreased threshold for VF• O2 consumption by 50%• Pulse by 50%• Significant hypoventilation

Patient Assessment• Severe hypothermia

– 80.6°F – Significant loss of reflexes and voluntary motion

– 78.8°F – Loss of reflexes and response to pain• Severe hypothermia

– 77.0°F• Cerebral blood flow 33% normal• Cardiac output 45% normal• Pulmonary edema may develop

– 75.2°F - Significant hypotension & bradycardia

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Patient Assessment• Severe hypothermia

– 74.3°F – No corneal reflexes– 71.6°F

• Maximum risk of ventricular fibrillation• Oxygen consumption by 75%

• Profound hypothermia– 68.0°F – Pulse 20% of normal– 66.2°F – Brain wave activity ceases– 66.4°F - Asystole

THEY AIN’T DEAD UNTIL THEY ARE

WARM AND DEAD!

Pre-hospital Treatment• Prevent further heat loss

– Remove from cold environment– Remove wet and/or restrictive clothing– If available, add wrapped heat sources to groin,

neck, axilla• Begin passive re-warming

– Wrap in layers– Start with polymer sheets– Add blankets/sleeping bags– Cover head!!!– Keep hands at sides– Avoid radiant heat

Pre-hospital Treatment

“Body to body re-warming is of no practical value.”

(Danzl, 2001, p. 504)

Pre-hospital Treatment•• If conscious with adequate airway, give warmed,

sweet beverages• Keep in horizontal position• Handle gently• Prevent excess movement• Establish IV/IO access• Fluid challenge with D5%NS• Any dextrose IV fluid• Avoid LR d/t lactate• Place IV bag under patient• Wrap IV tubing in chemical warmer

Pre-hospital Treatment•• Avoid massage of limbs• Attach cardiac monitor

– Increase “gain”– May have to use benzoin– Small gauge needles through electrodes may be

needed• Life support issues

– Intubate (ET or Combitube)• Avoid cuff overinflation• Ventilate with 100% oxygen

– Warmed & humidified, if available– Heat/moisture exchanger (HME) to prevent

further heat losses

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Pre-hospital Treatment•• Life support issues– Assess pulses for > 1 minute– If no pulse or signs of circulation, begin CPR– Defibrillate up to three times for:

• Pulseless ventricular tachycardia• Ventricular fibrillation

– Withhold further defibrillations

•• Life support issues– Continue CPR– Withhold medications– Transport to definitive care ASAP!

Hospital Treatment•• Continue passive re-warming• Consider arterial line• Avoid pulmonary artery or CVP catheter into

subclavian• Draw labs• X-rays for any trauma• Insert an NG tube• Insert foley catheter • Begin IV therapy

Hospital Treatment•• Use fluid warmer to deliver IVs• Fluid challenge with D5%NS• Any dextrose IV fluid• Avoid LR d/t lactate• Monitor for:

– Compartment syndrome– Rhabdomyolysis

• Life support issues– Intubate (ET or Combitube)

• Avoid cuff overinflation• Ventilate with 100% oxygen

– Warmed & humidified, if available– Heat/moisture exchanger (HME) to prevent further

heat losses

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Hospital Treatment•• Life support issues– Assess pulses for > 1 minute– If no pulse or signs of circulation, begin CPR– Defibrillate ONE TIME for:

• Pulseless ventricular tachycardia• Ventricular fibrillation

– Withhold further defibrillations until core temperature > 86°F

Hospital Treatment•• Life support issues– Continue CPR– Medications

• Hold until core temps > 86.0°F• Administer 2 – 3 X normal intervals• Consider thiamine if alcohol related

• Active re-warming required in core temps < 89.6°F• Active external re-warming

– TRUNCAL area only!– Forced, heated air– Wrapped, hot packs to groin, neck, axilla– Immersion – not practical

Hospital Treatment•• Active internal re-warming• Use as many modes as possible for best effect

– Airway re-warming• Heated, humidified oxygen• Prevents further heat loss

• Heated IV infusions– One L can core temp by 1.4°F – Tubing can loose a lot of heat– Will likely need significant volume to correct “cold

diuresis”

Hospital Treatment•• Naso-gastric irrigation– Monitor “ins and outs” to assure fluid balance– Intubate to maintain airway– 200 – 300 ml boluses of electrolyte solution (NS,

LR)– Allow 15 minute “dwell”

Hospital Treatment• Closed thoracic lavage

– Two tube method• Anterior/posterior tubes placed• Fluid instilled anterior• Drained posterior• After re-warming, DC anterior tube and

maintain posterior tube to drainage system

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Hospital Treatment• Closed thoracic lavage

– Single tube method• Single tube placed poster, with “Y” connector• 200 – 300 ml boluses of electrolyte solution (NS,

LR)• Allowed 15 minute “dwell”• Fluid suctioned out

• Peritoneal lavage– Large bore catheter inserted– Empty bladder and stomach– Up to 2 L electrolyte solution (NS, LR) instilled– Allowed 20 minute “dwell” & then siphoned out

Hospital Treatment• Aggressive internal re-warming

– VERY effective!!!– Usually only available at higher level trauma

centers– Multiple types

• Electrolyte disturbances – primarily potassium• Bacterial infection

– Alterations in immune system– Primarily pneumonia, but other sites possible– Significantly affected by extremes of age

Complications•• Coagulation disturbances – primarily loss

and/or malfunction of platelets• Possibility of local cold injuries and/or other

trauma

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•• OneOne–– TwoTwo•• ThreeThree–– FourFour

Non-Freezing Injuries•• Usually caused by cold and wet conditions• Risk factors, same as with hypothermia• Additional risk factors may make patient more

vulnerable• Additional risk factors

– Diabetes– Tight, constriction clothing– Tobacco use– Dehydration– Previous local cold injury– Vascular insufficiency/disease

Chilblain - Pernio•• Same basic cause – prolonged exposure to wet and

cold• Chilblain = 3 – 12 hour exposure• Pernio

– More than 12 hours exposure or– Repeated, frequent exposure

Chilblain•• 3 – 12 hour exposure • Swelling & tenderness that resolves with drying• May display blisters• Pain with > 6 hours exposure• May have deep sensitivity to foot pressure for several

days• Treatment

– Dry– Gentle massage

Pernio•• Extension of chilblain• > 12 hour or repeated, frequent exposure• Deep pain that persists for multiple days• Partial thickness blisters• Swelling• Treatment

– Dry– Elevation to help swelling– NSAID such as ibuprofen– Significant pain control issues

Pernio•• Sequela– Long term sensitivity to even mild cooling of limb– Pain– Numbness– Paresthesia

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Trench Foot•• Also known as “immersion foot”• Prolonged exposure to:

– Cold– Wet– Tight constricting boots

• Reduced blood flow caused by:– Vasoconstriction, leading to– Tissue hypoxia and – Cellular death

• Injuries compounded by walking on injured feet

Trench Foot•• Symptoms appear in three phases• Pre-hyperemic phase

– Extremity blanched & cold– Patient reports “cold and numb” feet– Balance is impaired

Trench Foot•• Hyperemic phase– Last 6 – 10 weeks– Upon warming, feet become:

• Red• Hot• Painful• Swollen

• Hyperemic phase– 7 – 10 days after injury:

• Pain intensifies• Loss of motor control & sensation• Pain & numbness with warming or dependency

of foot

Trench Foot•• Hyperemic phase– 7 – 10 days after injury:

• Blisters form (bloody = bad!)• Black eschars form• Nails slough without pain• Tissue mummifies • Gangrene may require premature surgery

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Trench Foot•• Post-hyperemic phase– Swelling, pain & numbness– Cold sensitivity – Neurological damage will affect balance and

mobility• Treatment

– Dry & elevate feet to heart level– Pain control issues significant– Minor injuries can produce significant problems in

later life = Cold sensitivitylife = Cold sensitivity

Frostbite•• Damage occurs in four phases• Pre-freeze phase – tissue cools• Freeze-thaw phase – ice crystals from in tissue• Freeze-thaw phase

– Extra cellular ice crystals• Caused by slow cooling• Cellular dehydration• Intra-cellular electrolyte concentration• Break down of cellular walls

Frostbite•• Freeze-thaw phase– Intra-cellular ice crystals

• Caused by fast cooling• Breakdown of cell walls• Breakdown of cell proteins• Cells rupture

• Vascular stasis phase– Plasma leaks into tissue– Emboli showers to small blood vessels

• Late ischemic phase– Thrombosis formation– Ischemia– Tissue death

Frostbite•• Initial classification VERY difficult• Superficial frost bite

– “First degree”• Numbness• White, firm plaque at site• Edema forms on re-warming

1st Degree Frostbite of Ear

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Frostbite

•• Superficial frostbite– “Second degree”• As with “First degree”• Blisters filled with clear fluid

• Deep frostbite– “Third degree”• As with “Second degree”• Blisters filled with bloody fluid

4 & 5 Weeks After Frostbite Frostbite

•• Deep frostbite– “Fourth degree”• Full thickness damage• Tissue may appear mummified

24 Hours after Frostbite 6 Weeks Later

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Frostbite•• Initial or presenting symptoms– Numbness with SIGNFICANT pain on re-warming– Tissue changes as described above– Tissue may appear mottled blue or “frozen”

• Symptoms on re-warming– Redness– Sensation returns until blisters form– Sensory loss persistent– Blisters form within 6 – 24 hours

Frostbite•• Edema forms within 3 hours and may last 5 days• Pain

– EXTREME on re-warming– Becomes throbbing– May have burning sensation– Electric current-like shock

• Eschars of black tissue form in 9 – 15 days• Mummification and lines of demarcation form in 22 –

45 days

Frostbite•• Prognostic signs

– Favorable• Sensation to pinprick• Normal color and warmth• Large, clear blisters

– Appear early–– Extend to tips of digitsExtend to tips of digits

• Prognostic signs– Unfavorable

• Small, dark blisters– Appear late– Do NOT extend to tips of digits

• Absence of edema• Cyanosis that does not blanch

Frostbite

“All but the most minor frostbite cases should be admitted to the hospital .”

(McCauley, p. 187)

Pre-Hospital Treatment•• Assess and treat:– Hypothermia– Dehydration– Trauma

• Handle gently!!• If < 2 hours from definitive care, do NOT re-warm• Remove wet/restrictive clothing• Keep away from dry heat sources (fires, car heaters)• Pad and splint extremity• Leave blisters intact• Elevate to level of heart

Pre-Hospital Treatment• Prohibit use of:

– Tobacco – Alcohol

• Provide rapid transport to definitive care• If > 2 hours from definitive care:

– Rapid re-warming with water– After re-warming, treat as above– DO NOT ALLOW INJURY TO BE RE-EXPOSED TO

COLD!!!

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Pre-Hospital Treatment

• Rapid re-warming in water 104 to 108°F for 30 minutes– Continue until tissue becomes pliable

and red– Active motion helpful– Massage contraindicated!!!!

Hospital Treatment• Favorable signs on re-warming

– Rapid return of skin warmth and sensation– Redness

• Unfavorable signs on re-warming– Skin that continues to be:

• Pale• Cold• Numb

Hospital Treatment• Blister management

– AVOID betadine– White blisters

• Represents superficial injury• Debride to remove inflammatory mediators• Aloe vera ointment every 6 hours

• Blister management– “Red” blisters

• Sub-dermal injury• Aspirate fluid• Leave blisters intact to prevent conversion to

full-thickness• Aloe vera ointment every 6 hours

Hospital Treatment• Medications

– Ibuprofen, 400 mg Q12 hours– Tetanus anti-toxin, if needed– Penicillin– Pentoxifylline

• blood viscosity• RBC flexibility

• Pain control– Morphine drip or PCA– Fentanyl drip or PCA– Avoid Demerol – may cause neurological

complications

Hospital Treatment• Long term therapy

– Physical therapy – maintains mobility– Occupational therapy – maintains functional

ability • Long term therapy

– Surgical intervention usually held until:• Tissue “declares” viability – may take months• Tissue infection

Amputation for Gangrene

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Complications•• VERY sensitive to cold re-injury during

recovery• Long term– sensitivity to cold & cold injuries for life– Changes in skin color– Joint stiffness & pain on movement

Sacred Heart Medical Center and Children’s

Hospital

Michael W. Day, RN, MSN, CCRNDaymw@shmc.org

509.474.7111

• Fax Materials to:

– Renee Anderson 509-232-8344 (fax)– 509-232-8155 (d)– andersr@inhs.org