hypothermia
TRANSCRIPT
HYPOTHERMIAHYPOTHERMIA
TLO
• Given a simulated casualty, treat hypothermia in accordance with the references.
ELOs
• Define Hypothermia.• List the five mechanisms by which the body
loses heat.• Describe why patients with hypothermia
should be handled gently
Bonus ELO
• Identify the four criteria which distinguish mild hypothermia from severe hypothermia
HYPOTHERMIA
• Hypothermia is defined as when the body’s core temperature falls to
95 degrees F or less.
Battle of Stalingrad
• Germany lost the entire Sixth Army – thousands lost to combination of starvation and hypothermia
Fino-Russian War
• Russian to Finnish casualty rate – 10 to 1
• Russians poorly equipped – expected to take down Fins in less than 2 months
• Thousands dead from hypothermia and starvation
Hypothermia- Causes
• Increased heat loss• Decreased heat production
Heat Loss
• Conduction• Evaporation• Respiration• Convection• Radiation
Heat Loss
• Conduction– Search for poor conductors– Air– Foam– Fibrous Material (Wood,
Cork)– Use IsoMat for insulation –
for casualties– Allowing maximum loft on
sleeping bags– Thickness equals warmth
Heat Loss
• Evaporation– Enormous amount of heat
lost– Much energy spent
transforming liquid to gas– Insensible sweat- cold air
dry- skin must remain moist– “Comfortably cool”
minimize sweating– Mountain Pace– Vapor Barrier
Heat Loss
• Respiration– 0F:
• 18 calories/hr warming• 24 calories/hr
evaporation/moisturize• 1000 cal/day• Breathe through
mask/gaiter
Heat Loss
• Convection– Try to retain dead air– Chimney effect– Wind chill– Velcro Closures/Neck
Gaitor
Heat Loss
• Wind Chill– 40 F
• 10 MPH: 28F• 20 MPH: 18F• 30MPH: 13F
– 20 F• 10MPH: +4F• 20 MPH: -9F• 30 MPH: -18F
Heat Loss
• Radiation– Infrared energy lost– Radiant energy will
heat up clothing– Thick enough
insulating layer or opaque layers to retain heat
– Lightly colored clothing reflects more radiation back to body
Heat Production
• Heat Generation:– Nonshivering
Thermogenesis:• Increase in metabolism• Food intake
Heat Production
• Non Shivering Thermogenesis-– Activity
• Isometrics• Sleeping Bag Late
Night/Early Morning
Heat Production
• Shivering Thermogenesis- can increase metabolic rate by a factor of 20
• Disadvantages- – short lived– Absent below 90F core
temp– Blunted by alcohol
Military Risk Factors
• Starvation• Dehydration• Exhaustion• Exposure• Poor/Excessive
Clothing• Sweating• Trauma/Burns
Hypothermia: Diagnosis- Measurement
• Rectal or Esophageal Monitoring are the most accurate
• May not be able to expose the casualty to the elements
• Field Method- ungloved hand on skin of trunk and observe signs and symptoms
SIMPLIFY
• Distinguish moderate/severe from mild hypothermia
Mild Hypothermia
• Shivering present• Mental Impairment
– Complex tasks– Simple tasks
• Physical Impairment– Fine Motor Movements– Gross Motor Movements
• Will resolve with minimal intervention with field re-warming techniques
Severe Hypothermia
• Any one of the following conditions will constitute life threatening hypothermia:
• Core temperature less than 90 degrees F• Decrease in vital signs- heart rate,
respiratory rate• Loss of consciousness or severely altered
level of consciousness• Cessation of shivering
Mild Hypothermia
- Hypothermia which fails to meet any of the criteria of life threatening hypothermia
Severe Hypothermia
• Requires an extraordinary amount of heat in order to resuscitate a casualty with severe hypothermia
• Institute field re-warming techniques in order to preserve existing heat
• CASEVAC Immediately to a facility which can resuscitate the casualty!
Treatment
A COLD HEART IS AN IRRITABLE HEART
• If a casualty is determined to have severe hypothermia then handle them very gently as they are prone to fatal arrhythmias.
Treatment
• Take your time to properly move a casualty who may have life threatening hypothermia
Treatment
• Rough Ride
Treatment
• Smooth Ride (relatively)
Field Rewarming Techniques
• Remove wet clothing• Insulation/Vapor Barrier (1.5 C/hr, 2.7 F/hr)• Insulated Hot Water Bottles to Axilla/Groin• Person to person rewarming• Effective with mild hypothermia• Not effective with severe hypothermia –
only serves to maintain warmth not to re-warm
Severe Hypothermia – Hospital Rewarming Techniques
• Warmed IVF (1 L= 0.33 degrees C/hr, 0.6 F/hr)- Avoid Lactated Ringers
• Warmed Inspired, Humidified Oxygen• Lavages (3 degrees C/hr, 5.4 F/hr)• Extracorporal Blood Rewarming• Bair Hugger
Field Re-warming Don’ts
• No alcohol• Nothing by
mouth with severe hypothermia
• Water bath with extreme caution
BLS Treatment
• ABCD’s ( Degrees) – monitor for at least 60 seconds
• Difficult to monitor vital signs because of decreased respiratory rate, decreased heart rate, and vasoconstriction
Treatment
• Breathing– Cut respiratory rate to 6 bpm secondary to
decreased metabolic demands
Treatment
• Circulation– Chest compressions- be absolutely sure of your
findings
CPR
• NO ONE IS DEAD UNLESS…….
CPR
• …….THEY ARE WARM AND DEAD….
CPR
• UNLESS THEY ARE DEAD!• Do not initiate CPR if: - Core temperature is less than 50 degrees
- Patient is obviously frozen- eg ice formation in the airway - Chest wall is so stiff that it is incompressable
ACLS
• Active core rewarming techniques are the primary therapeutic modality in hypothermic victims in cardiac arrest.
ACLS
• Red Herrings– Shivering = Ventricular Fibrillation– Cold skin = Asystole
ACLS
• Ventricular Fibrillation • Attempt three progressive unsynchronized
shocks at 200, 300, 360Js. If no response then continue CPR and REWARM VICTIM. Reattempt counter shocks when core temp rises above 86 degrees F.
• Attempt successive counter shocks at 86, 88, 90 degrees F ……
ACLS
• ACLS drug protocols- be wary of the medications being sequestered due to poor metabolism, once casualty is rewarmed may be toxic
• Employ ACLS drug protocols above 92 degrees F – at longer intervals
Future Rewarming Techniques
• High temperature IV fluids ( 2-3C/hr)• Low frequency microwave radiation – 90-
100 watts ( 1C/ 6-7 minutes)• ThermoStat ( 13 C/hr)
Afterdrop
• Continued decrease of core temperature after patient has been removed from the cold and rewarming has begun.– Extremity rewarming releases peripheral
vasoconstriction.– Process of warmer core equilibrating with
colder peripheral tissues.– Greatest drop seen with acute hypothermia.
Considerations with Frostbite
• If treating hypothermia with frostbite, DO NOT begin RX for frostbite until core temperature is above 93°F otherwise at risk for afterdrop
• Remember your first priority is to re-warm the body core.
Considerations with Trauma
• Treat possible sites of blood loss (especially in the extremities) prior to rewarming
• Hypothermia and cold may help control hemorrhage
• Be careful of hypovolemia once patient has been re-warmed – keep patient supine and replenish fluids
A Paradox of Sorts
• Paradoxical Undressing• Skin temperature is the critical factor to the
physiological and behavioral responses
QUESTIONS?????