HypothermiaHypothermia

OutlineOutline

What is HypothermiaWhat is Hypothermia What are the symptomsWhat are the symptoms What can be done to prevent itWhat can be done to prevent it How do you treat someone with How do you treat someone with

HypothermiaHypothermia SummarySummary

What is Hypothermia?What is Hypothermia?

Lowering of core body temperature.Lowering of core body temperature. Normal temperature 37.5Normal temperature 37.5˚C˚C Lowering of core body temperature to below Lowering of core body temperature to below

3535˚C (95˚F)˚C (95˚F) Mild Hypothermia 35Mild Hypothermia 35˚C˚C – 34 – 34˚C˚C Moderate hypothermia 30Moderate hypothermia 30˚C˚C – 33.9 – 33.9˚C˚C Severe Hypothermia below 30˚CSevere Hypothermia below 30˚C

What is HypothermiaWhat is Hypothermia

Body losses heatBody losses heat Radiation can occur when Radiation can occur when

ambient temperature is ambient temperature is below 98.6below 98.6˚F˚F

Conduction water Conduction water conducts heat away 25 conducts heat away 25 times faster than airtimes faster than air

Convection ie wind chill, Convection ie wind chill, swimming.swimming.

Evaporation ie sweatingEvaporation ie sweatingDiagram from Princeton University

SymptomsSymptoms

temp ˚C Body Symptoms

37.5 Normal

36 Feel Cold

35 Shivering

34 Clumsy, Irrational, Confused

33 Muscle Stiffness

32 Shivering stops, Collapse

31 Semi Conscious

30 Unconscious

29 Slow pulse and Breathing

28 Cardiac Arrest

Hospital

999

Regulating Core temperatureRegulating Core temperature

What your body doesWhat your body does HotHot

• Sweat – cools by evaporationSweat – cools by evaporation• Vasodilation – blood vessel open on surfaceVasodilation – blood vessel open on surface• Take layers offTake layers off

ColdCold• Shiver – muscle activityShiver – muscle activity• Vasoconstriction – reduce blood flow to surfaceVasoconstriction – reduce blood flow to surface• Put layers onPut layers on

PreventionPrevention

Wear the correct clothingWear the correct clothing Take layers off or put layers onTake layers off or put layers on

Stay DryStay Dry Prevent WindchillPrevent Windchill Provide EnergyProvide Energy Don’t get dehydratedDon’t get dehydrated Avoid alcohol Avoid alcohol

Wetsuits and DrysuitsWetsuits and Drysuits

Wetsuits work by trapping a layer of water Wetsuits work by trapping a layer of water near the skin thereby (when immersed)near the skin thereby (when immersed) Reducing conduction by insulationReducing conduction by insulation Reducing convectionReducing convection

Drysuits work by keeping occupant dryDrysuits work by keeping occupant dry Prevent convectionPrevent convection Require additional insulation to prevent Require additional insulation to prevent

conductionconduction

Other ClothingOther Clothing

Thermals under drysuitThermals under drysuit Man-made materials next to skin reduce Man-made materials next to skin reduce

moisturemoisture Hat – 30% heat loss through headHat – 30% heat loss through head Personal bouyancy – don’t need to work to Personal bouyancy – don’t need to work to

stay afloat (reduces convection)stay afloat (reduces convection)

Prevention - if you fall in!Prevention - if you fall in!

Get out of the water if possible Get out of the water if possible Climb onto upturned boatClimb onto upturned boat

Minimise movementMinimise movement BA/ LJ helps you stay afloat without swimmingBA/ LJ helps you stay afloat without swimming Help positionHelp position Stay with boatStay with boat

Share warmthShare warmth

Pictures from www.hypothermia.org

Picture from www.hypothermia.org

Survival time in water

Graph from www.hypothermia.org

TreatmentTreatment

Mild HypothermiaMild Hypothermia Reduce heat lossReduce heat loss

• Additional clothingAdditional clothing• Dry clothingDry clothing• ShelterShelter

Add Fuels and FluidsAdd Fuels and Fluids• Carbohydrates – warm liquids better than solidsCarbohydrates – warm liquids better than solids• Avoid Alcohol, Caffeine and NicotineAvoid Alcohol, Caffeine and Nicotine

Slowly Warm CoreSlowly Warm Core Consider Professional AssistanceConsider Professional Assistance

Moderate or Severe HypothermiaModerate or Severe Hypothermia

Check ABCCheck ABC Shelter, Insulate – keep horizontal if possibleShelter, Insulate – keep horizontal if possible Get assistance – 999Get assistance – 999 Patient should be kept horizontal, insulated and Patient should be kept horizontal, insulated and

breathing/signs of life monitored until ambulance breathing/signs of life monitored until ambulance crew arrive. Minimise any movement.crew arrive. Minimise any movement.

Treat the patient for ABC and shock only ON NO Treat the patient for ABC and shock only ON NO ACCOUNT IS EXTERNAL HEAT TO BE ACCOUNT IS EXTERNAL HEAT TO BE APPLIED IF THE PATIENT IS INCOHERENT APPLIED IF THE PATIENT IS INCOHERENT OR UNCONCIOUS.OR UNCONCIOUS.

Moderate or Severe HypothermiaModerate or Severe Hypothermia

RescueRescue Keep patient horizontalKeep patient horizontal Minimal physical activityMinimal physical activity

ExamineExamine ABC (airway, breathing, circulation)ABC (airway, breathing, circulation) Respiration and pulse may be very slowRespiration and pulse may be very slow Check for other injuriesCheck for other injuries Mental status (ability to think and walk)Mental status (ability to think and walk)

Moderate or Severe HypothermiaModerate or Severe Hypothermia

StabiliseStabilise CPRCPR Control bleedingControl bleeding Deal with shockDeal with shock Nil by mouthNil by mouth

Moderate or Severe HypothermiaModerate or Severe Hypothermia

InsulateInsulate Prevent further heat lossPrevent further heat loss Provide humidified, heated air via mask if Provide humidified, heated air via mask if

available (this is carried by SAR teams in available (this is carried by SAR teams in Canada)Canada)

Gentle heat to neck, armpitts and groin?Gentle heat to neck, armpitts and groin? External heat from rescuer?External heat from rescuer?

TransportTransport Get patient to hospital ASAPGet patient to hospital ASAP

Dangers of RewarmingDangers of Rewarming

Blood chemistry at extremities changes Blood chemistry at extremities changes and may cause cardiac failure (VF) if it and may cause cardiac failure (VF) if it returns to the heart.returns to the heart.

Cold blood at extremities may cause VF if Cold blood at extremities may cause VF if it returns to the heart.it returns to the heart.

Chart shows effect of rewarming.Chart shows effect of rewarming. Body capable of rewarming itself at 2Body capable of rewarming itself at 2˚C ˚C

per hour.per hour.

Rewarming Mild hypothermic Victim

Key pointsKey points

Advice from the RNLIAdvice from the RNLI At first sign of Hypothermia head for shoreAt first sign of Hypothermia head for shore Get out of the wind, warm them up with dry Get out of the wind, warm them up with dry

clothingclothing If deteriorates or doesn’t improveIf deteriorates or doesn’t improve

GET MEDICAL HELP NOWGET MEDICAL HELP NOW

SummarySummary

Hypothermia - cooling of core body Hypothermia - cooling of core body temperature to below 35temperature to below 35˚C˚C

Prevent further heat lossPrevent further heat loss Minimise movementMinimise movement Treat for shock – ABCTreat for shock – ABC Get HelpGet Help Don’t artificially rewarm incoherent or Don’t artificially rewarm incoherent or

unconscious casualtiesunconscious casualties

References/ResourcesReferences/Resources

Safety on the Sea series from RNLISafety on the Sea series from RNLI The RYA sailing manual Bob BondThe RYA sailing manual Bob Bond www.hypothermia.orgwww.hypothermia.org Princeton university outdoor education Princeton university outdoor education

guide from guide from www.princeton.edu/~oa/safety/hypocold.swww.princeton.edu/~oa/safety/hypocold.shtmlhtml

Search & Rescue society of British Search & Rescue society of British Columbia Columbia www.sarbc.org/hypo1.htmlwww.sarbc.org/hypo1.html