Wilderness Medicine & Hypothermia

8/2/2019 Wilderness Medicine & Hypothermia

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Strategies for TreatingHypothermia

How to deal with low core bodytemperature?

Joshua Bennett M1073



Relevance to Wilderness Medicine

Medical emergency

>50% mortality in patients aged 70 or olderwith temperature <32°C (Longmore et al., 2010)

Personal experience

Why I chose to talk about this



1 hour from car park, notice youngman slumped against stone wall.

Mumbling inaudibly and shivering

violently. Half empty bottle of vodka.

Equipment is your backpack

containing what you wouldnormally take for a day outdoors.

What would you do?

January 2011, Lake District, Sca Fell



Grades and types of hypothermia

Need to know basics in order to treat.

Essentials of hypothermia management

Do’s and Don'ts

Strategies to treat hypothermia

Spontaneous rewarming

Active external rewarming

Active core rewarming

Resuscitation and hypothermia

Objectives



Severity

Grade I – conscious and shivering

Grade II – impaired consciousness / no

shivering

Grade III – unconscious or cardiacinstability

Grade IV – apparent death

Grades of hypothermia

KEY POINT: Cold patients who have stoppedshivering will cool at an accelerating rate (due to

minimal heat generation).



Severity

Grading system

Speed of onset

Acute / immersion

Subacute / exhaustion / injury

Subchronic / urban

Types of hypothermia



irway

reathing

irculationisability

Where hypothermia management

fits

nvironment / evacuation



Hypothermia physiology

KEY POINT: ‘Core afterdrop’ or ‘rewarming collapse’

can occur if rewarming is too quick.



Do:

Remove from cold

Replace wet

clothing Insulate

Handle gently

Monitor regularly

For any hypothermic patient...

Don’t:

Suppress shivering

Give alcohol

Put in warmshower/bath

Warm peripheries

KEY POINT: Sudden movements may trigger

ventricular fibrillation.

(NESRA Medical Sub-Committee, 2010)



Spontaneous rewarming

May reverseGrade Ihypothermia

Requires patient togenerate heat

Layer system

Insulate fromground

Cover head andneck (leave

airway!)

‘Hypothermia wrap’



Active external rewarming

Indications:

Grade II hypothermia or worse

Trauma or other co-morbidity Apply heat source to armpits, groin and

flanks

Should be warm not hot- risk of burningpatient



Airway warming

Air humidifier devices

Warm tubing in warm drink

Warmed IV fluids Microwave

Can warm giving set in warm drink

Thoracic lavage

Peritoneal dialysis

Cardiopulmonary bypass

Active core rewarming

invasive

(Danzl and Lloyd, 2001)

http://www.hypothermia-ca.com/res-q-air.htm



Check carefully for pulse for

1 minute “No-one is dead until they

are warm and dead” >33°C

Resuscitation and hypothermia

“Active core rewarming techniques are the primarytherapeutic modality in hypothermia victims incardiac arrest or unconscious with a slow heartrate.”

(Emergency Cardiac Care Committee, 1992)



1 hour from car park, notice youngman slumped against stone wall.

Mumbling inaudibly and shivering

violently. Half empty bottle of vodka.

Equipment is your backpack

containing what you wouldnormally take for a day outdoors.

What would you do?

January 2011, Lake District, Sca Fell



Summary

KEY POINT: Cold patients who have stoppedshivering will cool at an accelerating rate (due to

minimal heat generation).

KEY POINT: ‘Core afterdrop’ or ‘rewarmingcollapse’ can occur if rewarming is too quick.

KEY POINT: Sudden movements may trigger

ventricular fibrillation.



References Danzl, D. F. and Lloyd, E. L. (2001) Medical

Aspects of Harsh Environments. Borden Institute. Emergency Cardiac Care Committee. (1992)

'Guidelines for Cardiopulmonary Resuscitationand Emergency Cardiac Care', Journal of the American Medical Association.

Longmore, M., Wilkinson, I. B., Davidson, E. H.,Foulkes, A. and Mafi, A. R. (2010) Oxford

Handbook of Clinical Medicine.8th ed: NESRA Medical Sub-Committee. (2010) Mountain

Rescue for Casualty Care student notes.2nd ed:

Questions?

Wilderness Medicine & Hypothermia

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