COLD WATER IMMERSION

Cold Water Immersion

The Cold Facts - Hypothermia and Drowning

• Physiology - What happens when we enter cold water

• Why and how does it kill

• How can it be prevented

• What can we do to help

Setting the StageCase History – P04 0589 April 23, 2004 - Duke Point

• Accidental Immersion in cold water can be a terrifying experience.

“We’re going down. We have 2 kids on board”

“You gotta get out here. It’s bloody cold. We aren’t going to last long”

• This incident fortunately had a happy ending – rescue of family of four by “Sea Shuttle” after approx 30 minutes in water

Hypothermia

• Results from the body’s inability to adequately replace heat lost to the surrounding environment

• Factors influencing heat loss include water temperature, sea state/water circulation, degree of immersion, insulating garments, rate of energy expenditure, body type, psychological factors

• To err on side of safety, we assess as either mild or severe

Submersion Incidents – Drowning and Near Drowning

• Drowning is defined as death through suffocation by submersion, especially in water

• Near Drowning has been defined as survival, at least temporarily, after aspiration of fluids into lungs

• Hypothermia is likely biggest factor in survival of near drowning/submersion patients

Drowning

• Laryngeal Spasm – May offer some early protection from aspiration but hypoxia causes relaxation of the vocal cords allowing water into the lungs

• Drowning does not occur without fluid aspiration – immersion victims without fluid in lungs probably did not drown

Drowning

• Drowning can occur at surface due to wave splash over mouth and nose

• Type of water – salt water (hypertonic) draws fluid into lungs, while fresh water (hypotonic) results in osmotic passage of some aspirated water into circulation

Drowning

• Males and children have the highest drowning mortality rates

• Prevention works – Prevention initiatives in developed countries have been successful

• According to the Lifesaving Society of Canada, two thirds of drowning victims had no intention of entering the water

Stages of an Immersion Incident

• 1. Cold Shock – first few minutes

• 2. Swimming Failure – 3-30 minutes

• 3. Long term – Hypothermia becoming severe

• 4. Post Rescue

The Cold Facts – Surviving Sudden Cold Water Immersion

1. Cold Shock• Responses, triggered by cold receptors in the

skin, last just a few minutes (peaking at about 30 seconds)

• Large inspiratory gasp upon immersion – may trigger drowning

• Uncontrollable hyperventilation and reduced breath hold

• Coordination of swimming stroke and breathing very difficult

1. Cold Shock• Survival activity often fails

• Aspiration of water is likely – leading to near drowning or drowning

• Massive increase in heart rate and blood pressure may trigger cardiac arrest in older or less healthy individual

2. Swimming Failure

• Cold incapacitates within 3 – 30 minutes of immersion, even before hypothermia sets in

• Water temperatures below 20C result in degradation of swim performance

• Peripheral cooling leads quickly to the loss of manual dexterity and muscle strength, with resultant inability to self rescue

2. Swimming Failure

• Even short swims may be impossible – many who drown are reported to have been “good swimmers”

3. Hypothermia• Water conducts heat away 25 times faster than air of

same temperature

• Predications of survival times are possible, but many variables make these unreliable

• If airway is protected (no drowning), death will occur somewhere below 24C, although the casualty is considered vulnerable below 30C

• Lowest recorded survival is core temperature of 13.7C

4. Post Rescue

• Vulnerable time for the casualty – up to 20% of immersion deaths

• Circum-rescue collapse – drop in blood pressure as result of release of hydrostatic pressure and vertical positioning during rescue

• Afterdrop – the continued decline in core tissue temps after removal from cold stress

4. Post Rescue

• Physical effort by survivor may trigger collapse or death

• Rough handling may trigger cardiac arrest (VF)

• VF responds poorly to defibrillation at core temps below 28C

Sometimes not everyone makes it May 1, 2004 – Cape Beale

• 5 persons in the water from over-turned 18’ pleasure craft, spotted by light-keeper

• 1 swam ashore, later recovered by EHS helicopter

Sometimes not everyone makes it May 1, 2004 – Cape Beale

• 4 recovered from water by RHIOT 1 and 2

• despite prolonged resuscitation attempt 1 person did not survive (core temp measured at Bamfield - 22C)

Prevention and Survival

Prevention and Survival

• Training, Preparation, Attitude and Experience

• Avoid entering water unless necessary – stay with your boat

• Floatation and Insulation – objective is warm and dry

• A dry suit or immersion suit is best if you must enter water

Rescue of Survivors• Assess survivor as being either mildly or

severely hypothermic - based on history, level of responsiveness, vital signs and if possible temperature

If possible; • Recover horizontal and keep horizontal during

transport• Handle gently - do not allow survivor to aid in

own rescue

Rescue of SurvivorsRemember that concerns at point of rescue

include;• Circum-Rescue Collapse – due to drop in blood

pressure on removal from water• Core Temperature Afterdrop – the continued

decline in core temperature after removal from cold stress

Treatment

• Remove wet clothing, provide shelter and insulate against further heat loss

• Avoid rapid full surface re-warming, alcohol or caffeine, and inappropriate speech

• Add heat to high heat loss areas (head and neck, chest, groin)

Treatment

• Evacuate to medical, monitoring continuously

Resuscitation

• Expect fluid in airway to be a problem – foaming may be present

• Stiffness may be due to cold rather than rigor mortis

• Prior to resuscitation, check carotid pulse for up to 45 seconds

Resuscitation

• Recovery following prolonged submersion is possible – don’t give up

“The casualty is not considered dead until they are warm and dead”

Summary

• Hypothermia, Drowning and Near Drowning

• Four stages of an immersion incident

• Prevention and Survival

• Rescue of Survivors

Summary

• Treatments issues, including resuscitation

• Questions?

For more information

• World Congress on Drowning – www.drowning.nl

• Essentials of Sea Survival – Dr. Frank Golden, Dr. Michael Tipton – Human Kinetics, 800-465-7301, orders@hkcanada.com

• The Cold Facts – Surviving Sudden Cold Water Immersion (A Canadian Forces Production)

• Dr. Chris Brooks – Survival in Cold Waters, TP 13822E http://www.tc.gc.ca/MarineSafety/TP/Tp13822/menu.htm

With thanks to Bob Ayres

CCG