Aim To give firefighters an overview of survival physiology and in-water survival techniques.
State the physiological effects of cold water immersion Demonstrate the treatment for hypothermia Demonstrate in-water survival techniques as a single survivor and in group conditions. Learning Outcomes At the end of the session students will be able to:
What is survival Survival is the ability to stay alive when life is threatened by voluntary or involuntary immersion in water.
Survival factors The equipment available The action taken by the survivors or any bystanders. Survival difficulties can be minimised by;
Survival difficulties Heat lost when immersed in water is 26 times greater than the normal loss of heat when dry Survival time will depend on the protection provided, movement of the body and build Alcohol and swimming increase the rate of heat loss.
Approximate survival times Survival times for a clothed person
Lifejackets Well-constructed life jackets can decrease heat loss rates by 40%-50% Must be able to: Hold the mouth and nose of an unconscious person clear of the water Right them from face down in no more than 5 seconds.
Marine lifejackets Duncan III Lifejacket: Used for offshore firefighting tug response Bulky garments with inherent buoyancy Do not require inflation to achieve full buoyancy.
Marine lifejackets Crewsaver BSI 150N Lifejacket: Carried on selected appliances with an identified water risk in the station area Contain synthetic material within the garment but full buoyancy is not achieved until inflated using the oral tube.
Aviation lifejackets Carried by airborne response stations Only type of lifejacket acceptable for helicopter travel Have no buoyancy until inflated Must not be inflated until clear of the aircraft.
Immersion hypothermia No matter how warm it is above the water, keep on wearing that life jacket! If you do end up in the water, it keeps you afloat, and helps slow heat loss from the trunk.
Water entry Remove any false teeth, spectacles and sharp objects Get down to less than 10 m if possible Block off nose and mouth with one hand brace with the other hand Look down and check clear below Stand up, look straight ahead, step off.
Actions in the water Immersion hyperventilation is the first risk... The first few seconds of immersion in cold water bring a breathing pattern of deep, involuntary gasps (Gasp Reflex) This is followed by a minute or more of deep, rapid breaths, with tidal (breathing) volumes about five times normal Drowning can easily happen in this early stage, especially if you are plunged deep below the surface, or fall into rough water.
Actions in the water However, most people immersed in cold water survive this initial stage If you have the time to exercise the choice, enter cold water as gradually as possible Consciously control your breathing, if at all possible, during entry and for the first few minutes afterward, until the feeling of not being able to catch your breath is gone.
Actions in the water Once immersed, swimming is a dangerous choice to make An average person who can ordinarily swim well probably will not be able to swim more than 1 km (.062 mi) in 50°F (10°C) water on a calm day People who tread water lose heat about 30% faster than people holding still while wearing a life jacket.
Actions in the water Any motion you make while you are in cold water takes heat away from you much more quickly than holding still Do not swim unless you need to avoid a hazard or self rescue is easily achieved Get into the single survivor position to conserve body heat If in a group form a huddle, any injured persons should be in the centre.
Actions in the water Huddling with one or more other people will reduce heat loss rates by about a third, especially if chest to chest contact is maintained
Actions in the water Single Survivor Placing your hands under the life jacket and raising your knees towards your chest will reduce your heat loss rate.
Immersion hypothermia Knowledge of how immersion hypothermia works and being prepared will definitely help you to extend your survival time.
At risk situations Unprotected immersion in water cooler than 60°-70°F (16°-21°C) places you at risk of developing hypothermia Injured people are more likely to develop hypothermia than healthy people due to shock or other complications caused by their injuries Hypothermia can develop rapidly if you are immobilized involuntarily or voluntarily.
Hypothermia In relation to hypothermia, cold water has two specific threat characteristics: Extreme thermal conductivity (the rate at which it can conduct heat away from you) The specific heat of water (the large amount of heat needed to raise water temperature) These, plus water’s ability to penetrate clothing, make immersion hypothermia a potential hazard.
Hypothermia Diagnosis Subject cold to touch Subject looks cold (blue) Subject may be shivering Subject shows signs of abnormal behaviour Subject is aggressive, speech slurred.
Treatment The coldest part of the body is always the surface Blood that has passed under the surface during a slow re-heating will be cooled This will further lower the core temperature, with possible fatal results
Treatment Rapid re-warming should not be undertaken except under medical supervision This may cause circulatory collapse with fatal results Spontaneous re-warming allows the victim to re-warm using their own body heat Wrap victim in blankets and allow them to slowly re-heat using their own body heat.
Treatment Do not under any circumstances use foil emergency blankets This is similar to wrapping a frozen chicken in tinfoil and expecting it to defrost.
Visual distress signals Gun or other explosive signal (1min intervals) Continuous sounding of any fog apparatus Rockets or Flares throwing red stars International code N.C Square flag with ball above or below Flames on a vessel Parachute or hand flare Smoke signal (orange smoke).
Visual distress signals Slowly raising and lowering arms SOS in morse by radio Spoken word ‘Mayday’ Radio-telegraph or radio alarm signal EPIRB
Means of location Nimrod Aircraft (1 hour readiness) Rescue Helicopters (15 min to 1 hour) Ships in the vicinity RNLI rescue craft. At night or poor visibility, nimrod will show green flares Survivors answer with red flares.
Confirmation State the physiological effects of cold water immersion Demonstrate the treatment for hypothermia Demonstrate in-water survival techniques as a single survivor and in group conditions. Assessments will be based on this lesson and the corresponding study note: