Circular
Letter
MSC.1/Circ.1185
GUIDE FOR COLD WATER SURVIVAL
(31.05.2006)
1.
The Maritime Safety Committee, at its eighty-first session (10 to 19 May 2006),
with a view to providing enhanced guidance for passenger ships operating in
cold water areas, approved the Guide to cold water survival, prepared by the
Sub-Committee on Radiocommunications and Search and Rescue, at its tenth
session (6 to 10 March 2006), as set out in the annex.
2.
Member Governments and international organizations are invited to bring the
annexed Guide to the attention of all concerned.
Annex.
GUIDE FOR COLD WATER SURVIVAL.
1.1
The purpose of this guide is to examine the hazards of cold exposure that may
endanger your life, and to provide you with advice on how to prevent or
minimize those dangers. A thorough understanding of the information contained
in this booklet may some day save your life.
1.2
The sinking of the Titanic in 1912 provided a dramatic example of the effects
of cold water immersion. Partially due to a lack of preparedness with
protective clothing, of adequate flotation equipment, and of knowledge of
survival procedures, none of the 1,489 persons immersed in the 0°C water was
obviously alive when rescue vessels arrived one hour and 50 minutes after the
sinking.
1.3
Countless lives could have been saved had the survivors and the rescuers known
more of how to cope with cold water: almost all of the people in the lifeboats
were alive.
1.4
During the Second World War the Royal Navy of the United Kingdom alone lost
about 45,000 men at sea, of whom it is estimated 30,000 died from drowning and
hypothermia. Many of those who drowned did so because of incapacitation due to
cold. Even today the pattern is similar.
1.5
It is important to realize that you are not helpless to effect your own
survival in cold water. Body heat loss is a gradual process, and research shows
that in calm water at 5°C a normally dressed person has a 50% chance of
surviving three hours. Simple self-help techniques can extend this time,
particularly if the person is wearing a lifejacket. You can make the
difference; this guide is intended to show you how.
2.1
An understanding of how your body reacts to cold air or water exposure, and
knowing the steps you can take to help your body delay the damaging effects of
cold stress, will help you in your struggle to stay alive in the event of cold
water exposure.
2.2
Imagine your body to consist of an inner core and an outer layer. Your body
produces a great deal of heat as a result of normal body functions, such as
physical exercise and digesting your food.
2.3
Nature requires that your body core be kept to an ideal temperature of 37°C. A
network of blood vessels running through the core and the outer layer of your
body picks up the heat produced, and distributes it throughout the body. Nature
also gives your body a very accurate system to regulate automatically the core
temperature at 37°C. For example, if the temperature around you is high, as on
a warm day or in a hot boiler room, the blood vessels near the skin of your
body will enlarge, allowing more blood to flow to the outer layer and increase
body heat loss. This will keep you comfortable and keep the core temperature
from rising. If the surroundings are cool, your body will narrow the blood
vessels in the outer layer and keep that valuable body heat from being lost too
rapidly.
2.4
This regulatory system strives to keep the core temperature of the body
constant despite variations in ambient temperature around you. The body can
only do this within certain limits. There are levels of cold exposure when the
body must have help in maintaining the core temperature at nature's choice of
37°C. You must give your body that help by taking correct actions and wearing
protective clothing.
3. Body heat loss and
insulation.
3.1
The body usually loses heat to the surroundings in the following ways:
.1 Transfer of
heat by direct contact with cold water or other materials. Heat passes from
your body, which is at a relatively high temperature, to a substance which is
lower in temperature. Certain substances are better conductors of heat than
others. Water conducts heat more than twenty times faster than air.
.2 Transfer of
heat by air or water currents: moving air is far cooler to the body than still
air. Cooling by wind is known as the 'wind-chill' effect. Similarly disturbed
or moving water around your body is more chilling than still water at the same
temperature.
3.2
In almost all parts of the world, man cannot survive without the aid of
clothes. Clothes by themselves do not warm the body; the body is actually
warmed by its own heat production. The body heat warms the layer of air trapped
between the skin and clothing. It is this layer of air that provides
insulation. If the layer of air is lost, then the insulation is diminished.
This layer of trapped air between skin and clothing may be disturbed by
movement or displaced by water. In either case, valuable warm air is displaced
and skin temperature will fall. Heat from the body core will them be used in an
endeavour to maintain skin temperature. If heat loss from the skin remains
unchecked, the body core temperature will fall.
4.1
The loss of body heat is one of the greatest hazards to the survival of a
person at sea. The rate of body heat loss depends on the:
.1 water and air
temperature;
.2 wind speed;
.3 sea
conditions;
.4 length of
time spent in the water;
.5 protective
clothing worn;
.6 body type of
the survivor;
.7 mental and
health status of the survivor;
.8 level of
alcohol and certain drugs in the survivor's body; and
.9 manner in
which the survivor conducts himself.
4.2
An abnormally low body core temperature can be recognized by a variety of
symptoms. Very early during exposure, the body tries to combat the excessive
heat loss both by narrowing its surface blood vessels (to reduce heat transfer
by blood to surface) and by shivering (to produce more body heat). However, if
the exposure is severe, the body is unable to conserve or produce enough heat.
Body core temperature begins to fall. When the body core temperature is below
35°C, the person is suffering from 'hypothermia'.
4.3
By then, discomfort, tiredness, poor coordination, numbness, impaired speech,
disorientation, and mental confusion are well established. As the internal
temperature falls further, unconsciousness may occur, shivering is replaced by
muscle stiffness, and the pupils of the eyes may be enlarged. The heartbeat
becomes irregular, slow and weak and the pulse is barely detectable. Although
death may occur at any stage of hypothermia, when a person's temperature is
very low it is difficult to understand, if the person is alive or dead. Death
by hypothermia is then defined as a failure to revive on re-warming.
5.1
Ships may sink in less than 15 minutes. This affords little time to formulate a
plan of action, so careful planning is essential to be ready in an emergency.
Here are some sound pointers for you to remember when abandoning a ship (see
also appendix 1):
.1 Put on as
many layers of warm clothing as possible, including foot protection, making
sure to cover head, face, neck, hands and feet. Fasten, close and/or button up
clothing to prevent cold water flushing through the clothing.
.2 If an
immersion suit is available, put it on over the warm clothing.
.3 If the
immersion suit does not have inherent flotation, put on a lifejacket and be
sure to secure it correctly before immersion. In cold water you will lose full
use of your fingers immediately.
.4 If time
permits all persons should, before boarding the survival craft or in any case
immediately after boarding, take some recommended anti-seasickness medicine.
Seasickness will interfere with your survival chances as vomiting removes
precious body fluid, and seasickness in general makes you more prone to
hypothermia and impairs your will to survive.
.5 Avoid
entering the water if possible, e.g. board davit-launched survival craft on the
embarkation deck or by the marine escape system. If davit-launched survival
craft, a marine escape system or other means of dry-shod embarkation are not
available, use over-side ladders or, if necessary, lower yourself by means of a
rope or fire hose.
.6 Stay out of
the water as long as possible! Try to minimize the shock of sudden cold
immersion. A sudden plunge into cold water can cause rapid death, or an
uncontrollable rise in breathing rate may result in an intake of water into the
lungs. If jumping into the water is unavoidable, you should try to keep your
elbows to your side and cover your nose and mouth with one hand while holding
the wrist or elbow firmly with the other hand. Avoid jumping onto the liferaft
canopy or jumping into the water astern of a liferaft, in case the ship has
some remaining headway.
.7 Once in the
water, whether accidentally or by ship abandonment, orient yourself and try to
locate the ship, lifeboats, liferafts, other survivors, or other floating
objects. If you were unable to prepare yourself before entering the water,
button up clothing now. In cold water, you may experience violent shivering and
great pain. These are natural body reflexes that are not dangerous. You do,
however, need to take action as quickly as possible before you lose full use of
your hands: button up clothing, turn on signal lights, locate whistle, etc.
.8 While afloat
in the water, do not attempt to swim unless it is to reach a nearby craft, a
fellow survivor, or a floating object on which you can lean or climb.
Unnecessary swimming will 'pump' out any warm water between your body and the
layers of clothing, thereby increasing the rate of body heat loss. In addition,
unnecessary movements of your arms and legs send warm blood from the inner core
to the extremities (arms and legs) and thus to the outer parts of the body.
This can result in very rapid heat loss. Stay calm and take up a good position
to prevent drowning.
.9 The body
position you assume in the water is also very important in conserving heat. Try
to float as still as possible – with your legs together, elbows close to your
side, and arms folded across the front of your lifejacket. This position
minimizes the exposure of the body surface to the cold water. Try to keep your
head and neck out of the water.
.10 Try to board
a lifeboat, raft, or other floating platform or object as soon as possible in
order to shorten the immersion time. Remember: you lose body heat many times
faster in water than in air. Since the effectiveness of your insulation has
been seriously reduced by water soaking, you must now try to shield yourself
from wind to avoid a wind-chill effect. If you manage to climb aboard a
lifeboat, shielding can be accomplished with the aid of a canvas cover, a
tarpaulin, or an unused garment. Huddling close to the other occupants of the
lifeboat or raft will also conserve body heat.
.11 Keep a
positive attitude of mind about your survival and rescue. This will improve
your chances of extending your survival time until rescue comes. Your will to
live does make a difference!
6. Treatment of the
immersion survivor.
6.1
The treatment for hypothermia will of course depend on both the condition of
the survivor and the facilities available. Generally speaking, survivors who
are rational and capable of recounting their experiences, although shivering
dramatically, merely require removal of all wet clothes and replacement with
dry clothes or blankets. If possible, they should be taken from the water
horizontally and carried this way, or else be returned to the horizontal (or,
better still, to the unconscious position) as quickly as possible and kept this
way. Hot sweet drinks should be given but only if the victim is fully conscious
with gag and cough reflexes. Rest in a warm environment not exceeding 25°C
(normal room temperature) is also recommended. Do not allow alcohol or smoking,
or massaging or rubbing of the cold skin. However, always bear in mind that
even conscious survivors can collapse and become unconscious shortly after
rescue. They should therefore be kept resting horizontally, with their legs
slightly elevated (the 'shock position'), and be watched until core rectal
temperature has exceeded 35°C (see also appendix 2).
6.2
In more serious cases, where the survivor is not shivering and is
semi-conscious, unconscious, or apparently dead, immediate first-aid measures
will be necessary to preserve life while awaiting medical advice on more
detailed management procedures. This advice should be sought as soon as
possible and first-aid measures should not be delayed while advice is being
sought. The recommended first-aid measures for such an immersion survivor are
as follows:
.1 On rescue,
always check the survivor's breathing and carotid pulse for one minute each
side of the neck.
.2 If the
survivor is not breathing, make sure the airway is clear (remove dentures, if
any), tilt the head back, lift the chin and start artificial respiration
immediately (mouth-to-mouth or mouth-to-nose). If the heart appears to have
stopped beating then cardiac compressions may be applied. However, you should
be certain that there is no pulse at all (remember that hypothermia slows and
weakens the pulse greatly) and, once started, it must be continued properly
until the patient is either fully re-warmed or delivered to a hospital.
.3 If the
survivor is breathing but unconscious, lay him in the unconscious position.
This is necessary to ensure that the person's breathing is not obstructed by
his tongue or by vomit.
.4 Avoid all
manhandling which is not necessary to determine whether there are any serious
injuries; do not even remove wet clothes; do not massage.
.5 Prevent
further heat loss through evaporation and from exposure to the wind. Carefully
wrap the patient in blankets and/or a casualty bag or large plastic bag and
transfer immediately to a (wind-) sheltered area or below decks to a
compartment at normal room temperature, keeping him horizontal, slightly head
down.
.6 Advice on
re-warming and decisions regarding further treatment should normally be given
only by a doctor. If no medical advice is immediately available, continue to
apply the essential life-saving procedures given in subparagraphs .1 to .5
above. In addition, even if the rescued person is cold and appears dead, or if
he deteriorates and/or the pulse and breathing are lost, resuscitation attempts
should not be ended before patient has been re-warmed. In a sheltered warm room
the person's clothing can be cut and removed with a minimum of disturbance.
Then wrap the person in blankets to reduce further heat loss. The best method
of 'active' re-warming is the use of forced warm air (maximum 40°C), which has
to be blown under the blankets covering the rescued person. Alternatively use
heated blankets or sheets (about 40°C, but not hotter). Never use a hot bath or
hot shower!
.7 'Passive'
methods of warming are not very effective. Do not attempt to warm the person by
vigorous actions. Apply heating pads or hot water bottles under the blanket, to
the person's head, neck, chest and groin – but never place these warm objects
against the bare skin as cold skin is easily burned.
6.3
If the above-mentioned methods of warming are not available then apply body
warmth by direct body-to-body contact with the rescued person. In addition,
wrap a blanket around both the rescued person and the person or persons
supplying the warmth. In all cases try to monitor the pulse and breathing.
6.4
The above basic guidelines on first aid treatment for the unconscious person
could be illustrated diagrammatically.
Start
(Recover
in a more or less horizontal position whenever possible)
Is
person breathing?
Yes
1. Insulate to
prevent further heat loss through evaporation and exposure to wind. Avoid
unnecessary manhandling – leave wet clothes on and enclose in blankets and/or
plastic bag. Move to sheltered location.
2. Lay down in
the unconscious position whenever possible.
3. Oxygen should
be given if available.
4. If water was
inhaled, encourage deep breathing and coughing.
5. Request
medical assistance.
6. Watch person
closely until shivering starts. In the absence of medical advice re-warm the
person by either the 'active' or 'passive' method described in paragraph 6.
No
1. Clear airway,
check carotid pulse.
2. Start
artificial respiration immediately (mouth-to-mouth, mouth-to-nose). If a pulse
cannot be detected, commence cardiac resuscitation.
3. Insulate to
prevent further heat loss through exposure to wind. Avoid unnecessary
manhandling – leave wet clothes on and enclose in blankets and/or plastic bag.
Monitor pulse, breathing and consciousness of victim and actively re-warm if
the person appears dead or if the person's condition deteriorates.
4. Seek medical
advice. If medical advice is not available, continue resuscitation until the
patient is either fully re-warmed* or delivered to a hospital.
Note: In the
context of hypothermia a person cannot be presumed dead until he is re-warmed
and shows no bodily functions.
A
person with cardiac arrest caused by severe hypothermia has a very good chance
of surviving if artificial respiration and cardiac resuscitation is carried out
until re-warming is finished. Mouth-to-mouth ventilation over a long period of
time is very difficult and exhausting. Doing conventional cardiac resuscitation
is a hard physical activity. As soon as possible use medical aids to make
resuscitation more bearable for the helper and more effective for the brain and
the heart of the rescued person, who is lacking oxygen: use a ventilation bag,
Guedel-airway, oxygen-delivery device, Combitube-airway (which enables the
helper to do rescue breathing directly into a pipe positioned in or at the
entrance of the trachea), etc. The chest and the muscles of a hypothermic
person are stiff. The pumping effect of chest compression can be improved by
using a handheld medical device equipped with a suction cup to actively lift
the anterior chest during decompression. Instruction in advance is necessary to
use these mechanical devices more effectively in basic life support.
7.1
We have briefly explained how your body responds to cold, what you can do to
help ward off the harmful effects of cold and, finally, how to administer aid
to an immersion survivor. We will now sum up the story with a number of
important reminders. Follow them for your life may depend on them.
1. Plan your
emergency moves in advance! Ask yourself what you would do if an emergency
arose. Where is your nearest exit to the deck for escape? Where is the nearest
available immersion suit, lifejacket, lifeboat, or raft? How would you quickly
get to your foul weather gear, insulated clothing, insulated gloves?
2. Know how your
survival equipment works. The time of the emergency is not the time to learn.
3. Even in the
tropics, before abandoning ship, wear many layers of clothing to offset the
effects of cold. Wear an immersion suit if available.
4. Put on a
lifejacket as soon as possible in an emergency situation.
5. When
abandoning ship, try to board the lifeboat or raft dry without entering the
water. Take anti-seasickness medicine as soon as possible.
6. If immersion
in water is necessary, try to enter the water gradually.
7. Swimming
increases body heat loss. Swim only to a safe refuge nearby.
8. To reduce
your body heat loss, try to float in the water with your legs together, elbows
to your side, and arms across your chest.
9. In a survival
situation, you must force yourself to have the will to survive. This will make
the difference between life and death.
7.2
In conclusion, advance planning, preparation and thought on your part can be
the most significant factors in your struggle with cold water immersion and in
your survival. Familiarize yourself with the contents of this guide.*
Appendix 1.
Checklist for cold water survival.
What
can I do for surviving a longer stay in cold water, even for several hours?
Preparation in advance:
- Hardy to cold.
- Fitness.
- Emergency
rescue training.
- Knowledge of
cold water survival.
- Have a plan!
In
a distress alert situation:
- Put on as many
layers as possible, alternating thin/close-meshed and thick/wide-meshed! The
outer layer should be as watertight as possible. Fasten, close and/or button-up
clothing to prevent cold water flushing through the clothing.
- Cover head,
neck and face.
- Wear robust,
laced boots (better than Wellingtons)!
- Put an
immersion suit over the warm clothing!
- Drink a lot
(warm tea is best, no alcohol: that reduces chances of survival in cold water!)
- Take
anti-seasickness tablets as soon as possible.
- Be sure that
all your clothing, life jacket and lifebelt are secured correctly! In cold
water you will lose full use of your fingers immediately. Check each other!
Ship
abandonment:
- Avoid entering
the water for as long as possible!
- Automatic life
vests should be manually activated before you enter the water and after you
leave the interior of your ship.
- Enter the
water as late as possible and as slowly (step by step) as possible to prevent
cold shock!
- Do not jump
into the water (danger of cold shock)!