Cold Water Paddling Safety

 

 

 

Introduction

 

Fact: Immersion in cold water kills more sea kayakers than any other factor in the sport. Cold water is the single most serious threat to the survival of an unprepared paddler.

Fact: Hypothermia is not normally the issue in cold water paddling, but rather a predictable series of shock reactions that first impair, then quickly preclude, effective self-rescue actions.

Fact: A review of 6 fatal and 12 near-fatal accidents (1985) noted that all but one involved water temperatures of 50F or less. A more recent review of 20 accidents, 19 involving immersion of 26 people in cold water noted that 10 died before they could be rescued and the remainder had varying degree of hypothermia.

Fact: "Cold Water Kills" Our goal is to provide you, the beginning, intermediate or advanced paddler with the information you will need to keep yourself safe, healthy and enjoying paddling no matter what the season

What is killing the kayakers?
For years, most paddlers thought that the foremost danger in cold water paddling was hypothermia, and mistakenly concluded that cold water drownings were caused by hypothermia. Mistakenly because new evidence suggests otherwise. So what is it? What is happening to the kayakers found upside down, still inside their boats, apparently never making attempts to exit or self rescue themselves? What happened to the 9 physically fit and tough U. S. Marines who capsized their boat one frigid winter day on the Potomac River, not one making it to shore alive? What could have happened to these paddlers? Did they drown? Did they die of hypothermia? Did they die of shame? Well, the answer may be both yes and no to all of these questions. What we can surmise though is that some sudden disabling event happened to precipitate these casualties. Most likely the injuries were part of a series of complex events that combines aspects of cold shock, hypothermia and drowning.



Cold Shock

A new theory, developed within the last few years by Moulton Avery may well explain what is happening to some paddlers when suddenly immersed in cold water. Cold Shock can best be described as a series of physiologic events within the human body, characterized by incapacitation, immediate loss of breathing control and a high risk of sudden drowning.


Cold Shock Responses

Cold shock happens when you are suddenly immersed in cold water. Don't mistakenly think that the water must be freezing. Cold shock can occur even in water temperature above 50F. Wearing a dry suit, without proper clothing beneath is not protection from cold shock.

Immersion in cold water is characterized by the rapid development of a number of shock responses that can result in sudden drowning. A few of these responses can be consciously suppressed or moderated but most are beyond control. The most important shock response involves loss of the ability to control breathing.

The Gasp Reflex

Loss of breathing control begins the moment water makes contact with the skin, triggering a series of huge involuntary gasps for air. If your head is underwater when you gasp, you will immediately drown. Example: Oct. 1987, Water temperature: 41F. Fit paddler, calm waters, folding double kayak with 36" beam. Found hanging upside down in his boat, having made no attempt to exit. Not dressed for immersion.

Have you ever been in the shower when the hot water stops and cold water continues? The uncontrolled gasp is what we worry about. Don't think you can control the gasp reflex, it is a physiological reflex. The only way to protect against the gasp reflex is to dress properly with full head gear including wet suit hood, nose clips and ear plugs. This is a subject we are still learning about and all the facts are not in


 

Hypothermia

Human Beings and the Cold

Hypothermia: Hypothermia is called the silent killer and can happen even if you don't capsize or get wet. Hypothermia occurs when the body core temperature begins to fall below its normal 98.6. Wind, rain or sweating can lead to hypothermia.

With slow onset hypothermia as the core temperature drops below 97 shivering usually starts and you might feel your hands and feet are cold (even if properly covered). This is why its said that, if your feet are cold, put on a hat. To preserve core heat, the body will slow the circulation of blood to its extremities, so they get cold first. This is one of the hypothermia warning signs. It should not be disregarded. Even at this early stage, hypothermia is very dangerous. The loss of dexterity can make it impossible to open a hatch for extra clothing, or you might be unable to use a paddle float to do a self rescue, and many kayakers have not been able to put their spray skirts back on. This can happen even with the best hand gear made. As stated, it isn't improper hand gear, but the bodies survival instinct of slowing circulation to the extremities.

As the core temperature drops to the lower nineties, shivering will slow or stop and the person might begin to feel warm again. This is when the real danger begins. The loss of mental alertness will occur, causing wrong decisions to be made. The victim will lose coordination, increasing the likelihood of a capsize. At this stage it becomes very difficult to warm the person safely outdoors, or for the person to save themselves. The victim's body will not be able to warm itself.


 

How Your Body Regulates Core Temperature

Vasodilatation (dilation of blood vessels) increases surface blood flow & increases heat loss (when ambient air/water temperature is less than body temperature).

Vasoconstriction (constriction of blood vessels) decreases blood flow to periphery & decreases heat loss.

Sweating - cools the body through evaporative cooling.

Shivering - generates heat through the increase in chemical reactions required for muscle activity. Visible shivering can maximally increase surface heat production by 500%. However, this is limited to a few hours because of depletion of muscle glucose and the onset of fatigue.

Increasing/Decreasing Activity will cause corresponding increases in heat production and decreases in heat production.

Behavioral Responses - putting on or taking off layers of clothing will result in heat regulation

How We Lose Heat to the Environment or Stay Dry = Stay Alive!

Radiation

The loss of heat to the environment due to the temperature gradient (this occurs only as long as the ambient temperature is below 98.6F). Factors important in radiant heat loss are the surface area and the temperature gradient.

Conduction

Through direct contact between objects, molecular transference of heat energy.

Water conducts heat away from the body 25 times faster than air because it has a greater density (therefore a greater heat capacity).

Steel conducts heat away faster than water. Example: Generally conductive heat loss accounts for only about 2% of overall loss. However, with wet clothes the loss is increased 5 times.

Convection

A process of conduction where one of the objects is in motion. Molecules against the surface are heated, move away, and are replaced by new molecules which are also heated. The rate of convective heat loss depends on the density of the moving substance and the velocity of the moving substance (water convection occurs more quickly than air convection). Wind chill is an example of the effects of air convection. The wind chill table gives a reading of the amount of heat lost to the environment relative to a still air temperature.

 

Wind Chill

Wind Speed

Actual Air Temperature (F)

MPH

50

40

30

20

10

5

48

36

27

17

-5

10

40

29

18

5

-8

15

35

23

10

-5

-18

20

32

18

4

-10

-23

25

30

15

-1

-15

-28

30

28

13

-5

-18

-33

35

27

11

-6

-20

-35

 


Evaporation

Heat loss from converting water from a liquid to a gas.

Perspiration - evaporation of water to remove excess heat.

Sweating - body response to remove excess heat.

Insensible Perspiration - body sweats to maintain humidity level of 70% next to skin - particularly in a cold, dry environment you can lose a great deal of moisture this way.

Respiration - air is heated as it enters the lungs and is exhaled with an extremely high moisture content.

It is important to recognize the strong connection between fluid levels, fluid loss, and heat loss. As body moisture is lost through the various evaporative processes the overall circulating volume is reduced which can lead to dehydration. This decrease in fluid level makes the body more susceptible to hypothermia and other cold injuries.

Response to Cold

Heat Retention - (positive factors)

Size/shape (Eskimo vs. Masai)

Insulation (layering/type)

Fat (as insulation)

Shell/core (shunt blood to core) shell acts as a thermal barrier Total = Heat Retention

Heat Production - (positive factors)

Exercise, shivering Limited by:

Fitness

Fuel stores (glycogen)

Fluid status (efficient exercise)

Food intake (kindling, sticks, logs) Total = Heat Production

Cold Challenge - (negative factors)

Temperature

Wet (rain, sweat, water)

Wind (blowing, moving, e.g. biking) Total = Cold Challenge

Heat Retention + Heat Production Less Cold Challenge = Hypothermia

 

Smoking decreases an individuals thermo regulation ability

 

Medications that are taken to treat emotional factors, cardiac function, blood pressure, etc. decreases an individuals thermo regulation ability

 





Types & Signs of Hypothermia

Hypothermia defined:

"A decrease in the core body temperature to a level at which normal muscular and cerebral functions are impaired".

Two types:

Sudden Onset - rapid chilling from cold water exposure.


Long Onset - progressive exposure over a period of time. Usually occurs with exposure below 50 wind, wet from rain, sea spray or perspiration all create problems. May develop silent hypothermia with gradual onset of physical and mental fatigue unaccompanied by shivering.
Conditions Leading to Hypothermia

Cold temperatures

Improper clothing and equipment

Wetness

Fatigue, exhaustion

Dehydration

Poor food intake

No knowledge of hypothermia

Alcohol intake - causes vasodilatation leading to increased heat loss

What are hypothermia temperatures

Below freezing

40 - Ex. Shenandoahs, wind and rain

60 - Ex. Rayanna and hurricane

Any temperature less than 98.6 can be linked to hypothermia (ex. hypothermia in the elderly in cold houses) or peripheral circulation problems such as trench foot and frostbite.

Signs and Symptoms of Hypothermia

Watch for the - Umbles - stumbles, mumbles, fumbles, and grumbles which show changes in motor coordination and levels of consciousness

Mild Hypothermia

Core temperature 98.6 - 96F.

Shivering - not under voluntary control

Can't do complex motor functions (ice climbing or skiing) can still walk & talk

Vasoconstriction to periphery

Moderate Hypothermia

Core temperature 95 - 93F.

Dazed consciousness

Loss of fine motor coordination - particularly in hands - can't zip up parka, due to restricted peripheral blood flow

Slurred speech

Violent shivering

Irrational behavior - Paradoxical Undressing - person starts to take off clothing, unaware he/she is cold

I don't care attitude - flattened affect

Severe Hypothermia

Core temperature 92 - 86 and below (immediately life threatening).

Shivering occurs in waves, violent then pause, pauses get longer until shivering finally ceases - because the heat output from burning glycogen in the muscles is not sufficient to counteract the continually dropping core temperature, the body shuts down on shivering to conserve glucose

Person falls to the ground, can't walk, curls up into a fetal position to conserve heat

Muscle rigidity develops - because peripheral blood flow is reduced and due to lactic acid and CO2 buildup in the muscles

Skin is pale

Pupils dilate

Pulse rate decreases

At 90 the body tries to move into hibernation, shutting down all peripheral blood flow and reducing breathing rate and heart rate.

At 86 the body is in a state of "metabolic icebox." The person looks dead but is still alive.

Death from Hypothermia

Breathing becomes erratic and very shallow

Semi-conscious

Cardiac arrhythmia's develop, any sudden shock may set off Ventricular Fibrillation (uncoordinated heart rhythm - quickly leads to death)

Heart stops, death

How to Assess if someone is Hypothermic

If shivering can be stopped voluntarily = mild hypothermia

Ask the person a question that requires higher reasoning in the brain (count backwards from 100 by 9's). If the person is hypothermic, they won't be able to do it. [Note: there are also other conditions such as altitude sickness that can also cause the same condition.]

If shivering cannot be stopped voluntarily = moderate - severe hypothermia.

If you can't get a radial pulse at the wrist it indicates a core temperature below 90 - 86.

The person may be curled up in a fetal position. Try to open their arm up from the fetal position, if it curls back up, the person is alive. Dead muscles won't contract - only live muscles.

An old Emergency Room adage: A person is never dead until they are warm and dead. This means that even if you don't have vital signs you assume the person is still alive and treat them for hypothermia. Remember, people have survived sustained periods of hypothermia and drowning from cold water. Cold water induced Mammalian reflex slows heart rate, oxygen and energy requirements in an effort to preserve life.

 


Treatment of Hypothermia

The best method of treating hypothermia and / or cold shock is to prevent it from happening in the first place.

Dress appropriately for the water temperature regardless of the air temperature. A general rule of thumb is to wear wet or dry suits when water temperatures is less than 50F.
 

Individuals who dump in narrow streams or very close to shore ( like 10 seconds of swimming ) to get to the shore and out of the water as soon as possible.    In wider water, get as much of your body out of the water  as you can.   Usually this means climbing on top of your boat.

 


The head is a primary heat loss area

Avoid cottons

Wool, nylon or synthetics will not prevent cold shock

Carry dry extra clothing

Carry a sleeping bag or space blanket

Field Treatment

Always remember your ABC's when assessing some one for cold related injuries. Their AIRWAY must be open, they must be BREATHING and their must be blood CIRCULATING, otherwise your efforts are for naught!

Learn CPR if you don't know already. Your training may save a life!

Gently remove cold, wet clothing. Place into dry clothing, sleeping bag, wrap with space blankets. Prevent further conductive or convective heat loss.

External heat - chemical or other heat packs to armpits, groin, around neck, scalp (near major blood vessels), body to body contact (share your heat but must be skin to skin contact).

Warm Liquids - Small sips of warm not hot liquids.

Avoid alcohol - A vasodilator, alcohol causes blood vessels to dilate and releases cold blood from the extremities into the core. May precipitate heart arrhythmias and sudden death.

Move gently and only horizontally - Avoid after drops of blood pressure and release of cold blood to the core. Sudden, vertical position changes can cause after drop and sudden death.

Seek medical attention as soon as possible



 

Cold Water Equipment

What you wear for cold water paddling will vary depending on the water temperature, weather and the wind, but the same theory applies for any temperature.

To keep warm your skin must be dry. The first layer is used to move the moisture away from your skin and into the outer layers. The shell is used to keep you and your insulation dry. Most insulation works much better when dry.

Dress light. As you stand on the shore before going out you should feel cool. As you start paddling you will warm up quickly. Adjust you temperature by adjusting your head gear and gloves. You can also put a wind breaker/Storm Cag over your dry suit.

Following is a list of clothing. It is listed in order from against your skin to the outer layer. The middle layers are used to adjust for different temperatures.