January, 2011

Cold-related Injuries

Hypothermia, Frostbite, Chilblains and Trench Foot

What This Presentation Covers

Summary of factors increasing risk of cold related injuries and illnesses Summary of preventive measures against cold related injuries and illnesses Causes, signs and symptoms, and treatment of: – Hypothermia – Frostbite – Frostnip – – Chilblains Immersion Foot (trench foot) See “Working in Cold Environments” for more information on the causes and risk factors of cold-related illnesses and injuries, and preventive measures to minimize the hazards from cold exposure.

Factors Increasing Risk of Cold Injuries/Illnesses

• Previous cold-related injury • Predisposing health conditions • Fatigue, poor physical condition • Poor nutrition • Dehydration • Medication • Alcohol • Caffeine • Nicotine (Smoking) • Age • Improper clothing and equipment • Under-activity • Over-activity • Cold conditions: – – – Temperature Wind Wetness • Length of exposure

Preventing Cold-related Injuries and Illnesses

• Wear appropriate clothing.

• Avoid wetness or excessive sweating.

• Stay dry. Change into dry clothes and shoes if they become wet.

• Keep active. Avoid sitting or standing still for prolonged periods.

• Take frequent breaks in warm, shielded areas. • Work in pairs to keep an eye on each other. • Consume warm, high calorie food often.

• Drink plenty of warm non-caffeinated, non-alcoholic liquids.

• Don’t smoke.

Hypothermia

Hypothermia ("low heat”) is a potentially serious and fatal health condition resulting from the body’s failure to maintain its normal core temperature of 98.6

°F. When exposed to cold conditions, your body begins to lose heat faster than it can be produced. Prolonged exposure to cold eventually uses up your body’s stored energy and your core body temperature drops to 95 °F or below. The result is hypothermia.

Hypothermia is a medical emergency!

Hypothermia

(Cont.)

Body temperature that is too low affects the brain, making the affected person unable to think clearly or move well.

This makes hypothermia particularly dangerous because a person may not realize it is happening and may deny being in any trouble. Recognition of symptoms depends on co-workers' ability to identify symptoms and to seek medical help.

Hypothermia

(Cont.) However, it can occur at warmer temperatures as high as 65 °F, or more, if a person becomes chilled from prolonged exposures to wetness (rain, snow, submersion in cold water, or sweat) and accompanying winds.

Generally, in cold dry environments, hypothermia occurs over a period of hours. In cold water, core temperature can drop to dangerous levels in a matter of minutes. Most cases of hypothermia occur in air temperatures from 30 °F to 40°F.

Immersion Hypothermia

Water transfers heat away from the human body 25 times faster than air, so even moderate water temperatures can be dangerous in a relatively short time.

Water Temperature in Degrees F (Degrees C) 32.5 (0.3) 32.5 to 40 (0.3 to 4.5) 40 to 50 (4.5 to 10) 50 to 60 (10 to 15.5) 60 to 70 (15.5 to 21) 70 to 80 (2 to 26.5) Over 80 (Over 26.5) Exhaustion or Unconsciousness Under 15 min.

15 to 30 min.

30 to 60 min.

to 2 hrs.

2 to 7 hrs.

2 to 12 hrs.

Indefinite Expected Time of Survival Under 15 to 45 min.

30 to 90 min.

to 3 hrs.

to 6 hrs.

2 to 40 hrs.

3 hrs. to indefinite Indefinite

Stages of Hypothermia Hypothermia progresses through three indistinct but sequential stages as core body temperature continues to decline:

Approximate Core Body Temperature

Mild hypothermia 98 °F - 95°F Moderate hypothermia Severe hypothermia 95 °F - 90°F <90 °F

Mild Hypothermia

Signs/Symptoms

Physical Mental • Shivering, mild to severe • Sensation of cold, then pain in extremities • Pale, waxy, cold skin • Numbness of hands • Unable to perform complex tasks (fumbling with items in the hand) • Able to walk and talk • Irritability If shivering can be stopped voluntarily  mild hypothermia

Moderate Hypothermia

Signs/Symptoms

Physical Mental • Intense shivering becomes persistent and violent • Sluggish; labored movements • Stumbling • Loss of fine motor coordination in hands (fumbling) Watch for the “-umbles” • stumbles • mumbles • fumbles • grumbles • Confused, may appear alert • Irrational behavior – “paradoxical undressing” (person starts to undress, unaware s/he is cold) • Apathetic/flattened affect – "I don't care” attitude" • Withdrawn behavior • Slurred speech, difficulty speaking • Sluggish thinking • Signs of depression

Severe Hypothermia

Signs/Symptoms

Physical • Shivering stops • Exposed skin blue or puffy • Muscle coordination very poor, muscle rigidity • Stupor • Can’t walk; falls to ground and curls up into fetal position to conserve heat • Decreased pulse and respiration rate • Irregular heart rhythm Mental • Incoherent, irrational behavior • May be able to maintain posture and appearance of awareness • Semi-conscious, drowsy • Loss of awareness of others • Amnesia, memory lapses

Possible Death from Hypothermia

Core body temperature below 82 °F - 78°F Physical Mental • Erratic, shallow breathing • May not be able to feel pulse • Pupils dilated and fixed • Cold, blue skin • Unresponsive to any stimuli • Pulmonary edema, cardiac and respiratory failure • Death possible below 78 °F • Brain activity seriously slowed • Unconscious, appears comatose or dead Worker may appear dead and show all the accepted clinical signs of death, but many of these people have made complete recoveries when re warmed.

“No one is dead until

warm

and dead”

Treatment of Hypothermia

Mild Hypothermia

Treatment depends on the severity of the hypothermia.

• Remove wet clothes from victim and replace with dry clothes and/or wrap in warm blankets; cover the head. • Move to a warm environment.

• Do not exercise to warm up. • Do not re-warm person in a warm bath or by massaging or rubbing.

• Drink a warm (not hot) sugary drink. Avoid drinks with caffeine (coffee, tea, or hot chocolate) or alcohol.

• Transport victim to an emergency medical facility for evaluation.

Handle the victim gently and minimize his or her exertion.

Treatment of Hypothermia

(con’t.)

Moderate Hypothermia

• Call for emergency help.

• Follow the procedures on the preceding slide. • In addition: Cover all extremities completely, place very warm objects, such as hot packs or water bottles on the victim's head, neck, chest and groin. Arms and legs should be warmed last.

Handle the victim gently. Rough handling can cause heartbeat irregularities and death.

Treatment of Hypothermia

(Con’t.)

Severe Hypothermia

• Call for emergency help.

• Give CPR if necessary.

• Follow the procedures for treating mild hypothermia. • Do not apply external heat (hot water bath, heat lamp, electric blanket, electric heater, etc.) to re-warm.

Handle the victim very gently.

Transport to hospital for treatment as soon as possible.

• Transport the victim to an emergency medical facility as soon as possible.

Frostbite

In cold conditions, your body reduces heat loss and increases heat production in order to maintain an internal (core) body temperature of 98.6

°F. Over time, your body will decrease blood flow to your extremities and outer skin and shift it to the body core to keep the internal organs warm. However, this allows exposed skin and the extremities to cool rapidly and increases the risk of cold-related injuries, such as frostbite.

Normal core body temperature: 98.6

°F

• •   

Body Core Heart Brain Lungs Liver Kidneys

• •

Extremities Legs, feet Arms, hands

Frostbite

(Con’t.) Frostbite occurs when the deep layers of the skin and other body tissues freeze (tissue temperature <28 °F-30°F). Ice crystals form, destroying tissues and causing permanent damage. In severe cases, amputation of the frostbitten area may be required. Frostbite typically affects the: • toes/feet • fingers/ hand • ears • nose • cheeks • chin These parts are farthest from the body core, receive less blood flow, and are thinner so they cool faster.

Frostbite

(Con’t.)

Causes

• Exposure to below freezing temperatures • Can occur in above freezing temperatures due to wind chill factors and wetness • • Contact with extremely cold objects (especially metal) Contact with cooled or compressed gases, at normal temperatures (e.g., liquid nitrogen)

air temp.

+ wind

+ wetness =

cold condition

Direct skin exposure to freezing metal, extreme cold, or high winds can cause frostbite in minutes.

Frostbite

(Con’t.)

Frostbite can be classified into two main divisions:

• Superficial (mild) • Deep (severe)

The extent of frostbite depends on the extremeness of conditions and duration of exposure.

Superficial Frostbite

• Includes all layers of the skin • Initially redness in light skin, grayish in dark skin • Burning, tingling, itching, or cold sensations in the affected areas, followed by numbness • Skin turns white, waxy; some resistance when pressed (feels firm or “wooden” but underlying tissue is soft); cold to the touch • May have blistering

Photos courtesy of USACHPPM

Deep Frostbite

• Involves skin, muscle, tendons, nerves, blood vessels; may include bone • White or yellowish waxy skin that turns purplish blue as it thaws • Underlying tissue hard, no resistance when pressed, may appear blackened and dead • Blood-filled blisters and swelling may develop • May develop blood clots

Deep Frostbite

• Significant pain as affected areas re-warm; dull continuous ache becomes throbbing sensation in 2-3 days and may last weeks to months • Frostbitten skin is highly susceptible to infection, and gangrene (death and decay of body tissues) may develop • Time will reveal the final amount of tissue damage

Photos courtesy of USACHPPM

• Many people with frostbite may also be experiencing hypothermia

Treatment of Frostbite

• Move the person to a warm dry area. Don’t leave the person alone.

• Remove any wet or tight clothing that may cut off blood flow to the affected area.

• Treat for hypothermia if victim is also experiencing hypothermia. Saving their lives is more important than preserving a finger or foot. Perform CPR if necessary.

• • Do not rub the affected area, because rubbing causes damage to the skin and tissue.

Gently place the affected area in a warm (105 °F) water bath and monitor the water temperature to slowly warm the tissue. Don’t pour warm water directly on the affected area because it will warm the tissue too fast causing tissue damage. Warming takes about 25-40 minutes.

Treatment of Frostbite

After the affected area has been warmed, it may become puffy and blister. The affected area may have a burning feeling or numbness. When normal feeling, movement, and skin color have returned, the affected area should be dried and wrapped to keep it warm.

Seek medical attention as soon as possible.

NOTE: If there is a chance the affected area may get cold again, do not warm the skin. If the skin is warmed and then becomes cold again, it will cause severe tissue damage.

Frostnip

Frostnip is the mildest form of a freezing cold injury. Only the very outer layers of the skin freeze, usually on the cheeks, earlobes, fingers, and toes, and also nose and chin. • • Usually occurs at about 29 °F Generally reversible, no tissue injury or permanent damage • Skin turns white, top layer of skin feels hard but deeper tissue still feels normal (soft) • May feel tingling or numbness

Frostnip

Treatment

• Gently re-warm affected area by blowing warm air on it or placing it against a warm body part (e.g., another person’s stomach or armpit). • Do not use very hot objects such as hot water bottles to re-warm the area or person.

• Do not rub the affected part - ice crystals in the tissue can cause damage if the skin is rubbed.

Frostnip can be prevented by wearing warm clothing, gloves and insulated footwear.

Chilblains

Chilblains is caused by prolonged and repeated exposure of bare skin to air temperatures above freezing (32 °F) to 60°F, accompanied by high humidity or wet conditions. It can develop in only a few hours. • The most commonly affected areas are the cheeks, ears, nose, fingers, and toes.

• Affected area appears as red, swollen skin which is tender, hot to the touch, and may itch • Can worsen to aching, prickly (pins and needles) sensation, then numbness. • In severe cases, open sores or bleeding lesions may result from continued exposure.

Chilblains

(Con’t.) • Warm affected area gently with direct body heat:

Treatment

– Put bare hands over the affected area on the face – Put affected areas against armpits or stomach of another person • Do not massage or rub affected areas.

• Do not wet the area or rub it with snow or ice.

• Do not expose affected area to open fire, stove, or any other intense heat source.

• Seek medical attention to evaluate for tissue damage. Signs and symptoms of tissue damage may be slow to appear.

I

mmersion Injury (Trench foot)

Immersion injury (trench foot) results from prolonged exposure of the feet to wet or damp cool conditions, such as in cold water, mud, or wet fields, or wearing damp socks. A similar condition of the hands can occur if a person wears wet gloves for a prolonged period under cold conditions.

• Usually develops slowly, over hours to days and at temperatures from 32 °F to 50 °F.

• Can occur at temperatures as high as 60 degrees F if the feet are constantly wet • The primary injury is to nerve and muscle tissue. There is no formation of ice crystals in the tissues but immersion injury can cause permanent damage.

Photo courtesy of USACHPPM

Immersion Injury (Trench foot) Symptoms

Note the cyanosis (blueness of skin) around the nail beds; redness and swelling; and blisters.

• Initially reddened skin, then turns pale and mottled, finally purple, grey, or blue • Tingling pain, itching, burning sensation, or numbness may occur, followed by leg cramps and swelling • May cause permanent damage to the circulatory system so person is more sensitive and prone to cold-related injuries in that area • May develop blisters, ulcers, and gangrene. Amputation may be necessary

Immersion Injury (Trench foot) Treatment

• Remove wet clothing and replace with dry, warm clothing. • Warm affected area slowly at room temperature. Carefully clean, dry, and wrap loosely with sterile dressing, taking care not to break the blisters. This can lead to infection.

• Elevate feet to reduce swelling.

• Do not walk on injured feet.

• Seek prompt medical attention; trench foot can cause severe disability.

Immersion Injury (Trench foot) Prevention

• Keep feet clean and dry. • Check them regularly; if they get wet from water or sweat, dry them and replace with dry socks.

• Change socks at least every 8 hours or whenever wet and apply foot powder. Foot powder with aluminum hydroxide can help.

• Don’t wear tight socks; this can further impair circulation.

• Don’t sleep with wet socks.

Resources – for further information

Canadian Centre for Occupational Health & Safety: “Cold Environments – Working in the Cold” NIOSH: Cold Stress OSHA: Cold Stress Card