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Environmental health risks. Altitude. At high altitude, atmospheric pressure is reduced. The consequent reduction in oxygen pressure can lead to hypoxia (i.e. reduced supply of oxygen to the tissues).
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Altitude • At high altitude, atmospheric pressure is reduced. • The consequent reduction in oxygen pressure can lead to hypoxia (i.e. reduced supply of oxygen to the tissues). • At altitudes of 1500–3500 metres, exercise tolerance is reduced and ventilation is increased. • At 3500–5500 metres, there is hypoxia and altitude sickness may occur.
Acute mountain sickness may occur after 1–6 hours at high altitudes. • Headache is followed by anorexia, nausea and vomiting, and insomnia, fatigue, lassitude, and irritability • the affected person becomes faint and may lose consciousness. • It is crucial to descend until symptoms begin to diminish if these signs are present.
The outcome is fatal in some cases due to the development of pulmonary and cerebral oedema. • Travellers with pre-existing cardiovascular or pulmonary disease or anaemia are highly sensitive to changes in altitude,
Precautions for travellers unaccustomed to high altitudes • ● Avoid direct travel to high altitudes if possible. Break the journey for 2–3 nights at 2500–3000 metres to help prevent acute mountain sickness. • If direct travel to a high altitude cannot be avoided, the traveller should avoid overexertion, large meals, and alcohol after arrival.
Travellers with pre-existing cardiovascular or pulmonary disease or anaemia should seek medical advice before deciding to travel to a high altitude.
Heat and humidity • High temperatures and humidity stress the body's ability to cool itself • Exposure to high temperature and humidity results in loss of water and electrolytes (salts) and may lead to heat exhaustion and heat stroke.
Irritation of the skin may be experienced in hot conditions (prickly heat). • Fungal skin infections such as tineapedis are often aggravated by heat and humidity. • A daily shower, wearing loose cotton clothing and applying talcum powder to sensitive skin areas help to reduce the development or spread of these infections.
In hot dry conditions, dehydration is particularly likely to develop unless care is taken to maintain adequate fluid intake. The addition of a little table salt to food or drink (unless this is contraindicated for the individual) can help to prevent heat exhaustion. • Consumption of salt-containing food and drink helps to replenish the electrolytes in case of heat exhaustion and after excessive sweating.
Older travellers should take particular care to consume extra fluids in hot conditions, as the thirst reflex diminishes with age. • Care should be taken to ensure that infants and young children drink enough liquid to avoid dehydration. • Exposure to hot, dry, dusty air may lead to irritation and infection of the eyes and respiratory tract.
There are three major forms of heat illnesses: • heat cramps, • heat exhaustion, and • heat stroke, with heat stroke being a life threatening condition.
Heat Cramps • Heat cramps are muscle spasms which usually affect the arms, legs, or stomach. Frequently they don't occur until sometime later after work, at night, or when relaxing. • Heat cramps are caused by heavy sweating, especially when water is replaced by drinking, but not salt or potassium. • Although heat cramps can be quite painful, they usually don't result in permanent damage.
To prevent them, drink electrolyte solutions such as Gatorade during the day and try eating more fruits like bananas.
Heat Exhaustion • Heat exhaustion is more serious than heat cramps. It occurs when the body's internal air-conditioning system is overworked, but hasn't completely shut down. • the surface blood vessels and capillaries, which originally enlarged to cool the blood, collapse from loss of body fluids and necessary minerals. This happens when you don't drink enough fluids to replace what you're sweating away.
The symptoms of heat exhaustion include: headache, heavy sweating, intense thirst, dizziness, fatigue, loss of coordination, nausea, impaired judgment, loss of appetite, hyperventilation, tingling in hands or feet, anxiety, cool moist skin, weak and rapid pulse (120-200), and low to normal blood pressure • .
Somebody suffering these symptoms should be moved to a cool location such as a shaded area or air-conditioned building. Have them lie down with their feet slightly elevated. Loosen their clothing, apply cool, wet cloths or fan them. Have them drink water or electrolyte drinks • Victims of heat exhaustion should avoid strenuous activity for at least a day, and they should continue to drink water to replace lost body fluids.
HEAT STROKE • Heat stroke is a very serious illness caused by failure of the thermonuclear regulatory center in the hypothalamus (heat regulatory center in the brain). • It is generally due to a hot external environment with high humidity. • The mechanism of illness is: increase in body heat plus loss of fluids and electrolytes.
Young children have smaller amounts of body fluids and electrolytes to lose and rapidly can become dehydrated. As little as 10% losses of body fluids and electrolytes can be lethal. • Older individuals frequently have co-existing medical conditions which make them more susceptible to heat.
Immediate treatment must be directed toward physical cooling, rehydration by cool fluid replacement, cool baths, removal of excessive clothing, and rapid transportation to the closest emergency facility.
Heat stroke is a life threatening illness with a high death rate. It occurs when the body has depleted its supply of water and salt, and the victim's body temperature rises to deadly levels. • A heat stroke victim may first suffer heat cramps and/or the heat exhaustion before progressing into the heat stroke stage, but this is not always the case.
The early symptoms of heat stroke include a high body temperature (103 degrees F); a distinct absence of sweating (usually); hot red or flushed dry skin; rapid pulse; difficulty breathing; constricted pupils; any/all the signs or symptoms of heat exhaustion such as dizziness, headache, nausea, vomiting, or confusion, but more severe; bizarre behavior; and high blood pressure.
Advance symptoms may be seizure or convulsions, collapse, loss of consciousness, and a body temperature of over 108 degrees F.
precautions to prevent heat-related illnesses: • • Condition yourself for working in hot environments. • Start slowly then build up to more physical work. • • Drink lots of liquids. Don’t wait until you’re thirsty! By then, there’s a good chance that you’re already on your way to being dehydrated. • Take frequent breaks, especially if you notice you’re getting a headache or you start feeling overheated. Cool off for a few minutes before going back to work.
Wear lightweight, light colored clothing when working out in the sun. • Take advantage of fans and air-conditioners.
Frost bite • Frostbite is the medical condition where localized damage is caused to skin and other tissues due to extreme cold. Frostbite is most likely to happen in body parts farthest from the heart and those with large exposed areas
Classification Cold injuries can result in a number of distinct conditions including: • Frostnip is a superficial cooling of tissues without cellular destruction. • Chilblains are superficial ulcers of the skin that occur when a predisposed individual is repeatedly exposed to cold • Frostbite, on the other hand, involves tissue destruction. • Hypothermia is a decrease in core body temperature below 35 C.
Mechanism • At or below 0 °C (32 °F), blood vessels close to the skin start to constrict. The same response may also be a result of exposure to high winds. This constriction helps to preserve core body temperature. • In extreme cold, or when the body is exposed to cold for long periods, this protective strategy can reduce blood flow in some areas of the body to dangerously low levels. This lack of blood leads to the eventual freezing and death of skin tissue in the affected areas.
Degrees of frostbite First degree • This is called frostnip and this only affects the surface skin, which is frozen. On onset there is itching and pain, and then the skin develops white and yellow patches and becomes numb. The area affected by frostnip usually does not become permanently damaged as only the skin's top layers are affected.
Second degree • If freezing continues, the skin may freeze and harden, but the deep tissues are not affected and remain soft and normal. Second degree injury usually blisters 1-2 days after becoming frozen. The blisters may become hard and blackened, but usually appear worse than they are. Most of the injuries heal in one month but the area may become permanently insensitive to both heat and cold.
Third degree • If the area freezes further, deep frostbite occurs. The muscles, tendons, blood vessels, and nerves will all freeze. The skin is hard, feels waxy. The deep frostbite results in areas of purplish blisters which turn black and which are generally blood-filled. Nerve damage in the area can result in a loss of feeling. This extreme frostbite may result in fingers and toes being amputated if the area becomes infected with gangrene.
Risk factors • Risk factors for frostbite include using beta-blockers and having conditions such as diabetes and peripheral neuropathy.
Causes • Factors that contribute to frostbite include extreme cold, inadequate clothing, wet clothes, and poor circulation. Poor circulation can be caused by tight clothing or boots, certain medications, smoking, alcohol use, or diseases that affect the blood vessels, such as diabetes. • Liquid nitrogen and other cryogenic liquids can cause frostbite to people working in chemical laboratories even with brief exposure.
If the weather is very cold and it is windy, wind can greatly reduce the time it takes for frostbite to set in. • Diabetes can also sometimes lead to frostbite, if diabetics take trips to ice-cold places.
Treatment • Treatment of frostbite is rewarming(and possibly thawing) of the affected tissue. The decision to thaw is based on proximity to a stable, warm environment. • Excessive movement of frostbitten tissue can cause ice crystals that have formed in the tissue to do further damage. Splinting and/or wrapping frostbitten extremities is therefore recommended to prevent such movement. For this reason, rubbing, massaging, shaking, or otherwise applying physical force to frostbitten tissues in an attempt to rewarm them can be harmful.
Warming can be achieved in one of two ways: • Passive rewarminginvolves using body heat or ambient room temperature to aid the person's body in rewarming itself. This includes wrapping in blankets or moving to a warmer environment.
Active rewarmingis the direct addition of heat to a person, usually in addition to the treatments included in passive rewarming. • Active rewarming requires more equipment and therefore may be difficult to perform in the prehospitalenvironment. When performed, active rewarming seeks to warm the injured tissue as quickly as possible without burning them. This is desirable as the faster tissue is thawed, the less tissue damage occurs. Active rewarming is usually achieved by immersing the injured tissue in a water-bath that is held between 40 - 42 C.
Surgery • Debridement and or amputation of necrotic tissue is usually delayed. This has led to the adage "Frozen in January, amputate in July“. With exceptions only being made for signs of infections or gas gangrene.
Prognosis • A number of long term sequelae can occur after frost bite. These include: transient or permanent changes in sensation, increased sweating, cancers, and bone destruction / arthritis in the area affected.
