Chapter 24: Environmental Emergencies
hypothermia
heat loss exceeds heat gain heat loss occurs through five mechanisms: radiation, convection, conduction, evaporation, and respiration
heat produced
metabolism of food, muscle and gland activity
lightening strike injuries
A lightning bolt's current ranges from 100 million to 2 billion volts with an amperage as high as 200,000. The speed of a lightning bolt is 1-2 million meters per second. The contact temperature of a lightning bolt is 15,000°F-60,000°F. Even though the contact temperature is so high, the extremely short duration of time prevents deep internal and external burns to the body. Contrary to a common misconception, lightning injuries are not typically major burn injuries; however, superficial linear patterns (called Lichtenberg lines) are common
risk factors for generalized hypothermia
Ambient temperature, wind chill, and moisture. Extremely low temperatures are not necessary for hypothermia to occur. It can occur in temperatures as high as 65°F, depending on the wind-chill factor. Wetness, either from perspiration or immersion in water (or rain), always compounds the problem and increases the risk of hypothermia (Figure 24-4). Age. People who are at the extremes of age, such as infants (especially newborns) and toddlers and the elderly, are at increased risk of hypothermia. Infants and young children have a large surface area in relation to their overall size, increasing both the amount and speed of heat loss. The ability to shiver (a heat-producing mechanism) is not well developed in children and does not exist in infants because of their small muscle mass. Both the young and old tend to have less body fat, which also contributes to heat loss. The elderly have an impaired recognition of cold, a diminished basal metabolism, and poor constriction of blood vessels in the extremities (a heat-conserving mechanism). This can lead to a condition known as urban hypothermia (discussed later), in which an elderly person becomes hypothermic in her own home (Figure 24-5). Infants and young children cannot use adaptive behaviors, such as moving to a warm environment or putting on warmer clothing. Medical conditions. At increased risk for hypothermia are people who have had recent surgery or who have shock, head injury, burns, generalized infection, spinal cord injuries, thyroid gland disorders, and diabetic emergencies such as hypoglycemia. The outcome of a trauma patient with hypothermia is dramatically worsened. Alcohol, drugs, and poisons. Some drugs, alcohol, and poisons can increase the risk of hypothermia. Substances that impair heat-generating or heat-conserving mechanisms include narcotics, alcohol, antiseizure medications, antihistamines, sedatives, antidepressants, and pain medications such as aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs. Duration of exposure. The longer the time a person spends unprotected in a cold environment, the greater the chance that he will become hypothermic. Clothing. Clothing that is inappropriate for the temperature enables a person to lose heat at a greater rate than if he had layers of clothing for cold environments. Layers of clothing provide insulation from the cold and protect against excessive heat loss. A hat reduces heat loss from the head, and appropriate gloves and boots protect against cold injuries to the extremities. Clothing that doesn't protect against rain and moisture and enables the body to become wet contributes to the rate of cooling. If in a body of water, it is recommended that a person keep his clothing on to trap a layer of water between the skin and the clothing. This layer of water will be heated by the body and provide something of a warm insulating water layer. Activity level. Physical activity requires muscular movement that produces heat as a by-product (thermogenic). Thus, a person who continues to move can generate internal heat that maintains the body's core temperature at a higher level than if he were not moving. To continue to move, however, the person must have an adequate amount of fuel in the form of carbohydrates, protein, or fat. In addition, the person must drink an adequate amount of water to remain hydrated. A person in a body of cold water who continues to move can cool faster from convection. As the person continues to tread water, he moves cold water molecules next to his skin, which promotes cooling at a faster rate. If instead he curls into a ball and floats, the water around him becomes warmer from his body heat and his curled-up position can lessen the cooling from convection.
high altitude sickness
At high altitudes, the pressure of the ambient atmosphere is decreased. As a consequence, the total pressure of oxygen is also decreased, making oxygen less available. An environment with less oxygen can aggravate existing medical conditions, such as angina, congestive heart failure, and respiratory diseases, or it can cause new illnesses to occur. Even healthy individuals can experience illness at a high altitude, especially if the ascent is rapid. A high altitude is an altitude above 5,000 feet. At this altitude, the hypoxic environment can be noticeable to the person, but serious illness rarely occurs. An altitude above 8,000 feet is where serious altitude illnesses can present, especially if a rapid ascent is involved. General signs and symptoms of altitude illness follow: General ill feeling Loss of appetite Headache Disturbance in sleep Respiratory distress upon exertion High-altitude sickness can be prevented by ascending gradually, allowing the body time to acclimate, limiting exertion at high altitude, descending to a lower altitude to sleep, and eating a high-carbohydrate diet. Some people take acetazolamide (Diamox) or nifedipine (Procardia, Adalat) to try to prevent altitude sickness.
Respiration
Breathing, or respiration, also produces heat loss. A person breathes in cold air from the atmosphere and breathes out air that has been warmed and humidified inside the lungs and the airway. Some of the body's heat is carried away with the exhalation of this warm, humidified air. Respiration alone comprises about 10-20 percent of heat loss under normal circumstances.
trench foot
Common in military personnel, trench foot results from exposure of the feet to a constant cold but not freezing temperature. Often there is restriction to blood flow from laced up boots. Trench foot can occur in temperatures as high as 65°F if the foot is constantly damp and cold.
types of lightning strikes
Direct strike. Lightning bolt makes direct contact with the patient. Contact strike. Lightning strikes an object the patient is in contact with. Splash or side flash strike. Lightning strikes an object and jumps to a nearby person. Ground current or step voltage strike. Lightning current energizes the ground. The direct strike carries the highest rate of injury and death. In a ground current, the farther the patient from the strike, the less the injury and other effects suffered by the patient. The nervous tissue and the heart are most sensitive to lightning strikes. The lightning can overwhelm and short circuit the body's electrical system. When lightning involves the heart, the heart is depolarized similarly to the depolarization that occurs in a defibrillation. Actually, defibrillation is nothing more than a direct-current shock. If an oscilloscope is present following the defibrillation in a patient, you can note the period of asystole (no rhythm or heart contraction that appears as a flatline on the monitor) following the discharge of energy. The same effect is created by a lightning strike. The heart is depolarized by the massive discharge of energy through the body. Because the energy is so massive, the asystole lasts for a much longer period. Because asystole is a condition in which there is no cardiac contraction, the result is cardiac arrest. This is called primary cardiac arrest. The brain is also sensitive to the lightning strike. The medulla, which houses the respiratory center, is shut down by the lightning strike, and the patient stops breathing.
stages of freezing cold injury
Early or superficial freezing cold injury (frostbite) usually involves the tips of the ears, the nose, the cheekbones, the tips of the toes or fingers, and the chin. The patient is usually unaware of the injury, which commonly develops after direct contact with a cold object, cold air, or cold water. As exposure time lengthens or temperature drops, the patient loses feeling and sensation in the affected area, and the skin can begin to turn a waxy gray or yellow color. The skin remains soft but cold to the touch, and normal skin color does not return after palpation. If the affected area is rewarmed, the patient usually reports a tingling sensation as the area thaws and circulation improves. Late or deep freezing cold injury (frostbite) involves both the skin and tissue beneath it. The skin is white and waxy in appearance. Palpation of the affected area reveals a firm-to-completely solid, frozen feeling. The injury can involve the whole hand or foot. Swelling and blisters filled with clear or straw-colored fluid can be present. As the area thaws, it can become blotchy or mottled, with colors from white to purple to grayish-blue. Deep freezing cold injury is an extreme emergency and can result in permanent tissue loss.
exposure to cold
Exposure to cold can cause two kinds of emergencies. One is generalized hypothermia, also called a generalized cold emergency, which is an overall reduction in body temperature affecting the entire body. The other is damage to body tissues that is localized to specific areas or parts of the body, categorized as nonfreezing cold injury or freezing cold injury.
physiological regulation
Input from the thermoreceptors provides information to the brain, and the body responds with a physiologic action to change the temperature disturbance without any conscious control by the patient. In a cold environment, the body constricts the peripheral vessels to preserve body heat and initiates shivering to involuntarily produce heat. In a hot environment, the body dilates the peripheral vessels to facilitate heat loss and initiates sweating to increase heat loss through evaporation.
heat exhaustion
Extreme physical exertion in a hot, humid environment can affect even an otherwise fit individual. It can produce a disturbance of the body's blood flow, resulting in a mild state of shock. This is brought on by the pooling of blood in the vessels just below the skin resulting from vasodilation as the body works to increase heat loss, but in extreme cases this can also cause excessive blood flow away from the major organs of the body. Prolonged and profuse sweating causes the body to lose large quantities of salt and water. When these are not adequately replaced, blood circulation diminishes, affecting the brain, heart, and lungs. This condition is referred to as "heat exhaustion." In such cases, the patient's skin is normal to cool in temperature, either pale or ashen gray in color, and sweaty. In summary, heat exhaustion is thought to occur when the body has maximized the heat-dissipating mechanisms to a point where other body systems are starting to dysfunction.
stages of hypothermia
Hypothermia can occur with little warning and can progress rapidly from mild to moderate to severe to profound
heat stroke
If measures are not taken to remove the patient to a cool environment or to stop the physical activity and replace lost fluid, the hyperthermic patient's condition can deteriorate into an extreme form of hyperthermia called "heat stroke." This is a life-threatening medical emergency with a mortality ranging from 20 to 80 percent. It occurs when the body's heat-regulating mechanisms break down and become unable to cool the body sufficiently. The body becomes overheated, body temperature rises, and sweating ceases in approximately one-half the patients. Because no cooling takes place, the body stores increasingly more heat, the heat-producing mechanisms speed up, and eventually the brain cells are damaged, causing permanent disability or death. Such patients are commonly unresponsive, and the patient's skin is hot and red; it can be either moist or dry because approximately one-half the patients in this stage of hyperthermia sweat, whereas approximately one-half cease to sweat. The patient with heat stroke does not have to first suffer from heat cramps or heat exhaustion. Heat stroke can occur independently and can be more than an extreme type of heat exhaustion. Classic nonexertional heat stroke (NEHS) occurs typically to elderly patients with sedentary lifestyles, patients who are chronically ill or are on medications inhibiting the temperature-sensing ability of the body, or patients who live in regions of the country that rarely experience heat waves. Exertional heat stroke (EHS) commonly occurs to younger individuals who are engaged in strenuous physical exertion in a hot environment for prolonged periods. In either instance, heat stroke is a dire medical emergency that carries with it high morbidity and mortality rates if treatment is delayed or inappropriate (up to 80 percent, as previously noted). With effective and timely treatment, morbidity and mortality drops to 10 percent.
Cold Incapacitation
If the immersed person survives the initial cold shock response, he has approximately 10 minutes before he becomes unable to perform any useful activity. He loses fine motor function first, followed by a loss of gross motor function, followed by the inability to perform any useful or meaningful activity. This loss of function is referred to as cold incapacitation. Peripheral vasoconstriction shunts blood to his core, which can slightly increase his body core temperature for a short period of time. If the person does not wear a PFD, it is unlikely he can keep his head above water after cold incapacitation takes place and he will likely drown. If the person wears a PFD, he should be instructed to do any activity that can likely help him survive; however, he should be instructed not to make unnecessary movements. When the person moves, more cold water molecules contact the skin and the resulting process of convection cools the person faster. Therefore, movement accelerates the onset and severity of hypothermia. After 30 to 60 minutes of immersion, the person is at great risk for hypothermia. If the PFD keeps his head above water, he can survive for up to 2 hours. Cold water immersion patients should be kept in a supine position and should not be asked to do any physical activity that is not necessary, including simply walking to the ambulance stretcher or the ambulance. You should do all the work for the patient to reduce the incidence of sudden death.
behavioral regulation
Input from the thermoreceptors provides information to the brain regarding the patient's comfort level. The patient makes a conscious effort to change the sensation and comfort level by taking some action. If too hot, the person might take off clothing, spray cool water onto himself, fan himself, or perform some other behavior to attempt to cool himself. However, if the patient is too cold, he might add clothing, stand next to a heat source, get out of the cold or wind, or move about to increase his muscular activity to produce more heat.
cold shock response
Respiratory pattern change with hyperventilation and a gasp response Loss of breath-holding ability if not acclimatized Breathing becomes erratic This phase can last a few minutes; however, during those few minutes the immersed person can hyperventilate to a point in which he loses consciousness or panics and aspirates water. If not wearing a personal flotation device (PFD), he can drown as a consequence. If the immersed person wears a PFD, he should be instructed to control his breathing and not to panic. If he can do this, he will likely survive the initial immersion event.
brown recluse spider
The brown recluse spider is generally brown but can range in color from yellow to dark chocolate brown. The characteristic marking is a brown, violin-shaped marking on the upper back. The bite of the brown recluse spider is a serious medical condition: The bite usually does not heal and might require surgical repair bite is often painless at first. Several hours after the bite, it becomes bluish surrounded by a white periphery, and then a red halo or "bull's-eye" pattern. Within 7 to 10 days, the bite becomes a large ulcer.
regulation of temperature
The human body stubbornly defends its constant core temperature of approximately 98.6°F (37°C). To do this, the body must constantly monitor its temperature and balance the amount of heat production and heat loss. The body temperature is monitored and controlled primarily by the hypothalamus in the brain. The hypothalamus contains a temperature control center called the thermoregulatory center. This center receives input from two different receptors: (1) the central thermoreceptors, which are located on or near the anterior hypothalamus and (2) the peripheral thermoreceptors, found in the skin and the mucous membranes. A thermoreceptor (thermo refers to temperature; receptor is a sensory nerve ending that receives various types of stimuli) is responsible for sending nerve impulses to the hypothalamus indicating the temperature of the body. The central thermoreceptors measure the core body temperature by monitoring the temperature of the blood, and the peripheral thermoreceptors monitor the body temperature found in the skin and extremities.
heat cramps
The least serious form of heat-related injury is muscle spasms, or cramps, that are thought by some researchers to result from the body losing too much salt during profuse sweating. The cramping is made worse when not enough salt is taken into the body, when calcium levels are low, or when too much water is consumed by the patient. Such cramping is occasionally caused by overexertion of muscles, inadequate stretching or warm-up, and lactic acid buildup in poorly conditioned muscles. This condition is referred to as "heat cramps." Heat cramps characteristically occur to the large flexor muscle groups of the body first, such as the abdominal muscles, gluteus muscles, and hamstrings (large flexor muscles surrounding the femur).
radiation
The most significant mechanism of heat loss is radiation, which involves the transfer of heat from the surface of one object to the surface of another without physical contact. Most heat loss through radiation is from the head, hands, and feet. This is why it is so important to cover a newborn's head after birth.
evaporation
The process in which a liquid changes to a vapor is called evaporation. Evaporation has a cooling effect. When body heat causes the body to perspire and the perspiration evaporates, the heat that has been absorbed by the sweat is dissipated into the air, and the body surface is cooled. When air temperature equals or exceeds skin temperature, evaporation is the only way the body has of losing heat.
how the body cools itself
Three organ systems are primarily responsible for cooling the body and reducing the body core temperature: (1) the skin, (2) the cardiovascular system, and (3) the respiratory system. As the core temperature rises, the warmed blood travels to the periphery, and blood vessels near the skin's surface dilate. An increased flow of warmed blood near the skin helps dissipate excess heat through radiation and convection (see the later explanation). However, this cooling system works only if the ambient air is cooler than the skin temperature. If the outside air is as warm as, or warmer than, the temperature of the skin, the body relies on dissipation of the heat through the evaporation of sweat from the skin surface. The cardiovascular system responds to increasing heat loads by elevating the heart rate and increasing the strength of contractions so that more blood can move to the surface of the skin to be cooled. Also, the increase in cardiac output maintains the blood pressure as the peripheral vessels dilate. Finally, the respiratory system contributes to the cooling of the body by eliminating heat through evaporation during exhalation.
hyperthermia
When the amount of heat the body produces or gains exceeds the amount the body loses Various stages of hyperthermia are commonly called "heat cramps," "heat exhaustion," and "heat stroke."
High-altitude pulmonary edema (HAPE)
a condition affecting the lungs and gas exchange. Changes in the pressure in the pulmonary vessels cause fluid to be forced out of the capillaries and to collect in and around the alveoli. Children and men are more prone to HAPE. The condition can occur above 8,000 feet; however, it more commonly occurs above 14,500 feet.
black widow spider
a shiny black body, thin legs, and a crimson red marking on its abdomen, usually in the shape of an hourglass or two triangles. Black widow spider bites are the leading cause of death from spider bites in the United States. Those at highest risk for developing severe reactions to the bites are children under the age of 16, people over the age of 60, people with chronic illness, and anyone with hypertension. In addition to the general signs and symptoms of bites and stings, black widow spider bites cause the following: A pinprick sensation at the bite site, becoming a dull ache within approximately 30 minutes Severe muscle spasms, especially in the shoulders, back, chest, and abdomen Rigid, boardlike abdomen Dizziness, nausea and vomiting, and respiratory distress in severe cases
Exercise-associated hyponatremia (EAH)
also known as exertional hyponatremia and water intoxication, is associated with prolonged exercise or exertion; however, the pathophysiology of the condition is not from an increased body core temperature but from a depletion of sodium relative to water content and a severe electrolyte imbalance. The condition is frequently found in recreational hikers, marathon runners, triathletes, military personnel, and others who exercise or exert themselves for a long period, usually greater than 4 hours. EMS often provides standby services at these events; therefore, it is important that you recognize the condition. EAH results from consuming large amounts of water (1.5 quarts or greater per hour) while doing prolonged physical activity, impaired urine output from too much secretion of antidiuretic hormone (ADH), and loss of sodium from sweating. Severe EAH results in cerebral edema from too little sodium concentration in the blood, enabling water to rapidly cross the blood-brain barrier. The patient presents with signs and symptoms of an increased intracranial pressure (ICP) similar to a head injured patient. The patient can also experience pulmonary edema. Emergency care for EAH includes placing the patient in an upright (Fowler's) position to maintain an airway and to decrease the effect of gravity on the increasing intracranial pressure. Be prepared for projectile vomiting, especially during transport. If the patient is unconscious or cannot be placed in a Fowler's position, place him in a left lateral recumbent position and be prepared to suction the airway. Administer a high concentration of oxygen. Do not administer fluids by mouth—the patient is already fluid overloaded. Transport rapidly. Be prepared to treat seizures.
snakebite
bites from one of the two types of poisonous snakes: coral snakes and pit vipers (rattlesnakes, copperheads, and water moccasins). The bites of nonpoisonous snakes are not considered serious and are generally treated as minor wounds; only bites of poisonous snakes are considered medical emergencies. In only approximately one-third of the cases of bites by poisonous snakes do the snakes inject venom into the victim. When venom is injected, symptoms generally occur immediately. If it is difficult to delineate the poisonous from nonpoisonous snakebite based on the patient's description of the snake or the appearance of the bite wound, assume the bite was from a poisonous snake and provide care as appropriate. A poisonous snakebite is characterized by one or two distinct puncture wounds (Figure 24-22). The exception is the coral snake, which leaves a semicircular pattern with its teeth as it "chews" the skin. Most poisonous snakes have the following characteristics: Large fangs; nonpoisonous snakes have small teeth. The exception is the coral snake, a poisonous snake that does not have fangs. Elliptical pupils or vertical slits, much like those of a cat; nonvenomous snakes have round pupils. A pit between the eye and the mouth. A variety of different-shaped blotches on backgrounds of pink, yellow, olive, tan, gray, or brown skin. The exception is the coral snake, which is ringed with red, yellow, and black. A triangular head that is larger than the neck.
conduction
causes body heat to be lost through direct contact. Water conducts heat 240 times faster than air, and conduction is the method of heat loss in water chill. This means that water and wet clothing conduct heat away from the body at a much higher rate than air and dry clothing and much more rapidly than the body can produce it. This is an important factor in drowning, in which cold water temperatures can lead to a dramatic change in body temperature. Conduction and convection combined produce about 15 percent of heat loss.
convection
causes cold air molecules that are in immediate contact with the skin to be warmed. The heated air molecules move away, and cooler ones take their place. Those are then warmed, and the process starts all over again. Anything that speeds movement of the air, such as the wind, also speeds the cooling process. That is where the concept of wind chill comes into understanding and predicting hypothermia
myxedema coma
certain medical illnesses and diseases can make a person more susceptible to becoming hypothermic. One such disease is hypothyroidism. Hypothyroidism is a clinical syndrome characterized by an absence or severe deficiency of a hormone secreted by the thyroid. The absence of this hormone causes metabolic processes to slow significantly. Symptoms of hypothyroidism can manifest in all organ systems and include a dull facial expression. The voice is often hoarse and the speech can be slow and drawn out. There is commonly facial puffiness and periorbital swelling with droopy eyelids. The hair appears sparse, coarse, and dry, and the skin appears coarse and dry. There is commonly weight gain. The patient's mental status can become altered, and forgetfulness is common. Hypothyroidism can also precipitate sudden psychosis (a condition called myxedema madness). The disease is typically chronic, occurring over months to years. Myxedema coma is a complication that occurs late in the progression of hypothyroidism and can be fatal. It occurs most commonly in elderly women who present with extreme hypothermia (core temperatures often 75°F-90°F or 24°C-32.2°C), seizures, slow reflexes, and respiratory depression. Although myxedema coma occurs rarely (in only 0.1 percent of hypothyroidism patients), it is a true emergency, as death from this complication is likely.
freezing cold injury
condition commonly called frostbite, results from the freezing of a localized area of body tissue. Localized freezing cold injury requires much colder temperatures than are needed to produce generalized hypothermia. Such a freezing cold injury often accompanies generalized hypothermia; in cases in which it does, emergency medical care for hypothermia always takes precedence over care for the local injury. Freezing cold injury occurs when ice crystals form between the cells of the skin and then expand as they extract fluid from the cells. Circulation is obstructed, causing additional damage to the tissue. Such injuries tend to be localized to the hands, feet, ears, nose, and cheeks, which are most commonly exposed to cold.
heat conserved
constricting blood vessels (vasoconstriction) and sending warm blood from the surface of the skin to internal organs. Hair on the skin surface erects (piloerection), thickening the layer of warm air that is trapped immediately next to the skin. (However, piloerection has been shown to have little effect in conserving heat in humans, especially when there is a breeze blowing.) Little or no perspiration is released to the skin surface, preventing cooling by evaporation. The patient might attempt to reduce heat loss by decreasing the surface area of the body through folding his arms across his chest, adding more clothing, or drawing his body up close in a fetal position.
High-altitude cerebral edema (HACE)
occurs from the collection of an excessive amount of fluid in the brain tissue. This increases the pressure within the skull and puts pressure on the brain. Most cases occur at altitudes above 12,000 feet; however, cases have been reported at 8,200 feet.
immersion hypothermia
occurs from the lowering of the body temperature from immersion in cool or cold water—water that is less than 77ºF. In water temperature less than 77°F, an immersed person who is not wearing protective gear can't generate enough heat from movement to maintain a normal body core temperature if not wearing protective gear. In water temperatures that are below 68°F, the person is at increased risk of dying from either drowning or severe hypothermia. body temperature drops 25 to 30 times faster in water than in air of the same temperature There are two phases to cold water immersion response: cold shock response and cold incapacitation.
urban hypothermia
occurs in those individuals who have a predisposition, disability, illness, or medication usage that renders them more susceptible to hypothermia. Predisposing factors include situations that result in increased heat loss (such as the young or old because of their lower amount of body fat), interference with heat production from medical illnesses or medication use, alterations in mental status, or limited mobility that make the person unable to take protective measures to minimize heat loss. Urban hypothermia can be further subdivided into two general etiologies: external and internal. The "external" category includes patients who are subject to hypothermia because they do not have the access to a warm environment during the cold months. These are patients who live on the streets or try to take refuge in shelters for the homeless. Because of a lack of access at times during cold temperatures, these patients can be found outdoors in a city without adequate shelter or clothing to keep them warm. This category of patients can suffer from hypothermia not from a medical or traumatic cause, but simply from lack of protection from the cold environment. Urban hypothermia can also occur when the person is indoors. This "internal" category of urban hypothermia includes patients (typically the elderly) who are subject to colder temperatures in the winter months when they attempt to minimize heating bills to save money. Because the elderly commonly have a limited ability to sense cold, coupled with decreased tissue insulation and likely a reduced mobility, they can become hypothermic in their own home without realizing hypothermia's insidious onset.
generalized hypothermia
results from an increase in the body's heat loss, a decrease in the body's heat production, or both. It is the most life-threatening cold injury because it affects the entire body. Mortality (death) from generalized hypothermia can be as high as 87 percent. Hypothermia can have a sudden onset, as when someone falls through ice, or a gradual onset, as from prolonged exposure to wind, cold air, or cool water.
immersion foot
results from prolonged immersion of the feet in cool or cold water or moisture. This can occur if the foot is kept in cool or cold wet socks for a long period of time.
tick
serious because ticks can carry tick fever, Rocky Mountain spotted fever, and other bacterial diseases. Lyme disease, usually transmitted by the tiny deer tick but now thought sometimes to be transmitted by the larger dog tick, can cause long-term neurological and other complications if not identified and treated early. Ticks are visible after they have attached themselves to the skin; they often choose warm, moist areas, such as the scalp, other hairy areas, the armpits, the groin, and skin creases. Many patients are unaware that they have been bitten by a tick. The only appropriate prehospital treatment for a tick bite is prompt removal of the tick, which can help prevent infection. To remove a tick, use tweezers and grasp the tick as close as possible to the point where it is attached to the skin. Pull firmly and steadily until the tick is dislodged. Do not twist or jerk the tick because that can result in incomplete removal. Never pluck an embedded tick out of the skin, as you might force infected blood into the patient. Avoid squashing an engorged tick during removal because infected blood can spread contamination. After removal, wash the bite area thoroughly with soap and water and apply an antiseptic.
thermal gradient
the thermal gradient operates by warmer temperatures moving toward cooler temperatures. In other words, the transfer of heat is always be from hot to cold. For example, the body skin temperature is normally approximately 90°F. If the outside temperature is 95°F, heat transfers from the outside air to the skin of the body. This causes the body to take on a greater heat load, thereby making the person feel warmer. The heat in this situation moves down the thermal gradient from the warmer air to the cooler body. If the outside temperature is 65°F, the heat transfers from the warmer skin of the body to the cooler outside air. In this instance, the thermal gradient causes the movement of heat down a temperature gradient from the body to the ambient air. If the rate of heat loss starts to exceed the body's heat production, the skin begins to cool excessively, and the peripheral thermoreceptors pick up the drop in temperature. In response, the patient begins to feel cool and might generate heat by shivering, moving about, or adding clothes.
Acute Mountain Sickness (AMS)
typically occurs in people who rapidly ascend to 6,600 feet or greater. Signs and symptoms could develop from 6 to 24 hours after the ascent.
Nonfreezing cold injury
which primarily refers to the conditions commonly known as immersion foot and trench foot, occurs because of exposure of the feet to a cold but nonfreezing environment resulting in damage to the peripheral tissue. As the name implies, the tissue of the foot or feet do not freeze as in frostbite. (This condition can also occur to the hands and with frostbite to other areas of the body.)
