Emergency Care Textbook Professional Responders-part-15 PDF

15 Environmental Illnesses Key Content Temperature Homeostasis...... Heat-Related Illness................ Heat Cramps......................... Heat Exhaustion................... Heat Stroke.......................... Cold-Related Illness................. Hypothermia........................ Frost Nip....

15 Environmental Illnesses Key Content Temperature Homeostasis...... Heat-Related Illness................ Heat Cramps......................... Heat Exhaustion................... Heat Stroke.......................... Cold-Related Illness................. Hypothermia........................ Frost Nip............................... Frostbite............................... Drowning................................. Cold-Water Immersion and Drowning.......................... High-Altitude Illness............... SCUBA-Related Illness............. Physiology............................ Barotrauma of Descent....... Barotrauma of Ascent......... 278 281 281 281 281 284 284 286 286 288 290 292 293 293 294 294 Introduction Illnesses caused by exposure to extreme temperature occur in stages but can rapidly become life threatening. If a patient shows any signs or symptoms of a heat- or cold-related illness, note the weather conditions and the patient’s activities to determine whether they might be related. Immediate intervention can prevent the condition from worsening and becoming life threatening. A patient in the water poses special challenges for the responder, as the patient must be safely extricated before assessment and interventions can be performed. ENVIRONMENTAL ILLNESSES While the human body is equipped with mechanisms for regulating body temperature, emergencies still occur when the body is overwhelmed by extremes of heat and cold. 277 Other environmental stressors like low barometric pressure (e.g., hiking at a high altitude) and high barometric pressure (e.g., scuba diving) also cause various illnesses. In this chapter, you will learn how environmental extremes affect the body, how to recognize environment-related illnesses, and how to provide treatment. TEMPERATURE HOMEOSTASIS The human body’s core temperature is normally around 37°C (98.6°F) and is maintained by balancing heat loss with heat gain. Under normal conditions, the body generates heat primarily by converting food into energy. Heat is also produced by contracting the muscles, which is either voluntary (e.g., exercising) or involuntary (e.g., shivering). The heat produced during routine activities is usually enough to balance normal heat loss. The hypothalamus is the part of the brain that controls thermoregulation, which is the body’s ability to maintain a constant core temperature. The hypothalamus receives temperature information from skin and central receptors. If the body is too warm, thermoregulatory heat loss responses include vasodilation (increasing blood flow to the skin) and/or sweating to facilitate evaporation. If the body is too cold, thermoregulatory responses include vasoconstriction (decreasing blood flow to the skin) and/or shivering, which produces heat by rapidly contracting and relaxing muscles (Figure 15–1). Heat moves from warm areas to cooler ones through four mechanisms (Figure 15–2): 1. Conduction (Warming or Cooling) Occurs through direct contact with a solid or liquid. Heat loss due to direct contact with cold snow could be decreased by minimizing contact or increasing insulation (e.g., sitting on an insulator pad on the snow). 2. Convection (Warming or Cooling) Occurs when air or liquid moves across the skin. In cold air, this creates the wind chill factor. Convective heating can also occur if warm air is blown across the skin. HUMAN THERMOREGULATION RESPONSES Warm / Hot Environment Cool / Cold Environment Heat Loss (vasodilation) Heat Loss (sweating) Heat Conserving (vasoconstriction) Heat Production (shivering) Sweating FOUR MECHANISMS OF HEAT LOSS Conduction: Through direct contact with a solid or liquid. Convection: Flowing water or air removes heat. CORE Radiation: Through space (air) by infrared radiation. Shivering Evaporation: Change from liquid to gas requires energy. Radiation CORE Evaporation (from wet clothing) Evaporation ENVIRONMENTAL ILLNESSES (from expired air) 278 Convection Conduction Vasodilation Vasoconstriction ROCK PAD Conduction GROUND Figure 15–1: Human thermoregulation responses in hot and cold environments. Convection Conduction Figure 15–2: Heating and cooling mechanisms. WATER The body’s ability to maintain normal core temperature is primarily affected by the following factors: Temperature of the surrounding air or water Air humidity Wind speed Physiological factors, including heat production Clothing properties (e.g., insulation, permeability, and moisture-transfer capacity) Total insulation (e.g., how many layers are worn) Skin moisture 3. Radiation (Warming or Cooling) Involves the direct loss or absorption of heat energy through electromagnetic waves. 4. Evaporation  (Cooling Only) Occurs when a liquid changes to a vapour. This process requires heat, which means the evaporation of sweat takes heat from the body’s surface. When sweat or water evaporates (either on the skin or in clothing that is in contact with the skin), the skin is cooled. In a cold environment, low ambient temperature and wind combine to increase heat loss through convection. The combination of temperature and wind speed results in wind chill, which is the apparent temperature in relation to the ambient temperature (Figure 15–3). For example, if the wind speed is 65 km/h and the ambient temperature is -25°C (-13°F), the temperature feels like -44°C (-47.2°F), and there is a high risk of frostbite to exposed skin within 2 to 5 minutes. Sweating occurs when the temperature of either the skin or the body’s core increases. In a cold environment, sweating should be minimized (e.g., clothing layers should be removed prior to hard work to minimize sweating). In a hot environment, evaporative heat loss is beneficial; however, any sweat that does not evaporate will not cause cooling. For example, when humidity is high, sweat does not evaporate as efficiently and may simply drip off the body. In a hot environment, heat and humidity combine to increase heat stress. An increase in humidity produces a corresponding increase in the apparent WIND CHILL INDEX WIND SPEED (km/h) 5 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 5 4 -2 -7 -13 -19 -24 -30 -36 -41 -47 -53 -58 10 3 -3 -9 -15 -21 -27 -33 -39 -45 -51 -57 -63 15 2 4 -11 -17 -23 -29 -35 -41 -48 -54 -60 -66 20 1 -5 -12 -18 -24 -30 -37 -43 -49 -56 -62 -68 25 1 -6 -12 -19 -25 -32 -38 -44 -51 -57 -64 -70 30 0 -6 -13 -20 -26 -33 -39 -46 -52 -59 -65 -72 35 0 -7 -14 -20 -27 -33 -40 -47 -53 -60 -66 -73 40 -1 -7 -14 -21 -27 -34 -41 -48 -54 -61 -68 -74 45 -1 -8 -15 -21 -28 -35 -42 -48 -55 -62 -69 -75 50 -1 -8 -15 -22 -29 -35 -42 -49 -56 -63 -70 -76 55 -2 -8 -15 -22 -29 -36 -43 -50 -57 -63 -71 -77 60 -2 -9 -16 -23 -30 -36 -43 -50 -57 -64 -72 -78 65 -2 -9 -16 -23 -30 -37 -44 -51 -58 -65 -72 -79 70 -2 -9 -16 -23 -30 -37 -44 -51 -58 -65 -72 -80 75 -3 -10 -17 -24 -31 -38 -45 -52 -59 -66 -73 -80 80 -3 -10 -17 -24 -31 -38 -45 -52 -60 -67 -74 -81 Figure 15–3: The Wind Chill Index. ENVIRONMENTAL ILLNESSES ACTUAL AIR TEMPERATURE (°C) 279 temperature, which increases the heat stress on the body, even if the actual temperature of the air remains the same. For example, if the relative humidity is 65% and the ambient temperature is 37°C (98.6°F), it actually feels like 54°C (129.2°F), and there is serious risk of heat stress. The Heat and Discomfort Index (Figure 15–4) provides a guide for determining how the combination of humidity and temperature will affect a patient’s heat stress and comfort level. Working and/or exercising in protective clothing or gear that inhibits heat exchange (e.g., football equipment, firefighter turnout gear, or chemical/biological protective suits). Working indoors in hot, humid, or poorly ventilated areas. Exposure to cold temperatures, exaggerated by wet and windy conditions. Boots or other footwear that is too tight. Poorly heated homes. Recreation in cold, wet, or windy conditions. CAUSES AND RISK FACTORS FOR HEAT- OR COLD-RELATED ILLNESS Some risk factors that may make a patient more prone to heat- or cold-related emergencies include: Age—particularly the elderly (especially those with dementia) and young children. Previous history of a heat- or cold-related illness. Respiratory or cardiovascular disease. Diabetes or other conditions that cause poor circulation. Taking medications to eliminate water from the body (diuretics). Some causes of heat- or cold-related illness include: Strenuous work or exercise in extreme temperatures with an inappropriate amount of insulation. HEAT AND DISCOMFORT INDEX HUMIDEX INDEX OF APPARENT TEMPERATURE (°C) ENVIRONMENTAL ILLNESSES 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 280 42° 48 50 52 55 57 59 62 64 66 68 71 73 75 77 80 82 41° 46 48 51 53 55 57 59 61 64 66 68 70 72 74 76 79 40° 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 39° 43 45 47 49 51 53 55 57 59 61 63 65 66 68 70 72 38° 42 44 45 47 49 51 53 55 56 58 60 62 64 66 67 69 37° 40 42 44 45 47 49 51 52 54 56 58 59 61 63 65 66 36° 39 40 42 44 45 47 49 50 52 54 55 57 59 60 62 63 35° 37 39 40 42 44 45 47 48 50 51 53 54 56 58 59 61 34° 36 37 39 40 42 43 45 46 48 49 51 52 54 55 57 58 33° 34 36 37 39 40 41 43 44 46 47 48 50 51 53 54 55 32° 33 34 36 37 38 40 41 42 44 45 46 48 49 50 52 53 31° 32 33 34 35 37 38 39 40 42 43 44 45 47 48 49 50 30° 30 32 33 34 35 36 37 39 40 41 42 43 45 46 47 48 29° 29 30 31 32 33 35 36 37 38 39 40 41 42 43 45 46 28° 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 27° 27 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 26° 26 26 27 28 29 30 31 32 33 34 34 35 36 37 38 39 25° 25 25 26 27 27 28 29 30 31 32 33 34 34 35 36 37 24° 24 24 24 25 26 27 28 28 29 30 31 32 33 33 34 35 23° 23 23 23 24 25 25 26 27 28 28 29 30 31 32 32 33 22° 22 22 22 22 23 24 25 25 26 27 27 28 29 30 30 31 Figure 15–4: The Heat and Discomfort Index. Heat cramps, heat exhaustion, and heat stroke are conditions caused by overexposure to heat. Cramps are the least severe indicator but are often the first sign of overexposure to heat. Heat exhaustion and heat stroke are more serious emergencies. Heat Cramps Heat cramps are painful spasms of skeletal muscles. Heat cramps develop fairly rapidly and usually occur after periods of physical exertion in warm or even moderate temperatures. Heat Exhaustion Heat exhaustion occurs when the body’s temperature rises and thermoregulatory responses are activated to compensate. Sweating is usually profuse, allowing heat loss through evaporation. Heat exhaustion is an early sign that the body’s temperature-regulating mechanisms are becoming overwhelmed. Heat exhaustion is not always preceded by heat cramps. The patient’s temperature will be normal or slightly elevated. Over time, the patient loses fluid through sweating, which decreases blood volume. Blood flow to the skin increases in an effort to increase heat loss, thus reducing blood flow to the vital organs. Because less blood is available for the vital organs, the patient may begin to experience sign and symptoms of shock. Without interventions, the patient’s condition will deteriorate for as long as the heat stress continues, and the body’s core temperature will continue to rise. The patient may vomit and begin to show changes in level of responsiveness. Without prompt intervention, heat exhaustion can quickly advance to heat stroke. Heat Stroke Heat stroke is the least common but most severe heat-related illness. Often, it occurs when signs and symptoms of heat exhaustion are ignored. Heat stroke begins when the body’s thermoregulatory mechanisms are overwhelmed by heat stress and begin to stop functioning. Sweating stops because the body’s fluid levels are low. When sweating stops, the body cannot actively cool itself effectively, and the body’s core temperature rises, usually above 40°C (104°F). It soon reaches a level at which the brain and other vital organs (i.e., the heart and kidneys) begin to fail. If the body is not cooled, heat stress can lead to seizures, coma, and death. Heat stroke is a serious medical emergency. You must recognize the signs and symptoms and provide treatment immediately. Signs and Symptoms of Heat-Related Illness Figure 15–5 shows the signs and symptoms of heat stress. Treatment for Heat-Related Illness If recognized in its early stages, a heat-related illness can usually be reversed. Follow these general treatment steps immediately (Figure 15–6): Pouring water on a patient’s torso is more effective if there is a layer of cloth to keep the water in contact with the skin until it evaporates. Pour the water onto clothing, a towel, or another layer of cloth rather than directly onto the patient’s skin. Fanning the patient after pouring the water encourages evaporation (in addition to creating or increasing convective cooling). Note that other liquids may be used if water is not available: Beverages are often cool and available, for example. Even IV fluid can be used, so long as it is not necessary for rehydrating the patient. Patients with heat-related illness should be given an electrolyte-replacement beverage or water. Electrolyte replacement is especially important for patients with heat cramps. ENVIRONMENTAL ILLNESSES HEAT-RELATED ILLNESS 281 ASSESSMENT OF A HEAT-STRESSED PATIENT SKIN PHYSICAL MENTAL PULSE ASSESSMENT OF A HEAT-STRESSED PATIENT HEAT CRAMPS HEAT CRAMPS SKIN moist warm moist warm PHYSICAL muscle contractions (mildmuscle to severe) contractions (mild to severe) MENTAL PULSE normal normal normal normal RESPIRATION RESPIRATION normal normal headache HEAT EXHAUSTION HEAT EXHAUSTION moist warm moist warm dry HEAT STROKE hot dry HEAT STROKE hot weakness/ headache exhaustion weakness/ nausea, exhaustion vomiting nausea, fainting vomiting fainting seizures coma seizures severe coma headache severe headache anxiety dizziness anxiety dizziness altered behaviour: altered irritable behaviour: aggressive irritable bizarre aggressive bizarre normal normal normal normal rapid rapid weak rapid shallow rapid weak CAUTION RAPID TRANSPORT CAUTION RAPID TRANSPORT shallow Figure 15–5: Signs and symptoms of heat stress. When caring for heat stroke, immerse as much of the patient’s body in cold water as possible with the resources available. If using a bucket, for example, the patient should immerse his or her hands and as much of the forearms as possible. ENVIRONMENTAL ILLNESSES When treating a patient with heat cramps, the patient can usually resume activity once the cramps stop and there are no other signs or symptoms of illness. A patient with heat exhaustion or heat stroke should not resume normal activities on the same day. 282 When treating an unresponsive patient for heat exhaustion or heat stroke, hydrate the patient intravenously with isotonic or hypertonic fluid if your scope of practice and protocols permit. A patient should be in the rapid transport category if he or she has heat stroke or any of the signs or symptoms listed in red above. If transportation is not yet on scene, cool the patient aggressively until it arrives. When transporting a patient with a heat-related illness, provide cooling en route as well. As a minimum, poor cool liquid onto the patient’s chest (with clothing or a towel over the skin as usual) and fan the patient to encourage evaporation. Keep the vehicle’s interior as cool as possible (e.g., turn up air conditioning). Refusing water, vomiting, and a changing level of responsiveness are signs that the patient’s condition may be deteriorating. Such a patient should in the rapid transport category. If the patient vomits, stop giving oral fluids and position the patient in the recovery position. Ensure that the patient has a protected, patent airway. Keep the patient lying down and continue to cool the body as quickly as possible. Monitor the patient closely, and be prepared to perform assisted ventilations and/or CPR if required. Heat Cramps Heat Exhaustion Heat Stroke Remove from heat Remove from heat Remove from heat Loosen tight clothing, remove padding from torso Loosen tight clothing, remove padding from torso Loosen tight clothing, remove padding from torso Do not dry skin Do not dry skin ACTIVE COOLING AGGRESSIVE COOLING (ORDER OF PREFERENCE) Pour water on torso Immerse body in cool water Fan skin Immerse forearms in cool water Gentle stretching Pour water on torso If patient is alert, provide cool drink Figure 15–6: General treatment for heat stress. If patient is alert, provide cool drink If patient is alert, provide cool drink ENVIRONMENTAL ILLNESSES Fan skin 283 COLD-RELATED ILLNESS Cold-related illness may occur when the body’s heating mechanisms are overwhelmed by prolonged or extreme cold temperatures. They may also occur as localized superficial injuries (as when patches of skin are frozen by frostbite). Hypothermia Hypothermia occurs when the body core temperature decreases from a normal 37°C (98.6°F) to 35°C (95°F) or below. Hypothermia can be life threatening, especially when the core temperature drops below 28°C (82°F). There are four distinct stages of cold stress. The signs and symptoms of each stage build upon the signs and symptoms of the previous stage (Figure 15–7). Cold Stressed—Not Hypothermic Shivering Normal mental status Normal or near-normal motor functions Mild Hypothermia Vigorous shivering; complaining of the cold Decreased motor and sensory function Difficulty taking care of self ENVIRONMENTAL ILLNESSES Moderate Hypothermia Weak and intermittent shivering, or shivering that later stops Complaints about the cold Lack of coordination or speech; confused or unusual behaviour Impaired judgment Apathy or a decreasing level of responsiveness Unresponsiveness 284 Severe Hypothermia Cessation of shivering Unresponsiveness Stiffening of body tissues Shallow or absent respirations Weak or absent pulse TREATMENT FOR HYPOTHERMIA A patient with hypothermia (mild, moderate, or severe) is in the rapid transport category. Handle the patient gently and keep him or her in a horizontal position. Place the patient in a hypothermia wrap immediately if his or her clothing is dry or damp, or if shelter or transport is less than 30 minutes way. If clothing is very wet and shelter or transport is less than 30 minutes away, wrap the patient without removing clothing. If shelter or transport is more than 30 minutes away, seek protection from the wind and wet weather (create shelter if necessary) and then remove any wet clothing. Dry the patient by blotting (not rubbing) the skin, and then apply a hypothermia wrap. If the patient is responsive, allow him or her to sit up, and provide a warm, sugary, non-alcoholic beverage to drink, taking care to ensure that the patient does not choke and that the drink is not too hot. Severe hypothermia can cause bradycardia and bradypnea. If vital signs seem absent and you suspect hypothermia, check for signs of pulse and respiration for 60 seconds. If neither are detected, start CPR. 1. Starting with the outside ring, assess the patient's responsiveness, movement, shivering, and alertness. Decide whether each one is normal or impaired/absent. 2. Provide the care described in the quadrant that matches the patient's condition. Mild Hypothermia Cold Stressed, Not Hypothermic 1. Handle gently 2. Keep horizontal 3. No standing/walking for at least 30 min. 4. Insulate/vapour barrier 5. Apply heat to upper trunk 6. Provide high-calorie food/drink 7. Monitor until improvement (at least 30 min.) 8. Rapid transport if no improvement 1. Reduce heat loss (e.g., add dry clothing) 2. Provide high-calorie food or drink 3. Increase heat production (e.g., exercise) T T NO I N R SH IVE NS G ASSUME SEVERE HYPOTHERMIA NO AL E RT IF COLD & UNRESPONSIVE E ALERT IV SHIVERI NG RED MOVEMEN PAI T IM RE SP O MO V E NO M RM E A RE SP O E IV NS E IV S N NTL 1. Treat as moderate hypothermia, and a) IF no obvious vital signs, THEN 60-second breathing check b) IF no breathing, THEN start CPR 2. Rapid transport Figure 15–7: Assessment and care of a cold-stressed patient. PO Moderate Hypothermia 1. Handle gently 2. Keep horizontal 3. No standing/walking 4. No drink or food 5. Insulate/vapour barrier 6. Apply heat to upper trunk 7. Rapid transport ENVIRONMENTAL ILLNESSES Severe Hypothermia S RE 285 Apply a hypothermia wrap by performing the following steps (Figure 15–8): 1. Place a tarp or large piece of plastic (external vapour barrier) on the ground. 2. Place an insulation pad (or pads) on the tarp or plastic. 3. Place as much additional insulation as possible on the pad (e.g., blankets or sleeping bags). 4. Place a piece of plastic or foil sheet (internal vapour barrier) on the insulation. 5. Gently place the patient in the wrap, apply warm water bottles or heating pads to the patient’s upper torso (if available), and close each layer. 6. Cover the patient’s head and neck with whatever appropriate material is available (e.g., toque, heavy hat, hood, scarf, or small blanket). Signs and symptoms of frostbite include: Skin that appears white or waxy. Skin that is cold and hard to the touch. A lack of feeling in the affected area. If heat sources are not immediately available (e.g., if water must be heated before it can be poured into a hot-water bottle), you can open the wrap once the heat source is ready, place it on the patient’s upper torso, and close the wrap again. TREATMENT FOR FROSTBITE Frost Nip Thaw the area only if you are certain that it will not freeze again: You may need to transport the patient to a warmer environment before providing care. Warm the affected area, preferably by submerging it in a container of warm water (38–40°C or 100.4–104°F). Use a thermometer to check the temperature of the water if possible. If a thermometer is unavailable, carefully use your own hand to test the water; the water should feel warm but not uncomfortable. Keep the affected body part away from the bottom or sides of the container, and leave it in the water until it starts to turn red and feels warm. Frost nip is a local, superficial condition that occurs when skin, usually on the face, is exposed to cold temperatures and begins to freeze. It is essentially a minor form of frostbite. If the tissues below the skin begin to freeze as well, frost nip will escalate to frostbite. If a patient has frost nip, his or her skin may appear pale, and there may be pain or stinging in the area. Treat frost nip by warming the area against warm skin or in warm water (38–40°C or 100.4–104°F). ENVIRONMENTAL ILLNESSES Frostbite 286 Extremities (i.e., toes, feet, fingers, hands, ears, and nose) are particularly prone to frostbite. When frostbite occurs, the water inside and between the body’s cells begins to freeze and swell. Inside the body, the ice crystals and swelling begin to damage or destroy the body’s cells, blood vessels, and nerves. After the area is thawed, the patient may experience a burning sensation, redness, pain or tenderness, and blisters. Frostbite may be classified as either superficial or deep. A patient with superficial frostbite may develop clear blisters after the affected area has thawed. Superficial frostbite may result in small amounts of tissue loss or no tissue loss at all. A patient with deep frostbite may develop dark, hemorrhagic blisters after the affected area has thawed. Deep frostbite is likely to result in tissue loss. When treating a patient for frostbite, handle the affected area gently. Do no rub the affected area or apply snow or ice (rubbing causes further damage to the frozen tissue). If a container of warm water is unavailable, frozen tissue may also be warmed through direct contact with warm skin from either the patient (e.g., arm pits) or responder (e.g., stomach). ENVIRONMENTAL ILLNESSES Figure 15–8: Applying a hypothermia wrap. 287 If the patient is responsive and does not have gastrointestinal symptoms, rehydrate the patient (preferably with sugary, warm, non-alcoholic beverages). To treat the pain that thawing may cause, advise the patient to take an over-thecounter nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen. The patient has limited forward motion, usually struggling for only 20 to 60 seconds before submerging. The patient has an expression of fear. The patient will usually be flailing his or her arms at the sides, alternately moving up and pressing down. Once the frozen area is thawed, refrain from breaking any blisters. Protect them with dry, sterile, non-adherent dressings. Place these dressings between the fingers or toes as well if they are affected. If possible, elevate the thawed area above the level of the patient’s heart. The patient should be assessed by a physician. ASSISTING A RESPONSIVE DROWNING PATIENT DROWNING Drowning is a form of suffocation caused by immersion in water or other liquid. Drowning begins as a person gasps for air, either while struggling to stay afloat or underwater once the patient can no longer hold his or her breath. As some water is inhaled, it can stimulate laryngospasm and the closing of the vocal cords. This is the body’s natural response to prevent water from entering the lungs, but it also prevents the inspiration of air. As suffocation continues, hypoxia worsens. The patient will become unresponsive and die. Laryngospasm may relax after unresponsiveness, and it will always cease with death (if not before). If the patient is face down, the lungs may remain dry and the patient may float. If the patient is face up, water can passively fill the lungs and the patient will sink. ENVIRONMENTAL ILLNESSES Responsive Drowning Patient 288 A responsive drowning patient will be struggling in the water. Submersion below the surface will occur repeatedly, and vocalization will be minimal to non-existent. Other signs that indicate a drowning patient include: The patient is not using his or her legs to move forward and tread water. The patient is vertical in the water, usually trying to rise out of the water to breathe rather than trying to swim forward. Water rescues should be performed by individuals who have been specifically trained for such situations. Additionally, all responders in and around water should be wearing lifejackets/PFDs if they are available. A responsive drowning patient is in the rapid transport category. Perform a scene assessment. If the scene is safe to enter, or if you are equipped to safely enter the scene, rescue the patient from land by following this order of steps to ensure your own safety: 1. Talk: Instruct and encourage the patient to perform a self-rescue. 2. Throw: Throw a rope or buoyant object, with or without an attached line, to the patient. 3. Reach: Reach out to the patient with a rigid object (e.g., a ladder, paddle, tree branch, rescue tube, water noodle). You must always remember not to endanger yourself. Rescues that involve entering the water and swimming to the patient require special training, (e.g., Red Cross Lifeguard training). Do not enter the water and swim to a drowning patient without this training; you are not likely to save the person, and you will be putting your life danger in addition to the patient’s life. Likewise, leaping into water, even shallow water, to help someone may seem courageous, but choosing a less dramatic method is safer and usually more effective. You can help a person only if you maintain your personal safety and stay in control of the situation. The talking (instructing), throwing, and reaching methods presented here help you do both. Talking (Instructing) Reaching Assists If the patient has some swimming ability, instruct and encourage the patient to swim for safety if the distance is appropriate for the patient’s swimming skills and energy level, and the conditions of the water. A reaching assist may be used if a throwing assist is unavailable or the circumstances make throwing an object ineffective. Extend your reach with any object that will reach the patient, such as a pole, oar, tree branch, shirt, belt, towel, or rescue tube (Figure 15–10). If there are no objects available to extend your reach, try to extend your arm and grasp the patient, or extend your leg so that the patient can grab onto your foot. As always, protecting yourself is your top priority: Always ensure that you are in a stable position and are not at risk of being pulled into the water yourself. If possible, lie down on a pool deck, dock, or pier. Motionless floating is useful for conserving energy. This is an effective survival skill in calm, warm water, but may be very difficult in cold water. Throwing Assists Throw an object that the patient can grab to stay afloat, such as a PFD/lifejacket or ring buoy (Figure 15–9). If a line is attached, you can pull the patient to safety. When throwing a device, follow these steps: 1. Speak clearly to the distressed swimmer while maintaining eye contact. 2. Face the patient and throw the assist, trying to throw it beyond him or her. 3. Get into stable position (e.g., lying down) before the patient grabs the assist. 4. Smoothly pull the patient to the nearest point of safety. Figure 15–9: Ensure your safety while using a throwing assist. To perform a reaching assist: 1. Get into a stable position, such as lying prone. 2. Extend the object to the patient. 3. When the patient grabs the object, slowly and carefully pull the patient to safety. 4. Keep your body low, and lean back to avoid being pulled into the water. ONCE THE PATIENT IS RESCUED If you suspect that the patient may have a head and/or spinal injury, you must support his or her head and neck, keeping it aligned with the body, before pulling the patient from the water. It may be necessary to turn the patient onto his or her back; if so, the patient’s head, neck, chest, and body must be aligned, supported, and turned as one unit. The patient should be floated, on his or her back, onto a firm support, such as a backboard, before being removed from the water. Figure 15–10: You can use many things for a reaching assist (e.g., a paddle, tree branch, belt, towel, or even a ladder). ENVIRONMENTAL ILLNESSES If the person has limited or no swimming skills, or if he or she is unable to swim normally due to exhaustion, injury, or cold exposure, encourage the patient to tread water or float on his or her back. Treading water to stay at the surface takes more energy than floating (but less energy than swimming). 289 Once the patient is out of the water, perform a primary assessment and provide care for any conditions found. The patient should be placed in the rapid transport category. All survivors of drowning incidents must be assessed by a physician immediately, regardless of how rapid the recovery may seem. You should attempt to resuscitate the patient even if he or she has been submerged for a prolonged period. Patients have been successfully resuscitated even after being submerged in cold water for longer than 30 minutes. SELF-RESCUE If you unexpectedly fall into the water without a PFD/lifejacket, you may need to remove clothing in order to swim or float; however, some clothing, such as a long-sleeved shirt that buttons, will actually help you float and protect you from cold. If your shoes are light enough for you to swim in comfortably, leave them on. If they are too heavy, remove them. Tread water to stay in an upright position while you signal for help or wait for rescue. To tread water, stay vertical, move your hands back and forth, and use a kick that you can do effectively and comfortably, using the least amount of energy. ENVIRONMENTAL ILLNESSES If you are wearing a PFD/lifejacket, you should await rescue and adopt the Heat Escape Lessening Position (HELP) (Figure 15–11): 1. Press your arms against your armpits. 2. Squeeze your thighs together and adjust the bend of your hips and knees as needed to keep stable in the water. 3. Place your forearms across your chest or use your hands to pull your knees towards your chest. 290 Unresponsive Drowning Patient Rescuing an unresponsive drowning patient requires specific qualifications and training. If you are not qualified, request specialized personnel to extricate the patient from the water. Figure 15–11: The Heat Escape Lessening Position (HELP). Cold-Water Immersion and Drowning Hypothermia caused by cold-water immersion occurs faster than hypothermia caused by coldair exposure; however, diagnosis and treatment remain the same, regardless of the cause. It is important to understand the four phases of cold-water immersion: 1. Cold Shock Response: A rapid cooling of the skin, causing the patient to gasp, followed by hyperventilation. This can last for 1 to 2 minutes. 2. Cold Incapacitation: A further cooling of deeper nerve and muscle fibres, which causes loss of coordination and weakness, leading to incapacitation within approximately 15 minutes. 3. Hypothermia: Requires 30 minutes or more for an appropriately dressed adult to become mildly hypothermic. 4. Circum-rescue Collapse (also referred to as post-rescue collapse): Can occur just prior to, during, or after a rescue. Symptoms range from syncope to cardiac arrest. Most deaths in cold water result from the Cold Shock Response (i.e., when the head is under water) or drowning due to Cold Incapacitation. Normally, a personal flotation device (PFD) must be worn to remain afloat long enough for a person to die from hypothermia. Cold-water immersion can occur in open water (e.g., when a boat capsizes) or after breaking through the ice. COLD-WATER RESCUE Self-Rescue Should you find yourself in cold open water and at risk of cold-water immersion, attempt to rescue yourself by climbing out of the water and into a boat, raft, or other mode of marine transportation, if available. If you have fallen through the ice, place your arms on the surface of the ice and control your breathing by taking some slow deep breaths. Kick your legs until your body is horizontal to the water’s surface, and then kick and pull forward until you are on top of the ice. Roll or crawl a safe distance away from the hole before standing up. Surviving to Await Rescue If self-rescue is not possible in cold open water, you may be able to increase your survival time by climbing out of the water as much as possible onto a capsized boat or other floating object. If you are wearing a PFD/lifejacket and there is nothing to climb up on, you may adopt the HELP position. If several people are together, adopt the Huddle position (Figure 15–12): 1. Face each other. 2. Have each person squeeze his or her thighs together. 3. Form a circle and hug each other. Each person should place one arm above and one arm below the arms of those adjacent and pull the sides of their chests together. 4. Sandwich any children or people without PFDs inside the Huddle. COLD-WATER DROWNING If a patient has drowned in cold water, he or she is in the rapid transport category. If the scene is safe to enter, perform the steps for rescuing an unresponsive drowning patient (see page 290). Depending on the situation, there may or may not be a chance of successfully resuscitating the patient. The relevant factors are the temperature of the water and the length of the time the patient was underwater (submersion time), if known. Colder water reduces the rate at which brain cells die when they become hypoxic, so drowning in colder water can increase a patient’s chances of resuscitation. You should attempt resuscitation in either of the following situations: The water temperature is less than 6°C (42.8°F) and the known submersion time is less than 90 minutes. The water temperature is 6 to 10°C (42.8 to 50°F) and the known submersion time is less than 30 minutes. Once you begin CPR, you should continue for 25 minutes. If the patient shows no signs of improvement after this period, or if your safety is threatened, you may cease CPR. Like water rescues, ice rescues require special training and equipment. If you have fallen through ice and you are unable to climb out of the water on your own, stop struggling. Place your arms onto the ice and allow them to freeze in place; this will prevent drowning if moderate hypothermia causes incapacitation or unresponsiveness. Figure 15–12: The Huddle position. ENVIRONMENTAL ILLNESSES The Huddle position is most effective for groups of three to five. 291 HIGH-ALTITUDE ILLNESS The body gradually adapts physiologically to changes in altitude. Within the first 10 days, the body compensates by increasing its respiration and pulse rates. Other adaptations may take place anywhere from 10 days to 6 weeks and include increased redblood-cell production, increased capillarization (development of capillary networks), and a gradually decreasing resting heart rate. Edema (accumulation of fluid in extravascular space) is a major factor contributing to highaltitude illness. Edema formation usually occurs in two places: In the brain (interstitial space): Primarily involved in acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) Eric Johnson At higher altitudes, the lower atmospheric pressure results in less available oxygen in the air, resulting in hypoxemia (decreased oxygen saturation of the arterial blood). The risk increases as the patient moves higher, but high-altitude illness may occur at elevations as low as 2,500 metres (8,202 feet) above sea level. Figure 15–13: A hyperbaric pressure bag. Two psi pressure is equivalent to an altitude decrease of about 1,600 m (5,249 ft). In  the lungs (alveoli): Primarily involved in high-altitude pulmonary edema (HAPE) The most common cause of death related to high altitude is HAPE. With all high-altitude illnesses, rapid recognition and treatment are crucial, as they can significantly reduce mortality. Signs, Symptoms, and Care for High-Altitude Illness Table 15–1 summarizes the signs, symptoms, and care for illnesses that result from high altitude. TABLE 15–1: SUMMARY OF ALTITUDE ILLNESSES CONDITION ENVIRONMENTAL ILLNESSES Acute mountain sickness (AMS) 292 SIGNS AND SYMPTOMS Headache, and one or more of the following: Nausea/vomiting Fatigue Lethargy Dizziness Difficulty sleeping Other signs and symptoms include: Loss of appetite Coughing and/or chest tightness Irregular breathing or shortness of breath Reduced urine output Peripheral edema (e.g., swelling around the eyes and face) Cyanosis at nail beds and around the mouth CARE Mild AMS: Stop ascent, rest and acclimatize Treat symptoms (e.g., provide analgesics and/or anti-emetics) If signs and symptoms persist, descend at least 500 metres (1,640 feet) Moderate to severe AMS: Provide supplemental oxygen (low flow) Apply hyperbaric therapy in a portable hyperbaric pressure bag (Figure 15–13) Give acetazolamide with or without dexamethasone OR Descend at least 500 metres (1,640 feet) Also: Hydrate regularly, with 4 to 6 L (16–24 cups) of fluids per day CONDITION SIGNS AND SYMPTOMS High-altitude cerebral edema (HACE) Worsening of all symptoms seen in moderate to severe AMS as well as one or more of the following: Ataxia (difficulty maintaining balance) Severe lethargy Altered level of responsiveness Other symptoms may include: Convulsions, stupor Unresponsiveness Vision disturbances Paralysis Seizures Hallucinations Cyanosis Increased blood pressure Decreasing heart rate Descend or evacuate immediately Provide supplemental oxygen (2 to 4 LPM) Apply hyperbaric therapy in a portable hyperbaric pressure bag Administer dexamethasone Signs and symptoms include the following: Headache Dyspnea at rest Wheezing Insomnia Coughing spasms (may have gurgling sound) Rales (crackling or clicking sounds) on auscultation Poor appetite General ache in the chest Continuous fast pulse Cyanosis In more severe cases: Extreme weakness Ataxia (loss of control of muscle movements) Frothy, blood-tinged sputum Mental confusion, delirium, and irrational behaviour Minimize exertion and keep warm Start descent immediately or apply hyperbaric therapy in a portable hyperbaric pressure bag Provide supplemental oxygen (4 to 6 LPM until improving, then 2 to 4 LPM) If above unavailable or not possible, consider administering one of the following: Nifedipine Sildenafil Tadalafil SCUBA-RELATED ILLNESS Divers Alert Network Physiology The Divers Alert Network (DAN) is a network of recreational divers. Membership is required. DAN’s mission is to provide emergency medical assistance to divers and to support diving safety. The human body is always under pressure as a result of the weight of the atmosphere pressing in and down on it. The standard level of pressure at sea level is referred to as one atmosphere (1 ATM). Pressure increases dramatically underwater because of the weight of the water itself. Descending to a depth of just 10 metres (33 feet) results in pressure two times higher than at sea level (2 ATM). At a depth of 50 metres (165 feet), the pressure is 6 ATM, or 6 times higher than at the surface. DAN has a diving medicine physician who is oncall 24/7 to help with diagnosis and treatment of suspected SCUBA-related illnesses. The DAN hotline number is 1-919-684-9111. If you have a membership available, contacting DAN can provide valuable information for assessment and treatment of a patient with a known or suspected diving injury. ENVIRONMENTAL ILLNESSES High-altitude pulmonary edema (HAPE) CARE 293 Barotrauma of Descent Normally, gas-filled spaces are in equilibrium with the pressure of the outside environment. For example, air in the middle ear remains equalized in pressure with the atmosphere via the Eustachian tube (which runs from the middle ear to the pharynx). Similarly, equalization occurs in the sinuses through connections to the nasal cavity, and this even occurs in a dive mask. Barotrauma of descent (sometimes referred to as a squeeze) results when something blocks the opening between the internal space and the environment, trapping gas within the space. As the diver descends and the external pressure increases, there is a relative decrease, or negative, pressure within the blocked space, causing pain and other symptoms, such as tympanic membrane rupture (middle ear); congestion, edema and hematoma (sinuses); and capillary rupture and edema in and around the eyes (mask). Barotrauma of Ascent ENVIRONMENTAL ILLNESSES As the pressure decreases during a diver’s ascent, gas in body spaces will expand. Normally this gas will escape, maintaining equilibrium with the external environment. However, if this venting is prevented due to obstruction, the expanding gases will distort the tissues within the body space and cause tissue damage and bleeding. This typically occurs in teeth and also in the gut (in those who swallow air or chew gum while diving). These patients typically present with local pain on ascent. 294 Some patients experience a more severe disorder called pulmonary barotrauma. This occurs when a diver ascends while holding his or her breath (breath holding). As external pressure decreases during ascent, the trapped air in the lungs expands against the closed glottis, causing the alveoli to rupture. Signs and symptoms include local capillary bleeding, pneumomediastinum, arterial gas embolism (AGE), chest pain, cough, and even froth in the mouth. ARTERIAL GAS EMBOLISM (AGE) As depth increases, air is compressed, but this process will reverse on ascent. If the compressed air in a diver’s lungs cannot freely escape during an ascent (particularly a rapid one), then rapid gas expansion within the lung may rupture lung tissue. Air entering the arterial blood through ruptured pulmonary vessels can distribute bubbles into body tissues (including the heart and brain), where they disrupt circulation. This is referred to as an arterial gas embolism (AGE). An AGE may cause minimal neurologic symptoms, dramatic symptoms requiring medical attention, or death. Common signs and symptoms of AGE include: Headaches. Seizures. Unresponsiveness. Confusion. Visual disturbances. Bloody froth from the airway (rare). Paralysis or weakness. Treatment of AGE includes the following: provide supplemental high-concentration oxygen and ensure rapid transportation to a medical facility (preferably one capable of dealing with diving injuries). The patient should remain in a supine position. If air transportation is used, the pilot should fly at an altitude of 305 metres (1,000 feet) or less, or use an aircraft that can be pressurized to 1 ATM. The best prevention for AGE is avoiding ascent with a closed glottis and remembering to exhale bubbles. In general, it should be assumed that a diver has suffered from AGE when he or she is unresponsive upon surfacing or loses responsiveness within 10 minutes after surfacing. DECOMPRESSION SICKNESS (DCS) Breathing air under pressure causes excess inert gas (nitrogen) to dissolve in the blood and body tissues. The amount dissolved is proportional to, and increases with, depth and time. As the diver ascends to the surface, the excess dissolved nitrogen comes out of solution. If the return to the surface is slow and controlled, the nitrogen is released from the blood through the alveoli and exhaled. If the ascent is too rapid, some of the gas can supersaturate within the tissues, coming out of solution to form bubbles in the surrounding tissues. This condition is known as decompression sickness. It is sometimes referred to as the bends. Symptoms of DCS typically occur 15 minutes to 24 hours after ascent. Treatment of DCS mirrors the treatment for AGE and involves providing supplemental highconcentration oxygen and rapid transportation to a medical facility (preferably one capable of dealing with diving injuries). The patient should remain in a supine position. If air transportation is used, the pilot should fly at an altitude less than 305 metres (1,000 feet) or use an aircraft that can be pressurized to 1 ATM. NITROGEN NARCOSIS Breathing pressurized air while diving can cause excess inert gas (usually nitrogen) to dissolve into the body’s tissues. The amount dissolved is proportional to, and increases with, the depth and duration of the dive. Nitrogen narcosis is caused when the dissolved nitrogen in the body increases to the point that it begins to impair the nervous system. This can alter a diver’s thought processes and decrease his or her ability to make judgments and calculations. It can also decrease motor skills, worsening performance in tasks requiring manual dexterity. Pressure increases with depth, and so does the severity of the narcosis. The effects vary widely from individual to individual, and even from day to day for the same diver. Nitrogen narcosis can have any of the following signs or symptoms: Euphoria Light-headedness Impaired judgment Confusion Hallucinations Delayed response to signals, instructions, and other stimuli Hysteria Because of the perception-altering effects of narcosis, a diver may not be aware of the changes in his or her mental state. The best prevention for nitrogen narcosis is vigilant monitoring of diving partners and helping a diver ascend safely if he or she shows any of the signs or symptoms. Some symptoms may become resolved with ascent to shallower depths (usually less than 20 metres or 65 feet). ENVIRONMENTAL ILLNESSES Signs and symptoms can include any of the following, depending on where in the body nitrogen bubbles appear: Itchiness, swelling Blotchy, mottled, or marbled skin rash Severe joint pain Fatigue or dizziness Personality changes Chest pain, cough, shortness of breath Numbness or tingling Weakness or paralysis Loss of bowel or bladder function Shock Unresponsiveness 295 SUMMARY FOUR MECHANISMS OF HEATING AND COOLING Radiation Effects: warming or cooling Occurs through direct loss or absorption of heat energy through electromagnetic waves Conduction Effects: warming or cooling Occurs through direct contact with a solid or liquid Convection Effects: warming or cooling Occurs when air or liquid moves across the skin Evaporation Effects: cooling only Occurs when a liquid changes to a vapour Assessment of a Heat-Stressed Patient HEAT CRAMPS HEAT EXHAUSTION ENVIRONMENTAL ILLNESSES HEAT STROKE 296 SKIN PHYSICAL MENTAL PULSE RESPIRATION moist warm muscle contractions (mild to severe) normal normal normal moist warm headache weakness/ exhaustion nausea, vomiting fainting anxiety dizziness normal normal dry hot seizures coma severe headache altered behaviour: irritable aggressive bizarre rapid weak rapid shallow CAUTION RAPID TRANSPORT SUMMARY Care for a Heat-Stressed Patient Heat Cramps Heat Exhaustion Heat Stroke Remove from heat Remove from heat Remove from heat Loosen tight clothing, remove padding from torso Loosen tight clothing, remove padding from torso Loosen tight clothing, remove padding from torso Do not dry skin Do not dry skin ACTIVE COOLING AGGRESSIVE COOLING (ORDER OF PREFERENCE) Pour water on torso Immerse body in cool water Fan skin Immerse forearms in cool water Gentle stretching Pour water on torso If patient is alert, provide cool drink If patient is alert, provide cool drink If patient is alert, provide cool drink ENVIRONMENTAL ILLNESSES Fan skin 297 SUMMARY Four Stages of Hypothermia 1. Starting with the outside ring, assess the patient's responsiveness, movement, shivering, and alertness. Decide whether each one is normal or impaired/absent. 2. Provide the care described in the quadrant that matches the patient's condition. Mild Hypothermia Cold Stressed, Not Hypothermic 1. Handle gently 2. Keep horizontal 3. No standing/walking for at least 30 min. 4. Insulate/vapour barrier 5. Apply heat to upper trunk 6. Provide high-calorie food/drink 7. Monitor until improvement (at least 30 min.) 8. Rapid transport if no improvement 1. Reduce heat loss (e.g., add dry clothing) 2. Provide high-calorie food or drink 3. Increase heat production (e.g., exercise) NS G T NO I N R SH IVE E T NO AL E IV ALERT RT RE SP O MO V E NO M RM E A ASSUME SEVERE HYPOTHERMIA SHIVERI NG RED MOVEMEN PAI T IM IF COLD & UNRESPONSIVE RE SP O E IV NS E IV S N NTL ENVIRONMENTAL ILLNESSES Severe Hypothermia 298 1. Treat as moderate hypothermia, and a) IF no obvious vital signs, THEN 60-second breathing check b) IF no breathing, THEN start CPR 2. Rapid transport S RE PO Moderate Hypothermia 1. Handle gently 2. Keep horizontal 3. No standing/walking 4. No drink or food 5. Insulate/vapour barrier 6. Apply heat to upper trunk 7. Rapid transport SUMMARY Hypothermia Treatment Assess patient’s clothing Do not remove clothing Apply hypothermia wrap Patient’s clothing very wet Assess proximity of shelter/ transport Shelter/transport < 30 minutes away Do not remove clothing Apply hypothermia wrap Approach to Rescuing a Responsive Drowning Patient 1. Talk: Instruct the patient to perform a self-rescue. 2. Throw: Throw a rope or buoyant object to the patient. 3. Reach: Reach out to the patient with a rigid object. Shelter/transport > _ 30 minutes away Seek/create shelter Remove any wet clothing Dry patient (blot, don’t rub) Apply hypothermia wrap Huddle Position  (for Groups) 1. Face each other. 2. Have each person squeeze his or  her thighs together. 3. Form a circle and hug each other. 4. Sandwich any children or people  without personal flotation devices (PFDs) inside the Huddle. Heat Escape Lessening Position (HELP) 1. Press your arms against your armpits. 2. Squeeze your thighs together. 3. Place your forearms across your chest or pull your knees towards your chest. ENVIRONMENTAL ILLNESSES Patient’s clothing dry or damp 299