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ENVIRONMENTAL EMERGENCIES

ENVIRONMENTAL EMERGENCIES. Environmental Objectives. Upon completion the student will be able to: Describe the four ways in which the body loses heat Describe mechanisms used by the body to maintain a core temperature in both warm and cold environments

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ENVIRONMENTAL EMERGENCIES

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  1. ENVIRONMENTAL EMERGENCIES Intermediate Lecture – Environmental Emergencies

  2. EnvironmentalObjectives Upon completion the student will be able to: • Describe the four ways in which the body loses heat • Describe mechanisms used by the body to maintain a core temperature in both warm and cold environments • Distinguish between hyperthermia and hypothermia • Identify the signs, symptoms, and recommended management techniques for heat cramps, heat exhaustion, water intoxication and heat stroke • Discuss the pathology of hypothermia and cold-related injuries Intermediate Lecture – Environmental Emergencies

  3. Objectives • Identify the stages of systemic hypothermia, and describe the physical signs and symptoms associated with them • Identify non-environmental causes of hypothermia • Discuss the concerns and precautions involved in rewarming a hypothermia patient in the field • Describe the events that occur during the near-drowning emergency • Identify the sources of ionizing radiation, and relate their relative penetrating potential • Name some of the factors that can help reduce exposure to a radiation source Intermediate Lecture – Environmental Emergencies

  4. EnvironmentalObjectives • Identify prehospital management of a patient who has been exposed to ionizing radiation • Identify common diving/hyperbaric emergencies • Describe the signs and symptoms of diving-related emergencies • Describe the management of the patient with a diving-related emergency Intermediate Lecture – Environmental Emergencies

  5. INTRODUCTION • Environment: all of the surrounding external factors that affect the development and functioning of a living organism. • External environment is a necessity of life but we must also be protected from it. • Most emergencies occur during the summer or winter. Intermediate Lecture – Environmental Emergencies

  6. THERMOREGULATION • Body functions within a very small temperature range. • Core temperature does not vary more than a degree or so from its normal 98.6 degrees F (37 degrees C). • This is known as the steady-state metabolism. This characteristic is normal in all warm-blooded animals. Intermediate Lecture – Environmental Emergencies

  7. Generation & Loss of Heat • Amount of heat in the body continually fluctuates between the heat generated and the heat lost. Intermediate Lecture – Environmental Emergencies

  8. Heat GenerationInternal Heat • Comes from routine cellular metabolism and a process called thermogenesis. • When the cell produces energy, it gives off heat. • Sympathetic stimulation will cause heat increases because of the increase in cellular metabolism. Intermediate Lecture – Environmental Emergencies

  9. Heat GenerationInternal Heat • The body can stimulate certain cells to generate heat through thermogenesis. • Primarily fatty tissue. • Shivering can further generate heat through skeletal muscle contraction. • Heat can also be generated through strenuous exercise, which increases metabolic rates. Intermediate Lecture – Environmental Emergencies

  10. Heat GenerationEnvironmental Heat • Body receives external heat from the environment via the thermal gradient. • Defined: difference in temperature between the environment and the body. • Environment is warmer than the body, heat flows from it to the body. • Body is warmer than the environment, heat flows from the body to the environment. Intermediate Lecture – Environmental Emergencies

  11. Heat GenerationEnvironmental Heat • Factors that affect the thermal gradient: • Ambient air temperature ( temp. of the surround air) • Infrared radiation (radiation with a wavelength longer than that of visible light) • Relative humidity (% of water vapor present in air) Intermediate Lecture – Environmental Emergencies

  12. Heat Loss • Heat generated by the body is constantly lost to the environment. • Occurs because the body is usually warmer than the surrounding environment. • Occurs through the following methods: Intermediate Lecture – Environmental Emergencies

  13. Heat LossRadiation • Unclothed person will lose approximately 60% of total body heat by radiation at normal room temperature. • Heat loss is in the form of infrared rays. • All objects not at absolute zero temperature will radiate heat. Intermediate Lecture – Environmental Emergencies

  14. Heat LossConduction • Direct contact of the body’s surface to another, cooler object causes the body to lose heat. • Heat flows from higher temperature matter to lower temperature matter. • Law of thermodynamics states that if ambient air temperature is higher than the skin temperature, then heat will flow from the air to the skin. Intermediate Lecture – Environmental Emergencies

  15. Heat LossConvection • Heat loss to air currents passing over the body. • However, heat must first be conducted to the air before being carried by convection currents. Intermediate Lecture – Environmental Emergencies

  16. Heat LossEvaporation • Occurs as water evaporates from the skin. • Great deal of heat loss occurs through evaporation of fluids in the lungs. • Water evaporates from the skin and lungs at approximately 600 ml/day. Intermediate Lecture – Environmental Emergencies

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  18. Heat-Controlling Mechanisms • Nervous or negative feedback mechanism regulate the body’s temperature almost entirely. • Most mechanism operate through temperature-regulating centers located in the hypothalamus. • Functions like a thermostat, produces neurosecretions important in the control of metabolic activities, including temperature regulation. Intermediate Lecture – Environmental Emergencies

  19. Heat-Controlling Mechanisms • There are temperature receptors in other parts of the body to help moderate temperatures. • They are located: in the skin, mucous membranes, selected deep tissues of the body. • Cold receptors outnumber warm receptors, peripheral detection of temperature consists mainly of detecting cold instead of warmth. Intermediate Lecture – Environmental Emergencies

  20. Heat-Controlling Mechanisms • Deep body temperature receptors lay mostly in the spinal cord, abdominal viscera, and around the great veins. • These receptors are exposed to the body’s core temperature rather than the surface temperature. • Respond mainly to cold rather than warmth. • Both skin and deep temperature receptors act to prevent hypothermia. Intermediate Lecture – Environmental Emergencies

  21. Heat Elimination • When the body becomes to hot, the hypothalamic thermostat attempts to eliminate body heat through 5 mechanisms. These include: • Vasodilation: blood vessels dilate due to the inhibition of the sympathetic centers in the hypothalamus. Heat is then lost through the skin by sweating and other mechanisms. Intermediate Lecture – Environmental Emergencies

  22. Heat Elimination • Perspiration: occurs when the core temperature rises above “normal”. This mechanism is ineffective if the relative humidity is 75% or greater due to decreased evaporation of perspiration from the skin surface. • Decrease in Heat Production: shivering and chemical thermogenesis are inhibited, causing decreased heat production. Intermediate Lecture – Environmental Emergencies

  23. Heat Elimination • Increased Cardiac Output: aids in increasing blood flow through the skin, thus aiding in the elimination of heat. • Increased Respiratory Rate: results in elimination of warm air and in water evaporation. Intermediate Lecture – Environmental Emergencies

  24. Heat Preservation • When body becomes too cold, the hypothalamic thermostat reacts in exactly the opposite fashion. • Body engages the following mechanisms: • Vasoconstriction: caused by stimulation of the hypothalamic sympathetic centers. Diverts the blood from the skin to the body’s core to maintain heat. Intermediate Lecture – Environmental Emergencies

  25. Heat Preservation • Piloerection: (hairs standing on end). Increases the insulating ability of body hair and decreases heat loss. • Increased Heat Production: increased by the metabolic systems in the following ways: • Thermogenesis (shivering): hypothalamus has an area called the primary motor center that controls shivering. It is excited by cold signals from the skin and spinal cord. Intermediate Lecture – Environmental Emergencies

  26. Heat Preservation • Sympathetic Stimulation: Norepinephrine and epinephrine are released following sympathetic stimulation, which causes an immediate increase in the rate of cellular metabolism and generates heat. Intermediate Lecture – Environmental Emergencies

  27. Heat Fluctuations • Summary: • Body temperature rises, cooling mechanisms are engaged. Hyperthermia • Body temperature drops, heat-preserving mechanisms are engaged. Hypothermia • Hyperthermia and fever are different. Fever occurs when the hypothalamus “resets” the “thermostat” in the brain. Part of the body’s defense mechanisms for infections. Intermediate Lecture – Environmental Emergencies

  28. THERMAL DISORDERS • Discuss the following heat-related disorders: • Hyperthermia • Fevers • Hyperpyrexia • Hypothermia • Frostbite Intermediate Lecture – Environmental Emergencies

  29. Hyperthermia • Increase in the body temperature caused by heat transfer from the external environment. • Manifests as: • Heat Cramps • Heat Exhaustion • Water Intoxication • Heat Stroke Intermediate Lecture – Environmental Emergencies

  30. Heat (Muscle) Cramps • Common in hot climates. • Result in intermittent, painful contractions of various skeletal muscles. • Caused primarily by a rapid change in extracellular fluid osmolarity resulting from sodium and water losses. • Sweating occurs as sodium is transported to the skin. Intermediate Lecture – Environmental Emergencies

  31. Heat Cramps • Because “water follows sodium” it is deposited on the skin surface. • Evaporation occurs, thus aiding in the cooling process. • Sweating not only involves the loss of water, but also the loss of electrolytes. • Presents with cramps in the fingers, arms, legs, or abdominal muscles. • Generally alert, hot sweaty skin, tachycardia, normal BP and a normal core temperature. Intermediate Lecture – Environmental Emergencies

  32. Heat Cramps Prehospital Management • Remove from the environment. • Fluid and sodium intake increased. • May require IV fluid replacement with NSS Intermediate Lecture – Environmental Emergencies

  33. Heat Exhaustion • Most common heat related illness. • Dehydration and salt loss due to sweating account for the presenting symptoms. • Be aware that these symptoms may mimic those of patients suffering from fluid and sodium loss. • History of exposure to hot weather is needed to obtain an accurate assessment. Intermediate Lecture – Environmental Emergencies

  34. History of low-fluid intake Decreased urine output Positive orthostatic vital signs Tachycardia Nausea and vomiting Dizziness and transient syncope Headache Muscle cramps Diarrhea Heat ExhaustionSigns & Symptoms Intermediate Lecture – Environmental Emergencies

  35. Heat Exhaustion • Working in a hot environment will lose 1-2 liters of water an hour. • Each liter lost contains 20-50 mEq’s of sodium. • The loss of water and sodium, combined with general vasodilation, leads to a decreased circulating blood volume, venous pooling, and reduced cardiac output. Intermediate Lecture – Environmental Emergencies

  36. Heat Exhaustion Prehospital Management • Remove from hot environment • Provide IV fluid replacement (NSS) • If untreated, heat exhaustion can progress to heat stroke. Intermediate Lecture – Environmental Emergencies

  37. Water Intoxication • Occurs when an individual in a hot environment drinks water at a rate that exceeds fluid loss from sweating and fails to replace associated sodium losses. • Sodium levels drop causing S&S similar to those seen with heat exhaustion. • Common S&S include: N/V, headache, alterations in mental status. Intermediate Lecture – Environmental Emergencies

  38. Water Intoxication • Patient usually reports water intake greater than 1 liter/hour and may exhibit urinary frequency and dilute urine. • Untreated may progress to alterations in mental status and coma. Intermediate Lecture – Environmental Emergencies

  39. Water Intoxication Prehospital Management • Encouraged to eat foods high in sodium. • Restrict further water intake. • Unresponsive patients, IV (KVO) NSS Intermediate Lecture – Environmental Emergencies

  40. Heat Stroke • Occurs when the body’s hypothalamic temperature regulation is lost, causing uncompensated hyperthermia. • Causing cell death and physiologic collapse. • Characterized by body temperature of at least 105 degrees F. • CNS disturbances, and usually the cessation of sweating. Intermediate Lecture – Environmental Emergencies

  41. Heat Stroke • Sweating is thought to stop due to destruction of the sweat glands or when sensory overload causes them to temporarily dysfunction. • Patient’s skin may be either dry or covered with sweat. Intermediate Lecture – Environmental Emergencies

  42. Increased core temperature Tachycardia followed by bradycardia Hypotension with low or absent diastolic reading Rapid, shallow respirations, which may later slow Confusion or disorientation Seizures Coma Heat StrokeSigns and Symptoms Intermediate Lecture – Environmental Emergencies

  43. Heat Stroke • If heat stroke is associated with exertion, the patient may develop severe metabolic acidosis caused by lactic acid accumulation. • Hyperkalemia may also develop because of the release of potassium from injured muscle cells, renal failure, or metabolic acidosis. Intermediate Lecture – Environmental Emergencies

  44. Rapid Patient Cooling Body temp. must be lowered to 102 F Administer oxygen method necessary. Pulse oximetry should be utilized. Establish IV(s). Initially run wide open Monitor ECG, dysrhythmias are common. Avoid Vasopressors and Anticholinergic Drugs: potentiate heat stroke by inhibiting sweating. Monitor core temp. Heat StrokePrehospital Management Intermediate Lecture – Environmental Emergencies

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  50. Fever (Pyrexia) • Elevation of the body temperature above the normal temperature for that person. • Body develops a fever when pathogens enter and cause infection, causing a stimulation of pyrogens. • Pyrogens are any substance that causes fever. • They reset the hypothalamic thermostat to a higher level. Intermediate Lecture – Environmental Emergencies

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