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Emergency Medical

Responder

Chapter 17

Caring for Environmental Emergencies

Temperature and the Body

Temperature regulation

● Process of maintaining proper body temperature

Hyperthermia

● When heat gain occurs faster than body can shed heat

Hypothermia

● When body loses heat faster than it can produce heat

It is late fall and you respond to a call for a teen who has fallen into the river after standing in his canoe. A

rescue team has been dispatched. How might he lose heat while waiting for help to arrive?

Conduction : This is the most significant factor here. Water conducts heat away from the body about 25 times faster than air of the same temperature. Since it's late fall, the river water will be quite cold, rapidly drawing heat from his body through direct contact.

Convection : As the cold water moves across his skin (even subtle currents), it continuously carries away the thin layer of warmed water next to his body, exposing him to more cold water and increasing heat loss.

Evaporation : While submerged, evaporation isn't the primary concern. However, if parts of his body are exposed to the cold air and he's wet, the evaporation of water from his skin would cause additional heat loss, especially if there's any wind.

Radiation : His body will naturally radiate heat into the colder environment (the water and the air). While less significant than conduction in cold water, it still contributes to overall heat loss.

Respiration : He will also lose a small amount of heat by breathing in cold air and warming it before exhaling.

Given these factors, the teen is at high risk of developing hypothermia due to the rapid and continuous loss of body heat in the cold river water.

Heat Emergencies

Core temperature

● Temperature in core of body 98.6 F (37 C)

● refers to the temperature of the internal organs (like the heart, liver, brain, and major vessels). It is

distinct from the shell temperature (skin and limbs), which can fluctuate much more widely.

Homeostasis : Maintaining this stable temperature is a critical example of homeostasis, the body's ability to

keep its internal environment in a state of balance despite changes in the external environment.

Heat is generation (Thermogensis)

The body constantly produces heat as a byproduct of its life-sustaining activities.

Digestion (Dietary Thermogenesis) : The process of breaking down food and absorbing nutrients requires energy, which generates heat. This is often why you feel warmer after a large meal.

Metabolism (Basal Metabolic Rate - BMR): Even at rest, the body's cells are performing thousands of chemical reactions to keep organs functioning (cellular respiration). The heat produced by this basal metabolism is the most consistent source of body heat.

Movement (Muscle Activity): Muscle contraction is a highly inefficient process, with about 80% of the energy consumed being released as heat.

Voluntary Movement: Exercise, running, or lifting greatly increases heat production.

Involuntary Movement (Shivering): When the core temperature drops, the body initiates shivering—rapid, small muscle contractions—as a powerful, temporary means to quickly generate heat.

Hypothalamus: The Body's Thermostat

The hypothalamus , a small region in the brain, acts as the body's control center for thermoregulation.

● Function: It functions like a thermostat, constantly monitoring the temperature of the blood flowing through it

and receiving information from temperature receptors ( thermoreceptors ) in the skin.

● Set Point: It maintains a set point (the desired 98.6 f core temperature).

● Corrective Actions:

○ If too hot: The hypothalamus triggers heat-loss mechanisms (vasodilation to flush blood to the skin,

sweating).

○ If too cold: It triggers heat-generating and heat-retaining mechanisms (vasoconstriction to keep blood in

the core, shivering).

This entire feedback loop ensures that the body maintains the narrow, life-sustaining temperature range required for

optimal physiological function.

Vulnerable Populations for Temperature Extremes

Certain groups have a reduced ability to regulate their body temperature ( thermoregulate ) or a decreased capacity to respond to thermal stress, making them highly susceptible to both heat (hyperthermia) and cold (hypothermia).

● Very Young ● Very Old ● Chronic Illness

The Very Old (Elderly Individuals)

● General Thermoregulatory Decline: Aging often leads to a blunting of the body's protective responses. ○ Reduced Thirst Sensation: They may not feel thirsty despite being dehydrated, increasing the risk of heat-related illness. ○ Impaired Sweating: Sweat gland function can decline, reducing the body's ability to cool itself via evaporation. ○ Slower Vasomotor Response: The ability of blood vessels to widen (vasodilate for cooling) or narrow (vasoconstrict for warming) may be slowed. ● Contributing Factors: ○ Medications: Many common medications (e.g., diuretics, beta-blockers, anticholinergics) interfere with fluid balance or the nervous system's ability to regulate temperature. ○ Immobility/Isolation: They may be physically unable to move themselves to a cooler or warmer environment.

Those with Chronic Illnesses

Many underlying conditions can severely compromise thermoregulation:

● Cardiovascular Disease (Heart Failure, CAD): These conditions impair the heart's ability to pump blood effectively. In the heat, the heart struggles to circulate blood to the skin for cooling; in the cold, the strain of vasoconstriction can trigger a cardiac event. ● Diabetes: ○ Can cause neuropathy (nerve damage), which impairs the function of sweat glands. ○ Can damage blood vessels, reducing blood flow to the skin, which is crucial for both heating and cooling. ● Thyroid Disorders (Hypothyroidism): A slow metabolism generates less heat, making individuals highly susceptible to cold. ● Neurological Conditions (Spinal Cord Injury, Stroke): Damage to the brain or spinal cord can directly interfere with the hypothalamus's ability to sense temperature or send commands to the body (like to sweat or shiver).

History Focus

Exposure Details: What was the patient doing? How long were they exposed to the hot/cold environment? What was the temperature? Was there wind/humidity?

Fluid Status: Have they been drinking water or electrolyte solutions? For how long?

Baseline Health: What chronic illnesses do they have (as mentioned above)? Have they been sick recently?

Medication Use: What medications do they take? (Crucial for identifying drugs that impair thermoregulation).

Symptoms: What did the patient feel? (e.g., muscle cramps, nausea, confusion, numbness, severe shivering).

Physical Exam Focus

The physical exam focuses on key indicators of the body's temperature status:

● Core Temperature Measurement: This is the most critical step. Oral, axillary, or temporal temperatures are often inaccurate in temperature emergencies; a rectal temperature is the most accurate measure of core temperature. ● Level of Consciousness (Mental Status): A patient's alertness and orientation (or lack thereof) is the most important indicator of the severity of heatstroke or hypothermia. Confusion is a red flag. ● Skin Assessment: ○ Heat: Is the skin hot and dry (suggesting heatstroke)? Or cool and clammy (suggesting heat exhaustion)? ○ Cold: Is the skin cold to the touch? Are there signs of frostbite (pale, waxy, frozen tissue)? ● Vitals Signs: ○ Heart Rate: Often fast (tachycardia) in heat illness, but slow (bradycardia) in severe hypothermia. ○ Blood Pressure: Often low (hypotension) due to dehydration or cardiovascular collapse. ○ Respiratory Rate: May be fast (tachypnea) as the body tries to compensate.

Heat Exhaustion

Exposure to excessive heat for prolonged period of time, Cooling mechanisms begin to fail, Body barely able to shed as

much heat as it is generating

Signs and Symptoms

● Mild to moderate perspiration

● Warm or cool skin temperature

● Skin color may be normal to pale

● Weakness, exhaustion, dizziness

● Nausea and vomiting

● Muscle cramps

○ Usually in legs and abdomen

● Rapid, weak pulse

● Rapid, shallow breathing

Emergency Care

● Take appropriate B S I precautions

● Complete primary assessment

● Ensure breathing is adequate

● Move patient to cool area

● Loosen or remove excess clothing

● Cool patient by fanning

○ Be careful not to overcool patient

● Place patient in recovery position

● Provide oxygen per local protocol

Heat Stroke

Temperature-regulating mechanisms fail

Unable to rid excess heat

Core temperature allowed to rise uncontrolled,

causing body to overheat

It is a life-threatening emergency

Temperature may increase to 105 F (40.5 C) or

higher

Signs and Symptoms

● Altered mental status

● Lack of sweating

● Skin red, hot and dry

● Rapid, shallow breathing

● Rapid pulse

● Weakness, exhaustion, dizziness

● Nausea and vomiting

● Convulsions