Heat Emergencies Prepared by: Steven Jones, NREMT-P

Thermoregulation Homeostasis requires stable temperature ~98.6ºF Control mechanism Hypothalamus Peripheral thermoreceptors Balance between heat production, heat loss

Heat Production Metabolism Voluntary large muscle movement Shivering

Heat Induced Illness Results from: Increase in body temperature outside normal range Prolonged efforts to compensate; profuse sweating Dehydration

Hyperthermia Caused by Overwhelmed thermoregulatory system Environmental conditions (exogenous) Excessive exercise (endogenous) Excessive clothing Drugs ? ? Methamphetamines are notorious for causing a rapid ↑ in body temperature Failure of thermoregulatory system CVA

Heat-Related Illness Heat Cramps Heat Exhaustion Heat Stroke

Heat Cramps

Pathophysiology Hot environment causes profuse sweating Na + (sodium) lost in sweat Lack of Na + causes muscle cramping

Heat Cramps Signs/Symptoms Patient usually in good condition; working in hot, humid environment Cramps of fingers, arms, legs, abdominal muscles Nausea Normotensive, mild hypotension Tachycardia Cool, pale skin Awake, alert, normal body temperature

Heat Cramps Management Move to cool place, rest, lie down Give balanced salt/water solution (Electrolyte Solution) Salt alone leads to increased nausea, increased water loss Water alone leads to worsened cramping (dilutional hyponatremia)

Heat Cramps Management IV NaCl if patient too nauseated to drink Avoid massaging muscles Avoid activity Increase fluid, Na+ intake

Heat Exhaustion

Pathophysiology Increased vascular space due to vasodilation Decreased blood volume due to sweating Decreased CNS perfusion

Heat Exhaustion Epidemiology People working in hot, humid environments Elderly, due to decreased thirst mechanism Hypertensives, due to medication effects

Heat Exhaustion Signs/Symptoms Headache, dizziness, fatigue, nausea, confusion Weakness, syncope Profuse perspiration, pallor Tachycardia, hypotension, tachypnea Orthostatic changes Normal core temperature

Heat Exhaustion Management Move to cool place, stop activity, lie down Supine, legs elevated Sponge with cool water, fan Balanced salt/water (electrolyte) solution, or IV with NaCl, if too nauseated to drink Assess glucose if altered mental status

Heat Exhaustion Management Transport indicated if: Loss of consciousness occurs Underlying cardiovascular disease Oxygen, EKG monitor if transport indicated

Heat Stroke

Altered LOC + Hot Environment = THINK - Heat Stroke

Heat Stroke Pathophysiology Body heat accumulation leads to increased temperature above F Increased temperature damages hypothalamus: Heat regulating mechanism failure occurs % mortality in elderly

Types of Heat Stroke Exertional Heat Stroke Occurs in healthy, young people in hot environments Heat builds up faster than it is removed Damage to hypothalamus occurs Patient sweats heavily

Types of Heat Stroke Classic Heat Stroke Elderly, alcoholics, obese, heart disease patients, phenothiazine users Body heat builds up slowly over several days Dry skin, absence of sweating

Heat Stroke Signs/Symptoms Headache, dizziness, irritability Decreased LOC, seizures Bounding pulse progressing to rapid, weak pulse Hypotension secondary to vasodilation Presence or absence of sweating is NOT a reliable sign

Heat Stroke Management Secure airway High concentration oxygen Rapid cooling to F IV NaCl Avoid volume in classic heat stroke Exertional heat stroke may need volume replacement Monitor EKG

Heat Stroke Management Drugs as necessary Glucose for hypoglycemia Diazepam for seizures, PRN Reassess for secondary complications Cardiac dysrhythmias Pulmonary edema Rapid Transport

Heat Emergencies