Environmental Emergencies: heat, height & “holy sh -t”

1. Amy Gutman MD Prehospitalmd@gmail.com / www.TEAEMS.com Environmental Emergencies: heat, height & “holy sh-t”

2. OVERVIEW • Heat Related Illnesses • High Altitude Illnesses • Lightening Injuries

3. DEFINITIONS • “Normal” temperature • 98.6oF (37oC) • Hypothermia • Core temp <95oF (35oC) • Hyperthermia • Core temp >105oF(45oC)

4. HOMEOSTASIS: THERMOREGULATION • Body’s desire to maintain a steady internal environment • Maintain enzyme / cell activities & organ functions • Body temp maintained by multiple interconnected mechanisms • Primarily set by hypothalamus acting as a thermostat • Peripheral & central thermoreceptors shunt blood to core to maintain homeostasis

5. THERMOREGULATION METHODS • Body Temperature • Core & Peripheral • Hypothalamus • Heat Dissipation • Sweating, vasodilatation • Heat Conservation • Shivering, vasoconstriction • Thermoreceptors • Central • Peripheral • Metabolic Rate • Basic metabolic rate • Exertional metabolic rate • Core temperature

6. HOMEOSTASIS: THERMOLYSIS • Conduction • Direct loss of heat from one object to another • Convection • Direct heat loss to air currents • Radiation • Heat loss to nearby objects without direct contact • Evaporation • Heat loss secondary to water evaporation from skin • Respiration • Convection, radiation & evaporation

7. HOMEOSTASIS: THERMOREGULATION • Body generates cellullar level heat via mitochondrial metabolism • Basal metabolic rate • Exertion metabolic rate • Shivering is an autonomic / automatic heat forming mechanism via muscle contraction

8. THERMAL REGULATION • Heat flows from area of high to low temperature • A body in warm environment gains heat, a body in a cool environment gives off heat • Other factors: • Wind • Relative humidity

9. Humidity Index

10. RISK FACTORS • Age • Age extremes less able to tolerate temp shifts • Poor Health & Predisposing PMH • IDDM: autonomic dysfunction reduces ability to vasodilate & sweat • Cardiac: fluid shifts not tolerated well • Medications • Beta blockers, Diuretics, Antipsychotics • Environmental Factors • Acclimitization, exposure time, ambient temperature, Humidity, Wind

11. PREVENTATIVE MEASURES • Adequate fluid intake • Dehydration prevents thermolysis • Recognizing SSX Early: • N / V / abd pain, vision disturbances, decreased urine output, poor skin turgor, hypovolemic shock • Treatment • Hydration • Gradual acclimatization • Limited exposure to hostile environments

12. HEAT EMERGENCIES SPECTRUM • Heat Cramps: • Muscle cramps relieved by salt & hydration • Heat Edema: • Swollen ankles relieved by leg elevation • Heat Syncope: • LOC from vasodilation; must r/o serious etiologies • Heat Exhaustion: • Volume depletion with vague, non-specific SSX • Heat Stroke: • CNS dysfunction is hallmark

13. HYPERTHERMIA • Abnormal elevation of core temperature typically caused by elevated external temperatures • Must differentiate from fever (“pyrexia”) • Fever: normal response to infection caused by pyrogens which reset hypothalamic thermostat & increase BMR • Fever makes body environment less hospitable to infectious organisms • Fever treatable with anti-pyretics, hyperthermia is not

14. HEAT CRAMPS • Painful “non-emergency” that must be differentiated from other disorders • Hyperthermia causes sweating • Sweat consists of water & salt • Sodium loss causes muscle cramping • Symptoms: • Extremity muscle cramping • A & O, though weak, faint or dizzy • Skin is warm & moist • Temp normal to mildly elevated • Vitals “reasonably” normal, often with tachycardia

15. HEAT EXHAUSTION • Most common heat illness seen by EMS • Etiology: • Sweat & sodium loss creates loss of blood volume • Vasodilation worsens problem ultimately causing a drop in cardiac output /BP with a rise in heart rate to compensate • SSX: • Body temp >100F (37.8) • Cool & clammy skin • Tachypnea, tachycardia, hypotension • Muscle cramping & generalized weakness • CNS: Headache, Anxiety, Impaired judgment • Progresses to Heat Stroke if not treated

16. DEVELOPMENT OF HEAT EXHAUSTION Heat Skin Arteriolar Dilation Excessive Sweating Hypovolemia Decreased Cardiac Output Decreased Mean Arterial Pressure Circulatory Collapse

17. HEAT EXHAUSTION TREATMENT • Remove from environment • Remove clothing, active & passive cooling • Oral electrolytes or IV crystalloids • Resolves with hydration, rest & supine • If symptoms do not resolve consider other causes

18. HEAT STROKE • Environmental emergency with 80% mortality if late or inadequate treatment • Hallmark: hot dry skin without sweat plus AMS • Lack of hypothalamic thermoregulation causes uncontrolled hyperthermia • Core temp often >105 F • Cellular death, protein denaturation • Damage to brain, kidney & liver causes multi-system failure • Rectal temperature is necessary to provide accurate reading

19. HEAT STROKE CATEGORIES • “Classic” • Secondary to altered thermoregulation • Elderly, chronically ill, patients with AMS • “Exertional” • Healthy individuals with significant heat stress • Skin initially moist due to exertional sweating

20. HEAT STROKE SSX • Core temp >105F (40.5C) • Mental status changes / anxiety / Confusion • Hypotension • Tachypnea • Renal failure • DIC • Hypotension with bounding or thready tachycardia • Possible seizures

21. DEVELOPMENT OF HEAT STROKE Strenuous Exercise Hot, Humid Environment Inadequate Temperature Regulation Core Temperature Elevates Impaired CNS Function Organ & Tissue Damage Coma & Death

22. HEATSTROKE TREATMENT • Transfer to cool environment • Remove clothing, start rapid active cooling • Cover with moist sheets • Mist with cool water • Target temperature 102F • Overcooling may cause reflex hypothermia • Administer O2 prn • IV rehydration • Cardiac monitor • AVOID vasopressors or anticholinergic drugs • Reassess vitals frequently

23. OEMS 2.3 HYPERTHERMIA /HEAT EMERGENCIES • Priorities: Rapid Recognition & Cooling! • Scene safety, BSI • Airway management, O2 as needed • Continually assess & record LOC, ABCs, vitals • SAMPLE history • Loosen / remove clothing, move to cool environment • If A&Ox3, give water or oral rehydration solution • Rapid transport w/wo ALS in position of comfort • Do not allow patient to exert themselves

24. OEMS 2.3 MANAGEMENT • Rapid but not “over” cooling; If shivering occurs, discontinue active cooling • Cool packs to armpits, neck, groin and evaporation techniques (fans, windows) • Keep skin wet with towels or sponges • Elevate legs if supine • ALS intercept if necessary & available; Rapid transport w/wo ALS • Notify receiving hospital • INTERMEDIATE AND PARAMEDIC • Advanced airway management if necessary • IV, O2, Monitor • If SBP <100 give 250 bolus NS, titrate to hemodynamic status • Medical Control for additional IVF boluses

25. HEAT EMERGENCIES NOTES • No minimum temp for heat related illnesses • Temperature severity does not necessarily correlate with severity of heat illness • Can be normothermic with heat cramps & exhaustion • Shivering begins when skin temperature drops, but core temp remains high • Versed given to stop shivering and prevent core temperature from rising despite cooling efforts

26. HEAT EMERGENCIES SUMMARY

27. LIGHTENING INJURIES • 2nd largest US storm killer; mortality 45-50 persons/yr  • Injuries 10x more commonly than fatalities • 10% lightening injuries are in persons who are indoors • Use of cell phones & portable electronic devices does not increase the risk of injury except via distracting

28. US LIGHTENING FACTS • 1/3 lightening injuries work-related • Most common days: Sat, Sun & Weds • Most common times: 1200–1800, 1800–midnight • Irrational fear of lightning: “astraphobia” • Study of lightning: “fulminology” by a “fulminlogist”

29. WHAT IS LIGHTNING? • Atmospheric electrostatic discharge of a “leader” bolt travelling at >220,000 km/h (140,000 mph) reaches temps of 30,000 °C (54,000 °F) • Hot enough to fuse sand into glass (fulgurites) • Causes air ionisation leading to formation of NO & nitric acid which act as fertilizer to green plant life

30. Lightning has (+) and (-) bolt polarity • (-) current 30,000 amperes, 500 megajoules of energy • (+) current 300 kA , 10X greater than (-) bolts • Average single bolt peak power output one trillion watts (terawatt), lasting for 30 millionthsof a second • Voltage proportional to length bolt • Bolt heats vicinity air to 20,000 °C (36,000 °F), 3X temp of sun’s surface which causes a supersonic acoustic shock wave (thunder) • Return stroke follows a charge channel 1cm wide

31. Upper cloud carries (+) charge, lower part carries (-) charge • “Step leader" originates from cloud for 50ms then zig-zags gaining (-) charge • High speed electrons ionize air, providing conducting path for bolt • As step leader nears ground, strong electric field drives (+) ground charge to neutralize (-) charge in the "return stoke“

32. LIGHTENING INJURIES • Not pure direct or alternating current • Most important difference between lightning & high-voltage electrical injuries is duration of current exposure • While energy briefly flows through person. vast majority of lightning energy flashes around body surface • Most energy mediated by other factors including surrounding objects that when are hit then transmits energy to person • <1/3 of affected persons have burns • When burns occur, they are usually superficial • Lightning strikes primarily neurologic injuries

33. LIGHTENING STRIKES • Direct • 3-5% of injuries • Side splash • 30% of injuries • Contact voltage from touching object that is struck • 1-2% of injuries • Current effect as energy spreads across ground • 40-50% of injuries • Upward leader does not connect w/downward leader • 20-25% of injuries

34. CARDIAC INJURIES • Massive defibrillation into VF (most common) or asystole, from which heart often spontaneously recovers • Respiratory arrest lasts longer than cardiac arrest • A secondary cardiac event arrest from hypoxia or CNS injury may occur • Most commonly ECG change is QT prolongation

35. NEUROLOGICAL INJURIES • Neurocognitive deficits similar to TBIs: difficulty processing new information or multitasking • Chronic pain syndromes • Sympathetic nervous system injury: vascular spasm, paralysis, transient HTN, extremity mottling (keraunoparalysis), vertigo &/ or tinnitus • If found unconscious, suspect CNS & spinal injury

36. DERMATOLOGIC INJURIES • Deep: • Rare due to extremely brief skin contact • If burned treat like high-voltage injury (i.e. rhabdomyolysis) • Superficial: • Linear burns secondary to vaporized sweat/ rainwater, pathognomonic fern pattern • Burns also secondary to heated metal such as necklaces, coins, cleats

37. BLUNT TRAUMA • Fractures more common in high-voltage injuries than directly related to lightning, but are common if patient fell or was thrown by the strike • Organ / cardiac / pulmonary contusions rare • Ear is sensory organ most commonly injured by lightning • TM rupture from concussive or explosive force, direct current entry, basilar skull fracture • Hearing loss, tinnitus, & CN 8 nerve symptoms • Eye injuries common: cataracts, macular holes, retinal separation, iritis

38. MANAGEMENT • Scene safety! • Resuscitation in the field if safe, otherwise evacuate • Spinal precautions if any LOC • ACLS protocols for specific arrythmia • AEDs effectively used in a number of cases

39. LIGHTENING & START TRIAGE • Lethal initial arrhythmia usually asystole or VF • How does lightening asystole affect START triage?

40. ALTITUDE RELATED ILLNESS • Elevations > 5000 ft produce physiologic consequences from low oxygen levels • Hypoxia results in spectrum of mild to critical illnesses • History: recent gain in altitude with complaints of headache PLUS one of: • GI upset • Fatigue • Dizziness • Insomnia

41. SPECTRUM • Mild • Nonspecific SSX similar to viral illness • High Altitude Pulmonary Edema (HAPE): • Dyspnea, fatigue, dry cough • High Altitude Cerebral Edema (HACE): • ALOC with neurological findings • High Altitude Retinal Hemorrhage (HARH) • General Treatment Guidelines: • Immediately descend • Acetazolamide (also preventative)

42. HIGH ALTITUDE PULMONARY EDEMA (HAPE) • Most common fatal high-altitude illness • Treatment: • Descend • Bed rest • Oxygen • HBO • Nifedipine • Intubation & diuresis

43. HIGH ALTITUDE CEREBRALEDEMA (HACE) • Least common, most severe • Symptoms: • Ataxia / Seizures • Slurred speech • Focal neurological deficits • AMS • Treatment: • Rapidly descend • 100% Oxygen • HBO

44. SUMMARY • Review of common environmental emergencies • “Heat” • “Height” • “Holy Sh-t”

45. QUESTIONS?prehospitalmd@gmail.com / www.TEAEMS.com