Transcript Document

Amy Gutman MD
[email protected] /
www.TEAEMS.com
OVERVIEW

Heat Related Illnesses

High Altitude Illnesses

Lightening Injuries
DEFINITIONS

“Normal” temperature
 98.6oF (37oC)

Hypothermia
 Core temp <95oF (35oC)

Hyperthermia
 Core temp >105oF (45oC)
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
THERMOREGULATION METHODS

Body Temperature

 Core & Peripheral


 Central
 Peripheral
Hypothalamus
Heat Dissipation
 Sweating, vasodilatation

Thermoreceptors
Heat Conservation
 Shivering,
vasoconstriction

Metabolic Rate
 Basic metabolic rate
 Exertional metabolic rate
 Core temperature
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
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
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
Humidity Index
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
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
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
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
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
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
DEVELOPMENT OF HEAT EXHAUSTION
Heat
Skin Arteriolar
Dilation
Excessive
Sweating
Hypovolemia
Decreased Cardiac Output
Decreased Mean Arterial Pressure
Circulatory Collapse
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
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
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
HEAT STROKE SSX

Core temp >105F (40.5C)

Renal failure

Mental status changes /
anxiety / Confusion

DIC

Hypotension with
bounding or thready
tachycardia

Possible seizures

Hypotension

Tachypnea
DEVELOPMENT OF HEAT STROKE
Strenuous Exercise
Hot, Humid Environment
Inadequate Temperature Regulation
Core Temperature Elevates
Impaired CNS Function
Organ & Tissue Damage
Coma & Death
HEATSTROKE
TREATMENT


Transfer to cool
environment

Administer O2 prn

IV rehydration
Remove clothing, start
rapid active cooling

Cardiac monitor
 Cover with moist sheets

AVOID vasopressors or
anticholinergic drugs

Reassess vitals
frequently
 Mist with cool water

Target temperature 102F
 Overcooling may cause
reflex hypothermia
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

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
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
HEAT EMERGENCIES SUMMARY
Condition
Muscle
Cramps
Mental
Status
Resp
Pulse
BP
Core Temp
Other
Heat
Cramps
Yes
Alert
Normal
Normal
Normal
Normal
Weakness
Dizziness
‘Feel Faint’
Heat
Exhaustion
Possible
Anxious,
ALOC
Rapid,
Shallow
Rapid,
Weak
Normal
Mildly
Elevated
Headache
“Pins &
Needles”
Diarrhea
Heat
Stroke
No
ALOC,
Delirium,
Coma
Deep &
Rapid with
late
Shallow
Slowing
Rapid, Full
with late
slowing
Low
Very High
Seizures
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
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”
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

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
• 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“
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
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
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
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
DERMATOLOGIC
INJURIES

Deep:
 Rare due to extremely brief
skin contact
 If burned treat like highvoltage 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
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
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
LIGHTENING & START TRIAGE

Lethal initial arrhythmia
usually asystole or VF

How does lightening
asystole affect START
triage?
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
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)
HIGH ALTITUDE PULMONARY
EDEMA (HAPE)

Most common fatal highaltitude illness

Treatment:
 Descend
 Bed rest
 Oxygen
 HBO
 Nifedipine
 Intubation & diuresis
HIGH ALTITUDE CEREBRAL
EDEMA (HACE)

Least common, most
severe

Symptoms:





Ataxia / Seizures
Slurred speech
Focal neurological deficits
AMS
Treatment:
 Rapidly descend
 100% Oxygen
 HBO
SUMMARY

Review of common
environmental
emergencies
 “Heat”
 “Height”
 “Holy Sh-t”
QUESTIONS?
[email protected] / www.TEAEMS.com