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