Transcript Chapter 38: Environmental Emergencies

Chapter 38
Environmental
Emergencies
National EMS Education
Standard Competencies
Trauma
Integrates assessment findings with principles
of epidemiology and pathophysiology to
formulate a field impression to implement a
comprehensive treatment/disposition plan for
an acutely injured patient.
National EMS Education
Standard Competencies
Environmental Emergencies
Recognition and management of
− Submersion incidents
− Temperature-related illness
National EMS Education
Standard Competencies
Environmental Emergencies
Pathophysiology, assessment and
management of
− Near drowning
− Temperature-related illness
− Bites and envenomations
National EMS Education
Standard Competencies
Environmental Emergencies
Pathophysiology, assessment and
management of
− Dysbarism
• High-altitude
• Diving injuries
− Electrical injury
− Radiation exposure
− High-altitude illness
Introduction
• Environmental emergencies: Medical
conditions caused or worsened by weather,
terrain, or unique atmospheric conditions at
high altitude or underwater
Introduction
• EMS providers
may be called to
emergencies in:
− Endurance sports
events
− Mass gatherings
− Acutely confused
older patients
© Martin Pisek/ShutterStock, Inc.
Introduction
• Certain weather conditions affect ability to
adapt to environment:
− Wind
− Rain
− Snow
− Temperature extremes
− Humidity
Introduction
• Emergency locations may affect:
− Learning about emergency
− Responding to scene
− Reaching patients in remote settings
Introduction
• Common risk factors predispose people to
environmental emergencies.
− Younger and older people—harder to maintain
thermoregulation
− Preexisting conditions (diabetes, cardiac
disease)
− Dehydration
Homeostasis and Body
Temperature
• Body processes that balance supply and
demand of body’s needs
• Thermoregulation: Thermosensitive
neurons in anterior hypothalamus balance
heat production and dissipation.
Homeostasis and Body
Temperature
• Body tries to keep temperature of 98.6°F.
• CBT: Temperature in part of body
consisting of heart, lungs, brain, and
abdominal viscera
• Starting temperature for:
− Hypothermia—95°F
− Heat stroke—104°F
Homeostasis and Body
Temperature
• Oral temperature used for measurement in
general medical conditions
− Can vary dramatically from CBT if patient is:
• Breathing by mouth
• Drinking hot or cold liquids
• Axillary temperature (armpit) about 1°F
cooler
• Rectal temperature about 1°F hotter
Homeostasis and Body
Temperature
• Rectal
thermometers most
accurate means of
determining CBT,
but CBT unlikely to
affect treatment
Thermoregulatory Mechanisms
• Hypothalamus hosts main thermoregulatory
center.
• Hypothalamus receives signals from:
− Thermoreceptors in skin and muscles
− Central receptors in core, triggered by blood
temperature changes
Thermoregulatory Mechanisms
• At rest, the body:
− Produces heat by metabolism of nutrients, with
liberation of water and carbon dioxide
• Basal metabolic rate (BMR): Heat energy
produced at rest from normal body
metabolic reactions
Thermoregulatory Mechanisms
• BMR of average 70-kg person is around
70 kcal/hour, based on factors including:
− Age
− Gender
− Stress
− Hormones
Thermoregulatory Mechanisms
• Heat loss to environment increases as ratio
of body surface area to body volume
increases.
− With two people of the same weight, the shorter
will have a higher BMR.
− Exertion affects metabolic rate.
Thermoregulatory Mechanisms
• Heat generated by metabolism and
glycogen breakdown warms the body.
− Excess dissipated by temperature gradient
between body and outside environment
− If environmental temperature is higher, body
heats by absorption of outside heat.
Thermoregulatory Mechanisms
• Skin plays vital role in body temperature
regulation.
− Can both conserve and liberate heat energy
through skin
• To liberate heat, blood flow to skin can include up to
8 L/min and 60% of cardiac output.
• In cold, blood flow can approach zero in certain
areas.
Physiologic Reponses to Heat
and Cold
• Thermolysis: Release of stored heat and
energy of the body
− Increase in CBT causes vasodilation and
sweating, which causes:
• Increased effective vascular system volume
• Increased heart output
• Increased pulse rate and stroke volume
Physiologic Reponses to Heat
and Cold
• Cooling can be done by:
− Radiation—via electromagnetic waves
− Conduction—via direct physical contact
− Convection—moving air or liquids
− Evaporation—conversion of liquid to gas
Physiologic Reponses to Heat
and Cold
• Thermogenesis: Production of heat and
energy to deal with cold stressors
− Skin is body’s thermostat in cold environment
− Shivers with cold skin, even if CBT not lowered
− Hypothalamus stimulates peripheral
vasoconstriction to shunt blood to core.
− Heavier people are more insulated from cold.
Pathophysiology, Assessment,
and Management of Heat Illness
• Heat illness: Increase in CBT due to
inadequate thermolysis
− Inability to rid heat buildup from body because
of:
• Hot and humid conditions, mobility
• General health/preexisting illness, age
Risk Factors for Heat Illness
• Older people are at particular risk
− Perspire less
− Acclimatize more slowly
− Feel thirst less readily
− Decreased mobility
− Chronic conditions
Risk Factors for Heat Illness
• Medications that affect temperature
regulation ability include:
− Diuretics—dehydration and electrolyte
disturbances
− Beta blockers—slow tachycardic response to
heat stress
Risk Factors for Heat Illness
• Infants and young children are vulnerable.
− Proportionately higher metabolic heat
production
− CBT rises faster during dehydration.
− Smaller organ and vascular systems do not
dissipate heat as well.
• Military recruits and athletes also at
increased risk
Heat Cramps
• Pathophysiology
− Acute, involuntary muscle spasms
− Occur from:
• Profuse sweating
• Sodium loss
− Most often afflict those in good physical
condition
Heat Cramps
• Assessment
− Starts during strenuous or prolonged activity
− Usual presentation:
• Severe, incapacitating pain
• Hypotension and nausea
• Rapid pulse
• Pale and moist skin
• Normal temperature
Heat Cramps
• Management
− Treatment to
eliminate exposure
and restore lost
salt and water:
• Move patient to
cool environment.
• Position supine if
feeling faint.
Heat Cramps
• Management (cont’d)
− If no nausea:
• Give one or two glasses of salt-containing solution.
− If nauseated:
• Rapidly infuse normal saline by IV.
Heat Syncope
• Pathophysiology
− Orthostatic syncopal episode in nonacclimated
people under heat stress
− Can occur from:
• Prolonged standing
• Standing suddenly from a sitting or lying positions
Heat Syncope
• Assessment and management
− Place patient in supine position.
− Replace fluid deficits.
− If patient does not recover quickly, suspect:
• Heatstroke
• Heat exhaustion
• Cardiac syncope
• Atypical acute coronary syndromes
Heat Exhaustion
• Pathophysiology
− Milder form of heat illness, with:
• Volume depletion
• Heat stress
− Two types:
• Water depleted
• Sodium depleted
Heat Exhaustion
• Exercise-associated hyponatremia
− Prolonged exertion with excessive fluid intake
− Too much water in body in relation to sodium
− Arginine vasopressin (AVP) contributing factor
• Hormone that increases water absorption in kidneys
Heat Exhaustion
• Symptoms include:
−
−
−
−
−
−
−
Headache
Fatigue
Weakness
Dizziness
Nausea
Vomiting
Abdominal cramping
• Other signs and
symptoms:
− Profuse sweating
− Pale, clammy skin
− CBT normal or slightly
elevated
− Tachycardia
− Orthostatic
hypotension
Heat Exhaustion
• Management
− Move to cool environment.
− Remove excess clothes.
− Place supine with legs elevated.
− If temperature is elevated:
• Sponge, spray, or drip with tepid water and fan
gently.
− Oral hydration with sports drinks
Heat Exhaustion
• If suspected exercise-associated
hyponatremia, no fluids by mouth
− Check blood sodium level.
− IV normal saline or hypertonic saline
Heatstroke
• Pathophysiology
− Least common but most deadly
− Caused by severe disturbance in body’s
thermoregulation
− Findings to determine heatstroke:
• Core temperature of more than 104°F (40°C)
• Altered mental status
Heatstroke
• Consequences are related to effects of
elevated temperatures on the body’s cells.
• Two heatstroke syndromes:
− Classic heatstroke
− Exertional heatstroke
Heatstroke
• Assessment
− Signs include:
• Irritability, combativeness
• Signs of hallucination
• Dehydration
• Dry, red, hot skin (classic heatstroke)
• Pale and sweaty skin (exertional heatstroke)
Heatstroke
• Fever and conditions that mimic heatstroke
− Fever can signal a fight against infection.
− Anticholinergic poisoning
− Syndromes that cause hyperthermia
− Malignant hyperthermia
Heatstroke
• Management
− Evaluate ABCs.
− Move patient to a cool environment.
− Cool as rapidly as possible.
− Start an IV line, and monitor cardiac rhythm.
− Prepare to treat for seizures.
Prevention of Heat Illness
• Measures to protect from heat illness:
− Acclimatize when possible.
− Maintain personal fitness.
− Limit time spent in heavy activity, especially
during hot periods.
− Maintain hydration, eat appropriately, and rest.
− Improve cardiovascular and muscular strength.
Prevention of Heat Illness
• Be alert for early heat illness symptoms:
− Headache
− Nausea
− Cramps
− Dizziness
Local Cold Injury/Frostbite
• Often localized to extremities or exposed
areas
• Frostbite: Ischemic injury classified as
superficial or deep
− Frostnip is a mild form of frostbite.
Local Cold Injury/Frostbite
• Deeper degrees of frostbite—tissue freezes.
• Risk factors:
− Cold exposure without adequate clothing
− Impeding circulation to extremities
− Fatigue, dehydration, or hunger
− Direct contact with cold objects
− Hypothermia
Local Cold Injury/Frostbite
• Superficial
frostbite: Altered
sensation of
numbness, burning
− Skin is:
• Waxy and white
• Firm to palpation
− Thawing causes:
• Cyanotic skin
• Hot, stinging
sensation
Courtesy of AAOS
Local Cold Injury/Frostbite
• Deep frostbite
− White, yellowwhite, or mottled
blue-white skin
− Feels hard, cold,
without sensation
− Major damage
when tissues thaw
• May cause
gangrene
Courtesy of Dr. Jack Poland/CDC
Local Cold Injury/Frostbite
• Management
− Difficult to determine depth of injury
− Reperfusion injury can be excruciating.
− Treatment is determined by distance to hospital
and if partially or completely thawed.
Local Cold Injury/Frostbite
• General principles:
− Remove from cold, and remove wet clothing.
− Do not rub or massage area.
− Transport with injured area elevated.
− Give pain medication as needed.
− Cover blisters with dry, sterile dressing.
− Consider rewarming if no potential of refreezing.
Local Cold Injury/Frostbite
• Principles of rewarming:
− Rewarm before transport if medical control
agrees.
• Water bath—ensure immersion without touching
container.
• Temperature between 98°F and 100°F
• Administer IV analgesia.
Trench Foot and Chilblains
• Trench foot similar to frostbite but can occur
at temperatures as high as 60°F
− From prolonged exposure to cool, wet
conditions
− Prevention best treatment—keep feet warm and
dry.
Trench Foot and Chilblains
• Chilblains–itchy reddish or purple lesions
on face or extremities
− Long exposure to temperature just above
freezing
− Treatment:
• Remove from cold environment.
• Room temperature rewarming
Hypothermia
• Decrease in CBT
starting at 95°F
due to:
− Inadequate
thermogenesis
− Excess
environmental cold
stress
© Andy Barrand, The Herald Republican/AP Photos
Hypothermia
• Body regulates cold stress by:
− Increasing thermogenesis
− Decreasing thermolysis
− Adaptive behavioral changes
Hypothermia
• Risk factors:
− Increased
thermolysis
− Decreased
thermogenesis
− Impaired
thermoregulation
Hypothermia
• Hypothermic condition results from:
− Cold temperatures
− Improper gear
− Wetness and dehydration
− Length of exposure
− Intensity of weather conditions
Hypothermia
• Alcohol is the most common cause of heat
loss in urban settings.
− Hinders body’s attempt to insulate warm core
• Impairs shivering thermogenesis.
• Promotes cutaneous vasodilation.
• Inadequate glycogen stores from liver disease
• Subnormal nutritional status
• Impairs judgment.
Hypothermia
• Others at risk include:
− Those using:
• Sedative medications
• Tricyclic antidepressants
• Phenothiazines
− Older patients
− Trauma patients
Hypothermia
• Ensure ambulance
is preheated.
− Conserve patient’s
body heat.
© Jim Cole/AP Photos
Hypothermia
• National Institutes of Health—focus on
“umbles” in early stages:
− Stumbles
− Mumbles
− Fumbles
− Grumbles
Hypothermia
• 2010 American Heart Association ACLS
guidelines define:
− Mild hypothermia—CBT greater than 93.2°F
− Moderate hypothermia—CBT between 86°F to
93.2°F
− Severe hypothermia—CBT below 86°F
Hypothermia
• Classifications:
− Acute
− Subacute
− Chronic
• Also classified as:
− Primary
− Secondary
Hypothermia
• No strong correlation between specific CBT
and signs and symptoms.
− Most dramatically apparent in CNS, where
everything slows
• Thinking and feeling
• Speaking slow and slurred
• Impaired reasoning ability and coordination
Hypothermia
• Signs and symptoms may resemble:
− Stroke
− Head injury
− Acute psychiatric disturbance
− Alcohol intoxication
Hypothermia
• Changes in cardiovascular system lead to:
− Increase in blood viscosity
− Impaired circulation and hypovolemic state
− State of hypovolemia
Hypothermia
• 2010 AHA guidelines
suggest attempting
defibrillation once.
− If persisting, treatment
may include repeating
attempts in
conjunction with
rewarming.
• Respiratory rate
initially speeds up,
then slows, with
decreased minute
volume:
− Tracheobronchial
secretions increase
− Bronchospasm
− Pulmonary edema
Hypothermia
• Muscular system slows.
− Initial reaction is shivering.
− Shivering stops at around 91°F.
• Cold muscles become progressively weaker and
stiffer.
Hypothermia
• Care aimed at preventing more heat loss
and rewarming
− Strip patient of wet cloths.
− Insulate patient from further heat loss.
Hypothermia
• Breathing patients with pulse
− Mild hypothermia (93.2°F)
• Passive rewarming
− Moderate hypothermia (86°F to 93.2°F)
• If perfusing rhythm, active external rewarming
− Severe hypothermia (Less than 86°F)
• Active core rewarming sequence in-hospital
Hypothermia
• Patients with no pulse or not breathing
− 2010 BLS guidelines recommend CPR if no
signs of life are present.
• Rapid rhythm identification
• One defibrillation attempt
• IV access and infuse warm normal saline
• Attempt advanced airway, and give warm, humid
oxygen.
Hypothermia
• Patients are generally considered dead if:
− Obvious lethal traumatic injuries
− So solidly frozen as to block airway or chest
compression efforts
• Resuscitation unlikely if submersion
precedes arrest.
Drowning
• Process of experiencing respiratory
impairment from submersion or immersion
in liquid
• Outcomes include:
− Death
− Morbidity
− Near morbidity
Drowning
• Drowning continuum:
− Breath holding
− Laryngospasm
− Accumulation of carbon dioxide/inability to
oxygenate lungs
− Respiratory and cardiac arrest from tissue
hypoxia
Drowning
• Risk factors:
− Toddlers—
bathtubs
− School-age
children—pools
− Teens—lakes and
rivers
− Comorbidities
Drowning
• Predictable sequences starting with inability
to keep face out of liquid
− Length of breath holding depends on:
• State of health and fitness
• Level of panic
• Water temperature
Drowning
• Resuscitation is
the same as for
others in
respiratory or
cardiac arrest.
• Reaching victim—
leave to those
trained/experience
d in water rescue
Drowning
• Treatment follows ABCs.
− Establish airway.
− Cervical spine precautions, especially if:
• History of diving or water slide
• Signs of injury
• Alcohol intoxication
Drowning
• Continue rescue breathing until on land.
• Once on solid surface:
− Start supplementary oxygen.
− Determine pulse.
− Continue to treat according to ABC guidelines.
Drowning
• Start chest compressions after two breaths.
− Establish IV access.
− Administer indicated medications.
− Perform cardiac monitoring.
− Defibrillate shockable rhythms.
− Do not perform manual abdominal thrusts.
− Suction to clear airway.
Drowning
• Most drowning victims receiving rescue
breathing or compressions will vomit.
− Remove vomit from mouth via:
• Suction
• Finger swipes
• Other devices
− Consider placing on side.
Drowning
• Maintain some positive pressure at end of
exhalation to:
− Keep alveoli open.
− Drive fluid accumulated in alveoli back into
interstitium or capillaries.
Drowning
• Positive end-expiratory pressure (PEEP)
− Maintains some positive pressure at end of
expiratory phase.
− Indicated for intubated patients with long
transports
− Some devices allow PEEP via endotracheal
tube.
− Portable ventilators usually have PEEP setting.
Drowning
• If ET tube inserted, insert nasogastric tube
to decompress stomach.
• If pulse absent, implement ALS measures
for cardiopulmonary arrest:
− IV access
− Epinephrine administration
− Cardiac monitoring, defibrillation if needed
Drowning
• Do not give up on submersion patient.
− Successful resuscitation with complete
neurologic recover in more than 1 hour of
submersion in icy water
• Hypothermia protects body and brain from hypoxia
• Hypothermia more often dangerous than protective
Drowning
• Search for comorbidities:
− Trauma
− Hypoglycemia
− Acute coronary syndrome
− Cerebrovascular accident
Drowning
• Major predictors of outcome:
− Length of submersion
− Response to field resuscitation
− If awake upon hospital arrival, likely a better
outcome
Drowning
• Postresuscitation complications
− Occur hours to days after submersion:
• Adult respiratory distress syndrome
• Hypoxic brain injury
• Multiorgan failure
• Sepsis syndrome
Diving Injuries
• Four modes of diving
− Scuba
− Breath-hold
− Surface-tended
− Saturation
General Pathophysiology: Physical
Principles of Pressure Effects
• Pressure—a force per unit area
− Different ways to express; for example, weight
of air at sea level:
• 14.7 pounds per square inch
• 760 mm Hg
• 1 atmosphere absolute (ATA) (most common)
General Pathophysiology: Physical
Principles of Pressure Effects
• Water much denser than air.
− For every 33 feet of seawater (fsw), pressure
increases 1 ATA
• Sea level—pressure is 1 ATA
• 33 fsw—pressure is 2 ATA
• 66 fsw—pressure is 3 ATA
− Majority of scuba diving is at depths between 60
and 120 fsw (3 to 5 ATA).
General Pathophysiology: Physical
Principles of Pressure Effects
• Liquid volume does not change with
pressure.
− Body/tissues primarily water—not so affected by
pressure changes in descent or ascent
− Gas-filled organs are compressible and follow
several physical laws.
General Pathophysiology: Physical
Principles of Pressure Effects
• Boyle’s law—at a constant temperature,
volume of a gas is inversely proportional to
its pressure:
− Double pressure on gas, halve volume (PV = K)
General Pathophysiology: Physical
Principles of Pressure Effects
• Effect is most
extreme near
surface.
• Explains
barotraumas that
occur in gas-filled
body areas
General Pathophysiology: Physical
Principles of Pressure Effects
• Dalton’s law—each gas in mixture exerts
same partial pressure it would exert if it
were alone in the same volume
− The total pressure of a mixture of gases is the
sum of the partial pressures of all gasses in the
mixture.
• Fresh air—Ptotal = PO2 + PCO2 + PN2
General Pathophysiology: Physical
Principles of Pressure Effects
• Henry’s law—the amount of gas dissolved
in a liquid is directly proportional to the
partial pressure of the gas above the liquid
− P – kC
General Pathophysiology: Physical
Principles of Pressure Effects
• Commercial divers use a decompression
schedule.
− Recreational divers—no-decompression limit to
keep from decompressing
− Enriched Nitrox gas decreases risk of nitrogen
narcosis.
General Assessment:
Diving History
• When did symptoms start?
• Type of diving and equipment?
• Type of tank?
• Diving site and water temperature?
General Assessment:
Diving History
• Number of dives in the last 72 hours, and:
− Depth?
− Bottom time?
− Surface interval?
• Dive computer used?
• Safety stops used?
General Assessment:
Diving History
• Any attempts at in-water decompression?
• Any dive complications?
• What were predive and postdive activities?
Injuries at Depth
• Nitrogen narcosis: Altered mental status
from breathing compressed nitrogencontaining air at depth
Injuries at Depth
• Signs and symptoms:
− Euphoria
− Inappropriate and dangers behavior
− Tingling of lips, gums, and legs
− May panic and surface too quickly.
Injuries at Depth
• Management
− Lower nitrogen partial pressure through:
• Controlled ascent
• Use of a mixed gas for diving with a decreased
nitrogen percentage
Barotrauma
• Result of pressure imbalance between gasfilled spaces in the body and external
atmosphere
− Can affect any gas-filled space in the body
− Scuba divers generally protected by breathing
compressed air
Barotrauma
• Pressure in middle
ear cannot be
equalized with outside
water pressure if:
− Blockage of
eustachian tube
− Valsalva maneuver
does not equalize
pressure.
• “Middle ear squeeze”
syndrome causes
severe pain.
• If tympanic
membrane ruptures
− Nausea/vomiting
− Vertigo
− Panic/rapid ascent
Barotrauma
• Treatment:
− Loose dressing for bleeding ear
− IV antiemetics or sedatives
− Possible decompression symptoms:
• Hearing loss
• Vertigo
Pulmonary Overpressurization
Syndrome (POPS)
• If divers fail to exhale during ascent,
pressure in lungs increases.
• POPS (“burst lung”) causes:
−
−
−
−
Pneumothorax
Mediastinal/subcutaneous emphysema
Alveolar hemorrhage
Lethal arterial gas embolism (AGE)
Pulmonary Overpressurization
Syndrome (POPS)
• Relative pressure and volume changes
greatest near surface of water.
− Small overpressurization can rupture alveoli.
− Diving students trained to exhale constantly
during ascent to vent air from lungs.
− COPD and asthma patients have slightly higher
risk
Pulmonary Overpressurization
Syndrome (POPS)
• Signs and symptoms depend on where
escaping air ends up; most often into
mediastinum and beneath skin, causing:
− Full sensation in throat
− Pain on swelling
− Dyspnea
− Substernal chest pain
Pulmonary Overpressurization
Syndrome (POPS)
• Physical examination may show:
− Palpable subcutaneous air above clavicles
− Crunching noise synchronous with heartbeat
audible by auscultation (Hamman’s crunch)
Pulmonary Overpressurization
Syndrome (POPS)
• Prehospital treatment depends on if arterial
gas embolism is present
• In the field, provide 100% oxygen by
nonrebreathing mask.
Arterial Gas Embolism
• Air bubbles from ruptured alveoli enter
pulmonary capillaries and travel back to left
side of heart.
− Bubbles may enter coronary arteries and
produce effects of MI.
− Majority rise to head, causing strokelike
symptoms.
Arterial Gas Embolism
• Dramatic clinical picture, with symptoms:
− Involving most cerebral functions
− Appearing within seconds to minutes after
surfacing
• History of panic or uncontrolled ascent, but
can occur in shallow water
Arterial Gas Embolism
• Patient can experience:
− Weakness or paralysis of extremities
− Seizure activity
− Unresponsiveness
−
−
−
−
Parasthesias
Visual disturbances
Deafness
Changes in mental status
Arterial Gas Embolism
• Transport to a
hyperbaric
chamber facility as
soon as possible.
Courtesy of Perry Baromedical Corporation
Arterial Gas Embolism
• Treatment includes:
− Ensure adequate airway.
− Administer 100% supplemental oxygen.
− Transport in supine position by ground.
− Establish IV access, and administer normal
saline.
− Monitor cardiac rhythm.
Decompression Sickness
• Nitrogen bubbles in blood and tissues come
out of solution during ascent.
− Bubbles cause damage by:
• Interfering mechanically with tissue perfusion
• Triggering chemical changes in body
− Multisystem disorder—can potentially affect
every organ in the body
Decompression Sickness
• Nitrogen and oxygen are carried to tissues;
oxygen is metabolized, but nitrogen
remains.
− If ascent slow enough, enough nitrogen will
escape with each breath.
− If ascent more rapid than nitrogen can be
removed, diver’s tissues will begin to bubble.
Decompression Sickness
• Other risk factors include:
− Obesity
− Dehydration
− Fatigue
− Flying within 12 to14 hours of diving
Decompression Sickness
• Risk of severe neurologic DCS if patient has
a patent foramen ovale
− Congenital defect in which foramen ovale
between atria fails to close at birth
− May allow nitrogen bubbles to travel from
pulmonary circulation into systemic circulation
− Increased damage to CNS and proximal spinal
cord
Decompression Sickness
• Type I—mild form that
involves only:
− Skin
− Lymphatic system
− Musculoskeletal
system
• Symptoms:
− Joint pain
− Mottled and pruritic
skin
− Fatigue and weakness
− Lymph dysfunction
leading to edema
(rare)
Decompression Sickness
• Type II—symptoms in all other organ
systems:
− Pulmonary
− Cardiovascular
− Nervous
Decompression Sickness
• Management :
− Transport to
hyperbaric facility,
even if symptoms
appear to resolve.
Courtesy of Mass Communication Specialist 2nd Class Rebecca J. Moat/U.S. Navy
− Administer 100%
oxygen.
− Manage acute
problems.
Hyperbaric Oxygen Therapy
• Intermittent inhalation of pure oxygen under
pressure greater than 1 ATA
− Mechanically reduces bubble size.
− Reduces nitrogen content.
− Increases oxygen delivery to ischemic tissues.
• Treatment pressures and times from
established tables
Hyperbaric Oxygen Therapy
• Indicated in patients with:
− AGE
− DCS
− Carbon monoxide poisoning
− Other subacute or chronic medical conditions
− Routine decompression of industrial divers
Hyperbaric Oxygen Therapy
• Risks:
− May convert a pneumothorax into a tension
pneumothorax if no chest tube
− Seizures from oxygen toxicity
− Barotrauma
Hyperbaric Oxygen Therapy
• Care recommended in patients who:
− Are pregnant
− Have lung disease
− Have fever
− Have seizure disorders
• In patients with possible AGE or DCS,
benefits may outweigh risks.
Other Gas-Related Problems
• Most recreational divers use compressed
air.
− Tanks with various mixtures of nitrogen/oxygen
allow divers to be underwater longer.
− Less nitrogen—less likely to develop DCS
− More oxygen—prone to oxygen toxicity (CNS
emergency)
Other Gas-Related Problems
• Signs and symptoms include:
− Dizziness
− Lack of coordination
− Confusion
− Twitching or paresthesia
− Underwater seizures
Other Gas-Related Problems
• Evacuation from water:
− Controlled ascent
− Ensure diver maintains airway and has air
access during ascent.
• AGE risk does not increase when seizing or
postictal patient is brought to surface.
− DCS may be a concern.
Other Gas-Related Problems
• Once back in boat or on shore, treatment
includes:
− 100% oxygen
− Supportive therapy
− Hyperbaric oxygen therapy in pregnant patients
or those with significant exposure
Shallow Water Blackout
• Frequently seen in teenage boys competing
in remaining the longest underwater
− May hyperventilate just before going under to
extend endurance
• Decreases PaCO2, causing cerebral
vasoconstriction
• PaO2 increases as swimmer descends.
Shallow Water Blackout
• Because PaCO2 is relatively low, respiratory
drive suppressed
− Diver can remain underwater longer, but oxygen
continues to be removed from alveoli
− Cerebral function maintained at depth by
increased PaO2
Shallow Water Blackout
• On surfacing:
− Ambient pressure rapidly decreases.
− PaO2 plummets.
− Hypoxia and cerebral vasoconstriction together
cause blackout just before reaching surface.
Shallow Water Blackout
• Treat as for any other case of drowning.
• When patient regains consciousness,
explain seriousness of injury.
Shallow Water Blackout
• DAN—24-hour consultation service
− (919) 684-8111
− Connect with physician experienced in diving
medicine who can:
• Assist with diagnosis.
• Provide advice for early management.
• Supervise referral to recompression chamber.
Altitude Illness
• Altitude: Terrestrial elevation above 1,500 m
(5,000 ft)
− Level where physiologic changes from
hypobaric hypoxia begin
− Altitude illness: Low partial pressure of oxygen
leads to hypoxia
Altitude Illness
• Barometric pressure varies according to:
− How far from the equator
− Season–typically lower in winter
− Local changes in barometric pressure, can alter
“relative altitude” by 500 to 2,500 ft.
Altitude Illness
• Types:
− Acute mountain sickness (AMS)
− High-altitude cerebral edema (HACE)
− High-altitude pulmonary edema (HAPE)
Altitude Illness
• Typically occurs in those rapidly ascending
to above 8,000 ft, but can occur as low as
6,500 ft.
− Symptoms usually within 6 to 10 hours.
− Directly related to how high and how quickly
arrived
Altitude Illness
• Body adjusts by defending amount of
oxygen available for delivery to tissues.
− First response is hyperventilation.
− Quickly leads to respiratory alkalosis
− Kidneys secrete bicarbonate in urine.
− Causes compensatory metabolic acidosis
Altitude Illness
• Hypoxia main problem but mechanism
poorly understood
− Initiates series of reactions that cause
overperfusion to brain and lungs, increasing:
• Capillary pressures
• Leakage
• Cerebral and pulmonary edema
Altitude Illness
• HAPE results from marked vasospasm of
pulmonary arteries.
− Results in high pressure driving fluid from
pulmonary vasculature into lungs
− Does not result from volume overload state
• Nitroglycerin and furosemide not used for HAPE
Altitude Illness
• Risk factors
− History of AMS
− Normal residence
below 3,000 ft
− Obesity
− Rapid or high
ascents
© Alan Heartfield/ShutterStock, Inc.
Altitude Illness
• Acute mountain sickness (AMS) symptoms
include headache plus:
− Fatigue or weakness
− GI symptoms
− Dizziness or light-headedness
− Difficulty sleeping
Altitude Illness
• High-altitude pulmonary edema (HAPE)
− Two of the following:
• Dyspnea at rest
• Cough
• Weakness
• Chest tightness or congestion
− Two of the following:
• Central cyanosis
• Audible rales or wheezing
• Tachypnea
• Tachycardia
Altitude Illness
• High-altitude cerebral edema (HACE)
− Presence of change in mental status or ataxia in
a person with AMS
− Presence of mental status changes and ataxia
in a person without AMS
Altitude Illness
• Signs of possible causes other than AMS:
− Symptoms develop 4 or more days after higher
elevations
− Lack of headache
− Failure of descent to improve signs or
symptoms
Altitude Illness
• Management of all altitude illnesses
includes
− Oxygen
− Descent
− Evacuation
− Various treatments specific to illness
Altitude Illness
• Prevention by:
− Acclimatization
− Use of acetazolamide for most susceptible
Altitude Illness
• AMS treatment :
− Acetaminophen or aspirin for headaches
− Antiemetics for nausea
− Acetazolamide for AMS and acclimatization
− Oxygen
− Do not ascend until symptoms resolve.
Altitude Illness
• HAPE treatment:
− Immediate descent
− Oxygen
− Medication as adjunctive treatment limited to
patients where:
• Descent and oxygen are not easily available.
• Descent and oxygen do not rapidly help patient.
Altitude Illness
• HACE treatment:
− Oxygen
− Mandatory descent
− Dexamethasone given as soon as possible
• 8 mg by any accessible route, followed by 4 mg
every 6 hours during descent/evacuation
Portable Hyperbaric Chambers
• Useful when descent cannot be carried out
• Patient placed inside bag and pressurized
air pumped in
− Provides equivalent of descent of several
hundred to several thousand feet
Lightning Strike
• Leading cause of environmental death in
United States
• Different than industrial electrical injuries:
−
−
−
−
Not AC or DC current
Massive unidirectional flow, voltages in millions
Duration miniscule
Energy flows over victim.
Lightning Strike
• Most common injury is side splash injury
• Bolt’s energy may act as a giant
depolarizing charge to body.
− Can cause asystole and respiratory arrest:
• Diaphragm depolarization
• Brainstem-induced central apnea
Lightning Strike
• After depolarization:
− Heart usually spontaneously resumes sinus
rhythm.
− Respiratory effort does not restart.
− If apnea remains, heart will go into secondary
hypoxic arrest.
Lightning Strike
• Morbidity high
− May have
“Lichtenberg
figure”
− Evaluate for
trauma.
© 2007 British Association of Plastic, Reconstructive and Aesthetic Surgeons
− As many as 75%
have long-term
complications
Lightning Strike
• “Reverse triage”
− Attend those who appear dead first.
− Strikes induce cardiac and respiratory arrest.
− CPR/rescue breathing
• All lightning strike victims should be
evaluated at a medical facility.
Envenomation: Bites and
Stings
• Most common venomous creatures
− Bees, wasps, hornets, fire ants
− Snakes
− Black widow, brown recluse, hobo spiders
− Scorpions
Envenomation: Bites and
Stings
• Most frequent cause of mortality—
anaphylactic reaction
− Most common and most deaths from
hymenoptera bites
− Treatment is same as in other cases of
anaphylaxis
Envenomation: Bites and
Stings
• Treatment includes:
− ABCs management
− Transport
− Obtain vascular access.
− Ensure scene is safe from venomous creatures.
Hymenoptera
• Most common
cause of deaths:
− European honey
bees (Aphidae)
− Yellow jackets,
wasps, hornets
(Vespidae)
− Fire ants
(Formicidae)
© Stuart Elflett/ShutterStock, Inc.
Hymenoptera
• Venom is a mixture of proteins causing local
reactions:
− Erythema
− Swelling
− Pruritus
• Melittin—protein that causes immediate
pain
Hymenoptera
• Local reaction in ¼ of stings.
− Reaction can be extensive.
• Anaphylaxis occurs rapidly, typically within
10 minutes (within 60 minutes 95% of time).
Hymenoptera
• If no history of allergic reaction and no
systemic reaction, transport is not
necessary.
− Advise patient of anaphylaxis signs.
− Wound should be checked if no improvement in
24 hours
− Infection likely from fire ant stings
Hymenoptera
• Treatment focuses on pain and
minimization of infection risk.
− Determine if stinger and venom sac are still
attached.
• If so, remove as rapidly as possible.
• Clean wound thoroughly.
• Cool compresses and elevation for reaction
• Antihistamines for symptomatic treatment
Hymenoptera
• Additional treatment for fire ant stings
include:
− Moving patient and crew away from site.
− Brushing off ants.
− Providing supportive care as needed.
Snake Bites
• Two snake families of concern in United
States:
− Viperidae
− Elapidae
• Most common in southeastern United
States
Snake Bites
• Pit viper venom has both hemolytic and
proteolytic enzymes, causing extensive
local tissue damage and systemic effects:
− Soft-tissue swelling and necrosis
− Local, then systemic bleeding
− Clotting problems
Snake Bites
• Coral snakes have potent neurotoxic
venom:
− Paresthesias
− Fasciculations
− Weakness
− Respiratory difficulty
− Strokelike symptoms
Snake Bites
• Pit vipers
− Heat-sensing pits
between the eye
and the nostril
− Main types:
• Rattlesnakes
• Cottonmouths
• Copperheads
Snake Bites
• Coral snakes
− Small fangs
− Snakes need to
stay attached for
envonemation.
− Several hours for
symptoms to show
− Transport if
possible bite
Courtesy of Luther C. Goldman/U.S. Fish & Wildlife Service
Snake Bites
• Be certain snake is no longer a danger.
• Note time of bite.
• Determine type of snake.
− Remember—dead snakes can still bite.
Snake Bites
• Crotalid venom
− Promotes tissue
destruction through:
• Proteolysis
• Hemolysis
• Thrombogenesis
• Elapid venom
− Neurotoxin causing
respiratory failure and
death
Snake Bites
• Crotalid bite
symptoms include:
− Swelling, bleeding
− Weakness
−
−
−
−
Unconsciousness
Tachycardia
Coagulopathies
Shock,
cardiovascular
collapse
Courtesy of AAOS
Snake Bites
• Degree of envenomation determined by
symptoms:
− Mild—minimal local swelling with no systemic
symptoms
− Moderate—swelling extending up extremity,
systemic symptoms; no significant bleeding
− Severe—extensive soft-tissue swelling and
severe systemic effects and bleeding
Snake Bites
• Treatment—provide antivenin (at hospital).
− Monitor ABCs.
− Clean wound with antimicrobials.
− Draw blood for hospital use (if protocols allow).
− Immobilize involved extremity in neutral position
below heart level.
− Do not use excessive constriction.
− Remove constricting jewelry.
Spider Bites
• Estimated 34,000 species worldwide
• Most carnivores and can bite
• Three species of concern in US:
− Black widow
− Brown recluse
− Hobo spiders
Spider Bites
• Black widow—only
female dangerous
− Glossy black with
½-inch oval body
− Orange or reddish
hourglass mark
− Lives in sheds,
basements,
woodpiles
− Most bites on
hands or forearms
© Crystal Kirk/ShutterStock, Inc.
Spider Bites
• Brown recluse
(fiddleback) spider:
− Southern Midwest
to Southeast
− Not aggressive,
bites only when
accidently
encountered
Courtesy of Kenneth Cramer, Monmouth College
Spider Bites
• Hobo spiders
− Found in Northwest
− Bite clinically similar to brown recluse
− Slightly more aggressive
Spider Bites
• History of spider bite not always confirmed.
− Patient may report:
• Sudden, sharp prick followed by cramping
• Numbing pain beginning at bite area and gradually
spreading
• Extreme restlessness (in case of black widow bite)
Spider Bites
• Black widow one of most venomous North
American spiders
− Local pain with rapid onset within 30 to 60 min
− Local muscle spasm and localized diaphoresis
− Diffuse and more muscle spasms
− If diaphragm affected, may have respiratory
difficulty
Spider Bites
• Brown recluse
bites usually
painless
• Small percentage
develop local
and/or systemic
symptoms
Courtesy of Department of Entomology, University of Nebraska
• Some may develop
loxoscelism.
Courtesy of Department of Entomology, University of Nebraska
Spider Bites
• Black widow spider
bite treatment:
− Intermittent ice use
− Antimicrobial
cleansing of wound
− Pain and muscle
spasm relief
− Prompt transport
• Further treatment:
− Monitor ABCs.
− IV access, oxygen
− Narcotics, muscle
relaxants/sedatives
− Antivenin reserved for
young and old with
severe envenomation
Spider Bites
• Brown recluse/hobo spider bite treatment:
− Antivenin not routinely available
− Previous treatments (dapsone, steroids) shown
to have no benefit
Scorpion Stings
• Only the bark
scorpion is a
potential threat to
humans.
− Most result in a
painful local
reaction.
− Venom located in
stinger’s glands
© Visual&Written SL/Alamy Images
Scorpion Stings
• Local sting symptoms within minutes, last
several hours:
− Erythema
− Pruritis
− Urticaria
− Sharp, burning pain
− Paresthesia
Scorpion Stings
• A sting from the more neurotoxic bark
scorpion causes few local symptoms.
− Systemic symptoms begin within minutes
− Peak at 4 to 6 hours
− Resolve within 24 to 72 hours
Scorpion Stings
• Symptoms
− Sympathetic
stimulation:
− Parasympathetic
stimulation:
• Tachycardia
• Bradycardia
• Hypertension
• Palpitations
• Hypotension
• Salivation
• Dry mouth
• Defecation
• Cranial nerve
findings
• High temperature
Scorpion Stings
• Symptoms (cont’d)
− Somatic stimulation
• Muscle contractions
• Myoclonic jerking
• Fasciculations
Scorpion Stings
• Prehospital treatment:
− ABCs
− Monitoring
− Transport
− Intubation if necessary
− IV for volumes needed for blood pressure
Scorpion Stings
• Prehospital treatment (cont’d):
− Ice pack for local swelling
− Immobilize extremity
− Constricting band
− Treat seizures per protocol
Scorpion Stings
• In-hospital treatment includes care for
ABCs:
− Alpha and beta blockers
− Atropine
− Vasoactive drugs
− Antivenin if available
Tick Bites
• Blood-sucking
arthropods found in
rural, wooded
areas
− Bites a concern
because of disease
transmission
• Lyme disease
• Rocky Mountain
spotted fever
© Joao Estevao A. Freitas (jefras)/ShutterStock, Inc.
Tick Bites
• Treatment
− Remove tick:
• Use curved forceps to grab head as close to skin as
possible.
• Pull straight up using even pressure.
• Do not twist or jerk.
• Dispose of it in container of alcohol.
Tick Bites
• Once tick is removed:
− Wash bite with soap and water.
− May be no reason to transport if patient is
asymptomatic (check with local protocol).
− Advise patient to see a physician.
Summary
• Environmental emergencies: Medical
conditions caused or worsened by weather,
terrain, or unique atmospheric conditions
such as underwater or high altitude
• Predisposing risk factors include very
young, elderly, poor state of health, and
certain medications.
Summary
• Thermoregulation: Body’s ability to ensure a
balance between heat production and
release, with the hypothalamus and skin
playing major roles
• Body produces heat through metabolism;
basal metabolic rate is the heat energy
produced at rest from normal metabolic
reactions.
Summary
• Thermolysis: Release of heat and energy
from the body
• Thermogenesis: Production of heat and
energy for the body
• The body has four main means of cooling
itself—radiation, conduction, convection,
and evaporation.
Summary
• Heat illness: Increase in core body
temperature from inadequate thermolysis
• Heat cramps: Acute, involuntary muscle
pains in abdomen or lower extremities from
profuse sweating and sodium loss
• Heat syncope occurs when overheated
patient suddenly moves. Place patient
supine and replace fluids.
Summary
• Heat exhaustion can result from
dehydration and heat stress.
• Heatstroke: Core temperature above 104 F
(40oC) and altered mental status
• Fever can mimic heatstroke.
• Dress appropriately, stay hydrated, and stay
in shade or air conditioning to prevent heat
illness.
Summary
• Frostbite: Local freezing of a body part and
is classified as superficial or deep
• Superficial frostbite is characterized by
numbness, tingling, or burning. The skin is
white, waxy, and firm to palpation.
• Deep frostbite is characterized by white,
yellow-white, or mottled blue-white injured
body part and is hard, cold, and without
sensation.
Summary
• Trench foot results from prolonged
exposure to cool, wet conditions.
• Hypothermia: Decrease in core body
temperature; can be mild, moderate, or
severe
• Mild hypothermia: Core body temperature of
greater than 93°F (33.9°C)
Summary
• Moderate hypothermia: Core body
temperature from 86°F to 93°F (30°C to
33.9°C)
• Severe hypothermia: Core body
temperature of less than 86°F (30°F).
• Resuscitate hypothermic patients who are
not breathing or without a pulse.
• Resuscitation can be attempted in cases of
cardiac arrest and hypothermia.
Summary
• Drowning: Process of experiencing
respiratory impairment from submersion or
immersion in liquid
• Rescuing a patient who has drowned
should be undertaken by specially trained
rescuers.
• For diving injuries, obtain details such as
type of diving, type of tank, number of dives
in the past 72 hours, and predive and
postdive activities.
Summary
• Barotrauma can happen during dive
descent from the pressure imbalance
between the inside of the body and the
outside atmosphere.
• Nitrogen narcosis: Altered mental status
from breathing compressed air at depth
• Pulmonary overpressurization syndrome
(POPS, burst lung) can occur if a diver
ascends too quickly.
Summary
• Pulmonary overpressurization syndrome
may lead to arterial gas embolism.
• Barotrauma treatment depends on whether
there is an air embolism. A pneumothorax
may require needle decompression. With an
air embolism, the patient must receive
treatment in a hyperbaric chamber.
• In decompression sickness, nitrogen
bubbles in blood and tissues during dive
ascent.
Summary
• Shallow water blackout occurs when a
person hyperventilates just before diving
and passes out before resurfacing.
• The Divers Alert Network is a resource for
diving-related injuries.
• Altitude illness occurs when unacclimatized
people ascend to altitude, with types
including AMS, HACE, and HAPE.
Summary
• Symptoms of AMS include headache and
fatigue, weakness, gastrointestinal
symptoms, dizziness, light-headedness,
and difficulty sleeping.
• Symptoms of HACE include mental status
changes and/or ataxia in a person with
acute mountain sickness or the presence of
both in a person without acute mountain
sickness.
Summary
• Symptoms of HAPE include at least two of
the following: dyspnea at rest, cough,
weakness, or chest tightness or congestion,
and at least two of the following: central
cyanosis, audible rales, wheezing,
tachypnea, or tachycardia.
• Treatment of altitude illness includes
descending or use of a portable hyperbaric
chamber, providing oxygen, and
administering IV medications.
Summary
• Cardiopulmonary resuscitation should be
started promptly for lightning strike victims.
• In lightning strike cases, victims who appear
to be dead should be treated first.
• Anaphylactic reaction is the most frequent
mortality cause from insect bites and
envenomations.
Summary
• To decrease toxin exposure, promptly
remove hymenoptera stingers or venom
sacs.
• Fire ant stings may result in infection.
• Most snake bites in the United States are
from pit vipers.
• If there are visible fang marks with no
bleeding with a crotalid bite, it is likely a “dry
bite” with no venom.
Summary
• For scene safety, ensure the snake is dead,
gone, or trapped in cases of envenomation.
• All significant snake envenomations require
antivenin treatment.
• The most concerning spider bites are from
the female black widow, the brown recluse,
and the hobo spider.
• A small subset of patients with brown
recluse spider bites may develop
loxoscelism.
Summary
• Scorpion stings produce a neurotoxic
reaction causing autonomic excitation.
• Scorpion sting treatment is largely
supportive and includes airway protection.
• Tick bites can transmit serious illnesses and
rarely cause life-threatening paralysis.
Credits
• Chapter opener: Courtesy of BM1 Kevin
Erwin/U.S. Coast Guard
• Backgrounds: Red – © Margo Harrison/
ShutterStock, Inc.; Green – Jones & Bartlett
Learning; Purple – Courtesy of Rhonda Beck;
Blue – Courtesy of Rhonda Beck.
• Unless otherwise indicated, all photographs and
illustrations are under copyright of Jones & Bartlett
Learning, courtesy of Maryland Institute for
Emergency Medical Services Systems, or have
been provided by the American Academy of
Orthopaedic Surgeons.