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Environmental Emergencies
Provincial Reciprocity Attainment Program
Environmental Emergencies
 A medical emergency caused by or
exacerbated due to exposure to
environmental, terrain, or atmospheric
pressure
Common terms
 Thermoregulation
 The maintenance of internal body temperature
at or near the set point of 36.5 ºC
 Thermogenesis
 The regulation of heat production
 Thermolysis
 Regulation of heat loss
Thermoregulation
 Regulatory centre located in posterior
hypothalamus
 Central thermoreceptor (stimulated by blood temp)
near anterior hypothalamus, peripheral
thermoreceptors of skin, and some mucous
membranes
 Control temperature through vasoconstriction /
vasodilation, perspiration, and increased circulation
to skin
Regulating heat production
 Heat is generated through
mechanical, chemical,
metabolic, and endocrine
activities
 Mechanical
 Shivering
 Chemically
 Cellular metabolism
 Endocrine
 Hormone release
Regulating heat production
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Cell metabolism
Breathing
Sweating
Arrector pilli (piloerection)
↑ HR
Shunting of blood
 Dilation/constriction of
blood vessels
 Core shunting
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Muscle movement
Fluid intake
↑ food intake
Sleep
ADH release
↑ urination
Catecholamine
release
Regulating heat loss
 Heat is naturally lost through
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Radiation
Convection
Conduction
Evaporation
Body Temperature
Maintenance
 Physiologic responses — controlled by the
brain (involuntary, such as shivering and
vasoconstriction)
 Deliberate actions — (such as exerting
yourself or putting on layers of clothing to
retain heat when you stop exercising)
Regulating Heat Loss
 Heat is lost from the body to the external
environment through the skin, lungs, and
excretions
 The skin is most important in regulating
heat loss
 Radiation, conduction, convection, and
evaporation are the major sources of
heat loss
Convection
 Happens when air or water with a lower
temperature than the body comes into
contact with the skin and then moves on
You use convection when you blow on
hot food or liquids to cool them
Amount of heat lost depends on the
temperature difference between your
body and the environment, plus the
speed with which the air or water is
moving
Convection
 If you are not moving, and the air is still,
you can tolerate a cold environment quite
well
 Air in motion takes away a LOT of heat
 With air in motion, the amount of heat
lost increases as a square of the wind’s
speed
 A breeze of 8 mph (12.8 km/h) will take
away FOUR times as much heat as a
breeze of 4 mph (6.4 km/h)
Convection
 Above wind speeds of 30 mph (48
km/h), the point becomes moot,
because the air does not stay in
contact with the body long enough to
be warmed to skin temperature
 Convective cooling is much more rapid
in cold water because the amount of
heat needed to warm the water is far
greater than the amount of heat
needed to heat the same volume of air
Conduction
 Transfer of heat away from the body to
objects or substances it comes into
contact with
 This is the one where grabbing a door
handle with a moist hand at -40º gives
you a chance to stick around...
 Stones and ice are good heat
conductors, which is why you get cold
when you sit on them
Conduction
 Air conducts heat poorly — still air is an
excellent insulator
 Water conductivity is 240 times greater
than that of dry air
 The ground is also a good heat
conductor, which is why you need a foam
pad or other insulating barrier under a
sleeping bag if you want to stay warm
overnight
Conduction
 Alcohol is an excellent heat conductor
that remains liquid well below the
freezing temperature of water
 At very cold temperatures, drinking
alcohol (ethanol) can result in flashfreezing of tissues inside the mouth
 If the back of the throat and the
esophagus become frozen this way, the
resulting injury is often lethal
Evaporation
 Responsible for 20% - 30% of heat loss
in temperate conditions
 About 2/3 of evaporative heat loss takes
place from the skin in thermoneutral
conditions
 Remaining evaporative heat loss
happens in the lungs and airway
 In cold weather, airway evaporative
heat loss increases as the incoming air
is humidified and warmed
Evaporation
 In cold weather, 3 - 4 litres of water per
day are required to humidify inhaled air
 1500 - 2000 kilocalories (Cal) of heat are
lost in this way on a cold day
 This fluid loss, if not replaced, results in
dehydration, causing a lowered blood
volume and increased risk of developing
hypothermia
Evaporation
 Wet clothing enhances heat loss
 Sweat-drenched clothing conducts heat
toward surface layers of clothing
 Wet outer clothing layers enhance heat
loss to the environment through
evaporation
 A combination of sweat-soaked inner
clothing layers and wet outer clothing
can be quite lethal
Radiation
 Direct emission or absorption of heat
 Heat radiates from the body to the
clothing, then from the clothing to the
environment
 The greater the difference between body
and environmental temperatures, the
greater the rate of heat loss
 Clothing that adequately controls the
rates of conductive and convective heat
loss will compensate for the radiation
heat loss
Cold / aquatic emergencies
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Localized cold injuries
Hypothermia
Hyperthermia
Drowning
Diving Emergencies
Localized cold Injuries
Classifications/Symptoms
 A common classification separates localized
cold injury into three categories
 Frostnip (the mildest form of cold exposure)
 may be treated without loss of tissue
 Superficial frostbite
 there is at least some minimal tissue loss
 Deep frostbite
 there is significant tissue loss even with appropriate
therapy
Frost nip
 AKA chilblains
 The mildest and most common form of localized
cold injury
 Fingertips, ears, nose and toes commonly affected,
characterized by numbness, coldness, and pain
without swelling
 Re-warming is safe even with friction if sure not
superficial frostbite
Frostbite
 A localized injury that results from
environmentally induced freezing of body
tissues
 Pathophysiology
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Ice tissues form
Vascular abnormalities occur
Cellular injury caused
Increased sensitivity to reoccurrence
Frostbite
 Predisposing factors
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Peripheral neuropathies
PVD
Alcohol / tobacco use
Inadequate protection
Nutritional deficiencies
Medication administration
PmHx frostbite
Injury / illness / fatigue
Superficial Frostbite
 Some freezing of dermal tissue
 Initial redness followed by blanching
 Diminished tactile sensation
 Pain
Deep Frostbite
 Freezing of dermal and subcutaneous layers
 White appearance
 Hard (frozen) to palpation
 Loss of sensation
 Management ?
Frostbite
 Edema and blister formation 24 hours after
frostbite injury in area covered by tightly
fitted boot.
.
Deep
Frostbite
 Gangrenous necrosis 6 weeks after frostbite injury
Hypothermia
Hypothermia
 Is defined as a core temperature less than 35°C
(95º F).
 Most commonly seen in cold climates, but can
develop without exposure to extreme
environmental conditions
 May result from:
 A decrease in heat production
 An increase in heat loss
 A combination of these factors
Hypothermia
 If left untreated, hypothermia can kill.
 Nobody ever froze to death — instead, they died of
hypothermia.
 The freezing part came later…
 ...and only if the temperature of the surrounding
environment was below freezing.
Predisposing Factors
 Age
 Medical conditions
 Prescription and over-the-counter medications
 Alcohol or recreational drugs
 Previous rate of exertion
Environmental Factors
 External environmental factors that may
contribute to a medical emergency
 Climate
 Season
 Weather
 Atmospheric pressure
 Terrain
Progression
 Clinical signs and symptoms may be divided
into three classes:
 Mild
 core temperature between 34º and 36º C (93.2º
and 96.8º F)
 Moderate
 core temperature between 30º and 34º C (86º
and 93º F)
 Severe
 core temperature below 30º C (86 º F)
Clinical Features
 Mild (34º and 36º C) - ( pissed off stage )
 LOC Withdrawn
Slurred Speech
 HR Normal (May increase initially)
 BP Normal (May increase initially)
 Other Shivering
Clinical Features
 Moderate (30º and 34º C) - ( stupid ass stage )
 LOC
 Confused, sleepy, irrational, Clumsy, Stumbling
 HR
 Slow and/or weak
 May see EKG changes
 BP
Decreasing
 RR
Bradypnea
 Other
 Cyanosis
 Dilated Pupils
Clinical Features
 Severe (below 30º C) - ( I’m going to die
stage )
 LOC Stupor to Unconscious
 HR Slow (may be irregular), Absent
EKG Changes (high risk)
 BP Hypotensive
 RR Bradypnea or apnea
 Other Cyanosis
Dilated Pupils
EKG Changes
 Hypothermia causes characteristic EKG
changes:
 T-Wave inversion
 PR, QRS, QT intervals may increase
 Muscle Tremor Artifact
 Arrhythmias
 Sinus Brady, AFib, AFlut, AV Block,
PVC’s, VFib, Asystole
Complications
 While the risk of complications are low in
healthy people, there are a few to be
aware of
 Most of these result from pre-existing
health problems
 Pneumonia
 Acute pancreatitis
 Thromboses
Complications
 Pulmonary edema
 Acute renal failure due to tubular
necrosis
 Increased renal potassium excretion
leading to alkalosis
 Hemolysis (breakdown of red blood
cells)
 Depressed bone marrow function
 Inadequate blood clotting
 Low serum phosphorus
Complications
 Seizures
 Hematuria (blood in the urine)
 Myoglobinuria (muscle pigment that
looks like blood in the urine)
 Simian deformity of the hand
 Temporary adrenal insufficiency
 Gastric erosion or ulceration
Stages of Hypothermia
 Shivering
 Apathy or Decreased Muscle Function
 Decreased Level of Consciousness
 Decreased Vital Signs
 Death
Immersion Hypothermia
 In relation to hypothermia, cold water has
two specific threat characteristics:
 Extreme thermal conductivity
 The specific heat of water
 Worsened with saturation of clothing by
water
 The body cannot maintain temperature is
water less than 92 degrees F
Immersion Hypothermia
 Sudden immersed in cold water causes;
 Peripheral vasoconstriction causing
increased BP
 Tachycardia due to anxiety
 Lethal dysrhythmias often occur, especially
in patients with cardiovascular /
cardioelectrical abnormalities
Immersion Hypothermia
 Immersion hyperventilation is the first
risk…
 Immersion in cold water initially causes a
breathing pattern of deep, involuntary gasps
 Followed by a minute or more of deep, rapid
breaths, with tidal volumes about five times
normal
 Drowning often occurs especially in
conjunction with deep immersion or rough
water
Immersion Hypothermia
 Hyperventilation causes alkalosis
 Alkalosis increases the blood’s pH
 Physiologic responses
causes cerebral hypoxia
to
alkalosis
 Syncope increases the risk of drowning
Immersion Hypothermia
 In 15°C (60°F) water breath can only be
held approx. 1/3 normal increasing the
risk of drowning when submersion
occurs for more than a few seconds
 Mammalian diving reflex phenomenon
occurs as a mode of self preservation
Mammalian Diving Reflex
 Cold water ( < 68 degrees F ) immersion
causes
 Results in apnea, vasoconstriction,
bradycardia and slowed metabolism without
the risk of aspiration
 Vascular bed also becomes engorged with
blood in attempt to equalize pressure from
outside the body
Mammalian Diving Reflex
 20 - 30 % reduction in heart rate
 Complete recovery after 60 min possible
 Redistribution of blood flow from the
periphery to the core
Mammalian Diving Reflex
 Muscles cool and nerve impulses slow,
causing slow, weak, poorly coordinated
movements
 Treading water or swimming much more
difficult
 Dysfunction increases as the tissues cool,
causing inability to swim or tread water after
10-15 minutes in 10°C (50°F) water
Immersion Hypothermia
 This stage is reached in as little as 5
minutes in icy water
 The patient is no longer able to assist in
his or her rescue
 In such cases water rescue is imperative
 Hypothermia does not cause deaths early in
cold water immersion emergencies
 Death results from drowning or cardiac
dysrhythmias
Immersion Hypothermia
 After 10-15 minutes of immersion,
shivering is constant and obvious
 Core temp cooling has not occurred
 Shivering may temporarily prevent heat
loss in dry air, but not in cold water (
remember 240 x )
 Core temp fall commonly occurs around
15-20 minutes in cold (50°F (10°C)) water
Immersion Hypothermia
68
59
50
41
32
Water Temperature
ºF
ºC
20
15
10
5
0
Cooling Rate
ºC/hr
0.5
1.5
2.5
4.0
6.0
Non-exercising adults, light clothing, wearing PFDs
Immersion Hypothermia
 Once immersed, swimming is a
dangerous choice to make
 An average person who can ordinarily swim
well probably will not be able to swim more
than 1 km (.062 mi) in 50°F (10°C) water on a
calm day
 People who tread water lose heat about 30%
faster than people holding still while wearing
a PFD
Systemic Heat Related Illness
Hyperthermia
 Heat illness results from one of two basic
causes:
 Normal thermoregulatory mechanisms
are overwhelmed by environment
 Excessive exercise
 Failure of the thermoregulatory
mechanisms
 Elderly, ill or debilitated
Maintenance of Thermoregulation
 Hyperthermic compensation
 Increased heat loss
 Vasodilatation of skin vessels
 Sweating
 Decreased heat production
 Decreased muscle tone and voluntary
activity
 Decreased hormone secretion
 Decreased appetite
Heat Illness
 Heat Illness can be described by three basic
forms:
 Heat Cramps
 Heat Exhaustion
 Heat Stroke
 Classic
 Exertional
Heat Cramps
 Brief, intermittent, and often severe
muscular cramps or spasms
 Believed to be caused primarily by a
rapid loss of salt during profuse sweating
 Cramps may worsen
 if salts are not replenished
 When Ca levels are low
 Too much water is drunk by patient
 ( Na / H2O ratio disruption )
Heat Cramps
 Signs and Symptoms
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A/O X3
Hot Sweaty Skin
Tachycardia
Normotensive
Normal Body Core Temp (BCT)
Heat Cramps
 Treatment
 Remove Pt from environment
 Remove excess clothing
 Replace salt and water if conscious (First
Aid treatment)
 1 – 2 tsp of sugar in 1 liter of water
 Gatorade et al
 If Severe, IV N/S
Heat Exhaustion
 A more severe form of heat illness
 Mild-to-moderate core temperature elevation
(less than 39ºC)
 A relative state of shock
 Most commonly associated with:
 Profuse sweating
 Water and salt deficiencies cause electrolyte
imbalance
 Vasomotor response causes inadequate
peripheral and cerebral perfusion from pooling
S / S of Heat Exhaustion
 LOC (Irritable, poor judgment, dizziness,
headache)
 Pale, Cool, Clammy Skin
 Tachycardia
 Tachypnea
 Cramps
 Nausea/Vomiting
 Blurred Vision or Dilated pupils
 In severe cases may see orthostatic
hypotension and syncope
Treatment of Heat Exhaustion
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Remove Pt from environment
Remove excess clothing
Replace salt and water if conscious
Oxygen (100% NRB)
Begin Cooling (Slowly)
IV N/S
Heat Stroke
 A syndrome that occurs when the
thermoregulatory mechanisms break down
entirely
 Body temperature elevated to extreme
levels (usually greater than 41º C)
 This produces multi-system tissue
damage and physiological collapse
Heat stroke is a true medical emergency
Heat Stroke
 Classic heat stroke
 Occurs during periods of sustained high ambient
temperatures and humidity
 Pts are unable to dissipate heat adequately
 Examples:
 Children left in enclosed vehicle on hot afternoon
 Elderly person confined to a hot room
 Predisposing factors:
 Age
 Chronic disease (DM, IHD, Alcoholism and schizophrenia)
 Medications
Heat Stroke
 Exertional heat stroke
 Patients are usually young and healthy
 Heat is accumulated faster than the body
can dissipate it
 Exacerbated by drugs i.e. Ephedra in
athletes
S / S Heat Stroke
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LOC (Restless, Headache, Fatigue, Dizziness)
Pt may be unconscious or in coma
Tachycardia, progress to weak
Noisy respirations
Classic Heat Stroke:
Hot, Dry Skin
Exertional Heat Stroke: Hot, Sweaty Skin
Nausea/Vomiting
Seizures
Will lead to DEATH if left untreated
Treatment of Heat Stroke
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Primary Survey and ABC’s
Early recognition important
Move pt to cool environment
Remove excessive clothing
Begin cooling
Watch for rebound hypothermia
IV access
May require fluid challenge
Near-Drowning
 Incidence
 551 drowning accidents in 1998
(Canadian)
 Classifications
 Drowning is defined as death by asphyxia
after submersion
 Near-drowning is submersion with at
least temporary survival
Drowning Pathophysiology
 Sequence of drowning:
 After submersion and panic
 Victim takes several deep breaths to conserve
oxygen
 Holds breath until reflex takes over
 Water is aspirated causing laryngospasm
 This results in hypoxia
 Hypoxia leads to arrhythmias and CNS anoxia
 Hypercapnia begins
 Acidosis
 Cardiac Arrest
Progression of a drowning
incident.
Salt Water
 Hypertonic
 Causes rapid shift of plasma and fluid
into the alveoli and interstitial spaces
 Causes:
 Pulmonary Edema
 Poor Ventilatory ability
 Hypoxia
Fresh Water
 Hypotonic
 Passes readily out of alveoli into circulation
 If sufficient amounts are aspirated may causes:
 Increase of blood volume causing hemolysis
 Surfactant Washout
 Hemolysis may result in hyperkalemia and
anemia
 May lead to dangerous / lethal electrolyte
imbalances
Near-Drowning
 Hypothermic considerations
 Common concomitant syndrome
 May be organ protective in cold-water
near-drowning
 Always treat hypoxia first
 Treat all near-drowning patients for
hypothermia
Factors That Affect Clinical
Outcome
 Temperature of the water
 Length of submersion
 Cleanliness of the water
 Age of the victim
Near-Drowning Management
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ABC’s
CPR if needed
IV
Possible sodium bicarbonate
Trauma considerations
 Immersion episode of unknown etiology warrants trauma
management
Post-resuscitation complications
 ARDS or renal failure often occur post-resuscitation
 Symptoms may not appear for 24 hours or more postresuscitation
All near-drowning patients should be transported for
evaluation
Diving Emergencies
 Medical emergencies unique to pressure-related
diving include those caused by:
 Mechanical effects of barotrauma
 Air embolism
 Decompression sickness and nitrogen narcosis
Mechanical Effects of
Pressure
 Water is denser than air
 Pressure changes are greater underwater (even
shallow depths)
 Gas-filled organs are directly affected by
changes
 Every 33 feet of water adds one atmosphere of
pressure (14 psi)
Atmosphere
mmHg
Volume
1
760
1 volume
2
1520 (2 X)
½ volume
3
2280 (3 X)
⅓ volume
4
3050 (4 X)
¼ volume
Mechanical Effects of
Pressure
 Basic properties of gases
 Increased pressure dissolves gases into
blood, oxygen metabolizes; nitrogen
dissolves
 Boyle's Law
 Charles’ Law
 Dalton's Law
 Henry's Law
Boyle’s Law
 The volume of a gas is inversely proportional to its
pressure.
 If the pressure is increased the volume will decrease
 May be written in the form of an expression: P1V1=P2V2
 Pressures in ventilation
 Atmospheric pressure
 Intra-alveolar (intrapulmonary) pressure
 Intra-pleural pressure
Charles’ Law
Volume is directly proportional to the
temperature as long as the pressure is
constant
So as air is heat within the respiratory
system it will expand
Dalton’s Law of Partial Pressures
Dalton surmises that the total
partial pressure of a gas (if
its mixture) is the sum of all
the partial pressures of its
components
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pTotal=pgas1+pgas2+pgas3+pgas4
p(air) = p(N2) + p(O2) + p(CO2) + ...
760 mmHg = 592.8 mmHg + 159.6 mmHg + 0.2 mmHg + ...
100 % = 76 % + 21 % + 0.03 % + …
Henry’s Law
The concentration of a gas in a solution
depends on the partial pressure of the gas
and its solubility (as long as the
temperature stays constant)
The higher the solubility, the more gas will
dissolve
The higher the pressure the more gas will
dissolve
Barotrauma
 Tissue damage caused by compression or
expansion of gas spaces
 Can occur with in a descent or a ascent
 Most common diving emergency
Barotrauma of descent
 Aka "squeeze"
 Compressed gas in enclosed spaces causes
vacuum effect
 Can occur in:
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Ears (Most common)
Sinuses
Lungs and airway
GI tract
Thorax
Teeth (decay or recent extractions)
Added spaces (Mask and diving suit)
S / S of squeeze
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Pain
Sensation of fullness
Headache
Disorientation
Vertigo
Nausea
Bleeding from the nose or ears
Management of squeeze
 Begins with gradual ascent to shallower depths
 Prehospital care primarily revolves around
management of findings and transport in reverse
Trendelenburg
 Definitive care may include
 bed rest with the head elevated
 avoidance of strain and strenuous activity
 use of decongestants and possibly antihistamines and
antibiotics
 surgical repair possibly required
Barotrauma of ascent
 Aka "reverse squeeze”
 The reverse process
 Assume pressures were equalized with a
slow descent
 As the diver ascends pressure decreases
causing volume to increase
 If air is not allowed to escape because of
obstruction the expanding gases distend the
tissues surrounding them
Reverse squeeze ( cont’d )
 Common causes include
 Holding breath
 Mucous plug
 Brochospasm (Panic)
 Last 6 feet are the most dangerous
Reverse squeeze ( cont’d )
 May result in Pulmonary Over
Pressurization Syndrome (POPS)
 This may cause alveolar rupture or
movement of air into other locations
S / S of POPS
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Gradually increasing chest pain
Hoarseness
Neck fullness
Dyspnea
Dysphagia
Subcutaneous emphysema
Complications of POPS
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Pneumomediastinum
Subcutaneous emphysema
Pneumopericardium
Pneumothorax
Pneumoperitoneum
Systemic arterial air embolism
Management of reverse
squeeze
 Oxygen administration
 Hyperbaric chamber if emboli present
 Reevaluate q 5 for changes
 Transport
Air Embolism
 The most serious complication of pulmonary
barotrauma
 Results as expanding air disrupts tissues and air
is forced into the circulatory system
 The emboli become lodged in small arterioles,
occluding distal circulation
 More likely to occur with a rapid ascent or holding
breath
 Leading cause of death and disability of sport
divers
S / S Air Embolism
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Focal paralysis (stroke-like symptoms)
Aphasia
Confusion
Blindness or other visual disturbances
Convulsions
Loss of consciousness
Dizziness
Vertigo
Abdominal pain
Cardiac arrest
Management of Air Embolism
 Unchanged regardless of color of tag
 Rapid transport for recompression
treatment
 Assess for S/S of POPS
 Should be transported in a LLR position
with a 15-degree elevation of the thorax
Decompression Sickness
 AKA the bends, dysbarism, caisson disease,
and diver's paralysis
 Nitrogen in compressed air is dissolved
into tissues and blood from the increase
in its partial pressure at depth
 DS is a multi-system disorder that results
when nitrogen in compressed air converts
back from solution to gas, forming bubbles
in the tissues and blood
Decompression Sickness
 Occurs with a rapid ascent and ambient
pressure decreases
 Equilibrium between the dissolved nitrogen
in tissue and blood and the partial pressure
of nitrogen in the inspired gas cannot be
established
Decompression Sickness
 The most significant mechanical effect of
bubbles is vascular occlusion, which impairs
arterial venous flow
 Since bubbles can form in any tissue,
lymphedema, cellular distention, and
cellular rupture also can occur
 The net effect of all these processes is
poor tissue perfusion and ischemia
 The joints and the spinal cord are the
areas most often affected
S / S Decompression Sickness
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SOB
Itch, rash
Joint pain
Crepitus
Fatigue
Vertigo
Paresthesias
Paralysis
Seizures
Unconsciousness
Management of
Decompression Sickness
 Should be suspected in any patient
who has symptoms within 12 to 36
hours after a scuba dive that cannot
adequately be explained by other
conditions
 Support of vital functions
 Oxygen administration
 Rapid transport for recompression
Nitrogen Narcosis
“Rapture of the deep”
 A condition in which nitrogen becomes
dissolved in solution as a result of greaterthan-normal atmospheric pressure
 Produces neurodepressant effects similar to
those of alcohol and may impair the diver's
judgment and discrimination
Nitrogen Narcosis
Signs and Symptoms
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Impaired judgment
Sensation of alcohol intoxication
Slowed motor response
Loss of proprioception
Euphoria
Nitrogen Narcosis
 Symptoms of nitrogen narcosis usually
become evident at depths between 75 and
100 feet
 300 feet and over with standard air will cause
unconsciousness
 Affects all divers but can be tolerated by
experienced divers
 Helium-oxygen mixtures are used to improve the
nitrogen complication for deep dives
 The syndrome is a common precipitating factor
in diving accidents and may be responsible for
memory loss at depth about events
Diving Injuries
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Depth of dive?
Bottom time?
Rapid or controlled ascent?
# of dives that day?
Fresh or salt water?
C-Spine?
Blood in mask from eyes, ears or nose?
Hx?
Amount of psi left in diver’s tank?
Was diver trained and/or experienced?
Recreation or commercial dive?
Gas mixtures?
High-Altitude Illness
 Principally occurs at altitudes of 8000 feet
or more above sea level
 Caused by reduced atmospheric
pressure, resulting in hypobaric hypoxia
 Activities associated with these
syndromes include:
 Mountain climbing
 Aircraft or glider flight
 Hot-air balloons
 Low-pressure or vacuum chambers
High-Altitude Illness
 Some Types
 Acute Mountain Sickness
 High Altitude Pulmonary Edema
 High Altitude Cerebral Edema
Acute Mountain Sickness
(AMS)
 A common high-altitude illness that results
from rapid ascent of an unacclimatized
person to high altitudes
 Usually develops within 4 to 6 hours of
reaching high altitude
 Attains maximal severity within 24 to 48
hours
 Ceases in 3-4 days with gradual
acclimatization
S / S AMS
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Headache (most common symptom)
Malaise
Anorexia
Vomiting
Dizziness
Irritability
Impaired memory
DOE ( Dyspnea on exertion )
S / S AMS ( cont’d )
 Tachycardia or bradycardia
 Postural hypotension
 Ataxia
 the most useful sign for recognizing
the progression of the illness
 May see coma within 24 hours of
ataxia onset
Management of AMS
 Oxygen administration
 Descent to lower altitude
 Should see physician
High-Altitude Pulmonary
Edema (HAPE)
 Caused by increased pulmonary artery pressure
that develops in response to hypoxia
 Results in:
 Increase pulmonary arteriolar permeability
 Leakage of fluid into extravascular locations
 Initial symptoms usually begin 24 to 72 hours
after exposure to high altitudes and are often
preceded by strenuous exercise
S / S HAPE
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Dyspnea, cyanosis
Cough (with or without frothy sputum)
Generalized weakness
Lethargy
Disorientation
Tachypnea
Crackles, rhonchi
Tachycardia
Management of HAPE
 Oxygen administration to increase arterial
oxygenation and reduce pulmonary artery
pressure
 Descent to lower altitude
 Should be seen by physician
 May require hospitalization for
observation
High-Altitude Cerebral Edema
(HACE)
 Most severe form of acute high-altitude illness
 A progression of global cerebral signs in the
presence of AMS
 Related to increased ICP from cerebral edema
and swelling
 Progression from mild AMS to unconsciousness
associated with HACE may be as fast as 12
hours but usually requires 1 to 3 days of
exposure to high altitudes
S / S HACE
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Headache
Ataxia
Altered consciousness
Confusion
Hallucinations
Drowsiness
Stupor
Coma
Management of HACE
 Delay in treatment will result in death
 Airway support
 Circulatory support
 Descent to a lower altitude