Environmental Emergencies

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Environmental Emergencies
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Environmental Emergencies

• A medical emergency caused by or exacerbated due
  to exposure to environmental, terrain, or
  atmospheric pressure

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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

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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

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Regulating heat production

• Heat is generated through mechanical, chemical,
  metabolic, and endocrine activities
• Mechanical
• Shivering
• Chemically
• Cellular metabolism
• Endocrine
• Hormone release

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Regulating heat production

• Cell metabolism
• Breathing
• Sweating
• Arrector pilli (piloerection)
• ? HR
• Shunting of blood
• Dilation/constriction of blood vessels
• Core shunting

• Muscle movement
• Fluid intake
• ? food intake
• Sleep
• ADH release
• ? urination
• Catecholamine release

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Regulating heat loss

• Heat is naturally lost through
• Radiation
• Convection
• Conduction
• Evaporation

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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)

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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

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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

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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 winds 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)

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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

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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

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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

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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 flash-freezing of tissues
  inside the mouth
• If the back of the throat and the esophagus
  become frozen this way, the resulting injury is
  often lethal

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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

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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

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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

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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

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Cold / aquatic emergencies

• Localized cold injuries
• Hypothermia
• Hyperthermia
• Drowning
• Diving Emergencies

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Localized cold Injuries
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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

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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

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Frostbite

• A localized injury that results from
  environmentally induced freezing of body tissues
• Pathophysiology
• Ice tissues form
• Vascular abnormalities occur
• Cellular injury caused
• Increased sensitivity to reoccurrence

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Frostbite

• Predisposing factors
• Peripheral neuropathies
• PVD
• Alcohol / tobacco use
• Inadequate protection
• Nutritional deficiencies
• Medication administration
• PmHx frostbite
• Injury / illness / fatigue

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Superficial Frostbite

• Some freezing of dermal tissue
• Initial redness followed by blanching
• Diminished tactile sensation
• Pain

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Deep Frostbite

• Freezing of dermal and subcutaneous layers
• White appearance
• Hard (frozen) to palpation
• Loss of sensation
• Management ?

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Frostbite

• Edema and blister formation 24 hours after
  frostbite injury in area covered by tightly
  fitted boot.

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Deep Frostbite

• Gangrenous necrosis 6 weeks after frostbite injury

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Hypothermia
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Hypothermia

• Is defined as a core temperature less than 35C
  (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

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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.

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Predisposing Factors

• Age
• Medical conditions
• Prescription and over-the-counter medications
• Alcohol or recreational drugs
• Previous rate of exertion

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Environmental Factors

• External environmental factors that may
  contribute to a medical emergency
• Climate
• Season
• Weather
• Atmospheric pressure
• Terrain

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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)

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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

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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

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Clinical Features

• Severe (below 30º C) - ( Im 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

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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, PVCs, VFib,
  Asystole

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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

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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

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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

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Stages of Hypothermia

• Shivering
• Apathy or Decreased Muscle Function
• Decreased Level of Consciousness
• Decreased Vital Signs
• Death

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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

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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

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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

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Immersion Hypothermia

• Hyperventilation causes alkalosis
• Alkalosis increases the bloods pH
• Physiologic responses to alkalosis causes
  cerebral hypoxia
• Syncope increases the risk of drowning

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Immersion Hypothermia

• In 15C (60F) 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

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Mammalian Diving Reflex

• Cold water ( lt 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

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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

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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 10C (50F) water

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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

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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 (50F (10C)) water

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Immersion Hypothermia
Water Temperature Water Temperature Cooling Rate
ºF ºC ºC/hr
68 20 0.5
59 15 1.5
50 10 2.5
41 5 4.0
32 0 6.0
Non-exercising adults, light clothing, wearing
PFDs
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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 50F (10C) water on a calm day
• People who tread water lose heat about 30 faster
  than people holding still while wearing a PFD

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Systemic Heat Related Illness
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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

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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

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Heat Illness

• Heat Illness can be described by three basic
  forms
• Heat Cramps
• Heat Exhaustion
• Heat Stroke
• Classic
• Exertional

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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 )

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Heat Cramps

• Signs and Symptoms
• A/O X3
• Hot Sweaty Skin
• Tachycardia
• Normotensive
• Normal Body Core Temp (BCT)

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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

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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

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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

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Treatment of Heat Exhaustion

• Remove Pt from environment
• Remove excess clothing
• Replace salt and water if conscious
• Oxygen (100 NRB)
• Begin Cooling (Slowly)
• IV N/S

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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

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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

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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

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S / S Heat Stroke

• 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

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Treatment of Heat Stroke

• Primary Survey and ABCs
• Early recognition important
• Move pt to cool environment
• Remove excessive clothing
• Begin cooling
• Watch for rebound hypothermia
• IV access
• May require fluid challenge

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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

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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

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Progression of a drowning incident.
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Salt Water

• Hypertonic
• Causes rapid shift of plasma and fluid into the
  alveoli and interstitial spaces
• Causes
• Pulmonary Edema
• Poor Ventilatory ability
• Hypoxia

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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

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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

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Factors That Affect Clinical Outcome

• Temperature of the water
• Length of submersion
• Cleanliness of the water
• Age of the victim

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Near-Drowning Management

• ABCs
• 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
  post-resuscitation
• All near-drowning patients should be transported
  for evaluation

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Diving Emergencies

• Medical emergencies unique to pressure-related
  diving include those caused by
• Mechanical effects of barotrauma
• Air embolism
• Decompression sickness and nitrogen narcosis

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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) ? volume
4 3050 (4 X) ¼ volume
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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

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Boyles 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
  P1V1P2V2
• Pressures in ventilation
• Atmospheric pressure
• Intra-alveolar (intrapulmonary) pressure
• Intra-pleural pressure

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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

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Daltons 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

• pTotalpgas1pgas2pgas3pgas4
• p(air) p(N2) p(O2) p(CO2) ...
• 760 mmHg 592.8 mmHg 159.6 mmHg 0.2 mmHg
  ...
• 100 76 21 0.03

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Henrys 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

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Barotrauma

• Tissue damage caused by compression or expansion
  of gas spaces
• Can occur with in a descent or a ascent
• Most common diving emergency

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Barotrauma of descent

• Aka "squeeze"
• Compressed gas in enclosed spaces causes vacuum
  effect
• Can occur in
• Ears (Most common)
• Sinuses
• Lungs and airway
• GI tract
• Thorax
• Teeth (decay or recent extractions)
• Added spaces (Mask and diving suit)

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S / S of squeeze

• Pain
• Sensation of fullness
• Headache
• Disorientation
• Vertigo
• Nausea
• Bleeding from the nose or ears

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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

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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

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Reverse squeeze ( contd )

• Common causes include
• Holding breath
• Mucous plug
• Brochospasm (Panic)
• Last 6 feet are the most dangerous

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Reverse squeeze ( contd )

• May result in Pulmonary Over Pressurization
  Syndrome (POPS)
• This may cause alveolar rupture or movement of
  air into other locations

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S / S of POPS

• Gradually increasing chest pain
• Hoarseness
• Neck fullness
• Dyspnea
• Dysphagia
• Subcutaneous emphysema

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Complications of POPS

• Pneumomediastinum
• Subcutaneous emphysema
• Pneumopericardium
• Pneumothorax
• Pneumoperitoneum
• Systemic arterial air embolism

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Management of reverse squeeze

• Oxygen administration
• Hyperbaric chamber if emboli present
• Reevaluate q 5 for changes
• Transport

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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

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S / S Air Embolism

• Focal paralysis (stroke-like symptoms)
• Aphasia
• Confusion
• Blindness or other visual disturbances
• Convulsions
• Loss of consciousness
• Dizziness
• Vertigo
• Abdominal pain
• Cardiac arrest

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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

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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

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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

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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

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S / S Decompression Sickness

• SOB
• Itch, rash
• Joint pain
• Crepitus
• Fatigue
• Vertigo
• Paresthesias
• Paralysis
• Seizures
• Unconsciousness

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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

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Nitrogen Narcosis

• Rapture of the deep
• A condition in which nitrogen becomes dissolved
  in solution as a result of greater-than-normal
  atmospheric pressure
• Produces neurodepressant effects similar to those
  of alcohol and may impair the diver's judgment
  and discrimination

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Nitrogen Narcosis

• Signs and Symptoms
• Impaired judgment
• Sensation of alcohol intoxication
• Slowed motor response
• Loss of proprioception
• Euphoria

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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

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Diving Injuries

• 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 divers tank?
• Was diver trained and/or experienced?
• Recreation or commercial dive?
• Gas mixtures?

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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

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High-Altitude Illness

• Some Types
• Acute Mountain Sickness
• High Altitude Pulmonary Edema
• High Altitude Cerebral Edema

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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

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S / S AMS

• Headache (most common symptom)
• Malaise
• Anorexia
• Vomiting
• Dizziness
• Irritability
• Impaired memory
• DOE ( Dyspnea on exertion )

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S / S AMS ( contd )

• 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

118
Management of AMS

• Oxygen administration
• Descent to lower altitude
• Should see physician

119
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

120
S / S HAPE

• Dyspnea, cyanosis
• Cough (with or without frothy sputum)
• Generalized weakness
• Lethargy
• Disorientation
• Tachypnea
• Crackles, rhonchi
• Tachycardia

121
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

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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

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S / S HACE

• Headache
• Ataxia
• Altered consciousness
• Confusion
• Hallucinations
• Drowsiness
• Stupor
• Coma

124
Management of HACE

• Delay in treatment will result in death
• Airway support
• Circulatory support
• Descent to a lower altitude