Environmental Emergencies Flashcards

1
Q

heat stroke

A

life threatening condition characterized by CNS dysfunction and multi-organ derangements

hyperthermia NOT fever
most severe form of heat illness

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2
Q

temperature ranges of hyperthermia

A

T < 106: heat stroke unlikely
T > 107: cellular dysfunction begins; requires immediate cooling
T > 109: severe organ damage

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3
Q

body protective mechanisms against heat stroke

A
  1. thermoregulation
  2. normal heat dissipation mechanisms
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4
Q

thermoregulation

A

controlled by the hypothalamus; maintains balance between heat load and heat dissipation

  1. radiation
  2. convection
  3. conduction
  4. evaporation
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5
Q

what are the main heat dissipation mechanisms in dogs/cats

A

radiation and convection
- radiation: heat exchange between objects in environment
- convection: movement of fluid or air over surface of body

evaporation occurs with panting when temperatures start to rise

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6
Q

causes of heat stroke

A
  1. increased heat load
  2. decreased dissipation
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7
Q

causes of increased heat load

A

environmental: non-exertional (temperature)

metabolic/exercise: exertional (occurs w/ exercise or seizures)

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8
Q

causes of decreased heat dissipation

A
  • confinement/poor ventilation
  • water deprivation
  • upper respiratory abnormalities
  • obesity/thick hair coat
  • lack of acclimatization
  • hypovolmeia/poor CO
  • drugs
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9
Q

pathogenesis of heat stroke

A

heat –>
1. direct cytotoxicity
2. increased immune modulators
3. coagulopathies
–> SIRS –> MODS –> death

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10
Q

clinical signs of heat stroke

A

affects ALL systems - CNS, GI, coagulation, CV, respiratory, renal, hepatic

  1. CNS: mentation changes, tremors, ataxia, cortical blindness, seizure
  2. GI: vomiting, diarrhea, melena
  3. coagulation: petechiae, ecchymosis, hematuria, bloody vomit/stools
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11
Q

lab values with heat stroke

A

CBC: hemoconcentration, high nRBCs, low platelets
chem: hypoglycemia, azotemia, high liver enzymes and bilirubin, low cholesterol and CCK
UA: glucosuria, casts
coag: prolonged PT/PTT, ACT
blood gas: lactic acidosis, hypoxemia

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12
Q

treatment of heat stroke

A
  1. cooling - wetting w/ room temperature water + fans
  2. fluid therapy - treats hypovolemia
  3. O2 supplementation
  4. neurologic treatments
  5. supportive GI care
  6. coagulation monitoring
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13
Q

at what temperature should you stop active cooling

A

103F

will continue to drop temperature, want to avoid hypothermia and shivering

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14
Q

prognosis for heat stroke

A

depends on the degree and duration of hyperthermia

dogs: up to 50%; guarded if onset of SIRS or severe CNS signs
RARELY occurs in cats

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15
Q

primary hypothermia

A

“accidental”

caused by excessive exposure to low temperatures

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16
Q

secondary hypothermia

A

caused by disease, trauma, surgery, drugs, etc that alter heat production and thermoregulation

17
Q

classification of hypothermia

A

mild: 90-99.5
- shivering, heat seeking, ataxia, vasoconstriction

moderate: 82-90
- altered mentation, hypotension, +/- shivering

severe: <82
- loss of shivering, cardiac arrhythmias, severe mentation abnormalities

18
Q

physiologic effects of hypothermia

A
  1. decreased BP and CO
    - tachycardia progressing to bradycardia
    - vasoconstriction progressing to vasodilation
    - ECG - ventricular arrhythmias
  2. thrombocytopenia
  3. hypovolemia (cold diuresis)
  4. impaired immune function
19
Q

treatment for hypothermia

A

mild: passive rewarming
- blankets, insulation to augment patient’s heat and minimize heat loss

moderate/severe: active rewarming
- apply exogenous heat source

20
Q

complications of rewarming

A
  1. rewarming shock: peripheral vasodilation –> relative hypovolemia and hypotension
  2. core temp afterdrop: cold peripheral blood returns to vital organs and decreases core temp even more
  3. rewarming acidosis: lactic acid returns to heart from periphery
21
Q

how to avoid rewarming complications

A
  • apply external heat to trunk
  • steady rewarming rate of 2-4 degrees F per hour
  • administer fluids
22
Q

effects of electrocution

A
  1. electrical injury
  2. thermal injury
  3. +/- mechanical injury
23
Q

electrical injury

A

direct effects of electrical current

disrupts the normal electrophysiologic activity in the body via electroporation (temporary holes in membranes –> osmotic damage)

  • muscle spams
  • cardiac arrhythmias
  • loss of consciousness
  • respiratory arrest
24
Q

thermal injury

A

transformation of energy into heat

superheated fluids: CNS, GI, and coagulation signs

causes necrosis and ischemic injury of tissues

25
Q

mechanical injury

A

“blast effect” as air cools off

can lead to broken bones/traumatic injury

most often occurs with lightning

26
Q

what factors affect severity of electrocution

A
  1. electrical resistance: greatest damage to wet skin/MM
  2. nature of current: alternating currents are more damaging than direct current
  3. intensity of current (amperage)
27
Q

PE findings from electrocution

A

Skin/MM: surface burns, oral trauma, tissue necrosis
CV: ventricular arrhythmias, death from Vfib/asystole
Resp: neurogenic pulmonary edema, respiratory arrest, cough, cyanosis, crackles
neuro: unconsciousness, focal muscle tremors, seizures, extensor rigidity, tetany
ocular: cataracts

28
Q

neurogenic pulmonary edema

A

major CNS insult causes increased sympathetic outflow -> increase in catecholamines –> vasoconstriction and hypertension –> pulmonary edema

resolves in 18-24 hours

29
Q

electrocution treatment

A
  1. O2 supplementation
  2. antiarrhythmics
  3. analgesia + wound care

prognosis good if survived the initial shock

30
Q

drowning

A

process resulting in primary respiratory impairment from submerson/immersion in a liquid medium

majority are WET - inhaled water into lungs

can be dry - intense laryngospasms from holding breath

31
Q

clinical effects of drowning

A
  1. hypoxemia
  2. neurologic abnormalities (hypoxic brain injury)
  3. cardiac arrhythmias/dysfunction
32
Q

dive reflex

A

submersion in cold water –> reflex shunting of blood to heart and brain

reduces hypoxemic effects

33
Q

treatment of drowning

A
  1. O2 supplementation
  2. fluids
  3. antiarrhythmics
  4. neurologic exam

prognosis: better with minimal respiratory, neuro, and CV abnormalities