Environmental Emergencies

Question 1

heat stroke

Answer 1

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

hyperthermia NOT fever
most severe form of heat illness

Question 2

temperature ranges of hyperthermia

Answer 2

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

Question 3

body protective mechanisms against heat stroke

Answer 3

1. thermoregulation
2. normal heat dissipation mechanisms

Question 4

thermoregulation

Answer 4

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

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

Question 5

what are the main heat dissipation mechanisms in dogs/cats

Answer 5

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

Question 6

causes of heat stroke

Answer 6

1. increased heat load
2. decreased dissipation

Question 7

causes of increased heat load

Answer 7

environmental: non-exertional (temperature)

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

Question 8

causes of decreased heat dissipation

Answer 8

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

Question 9

pathogenesis of heat stroke

Answer 9

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

Question 10

clinical signs of heat stroke

Answer 10

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

Question 11

lab values with heat stroke

Answer 11

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

Question 12

treatment of heat stroke

Answer 12

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

Question 13

at what temperature should you stop active cooling

Answer 13

103F

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

Question 14

prognosis for heat stroke

Answer 14

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

Question 15

primary hypothermia

Answer 15

“accidental”

caused by excessive exposure to low temperatures

Question 16

secondary hypothermia

Answer 16

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

Question 17

classification of hypothermia

Answer 17

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

Question 18

physiologic effects of hypothermia

Answer 18

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

Question 19

treatment for hypothermia

Answer 19

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

moderate/severe: active rewarming
- apply exogenous heat source

Question 20

complications of rewarming

Answer 20

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

Question 21

how to avoid rewarming complications

Answer 21

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

Question 22

effects of electrocution

Answer 22

1. electrical injury
2. thermal injury
3. +/- mechanical injury

Question 23

electrical injury

Answer 23

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

Question 24

thermal injury

Answer 24

transformation of energy into heat

superheated fluids: CNS, GI, and coagulation signs

causes necrosis and ischemic injury of tissues

Question 25

mechanical injury

Answer 25

"blast effect" as air cools off can lead to broken bones/traumatic injury most often occurs with lightning

Question 26

what factors affect severity of electrocution

Answer 26

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)

Question 27

PE findings from electrocution

Answer 27

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

Question 28

neurogenic pulmonary edema

Answer 28

major CNS insult causes increased sympathetic outflow -> increase in catecholamines --> vasoconstriction and hypertension --> pulmonary edema resolves in 18-24 hours

Question 29

electrocution treatment

Answer 29

1. O2 supplementation 2. antiarrhythmics 3. analgesia + wound care prognosis good if survived the initial shock

Question 30

drowning

Answer 30

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

Question 31

clinical effects of drowning

Answer 31

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

Question 32

dive reflex

Answer 32

submersion in cold water --> reflex shunting of blood to heart and brain reduces hypoxemic effects

Question 33

treatment of drowning

Answer 33

1. O2 supplementation 2. fluids 3. antiarrhythmics 4. neurologic exam prognosis: better with minimal respiratory, neuro, and CV abnormalities