Environmental Emergencies Flashcards
heat stroke
life threatening condition characterized by CNS dysfunction and multi-organ derangements
hyperthermia NOT fever
most severe form of heat illness
temperature ranges of hyperthermia
T < 106: heat stroke unlikely
T > 107: cellular dysfunction begins; requires immediate cooling
T > 109: severe organ damage
body protective mechanisms against heat stroke
- thermoregulation
- normal heat dissipation mechanisms
thermoregulation
controlled by the hypothalamus; maintains balance between heat load and heat dissipation
- radiation
- convection
- conduction
- evaporation
what are the main heat dissipation mechanisms in dogs/cats
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
causes of heat stroke
- increased heat load
- decreased dissipation
causes of increased heat load
environmental: non-exertional (temperature)
metabolic/exercise: exertional (occurs w/ exercise or seizures)
causes of decreased heat dissipation
- confinement/poor ventilation
- water deprivation
- upper respiratory abnormalities
- obesity/thick hair coat
- lack of acclimatization
- hypovolmeia/poor CO
- drugs
pathogenesis of heat stroke
heat –>
1. direct cytotoxicity
2. increased immune modulators
3. coagulopathies
–> SIRS –> MODS –> death
clinical signs of heat stroke
affects ALL systems - CNS, GI, coagulation, CV, respiratory, renal, hepatic
- CNS: mentation changes, tremors, ataxia, cortical blindness, seizure
- GI: vomiting, diarrhea, melena
- coagulation: petechiae, ecchymosis, hematuria, bloody vomit/stools
lab values with heat stroke
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
treatment of heat stroke
- cooling - wetting w/ room temperature water + fans
- fluid therapy - treats hypovolemia
- O2 supplementation
- neurologic treatments
- supportive GI care
- coagulation monitoring
at what temperature should you stop active cooling
103F
will continue to drop temperature, want to avoid hypothermia and shivering
prognosis for heat stroke
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
primary hypothermia
“accidental”
caused by excessive exposure to low temperatures
secondary hypothermia
caused by disease, trauma, surgery, drugs, etc that alter heat production and thermoregulation
classification of hypothermia
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
physiologic effects of hypothermia
- decreased BP and CO
- tachycardia progressing to bradycardia
- vasoconstriction progressing to vasodilation
- ECG - ventricular arrhythmias - thrombocytopenia
- hypovolemia (cold diuresis)
- impaired immune function
treatment for hypothermia
mild: passive rewarming
- blankets, insulation to augment patient’s heat and minimize heat loss
moderate/severe: active rewarming
- apply exogenous heat source
complications of rewarming
- rewarming shock: peripheral vasodilation –> relative hypovolemia and hypotension
- core temp afterdrop: cold peripheral blood returns to vital organs and decreases core temp even more
- rewarming acidosis: lactic acid returns to heart from periphery
how to avoid rewarming complications
- apply external heat to trunk
- steady rewarming rate of 2-4 degrees F per hour
- administer fluids
effects of electrocution
- electrical injury
- thermal injury
- +/- mechanical injury
electrical injury
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
thermal injury
transformation of energy into heat
superheated fluids: CNS, GI, and coagulation signs
causes necrosis and ischemic injury of tissues
mechanical injury
“blast effect” as air cools off
can lead to broken bones/traumatic injury
most often occurs with lightning
what factors affect severity of electrocution
- electrical resistance: greatest damage to wet skin/MM
- nature of current: alternating currents are more damaging than direct current
- intensity of current (amperage)
PE findings from electrocution
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
neurogenic pulmonary edema
major CNS insult causes increased sympathetic outflow -> increase in catecholamines –> vasoconstriction and hypertension –> pulmonary edema
resolves in 18-24 hours
electrocution treatment
- O2 supplementation
- antiarrhythmics
- analgesia + wound care
prognosis good if survived the initial shock
drowning
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
clinical effects of drowning
- hypoxemia
- neurologic abnormalities (hypoxic brain injury)
- cardiac arrhythmias/dysfunction
dive reflex
submersion in cold water –> reflex shunting of blood to heart and brain
reduces hypoxemic effects
treatment of drowning
- O2 supplementation
- fluids
- antiarrhythmics
- neurologic exam
prognosis: better with minimal respiratory, neuro, and CV abnormalities
