Heat Stroke

Question 1

What is heat stroke? When does this most commonly happen?

Answer 1

body’s ability to dissipate heat is exceeded by the heat load placed upon it –> hyperthermia

high external temperatures reduce dissipation from conduction, convection, and radiation and/or high humidity reduces effectiveness of evaporation

Question 2

What 3 things does heat stroke lead to? What cascade follows?

Answer 2

1. protein denaturation
2. apoptosis
3. activation of heat shock proteins

cardiovascular collapse –> hypercoagulability –> pro-inflammatory state (SIRS) –> thermal cellular injury and dysfunction

Question 3

What is the proposed critical temperature associated with heat stroke?

Answer 3

106 F

• negligible importance because at presentation you cannot know how high the patient’s temperature was or how long it was raised

Question 4

What animals are predisposed to developing heat stroke?

Answer 4

• obese dogs
• dogs with cardiovascular or respiratory disease (brachycephalics)

Question 5

How can heat stroke be avoided in predisposed dogs?

Answer 5

• avoid hot, humid, and poorly ventilated environments
• have water, cool surfaces, and shaded areas available

Question 6

What 4 clinical signs are associated with heat stroke?

Answer 6

1. incessant panting
2. staggering
3. collapse
4. altered mentation

Question 7

What is the first step in emergency treatment of heat stroke? What 2 options?

Answer 7

emergency cooling

1. soaking fur with tepid water and fanning - to avoid peripheral vasoconstriction, cooling efforts should be stoped at 103F
2. cool or room temp fluids

(ice packs to groin, axilla, and head/neck, immersion in cold water, cold saline enemas/lavages, and alcohol baths can be dangerous)

Question 8

After the patient is cooled, what emergency measure should be performed?

Answer 8

ABCs of emergency treatment

• Airway - ensure an adequate airway is allowing minimal work of breathing and adequate heat dissipation
• Breathing - oxygen supplementation (flow by, still allowing panting), ventilation for patients at risk of respiratory failure
• Circulation - place 1-2 large-bore catheters for administration of crystalloids/colloids at rapid infusion rates

Question 9

What secondary disability can result from heat stroke? Why? How is it prevented?

Answer 9

neurologic disability

hypoglycemia, increased intracranial pressure, seizures

Dextrose, Mannitol, Diazepam

Question 10

What 3 systems should be monitored when treating a patient with heat stroke?

Answer 10

1. COAGULATION - petechiae, bleeding, thrombocytopenia, coagulopathy
2. RENAL - electrolytes, BUN/CREAT, acid-base status, bladder size, urine output, specific gravity, urine color
3. GI - vomiting, (bloody) diarrhea

Question 11

How are the 3 systems affected by heat stroke treated?

Answer 11

1. COAGULATION - plasma, transfusion
2. RENAL - mannitol, furosemide, hemodialysis, urine alkalinization to a pH of 8 to prevent myoglobin precipitation in cases of rhabdomyolysis
3. GI - replace volume loss with IV fluids, protectants (Famotidine, Sucralfate), antibiotics with compromise