Heatstroke

Question 1

At what humdity percentage does evaporation start to be less effective and when does it stop working?

Answer 1

over 35%
over 85%

Question 2

What is the major cause for CNS derangements in heatstroke, secondary or primary heat injury?

Answer 2

secondary e.g., decreased perfusion, hemorrhage, cerebral edema and ischemia from microthrombi, hypoglycemia, acid base derangements, MODS

canine brains actually fairly heat resistant to direct thermal injury and CNS signs only midly caused by direct heat injury

Question 3

List 3 biomarkers indicating early AKI from heatstroke?

Answer 3

• urinary NGAL
• urinary retinol-binding protein
• CRP - C-reactive protein

Question 4

List causes for myocardial injury in heatstroke

Answer 4

• ischemia
• lactic acidosis
• hypoxemia
• electrolyte imbalance
• direct thermal injury
• DIC (hemorrhage and hyperemia found on necropsy)

Question 5

Describe the stages of changes to the intestinal perfusion during heatstroke

Answer 5

Initiatially:
* splanchnic vasoconstriction to redistribute blood from center to periphery –> peripheral vasodilation and hopefully heat dissipation
* casues ischemia
* increases risk of intestinal hyperthermia

Then
* excessive NO production
* uncontrolled splanchnic dilation followed by vascular collapse of patients

Question 6

Does CK elevation correlate with survival?

Answer 6

No

Question 7

List and describe the 2 biomarkers that may be predictive of outcome in heatstroke

Answer 7

Heatshock protein eHSP72
* heatshock proteins - molecular cytoprotective mechanisms&raquo_space; protect cells from excessive heat, hypoxia, inflammation, and IRI
* eHSP72 is the most sensitive one to measure
* reduction/recovery of eHSP72 cc at 24 hours consistent with favorable outcome

Histones
* protein - basic structure of chromatin in DNA
* core and linker histones
* leak from damaged and activated cells
* suspected to worsen inflammation, induce coagulation and toxicity
* elevated presentation histone cc association with nonsurvival

Question 8

What is the most recent definition of heatstroke?

Answer 8

hyperthermia associated with systemic inflammatory response leading to syndrome of multiple organ dysfunction and where encephalopathy predominates

previously: Hyperthermia with CNS disturbance

Question 9

By what mechanisms can people develop heat acclimatization and how long does it take?

Answer 9

2 weeks or longer

• increased cardiac performance
• RAAS system activation
• increased sweat capacity
• plasma volume expansion
• increased GFR
• increased resistance to exertional
• rhabdomyolysis

important : HSP72 increase

Question 10

What nRBC cutoff is indicative of high likelihood of death?

Answer 10

18 or more / HPF

Question 11

What is the presumed benefit of extracorporeal therapy in heatstroke?

Answer 11

• reduction of inflammatory cytokines
• need filter with binding range of 10-55 kDa