1. Mike McDonnell, MD

2. HUSAR team gets deployed to the collapse of an office tower in downtown Toronto people are trapped mid August, 30ºC with Humidex feels like 40ºC team member complains of cramps, stops working and drinks, goes back to work later found sitting in corner, staring, mumbling about mummy

3. physiology of heat transfer/cooling heat related illnesses types Treatment on the pile vs. in the pile

4. Supply and Demand relationship Supply (heat production) BMR without cooling, temperature increases 1.1ºC/hr Increases up to 20X with strenuous exercise

5. Demand (heat loss) Conduction warm body to cooler surroundings (2%) Convection heat loss to air and water better with loose clothing, higher wind velocity Radiation electromagnetic waves great in cool temperatures, net gain when warm Evaporation conversion of liquid to gas major factor – non-acclimatized – sweat 1 litre/hour not effective when relative humidity >75%

6. We are like a water cooled car....

7. Spectrum Not so bad, bad, very bad

8. Prickly Heat obstruction of the sweat gland pores, produces vesicles, sometimes ruptures, very itchy can get superinfected/rupture treated with chlorhexidine, antibiotic creams, loose clothing preventative

9. Heat edema nonacclimatized individuals standing for long periods of time affects feet and ankles treated with leg elevation

10. Heat Cramps brief, intermittent, severe cramps in working muscles early on in work in hot environment heavy sweaters with hypotonic fluid replacement more at risk usually after exertion treatment Rapid elevation of salt solutions: ½ tsp salt in quart of water, commercially available solutions taste better

11. Heat Syncope vasodilation and venous pooling from standing reduced circulating blood volume volume loss makes it worse elderly are more susceptible treatment – fix causes/injuries

12. Heat Exhaustion volume depletion under heat stress two types: water and salt depletion water: inadequate fluid replacement salt: hypotonic fluid replacement

13. Signs and Symptoms vague malaise, fatigue, headache core temperature often normal; if elevated, less than 40° C (104° F) mental function essentially intact; no coma or seizures tachycardia, orthostatic hypotension, clinical dehydration (may occur) other major illness ruled out if in doubt, treat as heat stroke

14. rest cool environment assess volume status fluid replacement: normal saline to replete volume if patient orthostatic, replace free water deficits slowly to avoid cerebral edema

15. Heat Stroke Hallmark: alteration in level of consciousness thermoregulation is overwhelmed and fails may be a prodrome, may be like heat exhaustion rapid treatment is essential

16. Diagnosis exposure to heat stress signs of severe CNS dysfunction (coma, seizures, delirium) core temperature usually above 40.5° C (105° F), but may be lower dry, hot skin common, but sweating may persist

17. Classic and exertional ExertionalClassic HealthyMedical problems YoungerOlder ExerciseSedentary SporadicHeat wave occurrence DiaphoresisAnhidrosis Acute renal failureOliguria

18. cooling immediately is key to survival use all methods of heat transfer spraying atomized cool water (evaporation) combined with fans (convection) very effective ice water immersion can be attempted rapid but take out when body temp < 39ºC ice packs/cooling blankets less effective

19. aspiration and seizures are common airway control tachyarrhythmias are common usually resolve with cooling dont over hydrate (IV fluids) – pulmonary edema agitation – benzodiazepines shivering – chlorpromazine, Demerol?