Heat Stroke: Recognition and Treatment

1. Heat Stroke:Recognition and Treatment Rodney S. Gonzalez, MD MAJ, MC, USA

2. Case 1 • 25yo AD male Ranger Student (28Jul08) • Arrived Ft. Drum, NY three days prior • Day 0 – Fitness Test • 4 mile mark noted to be fatigue and dizzy • Individual sought cadre care • Medic did rectal temp: 105.7 • Brought to Aid Station: • AAO x3 • Rectal Temp: 106.1

3. Case 2 • 23yo AD male Ranger Student (28Jul08) • Completed Infantry Officer training at Ft. Benning,GA • Day 0 – Fitness Test • 5 mile completed • Individual noted to be walking aimlessly • No colapse • Medic did rectal temp: 105.8 • Brought to Aid Station: • Confused; did not know name or location • Rectal Temp: 106.4

4. Heat stress is cumulative over the days preceding the injury H – Heat Category past 2 days E – Exertion Level past 2 days A – Acclimatization/Individual risk factors T – Temperature/Rest overnight Cluster of heat injuries on prior 2 days = HIGH RISK Note: 40% of heat injuries may occur under “green flag” conditions. This is probably due to previous days’ heat, work load and dehydration.

5. Heat Stroke • No temperature requirement • However usually (104-106 minimum) • Skin hot and flushed, usually dry • May be moist with exertional • Headache, dizziness • Nausea, diarrhea • Visual disturbances • Confusion, convulsions, coma • Initially respiratory alkalosis followed by a metabolic acidosis TBMED507, 2003 Bouchama & Knochel NEJM 2002

6. Acute CNS Manifestations • Hyperthermia-> Increased CNS metabolism • Increased cerebral vasoconstriction • Cerebellum most affected- Ataxia, Dysarthria, Dysmetria • AMNESIA • LOC, disorientated, combative

7. Prehospital Care • RAPID cooling is single most important intervention • Rest • Oral hydration • ???IV???

8. Soldier has suspected heat illness (dizziness, headache, dry mouth, nausea, weakness, muscle cramps) Are there? Mental status changes? OR Vomits 2x or more? OR Unconsciousness > 1 minute? OR Rectal temperature >104º F (Medic or EMT task)? NO YES TREAT: Stop, Cool • Loosen clothing • Place Soldier in shade or cool area • Provide fluids by mouth – 1 qt/30 Min min X 2 • Give salty snack • EVACUATE: Stop, Cool, Call • Place Soldier flat with legs elevated in cool area • Strip clothing • Apply iced sheets, soak, & fan Soldier • Evaluate Soldier: • Too much water, urine output, vomiting? Give salty snack. • Poor water, urine output? Sip cool electrolyte drink. Never force water. • IF evacuation delayed >10 min, only one 500 cc IV Normal Saline (IV preferably chilled in ice water). • Stop cooling if shivering or rectal temp is 100 F. (Medic or EMT task) • Reconfirm core temperature when evacuation arrives (EMT or Medic task) Soldier gets worse or does not improve in 30 minutes? YES Evacuate NO • Limited indoor duty for remainder of day • Medical evaluation within 24 hours

9. Exertional Heat Stroke • Laboratory “Heat Panel” • BMP, Ca, Mg, PO4, LFTs, CK, LDH, (+/-)Uric Acid, CBC, PT/PTT, U/A, Umyoglobin • Admit to Hospital for monitoring • Follow labs every 4-8 hours • Heat Stroke Profile upon discharge