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Heat Injuries Management and Prevention for the Royal Thai Army. Surajit Su ntorntham , MD FRCPT Division of Toxic ology Department of Medicine PhraMongkutklao Army Hospital and College of Medicine. A 21 yr M, Private, BKK.
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Heat Injuries Management and Prevention for the Royal Thai Army Surajit Suntorntham, MD FRCPT Division of Toxicology Department of Medicine PhraMongkutklao Army Hospital and College of Medicine
A 21 yr M, Private, BKK CC: Febrile, lost consciousness with generalized seizure ½ hr before admission PI: -Worked as a waiter prior to entering the training base, no history of regular exercise previously -Apparently well, started basic training 3 days ago -After evening exercise, found falling a sleep, unawakened and febrile and shortly later developed generalized seizure -First aid with aggressive tepid sponge then the patient was transported to PMK Army Hospital
The 21 yr Male SoldierUnconscious, Febrile, Seizureshortly after Basic Training At ER • BP 70/50 P 120 T 42oC, RR 30/min Dyspnea, comatosed, generalized seizure all the time • peticheae hemorrhage on forehead
The 21 yr Male SoldierUnconscious, Febrile, Seizure, Shock, Dyspnea, Hemostatic Disordershortly after Basic Training What are the differential diagnosis? • Exertional heat stroke (EHS) • Severe infection(Malaria, ricketsia, leptospirosis, DHF, meningococcemia, gm-ve sepsis…etc) • Metabolic disease (thyroid crisis) or drug induced severe hyperthermia(CNS-DA blockers eg haloperidol induced neuroleptic malignant syndrome) • Malignant hyperthermia(rare genetic disease, history with succinyl choline or halothane exposure)
Heat Stroke: Definition • Core body temp (rectal temperature > 40.6 oC /105 oF) • Functional disturbance of CNS • Hot dry skin (unnecessary) • Able to exclude all other causes of febrile illnesses
ER Management • Secure airway, secure big iv lines • Try intubation with mechanical ventilatory support • Seizure control • Circulatory resuscitation • Cool the body temperature • Seeking more information for correct Dx and rapidly transport the patient to ICU
Seizure Contol in Heat StrokeStatus Epilepticus? • Benzodiazepine • Short acting phenobarb?Sodium pentothal 50 mg/ml, 3-5 mg/kg iv • Muscle relaxant ?Succinyl choline 0.6 mg/kg iv (effect lasts within 3 mins)Tracrium 0.4-0.5 mg/kg iv (effect lasts within 20-45 mins) • Dilantinization ?10-15 mg/kg, not more than 50 mg/min iv
Circulatory Resuscitation • Crystalloid fluid 10-20 ml/kg/hr • Monitor CVP, urine output, watch for signs of pulmonary congestion
Cooling of the Body TemperatureWhat should be kept in mind ? • All antipyretics fail to bring down the body temperature in EHS • Liver failure from the heat usually occurs, this limits the use of acetaminophen • Cooling the body by physical method is the only way to decrease the body temperature
Confusion on the Options for Cooling TechniquesWhich one is the most effective and should be done first ? Conductive cooling • External • Cold water immersion • Application of cold packs or ice slushes over parts of the body • Use of cooling blankets • Internal • Cool gastric lavage through an NG tube • Cool peritoneal lavage / HD with cool dialysate solution Water evaporation and convective cooling • Fanning the undressed patients at room temp (cold air vs warm air?) • Continuous fanning after wetting / spraying the body surface with:- • Alcohol • Cold water • Room temp water
Principles of Cooling the Body (1) • To effectively and rapidly protect the vital organs from the heat • CNS • Heart and Lungs • Liver • Kidneys • Blood and Coagulation system • It is essential to rapidly cool the core body temperature rather than the peripheral parts of the body
Principles of Cooling the Body (2) • Circulatory system effectively transfers heat from the core to the skin, thus maintaining cutaneous vasodilation is essential (cutaneous T > 30oC) • Rapid transfer of heat from the skin to the external environment • Conduction • Convection by air plus evaporation of sweat or water • In a large series, it’s safe to halt cooling when rectal temp < 39.4oC Bouchama and Knochel. NEJM 2002;346:1986
Body Temperature Measurement • Difference between oral and rectal temperatures immediately after a long distance run was reported to be 3oC(36.7 vs 39.7)Rocycki. Am J Med Sports 2000;2:143-152 • Rectal temperature • Correlates best to the core body temperature(blood temp in pulmonary artery assessed by a thermometer placed at the tip of a Swan Ganz catheter, is the gold standard) • Easy for doing continuous monitoring
Duration of Cooling with 15oC Atomised Water Spraying Weiner JS and Khogali M. Lancet 1980;1:507-509 Average minutes spent during cooling N = 6 for each Rectal Temperature During Cooling (oC)
Essential Cooling Method(Hospital Setting) • Undressed the patient • Spray water at room temp over the body • Fanned warm air continuously over the body • Monitor body temperature (keep skin >30 oC, rectal <39 oC) • If rectal temp does not decrease after 10 minutes, begin NG irrigation with cold saline (or PD or HD using cold dialysate if indicated)
Field ManagementBouchama and Knochel. NEJM 2002;346:1986 • If the core temperature is >40 oC • Lower the core temperature to <39.4 oC • Move the patient to a cooler place • Remove his or her clothing • Promote cooling by conduction and evaporation
Initiate External Cooling • Cold packs on the neck, axillae, and groin • Continuous fanning • Opening of the ambulance windows • Spraying of the skin with water at 25 oC to 30 oC
Field ManagementBouchama and Knochel. NEJM 2002;346:1986 • Increase arterial oxygen saturation to >90% • Administer oxygen at 4 liters/min • Provide volume expansion • Give isotonic crystalloid (normal saline) • Rapid transfer the patient to an emergency department
Preventive Measures Weather monitor (assess heat stress index) and provide warning system Acclimatization program and maintain the physical fitness Adequate water supplement corresponded to the weather condition Restrict activity and work-rest cycle