Heat Injuries Heat Injuries Management Management and Prevention and Prevention

for the Royal Thai Armyfor the Royal Thai Army

SurajitSurajit Su Suntornthamntorntham, MD FRCPT, MD FRCPTDivision of Division of ToxicToxicologyology

Department of MedicineDepartment of MedicinePhraMongkutklao PhraMongkutklao

Army HospitalArmy Hospitaland College of Medicineand College of Medicine

SurajitSurajit Su Suntornthamntorntham, MD FRCPT, MD FRCPTDivision of Division of ToxicToxicologyology

Department of MedicineDepartment of MedicinePhraMongkutklao PhraMongkutklao

Army HospitalArmy Hospitaland College of Medicineand College of Medicine

A 21 yr M, Private, BKKA 21 yr M, Private, BKKCC:CC: Febrile, lost consciousness with generalized seizure ½ hr Febrile, lost consciousness with generalized seizure ½ hr

before admissionbefore admission

PI:PI: -Worked as a waiter prior to entering the training base, no -Worked as a waiter prior to entering the training base, no history of regular exercise previouslyhistory of regular exercise previously

-Apparently well, started basic training 3 days ago-Apparently well, started basic training 3 days ago

-After evening exercise, found falling a sleep, unawakened -After evening exercise, found falling a sleep, unawakened and febrile and shortly later developed generalized seizureand febrile and shortly later developed generalized seizure

-First aid with aggressive tepid sponge then the patient was -First aid with aggressive tepid sponge then the patient was transported to PMK Army Hospitaltransported to PMK Army Hospital

The 21 yr Male SoldierThe 21 yr Male SoldierUnconscious, Febrile, SeizureUnconscious, Febrile, Seizureshortly after Basic Training shortly after Basic Training

At ERAt ER

• BP 70/50 P 120 T 42BP 70/50 P 120 T 42ooC, RR 30/min C, RR 30/min Dyspnea, comatosed, generalized Dyspnea, comatosed, generalized seizure all the timeseizure all the time

• peticheae hemorrhage on foreheadpeticheae hemorrhage on forehead

The 21 yr Male SoldierThe 21 yr Male SoldierUnconscious, Febrile, Seizure, Shock, Dyspnea, Hemostatic DisorderUnconscious, Febrile, Seizure, Shock, Dyspnea, Hemostatic Disorder

shortly after Basic Training shortly after Basic Training

What are the differential diagnosis?What are the differential diagnosis?• Exertional heat stroke (EHS)Exertional heat stroke (EHS)• Severe infectionSevere infection

(Malaria, ricketsia, leptospirosis, DHF, (Malaria, ricketsia, leptospirosis, DHF, meningococcemia, gm-ve sepsis…etc)meningococcemia, gm-ve sepsis…etc)

• Metabolic disease Metabolic disease (thyroid crisis)(thyroid crisis) or drug or drug induced severe hyperthermiainduced severe hyperthermia (CNS-DA blockers eg haloperidol induced (CNS-DA blockers eg haloperidol induced neuroleptic malignant syndrome)neuroleptic malignant syndrome)

• Malignant hyperthermiaMalignant hyperthermia(rare genetic disease, history with succinyl choline or (rare genetic disease, history with succinyl choline or halothane exposure)halothane exposure)

Heat Stroke: DefinitionHeat Stroke: Definition• Core body temp Core body temp

(rectal temperature > 40.6 (rectal temperature > 40.6 ooC /105 C /105 ooF)F)

• Functional disturbance of CNSFunctional disturbance of CNS

• Hot dry skin (unnecessary)Hot dry skin (unnecessary)

• Able to exclude all other causes of Able to exclude all other causes of febrile illnessesfebrile illnesses

What would you do at the ER?What would you do at the ER?

ER ManagementER Management

• Secure airway, secure big iv linesSecure airway, secure big iv lines• Try intubation with mechanical ventilatory Try intubation with mechanical ventilatory

supportsupport• Seizure controlSeizure control• Circulatory resuscitationCirculatory resuscitation• Cool the body temperatureCool the body temperature• Seeking more information for correct Dx Seeking more information for correct Dx

and rapidly transport the patient to ICUand rapidly transport the patient to ICU

What would you do to stop What would you do to stop seizure in this patient?seizure in this patient?

Seizure Contol in Heat StrokeSeizure Contol in Heat StrokeStatus Epilepticus?Status Epilepticus?

• BenzodiazepineBenzodiazepine• Short acting phenobarb?Short acting phenobarb?

Sodium pentothal 50 mg/ml, 3-5 mg/kg ivSodium pentothal 50 mg/ml, 3-5 mg/kg iv

• Muscle relaxant ?Muscle relaxant ?Succinyl choline 0.6 mg/kg iv Succinyl choline 0.6 mg/kg iv (effect lasts within 3 mins)(effect lasts within 3 mins)Tracrium 0.4-0.5 mg/kg iv Tracrium 0.4-0.5 mg/kg iv (effect lasts within 20-45 mins)(effect lasts within 20-45 mins)

• Dilantinization ?Dilantinization ?10-15 mg/kg, not more than 50 mg/min iv10-15 mg/kg, not more than 50 mg/min iv

Circulatory ResuscitationCirculatory Resuscitation

• Crystalloid fluid 10-20 ml/kg/hrCrystalloid fluid 10-20 ml/kg/hr

• Monitor CVP, urine output, Monitor CVP, urine output, watch for signs of pulmonary watch for signs of pulmonary congestioncongestion

Cooling of the Body TemperatureCooling of the Body TemperatureWhat should be kept in mind ?What should be kept in mind ?

• All antipyretics fail to bring down the All antipyretics fail to bring down the body temperature in EHSbody temperature in EHS

• Liver failure from the heat usually occurs, Liver failure from the heat usually occurs, this limits the use of acetaminophenthis limits the use of acetaminophen

• Cooling the body by physical method is Cooling the body by physical method is the only way to decrease the body the only way to decrease the body temperaturetemperature

Confusion on the Options for Cooling TechniquesConfusion on the Options for Cooling TechniquesWhich one is the most effective and should be done first ?Which one is the most effective and should be done first ?

Conductive coolingConductive cooling• ExternalExternal

– Cold water immersionCold water immersion– Application of cold packs or ice slushes over parts of the bodyApplication of cold packs or ice slushes over parts of the body– Use of cooling blanketsUse of cooling blankets

• InternalInternal– Cool gastric lavage through an NG tube Cool gastric lavage through an NG tube – Cool peritoneal lavage / HD with cool dialysate solutionCool peritoneal lavage / HD with cool dialysate solution

Water evaporation and convective coolingWater evaporation and convective cooling• Fanning the undressed patients at room temp Fanning the undressed patients at room temp

(cold air vs warm air?)(cold air vs warm air?)

• Continuous fanning after wetting / spraying the body surface Continuous fanning after wetting / spraying the body surface with:-with:-– AlcoholAlcohol– Cold waterCold water– Room temp waterRoom temp water

Principles of Cooling the Body (1)Principles of Cooling the Body (1)

• To effectively and rapidly protect the vital To effectively and rapidly protect the vital organs organs from the heatfrom the heat– CNSCNS– Heart and LungsHeart and Lungs– LiverLiver– KidneysKidneys– Blood and Coagulation systemBlood and Coagulation system

• It is essential to rapidly cool the core body It is essential to rapidly cool the core body temperature rather than the peripheral parts temperature rather than the peripheral parts of the bodyof the body

Principles of Cooling the Body (2)Principles of Cooling the Body (2)

• Circulatory system effectively transfers heat from Circulatory system effectively transfers heat from the core to the skin, thus maintaining cutaneous the core to the skin, thus maintaining cutaneous vasodilation is essential (cutaneous T > 30vasodilation is essential (cutaneous T > 30ooC)C)

• Rapid transfer of heat from the skin to the external Rapid transfer of heat from the skin to the external environmentenvironment– ConductionConduction– Convection by air plus evaporation of sweat or waterConvection by air plus evaporation of sweat or water

• In a large series, it’s safe to halt cooling when In a large series, it’s safe to halt cooling when rectal temp < 39.4rectal temp < 39.4ooCCBouchama and Knochel. NEJM 2002;346:1986Bouchama and Knochel. NEJM 2002;346:1986

Body Temperature MeasurementBody Temperature Measurement

• Difference between oral and rectal temperatures Difference between oral and rectal temperatures immediately after a long distance run was immediately after a long distance run was reported to be 3reported to be 3ooCC(36.7 vs 39.7)(36.7 vs 39.7)Rocycki. Am J Med Sports 2000;2:143-152Rocycki. Am J Med Sports 2000;2:143-152

• Rectal temperature Rectal temperature – Correlates best to the core body temperatureCorrelates best to the core body temperature

(blood temp in pulmonary artery assessed by a thermometer (blood temp in pulmonary artery assessed by a thermometer placed at the tip of a Swan Ganz catheter, is the gold placed at the tip of a Swan Ganz catheter, is the gold standard)standard)

– Easy for doing continuous monitoringEasy for doing continuous monitoring

Duration of Cooling with 15Duration of Cooling with 15ooC Atomised Water SprayingC Atomised Water Spraying Weiner JS and Khogali M. Lancet 1980;1:507-509 Weiner JS and Khogali M. Lancet 1980;1:507-509

Rectal TemperatureDuring Cooling (oC)

Average minutes spent during cooling

N = 6 for each

Essential Cooling MethodEssential Cooling Method(Hospital Setting)(Hospital Setting)

• Undressed the patientUndressed the patient• Spray water at room temp over the bodySpray water at room temp over the body• Fanned warm air continuously over the bodyFanned warm air continuously over the body• Monitor body temperature Monitor body temperature

(keep skin >30 (keep skin >30 ooC, rectal <39 C, rectal <39 ooC)C)• If rectal temp does not decrease after 10 minutes, If rectal temp does not decrease after 10 minutes,

begin NG irrigation with cold saline (or PD or HD begin NG irrigation with cold saline (or PD or HD using cold dialysate if indicated)using cold dialysate if indicated)

Field ManagementField ManagementBouchama and Knochel. NEJM 2002;346:1986Bouchama and Knochel. NEJM 2002;346:1986

• If the core temperature is >40 If the core temperature is >40 ooCC– Lower the core temperature Lower the core temperature

to <39.4 to <39.4 ooCC

– Move the patient to a cooler placeMove the patient to a cooler place

– Remove his or her clothingRemove his or her clothing

– Promote cooling by conduction and Promote cooling by conduction and evaporationevaporation

Initiate External CoolingInitiate External Cooling

• Cold packs on the neck, axillae, and Cold packs on the neck, axillae, and groingroin

• Continuous fanning Continuous fanning – Opening of the ambulance windowsOpening of the ambulance windows

• Spraying of the skin with water at Spraying of the skin with water at 25 25 ooC to 30 C to 30 ooCC

Field ManagementField ManagementBouchama and Knochel. NEJM 2002;346:1986Bouchama and Knochel. NEJM 2002;346:1986

• Increase arterial oxygen saturation Increase arterial oxygen saturation to >90%to >90%– Administer oxygen at 4 liters/minAdminister oxygen at 4 liters/min

• Provide volume expansionProvide volume expansion– Give isotonic crystalloid (normal saline)Give isotonic crystalloid (normal saline)

• Rapid transfer the patient to an Rapid transfer the patient to an emergency departmentemergency department

Preventive MeasuresPreventive Measures

1.1. Weather monitor (assess heat stress Weather monitor (assess heat stress index) and provide warning systemindex) and provide warning system

2.2. Acclimatization program and maintain Acclimatization program and maintain the physical fitnessthe physical fitness

3.3. Adequate water supplement Adequate water supplement corresponded to the weather conditioncorresponded to the weather condition

4.4. Restrict activity and work-rest cycleRestrict activity and work-rest cycle