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EMBasic-Hypothermia Author:AndreaSarchiDO ©2016EMBasicLLC,SteveCarrollDO.Mayfreelydistributewithproperattribution Normalcorebodytemperature–37°C+/-.5°C(98.6°F+/-.9°F) Hypothermia–coretemperaturebelow35°C(95°F) Mechanism–heatlossbecomessogreatthatthebody’sregulatory mechanisms(ex.shivering)areoverwhelmedandcannolongersustain anadequatebodytemperature History HPI Obviousenvironmentalexposurepresent? Waspatientoutsidewhensuddenlybecameuncooperative, uncoordinated,andapathetic? Non-specificsymptomssuchashunger,nausea,chills,dyspnea, confusionpresent? PEARL–Intheelderly,hypothermiaoftenoccursindoorsandtheonly signsmaybeadecreaseincommunicationand/oraflataffect PastMedicalHx Anypre-existingcardiac,pulmonary,neurologic,orendocrinologic disease? Signsofhypothermiabystage Mild(32-35°C/90-95°F)–increasedshiveringthermogenesis, amnesia/dysarthria,hyperventilation,urinetemp~34.8°C Vitals–tachypnea,tachycardia,normalBP Moderate(28-32°C/82-90°F)–stupor/progressive↓inlevelofconsciousness, poikilothermia,cardiacarrhythmias,hypoventilation,dilatedpupils, hyporeflexia Vitals–proportionate↓inpulseandrespiratoryrate Severe(<28°C/<82°F)–greatestsusceptibilitytoventriculararrhythmias,loss ofreflexesandvoluntarymotion,lossofcorneal/oculocephalicreflexes,acid basedisturbances,pulmonaryedema Vitals–50%ormore↓inO2consumptionandpulse,markedhypotension PhysicalExam General–scanpatient’sentirebody,lookingforfrostbite/cold-relatedinjuries andtrauma Measuringcoretemperature: Mild-moderatehypothermia–userectalprobeorbladderthermometer Criticalpatientswithseverehypothermia–useesophagealprobe PEARL–thehypothermicheartisverysensitivetomovement,soavoidjostling thepatientasthiscouldprovokeanarrhythmiasuchasvfib Workup Fingerstickglucose(degreeofhypothermia)-↑inacutehypothermia, ↓insubacute/chronichypothermia Fibrinogenlevel(hypothermiacanleadtoaDIC-typesyndrome) CBC(leucopenia,thrombocytopenia,↑hematocrit) CMP(baselineelectrolytes,renalfailure,ischemicpancreatitis) Lactate/ABGuncorrectedfortemp(acid-baseabnormalities) CPK(rhabdomyolysis) EKG(prolongationallintervals,OsbornwaveinV2-V5) Imaging CXR(pulmonaryedema,aspirationpneumonia) SpinalXrays(ifpt.notalertandanypossibilityoftrauma) DifferentialDiagnosis Endocrinologiccauses(hypopituitarism,hypoadrenalism,myxedema)– suspectinapatientthatfailstorewarmdespiteaggressive interventions;orderserumcortisolandthyroidfunctionstudies Hypoglycemia,hypovolemia,overdose–suspectoneoftheseifpatient hasarelativetachycardiathatdoesn’tcoincidewithcoretemp Underlyingacidosis(DKA,ASAOD)–suspectifpatienthasarelative hyperventilation;orderUAandserumsalicylatelevel Malnutrition–d/tdecreaseinsubQfatandthuslossofinsulation Medications–anxiolytics,antidepressants,antipsychotics,opioids,oral antihyperglycemics,beta-blockers,generalanestheticagents,andalphaadrenergicagonsists(clonidine) Management Airway–endotrachealintubationsinptswithrespdistressorwho cannotprotecttheirairway Breathing–O2,heatedandhumidifiedifpossible Circulation 2largebore14or16gaugeperipheralIVs(orIOline) Isotonicsalinewarmedto40-42°C CheckcentralpulsewithDopplerU/Supto1min Ifincardiacarrest,beginchestcompressions Continueresuscitationuntilcoretemp32-35°C Biochemicalmarkersindicatingfutileresuscitation Extremehyperkalemia>10-12mEq/L Fibrinogenlevel<50mg/dL Ammonialevel>420ug/dL PEARL–it’sessentialtousewarmedsalinebcroomtempsalinecanworsen hypothermia Monitoring Temperature–see“Physicalexam” Vascularfluidshifts–indwellingbladdercatheterwithurinemeterbaginpts withmoderate-severehypothermia Rewarming Passiveexternalrewarming(mildhypothermia) Coverpatientwithinsulatingmaterialandsetroomtempto82°F/28°C Ifptcan’tmaintainrewarmingof.5-2°C/hr,useactivetechniques Activeexternalrewarming(mild-moderatehypothermiaorthosewhodon’t respondtopassivetechniques) Useswarmblankets,heatingpads,warmbaths,orforcedairwarming systemsthatapplyheatdirectlytoskin Warmpatient’strunkBEFOREextremitiestoavoidcoretempafterdrop Childrenshouldnotberewarmedbyactiveexternaltechniquesalone Activeinternal/corerewarming(severehypothermiaorthosewhofailto respondtoactiveexternaltechniques) Startwithleastinvasivemethods1standgraduallyworkupifcoretemp notincreasingbyatleast2°C/hr: 1. HeatedIVsaline(40-42°C)andwarmedhumidifiedO2 2. Peritonealand/orpleuralirrigationwith40-42°Csaline 3. Endovascularwarmingdevice 4. Extracorporealbloodrewarming:venovenous,hemodialysis, continuousarteriovenousrewarming,cardiopulmonarybypass, extracorporealmembraneoxygenation Arrhythmias Definitivemanagementfocusedonrewarmingsincemostresolveandaremore treatableathighercoretemperature Bradycardia Physiologicinseverehypothermia Pacingnotnecessaryunlesspersistsafterpatientrewarmedto32-35°C Ifpacingnecessary,transcutaneouspreferred Atrialarrhythmias–commonbelow32°C,convertonrewarming Ventriculararrhythmias Ifpatientincardiacarrest,attemptdefibrillationwithsingleshock Ifshockunsuccessful,furthersingleshocksattemptedwithevery1-2°C ↑incoretemp Vasopressorsmayormaynotbeattempted(noconsensus) Failuretorewarm - Ifpatienthasobvioussourceofinfectionorfailstoraisehis/her bodytempgreaterthan.67°C/hrdespiteappropriaterewarming measuresàempirictxwithbroadspectrumIVAB - Ifpatienthaspotentialadrenocorticalinsufficiencyà100mg hydrocortisoneIVor4mgdexamethasoneIV - Ifpatienthashxhypothyroidismorsuggestiveneckscaràdraw thyroidfunctionstudiesandthengive250-500mcglevothyroxine IVoverseveralminutes(patientwillreceivedailyinjectionsof50100mcgfor5-7days) Cold-inducedskininjuries Treatafterpatient’scoretempisstable Warmwaterbathsofaffectedareasfor15-30minw/40-42°Cwater Tetanustoxoidandanalgesiaasneeded Disposition Mildprimaryaccidentalhypothermia–dischargeoncerewarmed Moderate-severehypothermia–usuallyadmittomedicine (Contact:[email protected])