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8/10/2019 Hypothermia, Prevention, Recognition, Treatment_ Hypothermia Special Situations
1/13
HypothermiaPrevention,RecognitionandTreatment.
Articles,ProtocolsandResearchonLife-savingskills.
Therecommendedtreatmentofhypothermiainthefieldiscorerewarmingtopreventpost-rescue
col lapse.
PROTOCOLS
AlaskanProtocol
JAMA
TREATMENT
TreatingHypothermia
Scenarios
FieldChart
HospitalChart
RESEARCH
Dr.A.Weinberg
Dr.J.Hayward
PUBLICATIONS
Rescue1
Rescue(Expanded)
AirwayRewarming
AirwayTreatment
HypothermiainAnimals
HYPOTHERM IA
WHATTODO
InWater
OnLand
OTHERPAGES
HomePage
LinksPage
For your convenienceHypothermiaTreatment
Equipment Links
Courtesy of
www.hypothermia-
ca.com
RES-Q-AIR
HypothermiaSpecialSituations
ThispaperisprovidedherewithpermissionfromAndrewDWeinberg,MD
hypothermia;pathophystology;resuscitation;rewarming;treatmentalgorithm
FromHarvardMedicalSchool.Boston,Massachusetts.and
Brockton/WestRoxburyVAMC,WestRoxbury,Massachusetts.
AndrewDWeinberg,MD
Significanthypothermiaisanincreasingclinicalproblemthatrequiresarapidresponsewithproperlytrainedpersonnelandtechniques.Althoughtheclinicalpresentationmaybesuchthatthevictimappearsdead,aggressivemanagementmayallowsuccessfulresuscitationinmanyinstances.InitialmanagementshouldincludeCPRifthevictimisnotbreathingorispulseless.Furthercoreheatlossshouldbepreventedbyremovingwetgarments,insulatingthevictim,andventilatingwithwarmhumidifiedair/oxygentohelpstabilizecoretemperature.Coretemperatureandcardiacrhythmshouldbemonitoredintheprehospitalsetting,ifpossible,andCPRshouldbecontinuedduringtransport.In-hospitalmanagementshouldconsistofrapidcorerewarmingintheseverelyhypothermicvictimwithheatedhumidifiedoxygen,centrallyadministered
warmIVfluids(43C),andperitonealdialysisuntilextra-corporealrewarmingcanbeaccomplished.Postresuscitationcomplicationsshouldbemonitored;theyincludepneumonia,pulmonaryedema,cardiacarrhythmias,myoglobinuria,disseminatedintravascularthrombosis,andseizures.Thedecisiontoterminateresuscitativeeffortsmustbeindividualizedbythephysicianincharge.
[WeinbergAD:Hypothermia.AnnEmergMedFebruary1993;22(Pt2):370-377.]
OVERVIEWOFISSUES
Severeaccidentalhypothermia(bodytemperaturebelow30C)isassocia tedwithmarkeddepressionofcerebralbloodflowandoxygenrequirement,reducedcardiacoutput,anddecreasedarterialpressure.Victimsmayappearclinicallydeadbecauseofmarkeddepressionofbrainandcardiovascularfunction:fullresuscitationwithintactneurologica lrecoveryispossib le,althoughunusual.{1}Mostclinicallysignificantepisodesofhypothermiaresultfromaninjuryinacoldenvironment,submersionincoldwater,oraprolongedexposuretolowtemperatureswithoutadequateprotectiveclothing.Thevictimsperipheralpulsesandrespiratoryeffortsmaybedifficulttodetect,butlifesavingproceduresshouldnotbewithheldbasedonclinicalpresentation.
Theveryyoungandtheveryoldaremostsusceptibletohypothermia.{1-3}Ininfants,corebodytemperaturewillcoolmorequicklythaninadults,asinfantshavealarger
http://www.hypothermia-ca.com/res-q-air.htmhttp://www.hypothermia-ca.com/res-q-air.htmhttp://www.hypothermia-ca.com/res-q-air.htmhttp://www.hypothermia.org/links.htmhttp://www.hypothermia.org/index.htmlhttp://www.hypothermia.org/inwater.htmhttp://www.hypothermia.org/animalhypo.htmhttp://www.hypothermia.org/hypothermia2.htmhttp://www.hypothermia.org/hypothermia4.htmhttp://www.hypothermia.org/hypothermia1.htmhttp://www.hypothermia.org/hayward.htmhttp://www.hypothermia.org/weinberg.htmhttp://www.hypothermia.org/fieldchart.htmhttp://www.hypothermia.org/publications.htmhttp://www.hypothermia.org/hypothermia.htmhttp://www.hypothermia.org/jama.htmhttp://www.hypothermia-ca.com/IV-warmer.htmlhttp://www.hypothermia-ca.com/res-q-air.htmhttp://www.hypothermia-ca.com/res-q-air.htmmailto:[email protected]://www.hypothermia.org/links.htmhttp://www.hypothermia.org/index.htmlhttp://www.hypothermia.org/onland.htmhttp://www.hypothermia.org/inwater.htmhttp://www.hypothermia.org/animalhypo.htmhttp://www.hypothermia.org/hypothermia2.htmhttp://www.hypothermia.org/hypothermia4.htmhttp://www.hypothermia.org/hypothermia3.htmhttp://www.hypothermia.org/hypothermia1.htmhttp://www.hypothermia.org/hayward.htmhttp://www.hypothermia.org/weinberg.htmhttp://www.hypothermia.org/hospitalchart.htmhttp://www.hypothermia.org/fieldchart.htmhttp://www.hypothermia.org/publications.htmhttp://www.hypothermia.org/hypothermia.htmhttp://www.hypothermia.org/jama.htmhttp://www.hypothermia.org/protocol.htm8/10/2019 Hypothermia, Prevention, Recognition, Treatment_ Hypothermia Special Situations
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IV WARMER
TESTIMONIALS
from field
experiences
Testimonial 1Mayday
Shorelines
, . cannotproduceasmuchheatasadults.Olderindividualshavealowermetabolicratethantheyoung;thus,itismoredifficultforthemtomaintainnormalbodytemperaturewhenambienttemperaturesdropbelow18C.Agingalsoseemstobeaccompaniedbychangesintheabilitytodetecttemperaturechanges:olderpeop lemaynotseekshelterearlyenoughtoavoidbecominghypothermic.
Submersionincoldwatercancoolthecorebodytemperaturemuchmorerapidlythanexposuretocoldair,becausethermalconductivityofwateris32timesgreaterthanthatofair.{4}Hypothermiaalsocanoccurinrelativelywarmwaterconditionsifexposureis
longenoughandifcoretemperaturelossisincreasedbyconcurrentingestionofalcohol.
Alcoholingestionincreasestheriskofacquiringoraggravatinghypothermiabycausingcutaneousvasodilation(whichpreventsvasoconstriction),impairmentoftheshiveringmechanism,hypo thalamicdysfunction,andadecreaseinawarenessofenvironmentalconditions.{5-7}Othermedicalconditionsthatmaycausehypothermiaincludesepsisintheelderly(throughcentralmechanisms),hypothyroidism(throughdecreasedmetabolicrate),hypopituitarism,hypoadrenalism,headinjury(centralmechanisms),drugingestion(especiallybarbituratesorphenothiazinesthroughtheiractionsonthecentralnervoussystem),anddiabetes(especiallywhenhypoglycemiaispresent).
ClinicalFeatures
Ascorebodytemperaturedeclines,thebasalmetabolicrateandoxygenconsumptiondropgraduallybutprogressively.{3,4}Mildhypothermia(34to
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Oxygenationandacid -base balancealsocanbealteredbyhypothermia,withtheinitialmanifestationofmildhypothermia(34Corhigher)beinghyperventilation.
Ta bleKeyfindingsatdi fferentdeg reesofhypo thermia
Temperature(C)ClinicalFindings
{37}Normaloraltemperature
{36}Metabolicrateincreased
{35}Maximumshiveringseen/impairedjudgment
{33}Severecloudingofconsciousness
{32}Mostshiveringceasesandpupilsdilate
{31}Bloodpressuremaynolongerbeobtainable
{28~3O}
Severeslowingofpulse/respiration
Increasedmusclerigidity
Lossofconsciousness
Ventricularfibrillation
{27} Lossofdeeptendon.skinandcapillaryreflexes
Patientsappearclinicallydead
Completecardiacstandstill
Asdocumentedbylow-registeringthermometer.
Asthecoretemperaturedecreases,thereisrespiratorydepressionwithsubsequenthypoxemiaandhypercarbia.{3}Acombinedrespiratoryandmetabolicacidosismayoccurduetohypoventilation,carbondioxideretention,reducedhepaticmetabolismoforganicacidduetodecreasedperfusionoftheliver,andincreasedlacticacidproductionfromimpairedperfusionofskeletalmuscleandshivering.{3-8}Thereis
somecontroversyaboutwhetherarterialbloodgasesshouldbecorrectedfortemperatureinthehypothermicpatient,althoughrewarmingusuallycanbeexpectedtocorrectthemetabolicimbalanceafterthenormalcirculationisreestablished.{5-3-14}Metabolicacidosiscanbeseeninhypothermicpatientsandmaynotrespondtobicarbonatetreatment.{15}
Hypothermiaaffectsthefunctionofallorgansystems.{4}Itcancausetheinhibitionofreleaseofantidiuretichormoneanddecreaseoxidativerenaltubularactivity,causingdiuresisandvolumedepletion.{16}Thehematocritmaybeelevatedduetodehydrationandspleniccontraction,{4}andplasmaviscosityhasbeenfoundtoincreaseasthecoretemperaturefallsbelow27C{4}.Hyperglycemiaalsomaybeseeninhypothermicpatientsduetodecreasedinsulinreleaseandinhibitionof
peripheralutilizationofglucose.Thisconditionoftenwillbereversedwithrewarming,althoughtheuseofinsulinrarelymaybenecessaryinspecificcases.{17}Shivering,ifprolonged,maycausehypoglycemia,asglycogenstoresmaybecomecompletelydepleted.Hypoglycemiaalsomaybeaninitiallaboratoryfindinginpatientswhohavebeenexposedtolong-lastingphysicalenduranceandexhaustionandoftencanbe
notedinalcoholicpatients,whoalreadymayhavedepletedglycogenstores.{18}
Themammaliandivingreflexmaybeinvokedinpediatricsubmersionvictims.Facialcoolingtriggersapneaandcirculatoryshuntingtothebrainandheart,{15}whichmayproveprotective.Thisreflexalsomayoccurinadults,althoughtheclinicalsignificanceremainsunclear.{19}
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General PrinciplesofTreatment
Earlyrecognitionofhypothermiaisessentialtomaximizesurvival.Prehospitalemergencypersonnelandemergencydepartmenthealthcareprovidersmustmaintainahighindexofsuspicioninanypatientwithanalteredlevelofconsciousnesswhomayhavebeensubjectedtoevenamodestlycoolenvironment.Allemergencytreatmentfacilitiesmusthaveathermometercapableofregisteringatemperatureof30Corless.Emergencyhealthcareprovidersinareaswherecoldweatheremergenciesmaybeexpectedalsomustbeequippedwithandtrainedtouselow-registerthermometers
(tympanicorrectalprobes)andappropriaterewarmmgequipment.
MovementBecausethecoldheartisirritab leandsusceptibletoseriousarrhythmias(suchasVF),allpatientswithapulseshouldbemovedgentlyduringtransportationorduringtransferofthepatientfromastretchertoahospitalbed.Thepatientideallyshouldhavevitalsigns,coretemperature,andcardiacrhythmmonitoredcontinuouslyduringtransportation,andequipmentforresuscitation(includingadefibrillator)shouldbeimmediatelyavailable.Wheneverpossible,ahorizontalpositionshouldbemaintainedduringmovementinordertominimizeanypotentialorthostaticbloodpressuredropduetocold-inducedcardiovascularrefleximpairment.
LaboratoryTests
Whenpossible,routinelaboratoryevaluationshouldbeaccomplished,includingarterialbloodgases(ABGs),acompletebloodcount,prothrombintime,partialthromboplastintime,glucose,electrolytes,bloodureanitrogen,serumcreatinine,amylase,liverfunctiontests,ECG,chestradiography;andurinalysis.Thesetestswillallowabase linetobeestablishedandwillbemostusefulinthepostresuscitativeperiodwhencomplicationscanoccur.ThereisgeneralagreementthatABGsneednotbecorrectedduringthehypothermicphase,asrewarmingwillcorrectallhypothermic-inducedalterations.Rewarmingremainstheprimarytreatmentinseverehypothermiaforanyabnormalitiesdetected.
Interventions
Itisimportanttostressthattheseverelyhypothermicheart(
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victimsincardiacarrestorunconscioushypothermicpatientswithaslowheartrate.
Drugspertinentforresuscitationalsomaybeneededinreduceddosages,atlessfrequentintervals,orboth.Nospecificguidelinesexistonwhatreduceddoseshouldbetried,but,ingeneral,thelowestknowneffectivedosecanbetriedinitiallyifmedicationisindicated.Likewise,therearenospecificrecommendationsonchangingtheintervalofmedicationadministration,butdoublingtheusualrecommended timebetweendoseswouldbetheinitialintervalrecommended.However,medications,ingeneral,shouldbeavoidedinthehypothermicpatientincardiacarrestuntilthecoretemperatureisabove30C.Hypoglycemia,ifpresent,canbetreatedwithIVglucose.
Volumedepletionisacommonclinicalfindingintheseverelyhypothermicpatient,andIVfluidsareindicated.Theusualparametersforfluidassessmentmaybedifficulttouseinahypothermicvictim,duetolargequantitiesoffluidinthe"thirdspace"andtheclinicaldifficultyofobtainingorthostaticbloodpressuresandweight.Itshouldbeemphasizedthatperipheralaccessmaybequitelimitedduetovasoconstriction,andacentrallinemayneedtobeplaceduponarrivalintheED.IVinfusionsets,urinarycatheters,suctiontubes,andendotrachealtubesmaybecomestiffandbreakifnotpre-warmedpriortopre-hospitaluse.IVsolutionsalsoshouldbepreventedfromfreezing.butstandardformulationsofsalineanddextrosesolutionscanbeusedsafelyafterthawingifnovisibleprecipitatesarepresentandthebagsareintact.
IVfluidsshouldbewarmedtoapproximately43Cpriortoadministrationinthepre-hospitalsettingtopreventfurthercorecooling.Methodstowarmfluidsincludeusingstandardbloodwarmersadaptedforsalinebaguseorportablebattery,operatedIVlinewarmers,preheatingsalineIVbagsandstoringtheminheatedcarryingpacks,andmicrowavingliterbagsofsalinewithinsulationduringadministration.TheuseofaninsulationbarrieraroundallIVtubingandsolutionscanhelppreventheatlossfromwarmedsolutionsincoldenvironments.
Pre-hospitalManagementThedilemmaofanormothermiccardiacarrestinacoldenvironment(e.g.amiddle-agedmanwhohasanormothermiccardiacarrestwhileshovelingsnowandsubsequentlybecomeshypothermic)maypresentaconfusingclinicalpicture.Basiclifesupportandadvancedcardiaclifesupport(ACLS)shouldbe
institutedassoonasfeasible,andtheappropriatenormothermicACLSalgorithmshouldbefollowed.Rewarmingtechniquesmaybe addedtoassistintheresuscitativeeffort.TheFigurepresentsarecommendedhypothermiatreatmentalgorithm.Thisalgorithmpresentstherecommendedactionsthatprovidersshouldtake forallpossiblevictimsofhypothermia.Oncehypothermiaissuspected,everyeffortshouldbemadetopreventfurthercoretemperaturelossbyinsulationandbyremovingwetgarmentsandtocautiouslytransportthepatienttoanappropriatetreatmentfacility.
IncreasingbodytemperaturebyaggressiveexternalrewarmingtechniquesbeforeCPRisunderwaywillonlyincreasethemetabolicdemandsofthebodywithoutanyaccompanyingincreaseinblood supply,thusincreasingthechancesofinfarctionorgangrene.Wetgarmentsshouldberemovedcarefullyandreplacedwithdry(preferablywarm)garments.{4-20}Blanketsand/oraninsulatedsleepingbagmaybe
usedtoretainbodyheat,andeffortsshouldbemadetoshieldthevictimfromwindchill.Coldsleepingbagsshouldbeprewarmedwithavolunteerpriortoplacingavictiminsidetopreventcoretemperatureheatloss.Prehospitalpersonnelmaylie(strippedtotheirunderwear)alongsideaconsciousvictimunderneaththecoverstoassistinrewarming.Airwaytreatmentswithportableunitsthatcandeliverwarm,humidifiedair/oxygenheatedto42-46Ccanbeusedtodonateheatbacktothecoreandimprovethepatient'sheatbalance.{21}Exerciseisnotrecommendedasarewarmingstrategy(unlesscoretemperatureisabove35C)topreventfatalarrhythmiassecondarytoperipheralvasodilationleadingtoadeclineinbloodpressureaswellascausingcoolbloodtoreturntothecentralcirculation.{22}Afterdrop,adropincoretemperatureafterresuscitationeffortshavebegun,mayoccurthroughsignificantheatconductionfromthecoreofthebodytomoreperipherallayerswhichhave notbeenrewarmed.{23}
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ECGmonitoringshouldbeperformedintheprehospitalsettingwheneverpossibleduringresuscitationandtransport.Prehospitalpersonnelalsoshouldbeawarethatadhesivepadsformonitorleadswillnotsticktocoldskin,andconductionofelectricalsignalsacrosscoldskinmaybeimpairedinsuchsettings.Inpatientswithmoderate-to-severehypothermiainwhomsuchconductionofECGsignalsisaffected,needleelectrodesmayneedtobeinserted.Theneedlemaybeaninjectionneedlepuncturedthroughthegel-foamofaconventionaladhesivepadwhichisthen.inturn,connectedtotheECGelectrodeofthemonitor.Thismethodavoidstheneedtohavespecia lly-madeneedleelectrodesforeachmachine.Incoldenvironmentsinwhichcontinuous
monitoringisdesired,tinctureofbenzoinmaybeneededtomaintaincontactofthemonitorleads.TheQRSamplitudeshouldbemaximallyamplifiedifnocomplexesareseeninitially.
Mostelectricalmedica ldevicestobeusedintheprehospitalsetting(defibrillatorsandmonitors)haverecommendedoperatingtemperaturesabove 15.5C,andcircuitbreakersongeneratorsandpowerdistributionboardsshouldbecheckedoftentopreventfreezing.Anyrequiredmonitoringequipmentforprehospitaluseshouldbeproperlyinsulatedpriortoutilization.Batteriesareaffectedbyverylowtemperatures,whichmayaffectperformanceofequipment.
MildHypothermia(34Cto35C)
Patientswithmildhypothermia(34Corabove)generallyhaveagoodprognosisregardlessoftherewarmingmethodused.{4-8}Intheconsciouspatient,externalrewarmingisappropriate,eitherpassivelybyusingblanketsoractivelyusinghotwaterbottles,warmbaths,orchemicalheatpacksplacedunderthearmsandontheneck,chest,andgroin.These methodscanallowthepa tienttowarmatarateof0.5Cto1Cperhour.Althoughquiteeffective,warmbathshavethedisadvantageofnotallowingthecardiacrhythmtobemonitored.Roughmovementsshouldbeavoided,asdiscussedabove.Wetclothingshouldberemovedcarefully,andthepatientshouldbeinsulatedandprotectedfromwindchill.Thepatientshouldbecautionednottoexerciseasamethodofrewarmingbecauseofthepotentialforcardiovascularcollapse.Prognosisusuallyisquitegood.
ModerateHypothermia(30Cto33.9C)Pre-hospitaltreatmentofmoderatehypothermiashouldincludeallthebasicmeasureslistedaboveexceptexternalrewarming.CPRshouldbeinitiatedpromptlyifthepatientisincardiacarrest,althoughpulseandventilationsmayneedtobecheckedforlongerperiodsoftimetodetectminimalcardiopulmonaryefforts.Therecommenda tionthatpulseandventilationsbecheckedforonetotwofullminutespriortoinitiatingCPR{24-25}isprobablyexcessive.Amaximumof45secondsshouldbeadequatetimetoconfirmpulselessnessorprofoundbradycardiaforwhichCPRwouldberequired.Lossofpupilreflexes,hyporeflexia,absentbloodpressure,andlackofresponsetopainfulstimulimaynot
indicateclinicaldeathinthehypothermicpatient.Aroutinesearchforexternaltraumashouldbeaccomplishedbyprehospitalpersonnel,andtreatmentshouldbeinitiated
(e.g.,pressuredressings,etc.).Obviousphysicalevidenceofdeathwouldmitigateagainstbeginningresuscitation(e.g.,grossevisce ration,decomposition,decapitation).Stiffnessofthevictim'sbody,whichcanbecausedbyhypothermia,shouldnotbeconfusedwithclassicrigormortis.
Rewarmingisnotthemirrorimageofthecoolingprocess,especiallyforpatientswhohavedevelopedmoderate-to-severehypothermiaoveraprolongedperiodoftime.Attemptsatrewarmingsuchpatientsbyapplicationofexternalheat(suchasheatlamps,electricblankets,chemicalheatpacks,etc.)arehazardous,becausesuchinterventionswillcausesuddenperipheralvasodilationandallowcold,lacticacid-richbloodtoreturntothecoreandcauseaconvectiveafterdropincoretemperatureandpH,{21-23}increasingthelikelihoodofVE.{4}
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Minimizingconvectiveafterdropbypreventingreturnofcoo l.peripheralbloodandbydonatingheattothecoreduringinitialmanagementisakeygoa l.Thisisaccomplishedbypassiverewarmingandstabilizationmethods(coveringwithblankets,blockingexposuretowind,andremovingwetgarments).Mostafterdropsoccurduringthefirstfewminutesoftreatment,andrewarmingeffortsinthisgroupofhypothermicvictimsshouldbedirectedtothecore(warmhumidifiedoxygenorair;warmedIVfluids).
Inthehospitalsetting,patientswhoareconsciousandhaveaneffectivecirculationalsomaybetreatedwithexternalrewarmingtotruncalareasonly,butconstantmonitoringmustbemaintainedtodetectanypotentialafterdropthatcanoccur.
SevereHypothermia(
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Techniquesthatcanbeusedforrapidcorerewarmingincludetheadministrationofheated,humidifiedoxygen(42Cto46C).warmed(43C)IVfluids(normalsaline)infusedcentrallyatratesofapproximately150to200ml/hr(note:avoidoverhydration),peritonealdialysiswithwarmed(43C)potassium-freedialysateadministeredtwolitersatatime(nodwelltime),and/orextra-corporealbloodwarmingwithpartialbypass.{4-5-20-25}Acomplicationofove rvigoroushydrationispulmonaryedema,whichcanbetreatedwithstandardmedicationsafteraneffectivecirculationisrestored.Extra-corporealrewarmingshouldbeutilized,ifavailable,intheseverelyhypothermicpatient,
asthiswillallowthemostrapidandcontrolledcorerewarming.{9}TheuseofesophagealrewarmingtubeshasnotbeenreportedintheUnitedStates,althoughtheyhavebeenutilizedextensivelyinEuropeinhospitalswithoutextra-corporealrewarmingequipment.{28}Pleurallavagewithwarmsalineinstilledthroughachesttubealsohasbeenusedsuccessfully{26-29}toincreasecoretemperatureasmuchas2.5Cperhourbuthasthemajordisadvantagesofpossibleinfection,bleeding,andtherequirementforlargevolumesoffluid.Theroutineadministrationofsteroids,barbiturates,orantibioticshasnotbeendocumentedtobeofanyhelpinincreasingsurvivalordecreasingpostresuscitativedamage .{30}Additionally;theuseoflactatedRinger'ssolutionmaybedangerousduetoreducedhepaticmetabolismoflactateinthehypothermicstate.{25}
Bradycardiamaybephysiologicinseverehypothermia,andcardiacpacingisusually
notindicatedunlessbradycardiapersistsafterrewarming.Thetemperatureatwhichdefibrillationfirstshouldbeattemptedandhowoftenitshouldbetriedintheseverelyhypothermicpatienthave notbeenestablishedfirmly.Therearealsoconflictingreportsabouttheefficacyofbretyliumtosylateinthissetting,{31-32}althoughitmayprovehelpfulinVFbydecreasingthedefibrillationthreshold.
Recentlyarterialandvenouscathetershavebeenutilizedtocreateacirculatoryfistulathroughwhichtheblood isheatedbyamodifiedcommerciallyavailablecountercurrentfluidwarmer,thusachievingamoresimplifiedextracorporealrewarmingmethod.{33}Heparin-freesystemsarenowbecomingavailable{34}whichmaypreventaggravationofcoagulopathiesseeninhypothermicpatients.Radiofrequencyrewarmingisstillbeingdeve lopedasamethodofrapidcorerewarming.{35}
Continuouscoretemperatureandcardiacmonitoringshouldbeperformed,aswellasplacingaurinarycathetertomonitorurineoutput.Pulseoximetersdonotworkwellinvasoconstrictedhypothermicpatientsandwillnotaccuratelyreflectoxygenation.{5}
Postresuscitativecomplicationsmayincludepneumonia,pulmonaryedema.atrialarrhythmias,acutetubularnecrosis,acutepancreatitis,compartmentsyndromes,disseminatedintravascularcoagulation,hypophosphatemia,hemolysis,intravascularthrombosis,myoglobinuria,seizures,andtemporary,adrenalinsufficiency.{4-5-36}
Severeaccidentalhypothermiaisaseriousandpreventablehealthproblem.Cliniciansshouldlookfor''urban"hypothermiaininnercityareas,whereithasahighassociation
withpovertyanddrugandalcoholuse.{37-38}Inruralareas,over90%ofhypothermicdeathsareassociatedwithelevatedbloodalcohollevels.{39}
TerminatingResuscitativeEfforts
SomecliniciansbelievethatpatientswhoappeardeadafterprolongedexposuretocoldtemperaturesshouldnotbeconsidereddeaduntilcoretemperaturesarenearnormalandCPRstillelicitsnoresponse.Ifdrowningprecededthevictim'shypothermia,successfulresuscitationmaybeunlikely.Hypothermicvictimsshouldbetreatedaggressively,becauseevenwhenallvitalsignsareabsent,survivalwithoutneurologica limpairmentmaybepossib leincertainpatients.Althoughsomeinvestigatorshavesuggestedelevatedpotassiumasamarkerforpooroutcome,{40}
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nospec cc emca n ca o rcanpre c w comp e e accuracyw ow recover. eoldclinicalmaximthatnooneispresumeddeaduntiltheyhavebeenrewarmedtonearnormaltemperaturescannotbeappliedliterallyinallcases.Rewarmingefforts,ingeneral,probablyshouldbecontinueduntilcoretemperatureisatleast32Candmaybediscontinuedifthepatientcontinuestoshownoeffectivecardiacrhythmandremainstotallyunresponsivetoalltreatment.However,thedecisiontoterminateresuscitationmustbeindividualizedbythephysicianinchargeandshouldbebasedontheuniquecircumstancesofeachincident.
Successfultreatmentofhypothermiarequiresoptimaltrainingofemergencypersonnel
andappropriateACLSresuscitationmethodsateachinstitution.Becauseseverehypothermiaisfrequentlyprecededbyotherdisorders(e.g.,drugoverdose,alcoholuse,trauma,etc.),theclinicianmustseekandtreattheseunderlyingconditionswhilesimultaneouslytreatingthehypothermia.
COMMENTARY
Theintroductionofanewalgorithmforthetrea tmentofhypothermiawillfacilitatetheteachingofbasicassessmentandrewarmingtechniquestoallhealthcareproviders.Forhypothermicvictimsintheprehospitalsetting,theuseofCPR,removingwetclothingandshelteringfromwindchill,andstabilizationwithwarmedair/oxygenandIVfluidsconstitutetheinitialtreatmentmodalities.In-hospitalrewarmingandmanagementcanrequireintubation,centrallineplacement,warmedperitonealdialysatelavage,andextracorporealtreatment.Closepostresuscitativemanagementwillrequireclosein-hospitalobservationforavarietyofpotentialpulmonary,hematologic.andrenalcomplications.
RESEARCHINITIATIVES
AdditionalresearchontheuseofbretyliumandotherantiarrhythmicmedicationsinhypothermicVFclearlyisindicated,aswellasresearchondosingandintervalreductionsrequiredwhenadministeringmedicationsinhypothermicvictims.EvaluationoftheidealtemperaturetofirstattemptdefibrillationinpatientswithhypothermicVFalso
needstobeconducted.Furtherresearchonmicrowaverewarmingofhypothermicpatientsandotherprehosp italrewarmingtechniquesneedsexpansion.
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Hypothermiatreatmentalgorithm-fullsize(1038x1706)
(a)Mayrequireneedleelectrodesthroughtheshin.
(b)Manyexpertsthinkthisshouldbedoneonlyin-hospital.(c)Methodsincludeelectricorcharcoalwarmingdevices,hotwaterbottles,heatingpads,radiantheatsources,andwarmingbeds.(d)EsophagealrewarmingtubesarewidelyusedinEurope.
Abbreviations:
VF=ventricularfibrillationVT=ventriculartachycardiaJ=joulesKCL=potassiumchloride
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Theauthorgreatlyacknowledgestheadvice andcontributionofDrsRogerDWhite,Richard0Cummins,SveinHapnes,MadsGilbert,KristianLexow.andJamesLPaturas,EMT-P,inthedevelopmentofthismaterial.
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