Download Hypothermia Show Notes

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
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