高流量氧疗的生理效应医学课件

高流量氧疗的生理效应

PhysiologicalEffectofHighFlowNasalCannula(HFNC)Therapy1

高流量氧疗的生理效应PhysiologicalEffeCOIstatementTheauthorhasnoconflictof

interesttodeclare.2COIstatementTheauthorhasnoHighFlowaninterestingoxygenationmethod-novel-magic-gentleandmoderateSocool3HighFlowaninterestingoxygenHFNCshinesduringRSIPutthebigcannulaeintoyourpatient’snoseandlet’rrip.AddafacemaskorNIVorwhateveryourpreoxygenationpleasure,thenpushyourmedsandlaughtoyourselfasthesaturationrisesduringapnea.Whistlesweetlyastheinternilluminateseveryinchofthesoftpalatewithgreatdetermination.Hell,goseeanotherpatientandtellhimtocallyouwhenhe’sgivenup.Youremember,though,thedaysofthegiants.Whenbeingregardedasaskilledlaryngoscopistmeantsomething.Whentheword

airway

madeinternistsscatterlikemice.Whenitwasn’tsoeasytosavealife./2012/03/01/the-high-flow-nasal-cannula-in-the-emergency-department/4HFNCshinesduringRSIPutthePediatricianhaspromotedoxygentherapy1891­-E.BonnairedescribedO2inhalationsinthenewborn1963PatrickBouvierKennedydiesofrespiratorydistresssyndrome(RDS),34weeksgestation,birthweight2100gms.1963MariaDelivoria-PapadopoulosFirstsuccessfulventilationofapreterminfantwithhyalinemembranedisease(Assistedventilationinterminalhyalinemembranedisease.Arch.Dis.Child.,39:481-484,19641971GregoryUseofcontinuouspositiveairwaypressure(CPAP)forrespiratorydistresssyndrome(RDS)5PediatricianhaspromotedoxygOxygentherapy&oxygendeliverydevicesOxygenTherapyLowflowsystemsHighflowsystemsNasalcannulaFacetentO2tentVenturimaskPRBMNRBMNIV(CPAP)ETtubeSimplemaskHFNC6Oxygentherapy&oxygendeliveTheroleofHFNCinrespiratorytherapy7TheroleofHFNCinrespiratorWhatisHFNC?a“new”methodsofoxygentherapyair/oxygenappliedtopatientathighflowratesair/oxygenrunthroughanasalcannulaair/oxygeniswellconditionedbysufficientwarmthandhumidification

--socalledheated,humidifiedhigh-flownasalcannula(HHHFNC)therapy2-70L/min8WhatisHFNC?a“new”methodsoMechanismsofactionforHFNCWashoutofnasopharyngealdeadspaceReductionofinspiratoryresistance(workofbreathing)byprovidingadequateflowImprovedmechanicsbysupplyingadequatelywarmedandhumidifiedgasReductioninthemetaboliccostofgasconditioningProvisionofdistendingpressure9MechanismsofactionforHFNCWWashoutofnasopharyngealdeadspaceThehighvolumetricflowspouringfromasmallborecannulacausehighvelocityflowswhichcreateturbulentenergytoflushtheupperairwayofexpiratorygas.10WashoutofnasopharyngealdeadDeadspacewashoutimprovesventilationanatomicaldeadspaceinadults≥30%oftidalvolumeinneonates≈50%oftidalvolumechangethegascompositioninnasopharyngealspacereducerebreathingexpiredCO2

increasethefractionofinspiredO2increasealveolarventilationefficiencyMV=

(VT–VD)xRR PaCO2=PeCO2/(1–VD/VT)PaO2=(PBO2–PH2O)xFiO2–PaCO2/R–PA-aO211DeadspacewashoutimprovesveCO2washoutduringHFNCwithdifferentflowratesNHFrates0L/min 30L/min 60L/minMidwaythroughexpiration(t=1.2s)Endofexpiration(t=2.2s)VanHoveSC,etal.AnnBiomedEng(2016)44:3007-3019.12CO2washoutduringHFNCwithdHighflowandhighvelocityincreasealveolarventilationefficiencylikelyminimizetheinspiratoryresistanceassociatedwiththenasopharynxbyprovidingnasopharyngealgasflowsthatmatchorexceedapatient'speakinspiratoryflowCoandaeffectoccuringinthenasopharyngealregionduringexpirationpotentiallyassistexpiratoryeffortsbringaboutadecreaseinworkofbreathing

andrespiratoryratecreatemoreturbulentenergyformoreeffectivewashoutflushtheexpiratorygasfromtheupperairwayquicklyduringtheexhalationphaseofbreathing,whichiscriticalinpatientswithrapidbreathing13HighflowandhighvelocityinVentilatoryResponsestoHFNC

MündelTetal.MechanismsofnasalhighflowonventilationduringwakefulnessandsleepJApplPhysiol,2013.114:1058–106514VentilatoryResponsestoHFNCMucociliarytransportsystemHealthciliatedepithelium Damagedciliatedepithelium/files/images/hospital/respiratory-care-continuum/full-width/mucociliary-disfunction-table/15MucociliarytransportsystemHeMucosalfunctionsdependentoninspiredhumidityWilliams,RB.RespireCareClinNAm1998Jun;4(2):215-2816MucosalfunctionsdependentonTemperatureandhumidityLowtemperaturedoesmeaninsufficienthumidity.Enoughwatersupplementdoesnotalwaysmeansufficienthumidity.Anadultmayrequireapproximately150calories/min(10kcal/h)forconditioninginspiratoryairfromambienttoBTS.KacmarekRM,etal.Egan'sFundamentalsofRespiratoryCare.St.Louis,MO:Elsevier/Mosby,2013.17TemperatureandhumidityLowteInspiredgasneedsconditioningRespirationwithambientgas,notwarmedorhumidified,inducedbronchoconstrictionresponse,andresultedinasignificantdecreaseinbothpulmonarycompliance.ThenasalairpassagesexpendquiteafewenergytowarmandhumidityinspiratoryairfromambienttoBTS.Studiesfromthe1990'sdemonstratedthenegativeeffectsofusingnon-warmed,non-humidifiedgastosupportrespiration.18InspiredgasneedsconditioninFlowandPressurefundamentalsHFNCisintendedtobeanopensystem,withflowdeliveredtoapatientvianasalcannula,wherethecannulaprongsdonotoccludethenaresandwherethepatient’smouthisnotheldclosed.Inthisopensystem,thepressureineachcompartmentisafunctionoftheresistor(s)thatlieinseriesdownstreamfromthatcompartment.Inthisregard,circuitpressureswillalwaysbesubstantiallygreaterthanpressureinthenasopharynx.19FlowandPressurefundamentalsFactorsdeterminnasopharyngealpressuretheflowsettingthepatient’suniqueanatomicaldimensionstheleakoutofthenosearoundtheprongsandoutofthemouth(ODofcannulaprongvs.

IDofnares)20FactorsdeterminnasopharyngeaMechanismsofAction:

HFNCDiffersfromCPAPMündelTetal.MechanismsofnasalhighflowonventilationduringwakefulnessandsleepJApplPhysiol,2013.114:1058–106521MechanismsofAction:

EffectsofflowonairwaypressureduringHFNCHigherflowratecreateshigherairwaypressure.Pressureisdifferentwhenmouthclosedoropen.Onlymoderatepositiveairwaypressure(<10cmH2O)canbegeneratedbyHF