資源描述：
《心肺交互作用simplified.ppt》由會員上傳分享，免費(fèi)在線閱讀，更多相關(guān)內(nèi)容在工程資料-天天文庫。
1、心肺交互作用首都醫(yī)科大學(xué)北京朝陽醫(yī)院李文雄Basicphysiologyofheart–lunginteractionPumpfunction:PreloadatagivenHRPraorCVPAfterloadContractility.Returnfunction:Bloodvolume(vein)stressedandunstressedComplianceResistanceCOPreload—Transmuralpressure跨壁壓（Ptm）艙或血管內(nèi)外壓力差=血管內(nèi)收縮壓?Ppl非胸腔內(nèi)血管外壓=大氣壓（傳感器的零點(diǎn)）胸腔內(nèi)血管被胸膜腔內(nèi)壓包圍胸膜
2、腔內(nèi)壓隨通氣周期變化Ppl↑→RV前負(fù)荷↓自主呼吸或負(fù)壓呼吸時Ppl和血管內(nèi)主動脈壓力均下降Ppl下降幅度大于主動脈壓力下降幅度Ptm實(shí)際增加→LV后負(fù)荷↑、SV↓FourmechanismsparticipateinthecyclicchangesofSVobservedduringmechanicalventilation.First,duringinsufflation,venousreturndecreasesduetoanincreaseinpleuralpressure.ThisdecreaseinRVpreloadleadstoadecreasei
3、nRVoutputthatsubsequentlyleadstoadecreaseinleftventricularoutput.Second,RVafterloadincreasesduringinspirationbecausetheincreaseinalveolarpressureisgreaterthantheincreaseinpleuralpressure.However,leftventricularpreloadin-creasesduringinsufflationbecausebloodisexpelledfromthecapillarie
4、stowardtheleftatrium.Finally,leftventricularafterloaddecreasesduringinspirationbecausepositivepleuralpressuredecreasestheintracardiacsystolicpressureandthetransmuralpressureoftheintrathoracicpartoftheaortaCCM.2009VentricularafterloadDefinition:theforceopposingejectionVentricularafter
5、loadisrepresentedbytheleveloftransmuralpressure,inthecourseofsystole,withineithertheaorticroot(LVafterload)orthepulmonaryarterytrunk(RVafter-load)Thetransmuralratherthantheintraluminalpressuremustbeconsideredbecausethesegreatvesselsaswellastheventriclesareexposedtoanextramuralpressur
6、e(i.e.,ITP)whichisusuallynonatmospheric.ThemechanismswherebyrespirationinteractswithLVandRVafterloadaredifferent.LVafterloadAttheonsetofspontaneousinspiration,theintraluminalpressureintheaorticrootdecreaseslessthandoesITP,duetotheconnectionofthisvesselwithextrathoracicarteries.Asares
7、ult,aortictransmuralpressureincreases.Withspontaneousbreathingtherefore,LVafterloadisgreaterininspirationthaninexpiration.AsymmetricalchainofeventsleadstoareducedLVafterloadinthecourseofatransientincreaseinITP,suchaswithpositivepressureinflationofthelungs.SteadyincreasesinITP,aseffec
8、tedwithPEEP,
