（推荐课件）呼吸生理与呼吸力学

呼吸生理与呼吸力学,1,主要内容,肺换气肺通气呼吸力学,2,3,Terminalairway,Terminalbronchiole,Alveolarduct,Respiratorybronchioles,Smoothmuscle,Alveoli,4,Perfusionofthealveoli,Capillaries,Terminalbronchiole,Branchofpulmonaryartery,Alveolus,Branchofpulmonaryvein,Respiratorybronchiole,5,6,Alveolardesign,Aqueouslayer,Aqueousmacrophage,Lamellabody(storessurfactant),Typellpneumocyte-liningcell(producessurfactant),TypelLiningcell,Capillary,CO2,O2,7,8,9,O2运输,血浆溶解O21.5%（1mmHg0.003ml）血红蛋白结合O298.5%（1g1.34ml）,10,CO2运输,血浆溶解CO2710%化学结合CO22030%（HbCO2)血浆HCO36070%,11,大气成分,气体浓度%N278.6O220.9CO20.04H2O0.46,12,气体分压,分压=总压x浓度(%)大气压=760mmHg氧分压=760 x20.9=158.8mmHg二氧化碳分压=760 x0.04=0.30mmHg,13,肺泡气体分压,PACO2=40mmHgPAO2=(760-47)x20.9%-PACO2/呼吸商=15050=100mmHg,14,15,氧解离曲线,16,影响氧解离曲线因素,17,影响氧解离曲线因素,18,氧解离曲线位移的意义,PCO2曲线右移PCO240mmHg80mmHgSO275%65%10%O2组织细胞PCO2(肺内）SO2,19,LungVentilation/PerfusionRatios,Functionally:Alveoliatapexareunderperfused(overventilated).Alveoliatthebaseareunderventilated(overperfused).,Insertfig.16.24,Figure16.24,20,PO2=40PCO2=45,NormalVA/Q,LowVA/Q,HighVA/Q,CO2=45,PO2=150PCO2=0,PO2=100PCO2=40,PO2=150PCO2=0,.,.,.,VentilationPerfusionRatios,Noflow,21,PO2(mmHg),PCO2(mmHg),50,100,150,50,22,肺容量,潮气量(VT)深吸气量（IC）补呼气量（ERV）肺活量(VC)功能残气量(FRC)残气量(RV)肺总量(TLC),23,TotalLungCapacity,24,ExpiratoryReserve,ResidualVolume,VitalCapacity,VT,TotalLungCapacity,InspiratoryReserve,FRC,InspiratoryCapacity,TLC,RV,RV,IC,VT,IR,FRC,ER,VC,25,肺通气（1）,解剖死腔肺泡死腔生理死腔(VD)=解剖死腔+肺泡死腔VD=(PaCO2-PECO2)/PaCO2xVTPECO2:呼出气平均CO2浓度,26,肺通气（2）,肺通气量=VTxf肺泡通气量=（VTVD）xf肺泡CO2浓度=CO2产量/肺泡通气量肺泡通气量PACO2PaCO2肺泡通气量PACO2PaCO2,27,呼吸力学,弹性阻力非弹性阻力时间常数内源性呼气末正压,28,气体流动,高压低压,29,30,31,呼吸肌是动力,克服弹性阻力肺泡弹力纤维表面张力克服非弹性阻力,32,MechanicsofBreathing,33,Figure7-1FromJ.B.West,RespiratoryPhysiology:TheEssentials(8thed.),2008,usedwithpermissionbyLippincottWilliams&Wilkins,34,AnatomyofPleuralSac,TakenfromSherwood,HumanPhysiology:FromCellstoSystems,5thEd,35,36,Air,liquid,SURFACE,PolarH2Omoleculesattract,Surfacetension,37,肺表面张力,38,where:P=pressureST=surfacetensionr=radiusofthebubble,P=2ST/r,Laplaceslaw,39,P=2x1=0.2,10,P=2x1=0.4,5,10,5,Connectedbubbles,40,Alveoliasbubbles,41,Figure7-7FromJ.B.West,RespiratoryPhysiology:TheEssentials(8thed.),2008,usedwithpermissionbyLippincottWilliams&Wilkins,42,Figure7-3FromJ.B.West,RespiratoryPhysiology:TheEssentials(8thed.),2008,usedwithpermissionbyLippincottWilliams&Wilkins,43,Saline,Air,VonNeergaard,44,Figure7-5FromJ.B.West,RespiratoryPhysiology:TheEssentials(8thed.),2008,usedwithpermissionbyLippincottWilliams&Wilkins,45,呼吸压力,胸内压胸膜腔内的压力肺内压肺泡内压力经胸廓压肺内压与体表压之差值经肺压肺内压与胸内压之差值经胸壁压胸内压与体表压之差值,46,PA(cmH2O),+1,-1,0,+0.5,-0.5,0,AirFlow(L/s),1234,time(sec),-5,-8,Ppl(cmH2O),ThelinearDashedtraceisthePplrequiredtoovercomerecoilforces.MorePpl(solidcurve)isrequiredtoovercomeairwayresistancetoflow.N.B.P=PA-PBResistFlow.,VT(L),0.4,0,0.2,RespiratoryCycle,Inspiration,Expiration,-5,-8,-8,-6,-5,RestFRC,Inspiration,EndInspiration,+,0,0,-,AirFlow,PA=0,Ppl,Expiration,time,RespiratoryCycleSingleVTBreath,PB=0,47,顺应性,定义单位压力改变时容积的改变公式C=V/P肺顺应性C肺=肺V/经肺P胸壁顺应性C胸壁=肺V/经胸壁P呼吸系统顺应性C总=肺V/经胸廓P关系1/C总=1/C肺+1/C胸壁。,48,49,StaticComplianceCurves,50,51,52,53,54,55,最佳PEEP,曲线的下拐点吸气过程中，肺泡复张，肺容量增大，顺应性改善在呼吸周期中，反复出现肺泡复张，由于“剪切力”的作用，会造成肺组织损伤PEEP值高于下拐点，减少剪切力的损伤，对肺是一种保护这样设置减少肺损伤，改善氧合，又可减少PEEP的副作用，应称为“最佳PEEP”,56,对“拐点”的新认识,吸气过程中肺泡复张是一个连续的过程，开始是肺上部肺泡复张，随着吸气量的增加，肺的下垂部分的肺泡逐渐复张拐点的测定和估算一般是在PV曲线的吸气支上进行，而PEEP与呼气支关系更密切上拐点仅表明肺泡复张的数量减少而不一定与肺泡过度扩张或受到过度牵拉有关将PEEP设置在下拐点之上，不能有效减少剪切力对肺的损伤,57,ARDSNETVentilatorManagement,AnticipatedPEEPsettingsatvariousFIO2requirementsFiO20.30.40.40.50.50.60.70.70.70.80.90.90.91.0PEEP55881010101214141416182024MaintainSaO2/SpO28895%,58,顺应性的应用,肺病逐渐加重，顺应性随之下降轻度病变，吸气压1015cmH2O中度病变，1520cmH2O重度病变，2530cmH2O,59,60,非弹性阻力,粘性阻力肺形变，组织间产生的磨擦阻力，1020%气道阻力气流通过气道时遇到的磨擦阻力,80%,61,气流分类,层流湍流Reynolds数值=2Vrp/2300有湍流4000全湍流r半径p密度黏度V流速,62,Figure7-12FromJ.B.West,RespiratoryPhysiology:TheEssentials(8thed.),2008,usedwithpermissionbyLippincottWilliams&Wilkins,63,气道阻力（R）,定义R=P/V(P气道口与肺内压之差，V气体流速)层流R=8L/r4(气体黏度，L管道长度，圆周率，r管道半径)湍流R=VfL/2r5(f磨擦系数)小气道R20%,64,Figure7-14FromJ.B.West,RespiratoryPhysiology:TheEssentials(8thed.),2008,usedwithpermissionbyLippincottWilliams&Wilkins,65,气道阻力与顺应性,条件机械通气潮气量（VT）顺应性计算有效动态顺应性动态顺应性静态顺应性,66,67,顺应性计算,有效动态顺应性=VT/Ppeak动态顺应性=VT/P1静态顺应性=VT/Pplat,68,有效动态顺应性,易于监测包括了弹性阻力及非弹性阻力因素PpeakP1Pplat意义不同ARDS吸气末平台压30cmH2O,69,时间常数,不能单从吸气压和顺应性去估计潮气量的大小，必须考虑时间因素计算时间常数=顺应性X阻力举例婴儿顺应性2ml/cmH2O,阻力40cmH2O/L/s时间常数=0.002L/cmH2OX40cmH2O/L/s=0.08s意义1个时间常数63%VT3个时间常数95%VT5个时间常数100%VT,70,内源性PEEP,定义呼气末肺泡内仍保持正压,这一压力称为内源性PEEP原因时间常数延长而呼气时间不足,71,72,73,74,75,内源性PEEP的危害,增加呼