機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件

1、機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件主要內(nèi)容臨床重要的呼吸力學(xué)指標(biāo)呼吸力學(xué)指標(biāo)測(cè)定的方法和意義呼吸力學(xué)曲線的分析主要內(nèi)容臨床重要的呼吸力學(xué)指標(biāo)呼吸力學(xué)應(yīng)用進(jìn)展呼吸力學(xué)監(jiān)護(hù)已成為呼吸監(jiān)護(hù)的重要內(nèi)容壓力、阻力、順應(yīng)性、 auto-PEEP呼吸力學(xué)曲線監(jiān)測(cè)應(yīng)用日趨廣泛提倡呼吸力學(xué)指導(dǎo)下的個(gè)體化通氣治療肺保護(hù)通氣策略的實(shí)施需要呼吸力學(xué)指導(dǎo)呼吸力學(xué)應(yīng)用進(jìn)展呼吸力學(xué)監(jiān)護(hù)已成為呼吸監(jiān)護(hù)的重要內(nèi)容Volume Change Gas FlowPressure Difference 自 主 呼 吸Volume Change Gas FlowPressurVolume C

2、hangeTimeGas FlowPressure Difference 機(jī) 械 通 氣Volume ChangeTimeGas FlowPress重要的呼吸力學(xué)指標(biāo)壓力 阻力 容量 峰壓力 吸氣阻力 吸氣潮氣量平臺(tái)壓力 呼氣阻力 呼氣潮氣量 平均氣道壓力 彈性阻力 可壓縮氣量胸膜腔內(nèi)壓力 呼氣末肺容積 autoPEEP重要的呼吸力學(xué)指標(biāo)壓力 重要的呼吸力學(xué)指標(biāo)順應(yīng)性靜態(tài)順應(yīng)性動(dòng)態(tài)順應(yīng)性呼吸系統(tǒng)順應(yīng)性肺順應(yīng)性（C=V/ P，正常肺0.2-0.3L/cmH2O）胸壁順應(yīng)性（C= V/ Ppl，正常0.2 L/cmH2O）流速呼吸功 P-V曲線P0.1重要的呼吸力學(xué)指標(biāo)順應(yīng)性呼吸力學(xué)三要素壓力（P

3、）、阻力（R）、流速（V）P= RV壓力和流速為可控因素流速對(duì)時(shí)間積分得到容量控制壓力時(shí)阻力改變可導(dǎo)致容量降低控制流速時(shí)阻力增大可導(dǎo)致壓力增高呼吸力學(xué)三要素壓力（P）、阻力（R）、流速（V）timePressurePEEPPIPPplatAlveolar Distending (recoil) Pressure difference (Pdis)Flow-Resistive Pressure difference (Pres) 壓力組成dP = R x Flow + dV / C sttimePressurePEEPPIPPplatAlveol機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件壓力監(jiān)測(cè)部

4、位壓力監(jiān)測(cè)部位流速監(jiān)測(cè)部位流速監(jiān)測(cè)部位床旁監(jiān)測(cè)氣道壓力的意義峰壓力增高而平臺(tái)壓無(wú)改變 氣道阻力增高（分泌物堵塞、氣管痙攣）峰壓力與平臺(tái)壓同時(shí)增高 提示肺或胸壁擴(kuò)張受限 明顯腹脹肺不張氣胸肺水腫、ARDS、肺炎autoPEEP人-機(jī)對(duì)抗氣道峰壓降低（管路漏氣、氣囊漏氣）床旁監(jiān)測(cè)氣道壓力的意義峰壓力增高而平臺(tái)壓無(wú)改變肺（氣道）阻力與順應(yīng)性的改變都可導(dǎo)致氣道壓力的改變通過(guò)氣道壓力的改變可以推測(cè)病變的性質(zhì)和部位肺（氣道）阻力與順應(yīng)性的改變都可導(dǎo)致氣道壓力的改變通過(guò)氣道壓 Paw (cm H2O)NormalNormal PPlat(Normal Compliance)Increased PIPIncr

5、eased PTA(increased Airway Resistance)NormalPIPPPlatHigh RawPIPPPlatIncreased Airway Resistance Paw (cm H2O)NormalNormal PPl DECREASED COMPLIANCETime (sec)Paw (cm H2O)Low CompliancePIPPPlatNormalPIPPPlatNormal PPlat(Normal Compliance)Increased PPlat(Decreased Compliance)NormalPIP DECREASED COMPLIANC

6、ETi小結(jié)壓力升高或降低都應(yīng)進(jìn)一步查找原因壓力增高肺或胸腔順應(yīng)性下降（變硬）氣流阻力增高順應(yīng)性降低和阻力增高處理原則不同小結(jié)壓力升高或降低都應(yīng)進(jìn)一步查找原因 阻 力 阻 力氣道阻力的計(jì)算公式和意義RI=（PIPPpla）/吸氣末流速RE=（PplaPEEP）/最大呼氣流速 氣管插管阻力在總的呼吸阻力中占很大比例與管腔內(nèi)徑關(guān)系最大流速和氣管插管長(zhǎng)度氦-氧混合氣也可減低吸氣阻力，減少呼吸功氣道阻力的計(jì)算公式和意義RI=（PIPPpla）/吸氣末流氣道阻力大氣道以湍流為主，占總阻力的80%小氣道以層流為主，占總阻力的20%正常人氣道阻力為1cmH2O/L/S哮喘和COPD患者氣道阻力為5-10cmH

7、2O/L/S8號(hào)氣管插管阻力為5 cmH2O/L/S7號(hào)氣管插管阻力為8 cmH2O/L/S 氣管插管時(shí)氣道阻力相當(dāng)于中度哮喘發(fā)作氣道阻力大氣道以湍流為主，占總阻力的80%氣道阻力的計(jì)算方法Resistance =PIP - PlateauPeak FlowResistance = 20 - 151 L / sec= 5 cmH20 / L / secPlateau Pressure 15 cmPIP 20 cmVTE 500 ccPeak Flow = 60 L/min氣道阻力的計(jì)算方法Resistance =PIP - PlVolume Change = Pressure Differen

8、ce x Compliance of the BalloonVolumePressureD VD PC = D VD P 順應(yīng)性Volume Change =VolumePressureD靜態(tài)順應(yīng)性與動(dòng)態(tài)順應(yīng)性順應(yīng)性肺的“硬度”或彈性變性能力StaticNo flowdynamicflow and resistance靜態(tài)順應(yīng)性與動(dòng)態(tài)順應(yīng)性順應(yīng)性肺的“硬度”或彈性變性能力肺順應(yīng)性監(jiān)測(cè)的意義靜態(tài)順應(yīng)性（Cs）反映肺和胸壁的彈性（彈性阻力）特征,排除了氣道阻力成分動(dòng)態(tài)順應(yīng)性（Cd）反映氣道的阻力（非彈性阻力）和呼吸系統(tǒng)彈性（彈性阻力）特征，氣道阻力可明顯影響Cd的水平順應(yīng)性的動(dòng)態(tài)變化趨勢(shì)更有意義肺

9、順應(yīng)性監(jiān)測(cè)的意義靜態(tài)順應(yīng)性（Cs）反映肺和胸壁的彈性（ 順應(yīng)性測(cè)定要求The gold standard for measuring compliance and resistance utilizes a volume breath delivered with a square wave flow and adequate plateau40PCIRCcmH2OINSPLminEXPPLOT SETUP302010 010-2080604020020-804060V.04812s2610UNFREEZE 順應(yīng)性測(cè)定要求The gold standard for Compliance Cal

10、culations 500 15-5= 50 ml/cmH20Compliance =VtePlateau - PEEPPlateau Pressure 15 cmPEEP 5 cmVTE 500 ccPeak Flow = 60 L/minVTE 500 cc10 cmH20Compliance Calculations 500 區(qū)分肺順應(yīng)性和胸壁順應(yīng)性的意義CRS=（CLCW）/（CL+CW）胸壁順應(yīng)性相對(duì)穩(wěn)定時(shí)，CRS的動(dòng)態(tài)變化可代表肺的順應(yīng)性改變?cè)u(píng)價(jià)PEEP對(duì)血流動(dòng)力 學(xué)的影響Crs = Vt / dPdist (aw)Ccw = Vt / dPdist (pl)CL = Vt / P

11、dist (aw - pl)區(qū)分肺順應(yīng)性和胸壁順應(yīng)性的意義CRS=（CLCW）/（CL胸壁順應(yīng)性降低對(duì)跨肺壓的影響胸壁順應(yīng)性降低對(duì)跨肺壓的影響機(jī)械通氣時(shí)氣體分布機(jī)械通氣時(shí)氣體分布機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件機(jī)械通氣時(shí)氣體在肺內(nèi)分布特點(diǎn)自主呼吸時(shí)氣體主要進(jìn)入肺的下垂區(qū)域和肺周邊胸膜下部位機(jī)械通氣時(shí)氣體主要分布在肺非下垂區(qū)和大氣道內(nèi)ARDS機(jī)械通氣時(shí)氣體主要進(jìn)入非下垂區(qū)域COPD和哮喘患者除存在肺內(nèi)氣體分布不勻外，還存在較嚴(yán)重的小氣道塌陷氣流波形（方波和正弦）對(duì)氣體的分布無(wú)明顯影響機(jī)械通氣時(shí)氣體在肺內(nèi)分布特點(diǎn)自主呼吸時(shí)氣體主要進(jìn)入肺的下 機(jī)械通氣

12、時(shí)肺內(nèi)氣體分布 機(jī)械通氣時(shí)肺內(nèi)氣體分布機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件提倡應(yīng)用自主通氣模式提倡應(yīng)用自主通氣模式壓力-容積曲線壓力-容積曲線機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件P-V曲線的測(cè)定方法大注射器法吸氣阻斷法持續(xù)氣流法準(zhǔn)靜態(tài)順應(yīng)性測(cè)定注意事項(xiàng)鎮(zhèn)靜、肌松近口端壓力和流速監(jiān)測(cè)注意干擾因素（如明顯腹脹）P-V曲線的測(cè)定方法大注射器法PEEP對(duì)血流動(dòng)力學(xué)的影響Ppl=PEEPCL/（CL+CW）正常人CLCW，故Ppl1/2（PEEP）相當(dāng)于大約一半的胸腔內(nèi)壓（PE

13、EP 或PEEPi）傳遞到胸膜腔，引起胸內(nèi)壓增高。當(dāng)肺實(shí)變、肺順應(yīng)性減小時(shí)，傳遞比例減少。而胸壁順應(yīng)性減小時(shí)，氣道內(nèi)壓力向胸膜腔內(nèi)傳遞增加。ARDSPEEP水平在15cmH2O以下，可不必考慮對(duì)PCWP讀數(shù)的影響。肺順應(yīng)性增大（肺氣腫）或胸壁順應(yīng)性減小時(shí)較低水平的PEEP就可能干擾肺毛細(xì)血管楔壓的判斷，測(cè)定值高于實(shí)際水平。PEEP對(duì)血流動(dòng)力學(xué)的影響Ppl=PEEPCL/（PEEP對(duì)血流動(dòng)力 學(xué)的影響Compensation of the PCWP for PEEP:Compliant lungs corrected PCWP = PCWP - PEEP (mm Hg)Noncompliant

14、lungs corrected PCWP = PCWP - 1/4 PEEP (mm Hg)PEEP (cm H2O) /1.36 = PEEP (mm Hg)PEEP對(duì)血流動(dòng)力 學(xué)的影響Compensation of 機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件Low VT vs High VTLow PEEP vs High PEEP HFOVProne ProtectiveLow VT vs High VTLow PEEP vs HAuto-PEEP檢查方法呼氣末阻斷氣流法當(dāng)存在嚴(yán)重氣道狹窄及氣體陷閉時(shí)不能反映真實(shí)的肺泡壓力，用平臺(tái)壓更準(zhǔn)確吸氣末肺容積（VEI）食道內(nèi)壓測(cè)定Auto-PEEP

15、檢查方法呼氣末阻斷氣流法Auto-PEEP ManeuverPress Exp Pause key to schedule automatic expiratory pause maneuverDuring the next exhalation, the inspiratory and expiratory valves will close and pressure will equilibrate between the circuit and the patient PTEnd Exp HoldAuto-PEEP ManeuverPress Exp Pa 痰液栓對(duì)呼吸力學(xué)評(píng)估的影響 痰

16、液栓對(duì)呼吸力學(xué)評(píng)估的影響auto PEEP臨床跡象不能解釋的心動(dòng)過(guò)速、低血壓，特別是機(jī)械通氣治療剛開(kāi)始時(shí)（由人工通氣過(guò)度為機(jī)械通氣時(shí)）患者觸發(fā)每次呼吸非常費(fèi)力患者的吸氣努力并非每次都能觸發(fā)呼吸下一次吸氣開(kāi)始時(shí)呼氣（喘鳴音）仍在進(jìn)行壓力流速圖形顯示異常auto PEEP臨床跡象不能解釋的心動(dòng)過(guò)速、低血壓，特別是動(dòng)態(tài)過(guò)度充氣對(duì)循環(huán)功能影響動(dòng)態(tài)過(guò)度充氣對(duì)循環(huán)功能影響Air TrappingInspirationExpirationNormalPatientTime (sec)Flow (L/min)Air TrappingAuto-PEEPAir TrappingInspirationExpirat

17、機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件auto PEEP監(jiān)測(cè)auto PEEP監(jiān)測(cè)auto PEEP的處理改變呼吸機(jī)參數(shù)增加呼氣時(shí)間，減少通氣頻率，減少潮氣量降低病人的通氣需要減少碳水化合物的攝取，減少死腔通氣，治療焦慮、寒戰(zhàn)、疼痛、發(fā)熱減低呼吸道阻力（用大口徑的氣管插管，經(jīng)常吸痰避免分泌物潴留，應(yīng)用支氣管擴(kuò)張劑）加用適當(dāng)?shù)耐庠葱訮EEP，一般為PEEPi的75%左右auto PEEP的處理改變呼吸機(jī)參數(shù)外源性PEEP改善觸發(fā)的機(jī)理外源性PEEP改善觸發(fā)的機(jī)理重癥哮喘患者外源性PEEP的影響重癥哮喘患者外源性PEEP的影響死腔通氣問(wèn)題解剖死腔正常人100-150ml機(jī)械通氣時(shí)可明顯增大（延長(zhǎng)

18、管、濕化器）肺泡死腔肺栓塞時(shí)VD/VT可顯著增大（0.6）COPD、Asthma時(shí)V/Q比例失衡， VD/VT增大VD/VT增大將導(dǎo)致分鐘通氣量顯著增大死腔通氣問(wèn)題解剖死腔呼吸力學(xué)測(cè)定的質(zhì)量控制No significant leaksCompliance should subtract out circuit compliance, especially in pediatricsManual calculations often contribute to errors呼吸力學(xué)測(cè)定的質(zhì)量控制No significant leakRespiratory Mechanics Requiremen

19、ts For AccuracyThe patient must be at rest during peak and plateau pressure measurementsAdding plateau should not restrict exhalation and create auto-PEEPPlateau time must not be too short or too long Respiratory Mechanics RequiremPatient Effort During Inspiratory Plateau PTDiaphragm EffortsPlateau

20、Pressure = ?Patient Effort During InspiraPlateau Time Too Short 500 20-5= 33 ml / cmH20 500 15 - 5= 50 ml / cmH20Results in falsely low compliance values !Displayed Plateau Pressure 20 cmPEEP 5 cmActual Plateau Pressure 15 cm VTE 500 ccPTPlateau Time Too Short 500 Static Compliance Leaks and/or Too

21、Long a Plateau 500 15-5= 50 ml / cmH20 500 10 - 5= 100 ml / cmH20Results in falsely high compliance values !Displayed Plateau Pressure 10 cmPEEP 5 cmActual Plateau Pressure 15 cm VTE 500 ccPTStatic Compliance Leaks and/oAir LeakVolume (ml)Time (sec)Air LeakAir LeakVolume (ml)Time (sec)AAir LeakVolum

22、e (ml)Pressure (cm H2O)Air LeakAir LeakVolume (ml)Pressure (cAir LeakInspirationExpirationVolume (ml)Flow (L/min)Air Leak in mLNormalAbnormalAir LeakInspirationExpirationVResponse to BronchodilatorBeforeTime (sec)Flow (L/min)PEFRAfterLong TEHigher PEFRShorter TEResponse to BronchodilatorBefoInadequa

23、te Inspiratory Flow Adequate FlowTime (sec)Inadequate FlowPaw (cm H2O)Inadequate Inspiratory Flow AdInadequate Inspiratory FlowFlow (L/min)Time (sec)NormalAbnormalActive Inspiration or AsynchronyPatients effortInadequate Inspiratory FlowFlo機(jī)械通氣的呼吸力學(xué)基礎(chǔ)(同名530)課件Flow versus TimeACCELERATINGDECELERATING

24、SINESQUAREFlow versus TimeACCELERATINGDELung Compliance Changes and the P-V LoopVolume (mL)Preset PIPVT levelsPaw (cm H2O)COMPLIANCEIncreasedNormalDecreasedPressure Targeted VentilationLung Compliance Changes and thVPPEEP: 3 cmH2OVPPEEP: 8 cmH2OOptimising PEEPVPPEEP: 3 cmH2OVPPEEP: 8 cmH2O呼氣阻力增加Prolonged expiratory flow indicates an obstruction to exhalation and may be caused by obstruction of a large airway, bronchospasm, or expiratory valve failure of the ventilatorTimeFlow呼氣阻力增加Prolonged expiratory floInsufficient Expiratory