环路分析在机械通 气中的应用武警医学院附属医院呼吸科 刘阳Critical in assessing the Mechanically Ventilated Patient机械通气目的n提供足够的肺泡通气量（VA） n在安全的供氧浓度下达到适宜的动脉氧分压 n胸腔压升高的情况下避免发生气压 n病人舒适 n合适的呼吸肌负担 n良好的人机同步进行波形分析的必要性lPatientventilator dyssynchrony imposes an additional burden on the respiratory system and may increase the morbidity of critically ill patients.Thille A W, Rodriguez P, Cabello B, et al. Intensive Care Med, 2006. 32(10): p. 1515-22. Ignorance of these issues may prevent the ventilator from achieving its goals and may cause patient harm.Georgopoulos D, Prinianakis G, and Kondili E. Intensive Care Med, 2006. 32(1): p. 34 -47. Inspection of pressure, flow and volume waveforms represents a valuable tool for the physician to recognize and take the appropriate action to improve patientventilator synchronyEumorfia Kondili, Nektaria Xirouchaki and Dimitris Georgopoulos. Curr Opin Crit Care 13:8489.Nilsestuen J O and Hargett K D. Respir Care, 2005. 50(2): p. 202-34; discussion 232-4.Pressure versus TimeInspiration ExpirationPaw (cm H2O)Time (sec) TIPeak Inspiratory Pressure PIPPEEPPEEPTEPressure-Volume LoopControlledAssistedSpontaneousVol (ml)Paw(cm H2O)I: Inspiration E: ExpirationIEEEIIFlow-Volume LoopVolume (ml)Volume (ml)PEFRFRCInspirationExpirationFlow (L/min)Flow (L/min)PIFRVTMechanical MonitoringAirway PressuresStatic or Plateau Pressure静 态顺应性和平台压Separates resistance from elastic recoil吸气末测量Should be kept 10 L/min 常常提示撤机失败VE,VA, and PaCO2Flow versus TimeThe flow-time curve can be used to detect:Waveform shapeType of breathingPresence of Auto-PEEP (Intrinsic PEEP)Patients response to bronchodilatorsAdequacy of inspiratory time in pressure control ventilationPresence and rate of continuous air leaks判断流速波形Inspiratory flow patterns can vary based on the flow waveform setting or the set breath type as illustrated减速波 呼气流速波形在下一个吸气相呼气流速波形在下一个吸气相 开始之前呼气流速突然回到开始之前呼气流速突然回到0, 0, 这是由于小气道在呼气时过早这是由于小气道在呼气时过早 地关闭地关闭, , 使部分气体阻滞在肺泡使部分气体阻滞在肺泡 内而引起内而引起Auto-PEEP( Auto-PEEP( PEEPiPEEPi) )存存 在在不同类型呼吸下，五种类型的流速-时间 曲线评估支气管扩张剂的反应effect of inspiratory time in pressure control on flow delivery to the patient.may be desirable in some cases患者对支气管扩张剂的反应性BeforeTime (sec)Flow (L/min)PEFRAfterLong TEHigher PEFRShorter TE漏气对吸呼切换的影响：漏气会导 致吸气流速下降缓慢，达不到预设 的切换标准（set termination threshold）吸气峰流量Tinsp45% 15%Threshold can not be reachedthe period of mechanical inflation must match the period of neural inspiratory time (the duration of inspiratory effort), and the period of mechanical inactivity must match the neural expiratory time While the ventilator was still pumping gas into the patient, his expiratory muscles were recruited, causing a bump in the airway-pressure curve. That the flow never returned to zero throughout expiration reflected the presence of autopositive end-expiratory pressure. Auto PEEP吸呼切换延迟Delayed termination present患者呼气肌开始活动时，呼吸机的吸气过程 还未完成，因此发生亚临床的人机对抗。 Note there is also a small airway pressure spike near the end of mechanical inflation, which coincides with the patients neural expiratory activity.切换延迟Cycle Criteria?吸气预置流速不足Flow (L/min)Time (sec)Normal AbnormalActive Inspiration or AsynchronyActive Inspiration or Asynchrony Patients effort吸气预置流速不足或者患者主动吸气(SIMV)/volume-limited/pressure support approach“double breathing”assist volume control 恒定流速患者持续吸气，气道压力下 降，在呼气阀打开时，发生 double breathingAir TrappingInspirationExpirationNormalNormal PatientPatientTime (sec)Flow (L/min)Air Trapping Auto-PEEPPRESSURE-TIME CURVESBreath type delivered to the patient Work required to trigger the breath Breath timing (inspiration vs exhalation) Pressure waveform shape Adequacy of inspiration Adequacy of inspiratory plateau Adequacy of inspiratory flow Results and adequacy of a static mechanics maneuver Adequacy of the Rise Time settingBreath type delivered to the patientBreath type delivered to the patientCMV, with auto-flow onMeasuring Static Mechanicsillustrates a stable static pressure plateau measurement that differentiates the pressure caused by flow through the breathing circuit and the pressures required to inflate the lungs. The pressure-time curve can be used to verify the stability of the plateau when calculating static compliance and resistance.C 代表不稳定的气道平台压 力，常见原因为漏气或者患 者出现自主吸气Assessing Rise Time 吸气斜率Chiumello D, Pelosi P, Croci M, et al.,Eur. Respir. J., 2001. 18(1): p. 107-114.A the rise to pressure may be too slow.B ideal waveform 恰当的斜 率设置C A rise time that is too fast流速不足 Adequate FlowInadequate FlowPaw (cm H2O)Time (sec)Inadequate Flow 预置流速不足The dished-out appearance of the airway pressure waveform illustrates the changes from the passive breath when flow does not meet patient demand.Progressive increases in patient effort during breaths 2 and 3 were created by manually lifting the test lungTriggering difficulty and unnecessary patient work 触发困难第三次为患者触发的通气 ，虽然患者触发了呼吸机 ，但是P-T曲线呈下凹型 ，显示了预制流速不足 第一次呼吸患者未达到触发阈值，但 是启动了按需阀，为时间触发； The sen