呼吸机波形分析在机械通气的应用（可编辑）

呼吸机波形分析在机械通气的应用（可编辑） 呼吸机波形分析在机械通气的应用 环路分析在机械通 气中的应用 Critical in assessing the Mechanically Ventilated Patient 武警医学院附属医院呼吸科 刘阳机械通气目的 提供足够的肺泡通气量(V ) A 在安全的供氧浓度下达到适宜的动脉氧分压 胸腔压升高的情况下避免发生气压 病人舒适 合适的呼吸肌负担 良好的人机同步进行波形分析的必要性Patient?ventilator 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, 20063210: 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. 321: 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 patient?ventilator Nilsestuen J O and Hargett K D. Respir synchrony Care, 2005. 502: p. 202-34; discussion Eumorfia Kondili, Nektaria Xirouchaki and Dimitris 232-4. Georgopoulos. Curr Opin Crit Care 13:84?89.P Pr re es ss su ur re e v ve er rs su us s T Tiim me e Peak Inspiratory Pressure PIP Inspiration Expiration TI TE PEEP PEEP Time sec P cm H O aw 2Pressure-Volume Loop Pressure-Volume Loop E E E I I I P aw cm H O 2 Spontaneous Controlled Assisted I: Inspiration E: Expiration Vol mlFlow-Volume Loop Flow-Volume Loop Inspiration PIFR Volume ml Volume ml FRC V T PEFR Expiration Flow L/min Flow L/minMechanical Monitoring C Com omp pon one en nt ts s of ofI In nf fl lat ati ion on P Pr re es ss su ur re e PIP PIP Transairway Pressure P TA Exhalation Valve Opens P plateau Inspiratory Pause Palveolar Expiration Expiration Time sec Begin Inspiration Begin Expiration P cm H O aw 2Airway 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 35 cm H2O to avoid volutrauma Allows computation of static compliance, which decreases as the lungs become stiff Vt Static compliance PplatPEEP静态顺应性 定容模式下压力 、流速、容量-时 间曲线简图 Vt Static compliance PplatPEEP通气模式为定容 the pressure in the ventilator circuit "inspiratory plateau pressure" equals the amount of pressure needed to distend the lungs and chest wall by the amount of tidal volume just delivered 因此静态顺应性可以表示为Crs 潮气量/气道平台压-PEEPi. Normal Crs is approximately 100 mL/cm H2O in the range of usual operational lung volumeVt Static compliance PplatPEEPVtStatic compliance Crs, st PplatPEEP 肺纤维化的P-V曲线阻力 P I PR ?P / flow P P i i n n P P o o u u t t f f l l o o w w P p l a t R阻力Opposition to airflow by nonelastic forcesNormally 2-5 cmH2O/L/sec气道分泌物增多或者气 道痉挛时会显著增加对于评价支气管扩张剂 的效果十分有用 PpeakPplat Raw flow Increased Airway Resistance P PI IP P High R High R aw aw Normal Normal P PI IP P P P P P Plat Plat Plat Plat Increased PIP Increased P TA increased Airway Resistance Normal P Plat Normal Compliance Normal P Pa aw w c cm m H H O O 2 2Measured VolumesTidal Volume 潮气量 5-7 mL/kg IBW VT VA + VD VD 1 mL/lb IBW Mechanical tidal volume varies with disease process 定容量模式下设定VT与呼出VT 的差值为漏气量 leak: ETT cuff leak Pneumothorax Tubing disconnection 随着气道顺应性的下降,在 PCV模式下,VT将出现显著下 降Measured VolumesMinute Ventilation VE 分钟通气量 VT x f 4-8 L/minute VE of 6 L/min associated with a PaCO2 of 40 mm Hg High PaCO2 with a high VE indicates increased dead space or increased metabolism 自主呼吸时(T-管实验)VE 10 L/min 常常提示撤机失败VE,VA, and PaCO2 VCO2 PCO2 ?800VA VAVE V Df? V TV D? P a C O2P E C O2V D V TP a C O2Flow versus TimeThe flow-time curve can be used to detect: Waveform shape Type of breathing Presence of Auto-PEEP Intrinsic PEEP Patient’s response to bronchodilators Adequacy of inspiratory time in pressure control ventilation Presence and rate of continuous air leaks判断流速波形 减速波Inspiratory flow patterns can vary based on the flow waveform setting or the set breath type as illustrated? 呼气流速波形在下 一个吸气相开始呼气流速波形在下一个吸气相开始 不同类型呼吸下,五种类型的流速-时间 之 之前 前呼 呼气 气流 流速 速突 突然 然回 回到 到0 0,, 这 这是 是由 由于 于 小气道在呼气时过早地关闭, 使部 曲线 小气道在呼气时过早地关闭, 使部 分气体阻滞在肺泡内而引起Auto- 分气体阻滞在肺泡内而引起Auto- PEEP PEEPi存在 PEEP PEEPi存在may be desirable in some cases effect of inspiratory time in 评估支气管扩张剂的反应 pressure control on flow delivery to the patient.患 患者 者对 对支 支气 气管 管扩 扩张 张剂 剂的 的反 反应 应性 性 After Before Time sec Long T E PEFR Shorter T E Higher PEFR Flow L/min吸气峰流量 45% 15%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) Tinsp Threshold can not be reachedAuto PEEP the 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 curveThat the flow never returned to zero throughout expiration reflected the presence of auto?positive end-expiratory pressure. 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 patient’s neural expiratory activity.切换延迟 Cycle Criteria?吸气预置流速不足 吸气预置流速不足 Active Inspiration or Asynchrony Active Inspiration or Asynchrony Patient’s effort Normal Abnormal Time sec Flow L/min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 Trapping Air Trapping Inspiration Normal Normal Patient Patient Time sec Air Trapping Auto-PEEP Expiration Flow L/minPRESSURE-TIME CURVESBreath type delivered to the patientWork required to trigger the breathBreath timing inspiration vs exhalationPressure waveform shapeAdequacy of inspirationAdequacy of inspiratory plateauAdequacy of inspiratory flowResults and adequacy of a static mechanics maneuverAdequacy of the Rise Time settingBreath type delivered to the patientBreath type delivered to the patient CMV, 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.,EurRespir. J., 2001. 181: 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 Flow Inadequate Flow Time sec Paw cm H O 2Inadequate 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 The sensitivity setting is ?4 cm H2O 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 第二次患者仍打开了按需阀,启动了 第一次呼吸患者未达到触发阈值,但 自主呼吸,自主呼吸末,时间触发了 是启动了按需阀,为时间触发; 一次同步间歇指令通气 吸气时 的作功大小 吸气做功主要由吸气负压大 小和持续时间长短决定,吸 气负压越大和持续时间越长 ,吸气功越大,反之亦然