环路分析在机械通气中的应用.ppt

环路分析在机械通气中的应用 机械通气目的 提供足够的肺泡通气量（VA） 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, 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 patient–ventilator synchrony Eumorfia Kondili, Nektaria Xirouchaki and Dimitris Georgopoulos. Curr Opin Crit Care 13:84–89. Pressure versus Time Pressure-Volume Loop Flow-Volume Loop Mechanical Monitoring Airway Pressures Static 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 静态顺应性 阻力 R = ?P / flow 阻力 Opposition to airflow by nonelastic forces Normally 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 Measured Volumes Tidal 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 Volumes Minute 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 Flow versus Time The 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