ards肺复张—workshop-课件PPT.pptVIP

ARDS肺复张 ——Workshop ARDS大量肺泡塌陷 02-22 02-23 02-22 肺顺应性明显降低 Reduced range of volume excursion: Low compliance Flattening at low and high volumes: Lower and upper inflection points Volume Pressure NORMAL ARDS 顺应性曲线明显向右下移位 肺内分流增加 肺泡塌陷：ARDS重力依赖区，炎症或不张区 生理性低氧缩血管反应：障碍 肺泡塌陷的后果之一-剪切力伤 Crit Care Med, 2001, 29:1049 –1055. Pressure Volume Pressure wedge Shear force 1. 控制性肺膨胀(SI)法 2. PEEP递增法 3. 压力控制(PCV)法 肺开放的实施方法 Crit Care Med 2004; 32:2371–2377 RM－SI 控制性肺膨胀法(SI) PS/CPAP: 压力支持调至 0 cmH2O，PEEP 40 cmH2O，持续时间30 s BIPAP：高压与低压均为40 cmH2O，持续时间30 s PEEP递增法（IP） PC/BIPAP: 调节气道压上限为35 cmH2O，先保持压力差不变，低压每30 s递增5 cmH2O，高压随之上升5 cmH2O，直至PEEP为35 cmH2O，维持30 s。随后低压和高压每30 s递减5 cmH2O RM－IP 压力控制法(PCV) PC/BIPAP:高压 40 cmH2O，低压16-20 cmH2O，维持90 – 120 s，呼吸频率不变 RM －PCV 肺复张后 氧合 血流动力学 呼吸力学 肺容积 肺内分流 In a low ARDS, the compliance curve shifts to the right. This results in either low volumes for any set pressure or higher pressure for any set volume. Why does V/Q matching matter? And….. Why does the supine position contribute to a V/Q mismatch for the ARDS patient? We have to have two things in order for diffusion to occur successfully. We have to have gas in the alveoli and we have to have adequate perfusion in the capillary. When the blood and gas match, diffusion is an efficient process for oxygen delivery. When all goes well, Oxygen will diffuse from the alveoli into the capillary and CO2 will diffuse from the capillary into the alveoli to be removed through exhalation based upon a simple pressure gradient. There are several factors that can hinder this process in an injured or diseased lung. If we have inadequate ventilation, inadequate perfusion or a diffusion defect, Oxygen delivery can be impaired. If we have a decreased (low) V/Q ratio, the result is typically some degree of pulmonary shunting. Pulmonary shunting is defined as that portion of the cardiac output (blood) that enters the left side of the heart without exchanging gases with alveolar gases. No