Jonson B, Richard J C, Straus C, Mancebo J, Lemaire F, Brochard L
Medical Intensive Care Unit, INSERM U492, Hôpital Henri Mondor, AP-HP Paris XII University, Créteil, France.
Am J Respir Crit Care Med. 1999 Apr;159(4 Pt 1):1172-8. doi: 10.1164/ajrccm.159.4.9801088.
Measuring elastic pressure-volume (Pel-V) curves of the respiratory system and the volume recruited by a positive end-expiratory pressure (PEEP) allows one to study the pressure range over which recruitment occurs in acute lung injury (ALI), and to explain how recruitment affects the compliance. Pel-V curves were measured with the low flow inflation technique in 11 patients mechanically ventilated for ALI. Curve I was recorded during inflation from the volume attained after a prolonged expiration (6 s) at PEEP (9.0 +/- 2.2 cm H2O), and Curve II after expiration to the elastic equilibrium volume at zero end-expiratory pressure (ZEEP). By using the end-expiratory volume of the breaths, the curves were aligned on a common volume axis to determine the effect of a single complete expiration. In each patient, Curve II (from ZEEP) was shifted toward lower volumes than Curve I. The volume shift, probably due to derecruitment, was 205 +/- 100 ml at 15 cm H2O (p < 0.01) and 78 +/- 93 ml at 30 cm H2O (p < 0.01); thus, during inflation from ZEEP, the volume deficit was successively regained over a pressure range up to at least 30 cm H2O. At any pressure, compliance was higher on the curve from ZEEP than from PEEP, by 10.0 +/- 8.7 ml/cm H2O at 15 cm H2O (p < 0.01), and by 5.4 +/- 5.5 at 30 cm H2O (p < 0.01). It is concluded that in ALI, a single expiration to ZEEP leads to lung collapse. High compliance during insufflation from ZEEP indicates that lung recruitment happens far above the lower inflection point of the Pel-V curve.
测量呼吸系统的弹性压力-容积（Pel-V）曲线以及呼气末正压（PEEP）所募集的容积，能够使人们研究急性肺损伤（ALI）中发生肺复张的压力范围，并解释肺复张如何影响肺顺应性。采用低流量充气技术对11例因ALI接受机械通气的患者测量了Pel-V曲线。曲线I是在从PEEP（9.0±2.2 cm H2O）下长时间呼气（6秒）后达到的容积开始充气时记录的，曲线II是在呼气至呼气末压力为零（ZEEP）时的弹性平衡容积后记录的。通过使用呼吸的呼气末容积，将曲线在共同的容积轴上对齐，以确定单次完全呼气的影响。在每名患者中，曲线II（从ZEEP开始）比曲线I向更低的容积偏移。这种容积偏移可能是由于肺萎陷，在15 cm H2O时为205±100 ml（p<0.01），在30 cm H2O时为78±93 ml（p<0.01）；因此，从ZEEP开始充气时，容积不足在高达至少30 cm H2O的压力范围内逐渐恢复。在任何压力下，从ZEEP开始的曲线上的顺应性均高于从PEEP开始的曲线，在15 cm H2O时高10.0±8.7 ml/cm H2O（p<0.01），在30 cm H2O时高5.4±5.5（p<0.01）。得出结论，在ALI中，单次呼气至ZEEP会导致肺塌陷。从ZEEP开始充气时的高顺应性表明肺复张发生在Pel-V曲线下拐点之上很远的位置。
