van Genderingen Huibert R, van Vught Adrianus J, Jansen Jos R C
Department of Clinical Physics and Informatics, Vrije Universiteit Medical Center, PO Box 7057, 1007 MB, Amsterdam, The Netherlands.
Intensive Care Med. 2003 Feb;29(2):233-40. doi: 10.1007/s00134-002-1586-x. Epub 2002 Dec 14.
To assess the degree of linearity between lung volume and impedance change by electrical impedance tomography (EIT) in pigs with acute lung injury and to investigate regional impedance changes during a pressure-volume maneuver.
Experimental animal study in a university research laboratory.
Nine pigs with lung injury induced by lung lavage.
The lungs were insufflated to four different lung volumes. Next the lungs were inflated in steps up to 40 cm H(2)O and then in steps deflated.
EIT measurements were performed. Impedance was highly linear with lung volume ( r(2)=0.97). From the pressure-volume maneuver regional pressure-impedance (P-I) curves were obtained in the upper half (ventral) and lower half (dorsal) of the thoracic cross-section. Excellent fit was found of the regional P-I curves with a predefined sigmoid equation ( r(2)=0.998). The P-I curves after lavage were markedly different than before lavage. The P-I curves recorded after lavage displayed a strong heterogeneity on the inflation limb: Lower corner pressure (traditionally lower inflection point) was significantly higher in the dorsal (28.3+/-4.1 cm H(2)O) than in the ventral region (17.5+/-4.3 cm H(2)O). The deflation limb displayed a more homogeneous pattern. Upper corner pressure and true inflection point, where the curve slope is maximal, in the dorsal region were only slightly higher than in the ventral region (1-2 cm H(2)O).
EIT and automated curve fitting provide information on regional lung inflation and deflation which may be of clinical use for optimizing ventilator settings.
通过电阻抗断层成像（EIT）评估急性肺损伤猪肺容积与阻抗变化之间的线性程度，并研究压力 - 容积操作期间的区域阻抗变化。
大学研究实验室的实验动物研究。
9只通过肺灌洗诱导肺损伤的猪。
将肺充气至四个不同的肺容积。接下来，将肺逐步充气至40 cm H₂O，然后逐步放气。
进行EIT测量。阻抗与肺容积高度线性相关（r² = 0.97）。通过压力 - 容积操作，在胸段横截面的上半部分（腹侧）和下半部分（背侧）获得了区域压力 - 阻抗（P - I）曲线。发现区域P - I曲线与预定义的S形方程拟合良好（r² = 0.998）。灌洗后的P - I曲线与灌洗前明显不同。灌洗后记录的P - I曲线在充气支上显示出强烈的异质性：背侧的下角压力（传统上的下拐点）（28.3±4.1 cm H₂O）显著高于腹侧区域（17.5±4.3 cm H₂O）。放气支显示出更均匀的模式。背侧区域的上角压力和曲线斜率最大处的真正拐点仅比腹侧区域略高（1 - 2 cm H₂O）。
EIT和自动曲线拟合提供了有关区域肺充气和放气的信息，这可能对优化呼吸机设置具有临床应用价值。
