Albaiceta Guillermo M, Taboada Francisco, Parra Diego, Luyando Luis H, Calvo Juan, Menendez Rafael, Otero Jesús
Department of Intensive Medicine, Hospital Universitario Central de Asturias, Oveido, Spain.
Am J Respir Crit Care Med. 2004 Nov 15;170(10):1066-72. doi: 10.1164/rccm.200312-1644OC. Epub 2004 Aug 18.
The inflection points of the pressure-volume curve have been used for setting mechanical ventilation in patients with acute lung injury. However, the lung status at these points has never been specifically addressed. In 12 patients with early lung injury we traced both limbs of the pressure-volume curve by means of a stepwise change in airway pressure, and a computed tomography (CT) scan slice was obtained for every pressure level. Although aeration (increase in normally aerated lung) and recruitment (decrease in nonaerated lung) were parallel and continuous along the pressure axis during inflation, loss of aeration and derecruitment were only significant at pressures below the point of maximum curvature on the deflation limb of the pressure-volume curve. This point was related to a higher amount of normally aerated tissue and a lower amount of nonaerated tissue when compared with the lower inflection point on both limbs of the curve. Aeration at the inflection points was similar in lung injury from pulmonary or extrapulmonary origin. There were no significant changes in hyperinflated lung tissue. These results support the use of the deflation limb of the pressure-volume curve for positive end-expiratory pressure setting in patients with acute lung injury.
压力-容积曲线的拐点已被用于指导急性肺损伤患者的机械通气设置。然而，这些点处的肺状态从未得到过具体研究。我们对12例早期肺损伤患者通过逐步改变气道压力来描绘压力-容积曲线的两个分支，并在每个压力水平获取一张计算机断层扫描（CT）图像。尽管在充气过程中，通气（正常通气肺增加）和复张（未通气肺减少）在压力轴上是平行且连续的，但在压力-容积曲线呼气支上，通气丧失和肺萎陷仅在低于最大曲率点的压力水平时才显著。与曲线两个分支的较低拐点相比，该点与更多的正常通气组织和更少的未通气组织相关。肺或肺外源性肺损伤时拐点处的通气情况相似。过度充气的肺组织无明显变化。这些结果支持将压力-容积曲线的呼气支用于急性肺损伤患者的呼气末正压设置。
