Vieillard-Baron Antoine, Chergui Karim, Augarde Roch, Prin Sebastien, Page Bernard, Beauchet Alain, Jardin François
University Hospital Ambroise Paré, Assistance Publique Hôpitaux de Paris, France.
Am J Respir Crit Care Med. 2003 Sep 15;168(6):671-6. doi: 10.1164/rccm.200301-135OC. Epub 2003 Jul 17.
It has long been known that there are cyclic changes in arterial pressure during mechanical ventilation. They are caused by cyclic changes in both the right and left ventricular stroke output, occurring in opposite phases. As a result, arterial pulse pressure is increased during inspiration and decreased during expiration. A cyclic improvement in left ventricular systolic function could thus be expected during mechanical lung inflation. We tested this hypothesis in 31 septic patients who were mechanically ventilated in controlled mode by combining left ventricular measurements by transesophageal echocardiography with invasive arterial pressure recordings and Doppler analysis of pulmonary venous flow and right and left ventricular stroke volume. Lung inflation by tidal ventilation significantly improved left ventricular stroke volume (26 +/- 0.4 cm3/m2 [mean +/- SEM] vs. 22.3 +/- 0.4 cm3/m2 at end deflation). Beat-to-beat analysis of pulmonary venous flow velocity illustrated the boosting effect of lung inflation on pulmonary venous return. The beneficial effect of inspiration thus appeared directly related to a significant increase in left ventricular diastolic volume (60.3 +/- 1.5 cm3/m2 vs. 53.3 +/- 1.4 cm3/m2 at end-expiration) and to a lesser extent to an improved left ventricular ejection fraction. We concluded that the transient beneficial hemodynamic effect of tidal ventilation on the left ventricular pump is essentially mediated by an improved left ventricular filling.
长期以来，人们已经知道在机械通气过程中动脉压存在周期性变化。它们是由左右心室每搏输出量的周期性变化引起的，且这两个心室的变化相位相反。因此，吸气时动脉脉压升高，呼气时降低。由此可以预期，在机械通气肺膨胀时左心室收缩功能会有周期性改善。我们通过经食管超声心动图测量左心室、有创动脉压记录以及肺静脉血流和左右心室每搏量的多普勒分析，对31例接受控制模式机械通气的脓毒症患者验证了这一假设。潮气量通气引起的肺膨胀显著改善了左心室每搏量（潮气量通气时为26±0.4cm³/m²[均值±标准误]，呼气末时为22.3±0.4cm³/m²）。肺静脉血流速度的逐搏分析显示了肺膨胀对肺静脉回流的促进作用。因此，吸气的有益作用似乎直接与左心室舒张末期容积显著增加有关（呼气末时为53.3±1.4cm³/m²，吸气时为60.3±1.5cm³/m²），在较小程度上与左心室射血分数的改善有关。我们得出结论，潮气量通气对左心室泵的短暂有益血流动力学效应主要是由左心室充盈改善介导的。
