Lessard M R, Guérot E, Lorino H, Lemaire F, Brochard L
Department of Anesthesia, Hôpital de l'Enfant-Jésus, Quebec, Canada.
Anesthesiology. 1994 May;80(5):983-91.
Pressure-controlled (PCV) and pressure-controlled inverse ratio ventilation (PCIRV) have been proposed instead of volume-controlled conventional ratio ventilation (VC) with positive end-expiratory pressure (PEEP) for patients with adult respiratory distress syndrome (ARDS). The advantages advocated with the use of PCIRV are to decrease airway pressures and to improve gas exchange. However, most studies did not compare PCIRV and VC while keeping both the level of ventilation and end-expiratory alveolar pressure (total-PEEP) constant.
Nine patients with moderate to severe ARDS (lung injury score 2.83 +/- 0.18) had their lungs ventilated with VC, PCV with a conventional ratio (I:E 1:2; PC 1/2), and PCIRV (I:E 2:1 and 3:1; PC 2/1 and PC 3/1, respectively). Ventilator settings were adjusted to keep tidal volume, respiratory rate, FIo2, and total-PEEP constant in every mode. With each mode, a complete set of ventilatory, hemodynamic, and gas exchange parameters was obtained after 30 min.
In PC 3/1, the data obtained could not be strictly compared to the other modes because total-PEEP was higher despite external-PEEP being set at zero. For the other modes (VC, PC 1/2, and PC 2/1), despite differences in peak airway pressures, no difference was noted for end-inspiratory and end-expiratory static airway pressures (which better reflect alveolar pressures) nor for lung and respiratory system compliance. Arterial oxygenation deteriorated slightly with PC 2/1 despite a higher mean airway pressure, whereas alveolar ventilation tended to be slightly, but not significantly, improved (lower PaCo2). A decrease in systolic and mean arterial pressure also was observed with PC 2/1 without other significant hemodynamic change.
In this prospective controlled study, no short-term beneficial effect of PCV or PCIRV could be demonstrated over conventional VC with PEEP in patients with ARDS.
对于成人呼吸窘迫综合征（ARDS）患者，有人提议采用压力控制通气（PCV）和压力控制反比通气（PCIRV）来替代带呼气末正压（PEEP）的容量控制常规通气（VC）。主张使用PCIRV的优点是可降低气道压力并改善气体交换。然而，大多数研究在保持通气水平和呼气末肺泡压力（总PEEP）不变的情况下，并未对PCIRV和VC进行比较。
9例中重度ARDS患者（肺损伤评分2.83±0.18）分别接受VC、常规比例的PCV（I:E 1:2；PC 1/2）和PCIRV（I:E 2:1和3:1；PC分别为2/1和PC 3/1）通气。在每种模式下，调整呼吸机设置以保持潮气量、呼吸频率、吸入氧浓度（FIo2）和总PEEP不变。每种模式下，30分钟后获取一套完整的通气、血流动力学和气体交换参数。
在PC 3/1模式下，尽管外部PEEP设定为零，但总PEEP较高，因此所获得的数据无法与其他模式进行严格比较。对于其他模式（VC、PC 1/2和PC 2/1），尽管气道峰压有所不同，但吸气末和呼气末静态气道压力（能更好地反映肺泡压力）以及肺和呼吸系统顺应性并无差异。尽管平均气道压力较高，但PC 2/1模式下动脉氧合略有恶化，而肺泡通气倾向于略有改善（PaCo2降低），但无显著差异。PC 2/1模式下还观察到收缩压和平均动脉压下降，无其他显著血流动力学变化。
在这项前瞻性对照研究中，对于ARDS患者，未证明PCV或PCIRV相较于带PEEP的传统VC有短期有益效果。
