呼气末正压对急性呼吸窘迫综合征肺复张容积及氧合影响的临床研究

目的　评价呼气末正压 (PEEP)对急性呼吸窘迫综合征 (ARDS)肺复张容积的影响 ,探讨ARDS患者 PEEP的选择方法。方法　以 11例血流动力学稳定、接受机械通气的 ARDS患者为研究对象 ,采用压力容积曲线法分别测定 PEEP为 5、10、15 cm H2 O(1cm H2 O=0 .0 98k Pa)时的肺复张容积 ,观察患者动脉血气、肺机械力学和血流动力学变化。结果　 PEEP分别 5、10和 15 cm H2 O时肺复张容积分别为 (4 0 .2±15 .3) ml、 (12 3.8± 4 3.1) ml和 (178.9± 4 3.5 ) m l,随着 PEEP水平的增加 ,肺复张容积亦明显增加 (P均 <0 .0 5 )。动脉氧合指数也随着 PEEP水平增加而增加 ,且其变化与肺复张容积呈正相关 (r=0 .4 83,P<0 .0 1)。不同 PEEP条件下 ,患者的肺静态顺应性无明显变化 (P>0 .0 5 )。将患者按有无低位转折点 (L IP)分为有 L IP组与无 L IP组 ,两组患者的肺复张容积都随着 PEEP水平的增加而增加 ,其中 PEEP15 cm H2 O时 L IP组患者的肺复张容积大于无 L IP组 (P<0 .0 5 )。结论　 PEEP水平越高 ,肺复张容积越大 ,肺复张容积增加与动脉氧合指数的变化呈正相关

Effects of positive end-expiratory pressure on lung recruited volume and oxygenation in patients with acute respiratory distress syndrome

OBJECTIVE: To access alveolar recruitment with positive end-expiratory pressure (PEEP) and to correlate the recruited volume with arterial oxygenation in acute respiratory distress syndrome (ARDS). METHODS: Eleven ventilated patients satisfying criteria of ARDS were included in the study group. Recruited volume of three different PEEP levels 5 cm H2O, 10 cm H2O, 15 cm H2O (1 cm H2O=0.098 kPa)] were measured by pressure-volume curve method. Effects of different PEEP levels on lung mechanics and gas exchange were compared. RESULTS: Lung recruited volume elevated when PEEP increased from 5 cm H2O to 15 cm H2O(40.2+/-15.3)ml vs. (123.8+/-43.1)ml vs. (178.9+/-43.5)ml, all P<0.05]. Arterial oxygenation index increased with PEEP and a positive correlation was found between recruited volume and changes in arterial oxygenation index (r=0.483, P<0.01). There was no significant difference during the static compliance at different PEEP levels at a fixed tidal volume (P>0.05). Recruited volume at PEEP 15 cm H2O in the patient group with lower inflection point (LIP) was larger than the group without LIP. CONCLUSION: Recruited volume increases with PEEP, and the PEEP-induced increase in arterial oxygenation is significantly correlated to recruited volume.