ARDS患者行俯卧位通气时应用死腔分数评价疗效

目的 探讨死腔分数 (dead space fraction, VD/VT) 是否可以作为判断重度急性呼吸窘迫综合征 (acute respiratory distress syndrome, ARDS) 患者行俯卧位通气 (prone position ventilation, PPV) 治疗有效的指标.方法30例重度ARDS患者 (PaO2/FiO2<100 mm H) g纳入本研究.按不同病因分为肺内源性ARDS组 (ARDSp) 和肺外源性ARDS组 (ARDSexp) , 记录仰卧位和俯卧位通气2 h、4 h、6 h、8 h、10 h的PaO2/FiO2和VD/VT.结果PPV使VD/VT下降和PaO2/FiO2升高, 在PPV不同时间点PaO2/FiO2、VD/VT差异均有统计学意义 (P<0.001) , VD/VT的最大变化发生在PPV 4 h, 而PaO2/FiO2在PPV 6 h后才出现最佳变化 (PaO2/FiO2上升>20mm H) g.VD/VT与PaO2/FiO2经Pearson相关性分析呈正相关关系 (t=0.67, P<0.001) .ARDSp组与PPV前比较, PPV 2 h PaO2/FiO2和VD/VT无明显变化, 通气4 h PaO2/FiO2明显升高 (t=2.37, P=0.03) 、VD/VT明显下降 (t=5.26, P=0.001) , 通气6 h PaO2/FiO2和VD/VT较通气4 h无明显变化;ARDSexp组与PPV前比较, PPV 2 h PaO2/FiO2明显升高 (t=4.65, P=0.04) 、VD/VT明显下降 (t=3.56, P=0.009) , 且4 h较通气2 h无明显变化, 通气6 h PaO2/FiO2和VD/VT仍维持在相同水平.结论 VD/VT可作为评价ARDS患者行PPV治疗有效的指标, 在评价PPV疗效上比PaO2/FiO2更灵敏, 可以指导肺内、外源性ARDS患者的治疗.

Effects of Dead Space Fraction on Prone Position Ventilation in ARDS Patients

Objective To evaluate the effects of dead space fraction (VD/VT) on prone position ventilation (PPV) in patients with severe acute respiratory distress syndrome (ARDS) . Methods A total of 30 patients with severe ARDS (PaO2/FiO2< 100 mm H) g were enrolled in this study and were divided into pulmonary insult ARDS group (ARDSp) and extrapulmonary insult ARDS group (ARDSexp) according to different etiological factors. PaO2/FiO2 and VD/VT were recorded in supine position and prone position at 2 h, 4 h, 6 h, 8 h and 10 h after ventilation. Results VD/VT decreased and PaO2/FiO2 increased with PPV. PaO2/FiO2 and VD/VT showed significant difference at different time points (P < 0.001) , with the biggest change of VD/VT at PPV 4 h and the best transformation of PaO2/FiO2 (increase of PaO2/FiO2>20 mm H) g after PPV 6 h. There was a positive correlation between VD/VT and PaO2/FiO2 by Pearson correlation analysis (t=0.67, P < 0.001) . In ARDSp group, there was no significant change of PaO2/FiO2 and VD/VT between supine position and PPV 2 h. At PPV 4 h, PaO2/FiO2 significantly increased (t=2.37, P=0.03) and VD/VT significantly decreased (t =5.26, P=0.001) . No significant difference was found in PaO2/FiO2 and VD/VT at PPV 4 h to PPV 6 h. In ARDSexp group, PaO2/FiO2 significantly increased (t=4.65, P=0.04) and VD/VT significantly decreased (t=3.56, P=0.009) at PPV 2h. There was no significant change from PPV 2 h to PPV 4 h. PaO2/FiO2 and VD/VT remained at the same level at PPV 6 h. Conclusion VD/VT can be used as an effective index to evaluate the efficacy of PPV in patients with ARDS and is more sensitive than PaO2/FiO2, so it can be used to guide the treatment of patients with pulmonary and extrapulmonary ARDS.