ARDS患者行俯卧位通气时应用死腔分数评价疗效

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

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(PaO_2/FiO_2<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PaO_2/FiO_2和VD/VT.结果PPV使VD/VT下降和PaO_2/FiO_2升高,在PPV不同时间点PaO_2/FiO_2、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PaO_2/FiO_2在PPV 6 h后才出现最佳变化(PaO_2/FiO_2上升>20mm H)g.VD/VT与PaO_2/FiO_2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 PaO_2/FiO_2和VD/VT无明显变化,通气4 h PaO_2/FiO_2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 PaO_2/FiO_2和VD/VT较通气4 h无明显变化;ARDSexp组与PPV前比较,PPV 2 h PaO_2/FiO_2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 PaO_2/FiO_2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PaO_2/FiO_2更灵敏,可以指导肺内、外源性ARDS患者的治疗.

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 of30patients with severe ARDS(PaO2/FiO2<100mmHg)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/FiO2and VD/VT were recorded in supine position and prone position at2h,4h,6h,8h and10h after ventilation.Results VD/VT decreased and PaO2/FiO2increased with PPV.PaO2/FiO2and VD/VT showed significant difference at different time points(P<0.001),with the biggest change of VD/VT at PPV4h and the best transformation of PaO2/FiO2(increase of PaO2/FiO2>20mmHg)after PPV6h.There was a positive correlation between VD/VT and PaO2/FiO2by Pearson correlation analysis(t=0.67,P<0.001).In ARDSp group,there was no significant change of PaO2/FiO2and VD/VT between supine position and PPV2h.At PPV4h,PaO2/FiO2significantly 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/FiO2and VD/VT at PPV4h to PPV6h.In ARDSexp group,PaO2/FiO2significantly increased(t=4.65,P=0.04)and VD/VT significantly decreased(t=3.56,P=0.009)at PPV2h.There was no significant change from PPV2h to PPV4h.PaO2/FiO2and VD/VT remained at the same level at PPV6h.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.