无创正压通气不同压力上升时间对慢性阻塞性肺疾病急性发作期患者呼吸功的影响

Effect of Different Inspiratory Rise Time on Work of Breathing in Patients with Acute Exacerbation of COPD during Noninvasive Positive Pressure Ventilation

目的探讨无创正压通气(NPPV)不同压力上升时间对慢性阻塞性肺疾病急性发作期(AECOPD)患者呼吸功的影响。方法 11例AECOPD患者接受NPPV治疗,压力支持水平设置为试验前感觉舒适的水平,压力上升时间设置为0.1、0.3和0.5 s(分别称为T1、T2和T3),观察患者吸气肌肉用力和呼吸方式的变化。结果①与自主呼吸(SB)相比,NPPV时T1、T2和T3呼吸频率稍增快,但无显著差异;SB时吸气时间(Ti)为(0.97±0.04)s,T2和T3时Ti均显著增高,分别为(1.08±0.05)s和(1.14±0.06)s(P<0.05);与SB时的潮气量(VT)和分钟通气量(VE)相比,NPPV的VT和VE稍升高,但无显著增高(P>0.05)。②SB时的压力时间乘积(PTP)与跨膈压(Pdi)分别为(19.02±1.86)cm H2O.s和(12.21±2.56)cm H2O,3种不同压力上升时间时的患者PTP均明显减少(P<0.01),分别为T1(7.09±1.04)cmH2O.s、T2(10.43±2.04)cmH2O.s和T3(12.94±1.72)cmH2O.s;NPPV时的Pdi也显著降低(P<0.01),分别为T1(4.98±0.93)cm H2O、T2(6.89±1.21)cm H2O和T3(8.11±1.29)cm H2O。与T1比较,T2和T3的PTP和Pdi则增高(P<0.05)③SB时的呼吸做功(WOB)为(8.29±0.43)J/L,T1、T2和T3时的WOB均明显减低(P<0.01)。与T3比较,T1的WOB降低更明显(P<0.05)。结论在接受NPPV治疗的AECOPD患者中,感觉舒适的压力支持水平时不同压力上升时间均可减轻患者的吸气肌肉负担,3种不同的压力上升时间均可以在保证患者的通气同时,降低患者的吸气努力,T1时的Pdi、PTP和WOB分别较SB时下降59.2%、62.7%和49%。T1时患者感觉最舒适,又能更有效地减轻吸气负荷。

Objective To investigate the effects of different inspiratory rise time during noninvasive positive pressure ventilation(NPPV) on work of breathing in patients with acute exacerbation of chronic obstructive pulmonary disease(COPD).Methods Eleven patients with acute exacerbation of COPD received different inspiratory rise time(0.1sec,0.3sec,0.5sec) during NPPV.The changes of inspiratory muscle effort and breathing pattern of the patients were observed.Results The average respiratory rate,minute ventilation,and tidal volume were higher during NPPV compared with spontaneous breathing.But the changes of average minute ventilation and tidal volume were not significant(P>0.05).The pressure time product(PTP),transdiaphragmatic pressure(Pdi),and work of breathing of inspiratory muscle reduced significantly during different inspiratory rise time as compared with spontaneous breathing(P<0.01).PTP,Pdi,and work of breathing reduced 59.2%,62.7%,and 49% respectively when inspiratory rise time was 0.1sec.They reduced more significantly during inspiratory rise time of 0.1sec.Conclusions The present study confirms NPPV can unload inspiratory muscles in patients with acute exacerbation of COPD.It is more effective to reduce inspiratory load when inspiratory rise time is set at 0.1sec while the patients feel most comfortable.