无创正压通气抑制慢性阻塞性肺疾病急性加重期患者吸气肌肉活动的机制

Mechanism of inspiratory muscle activity inhibition during noninvasive positive pressure ventilation in patients for acute exacerbation of chronic obstructive pulmonary disease

目的探讨无创正压通气（NIPPV）抑制慢性阻塞性肺疾病（COPD）急性发作期患者吸气肌肉活动的机制。方法12例COPD急性加重期患者接受感觉最舒适通气压力水平时的NIPPV,观察患者吸气肌肉用力和呼吸方式的变化。结果与自主呼吸（SB）相比,NIPPV时的潮气量（VT）显著增高（从408ml升到462ml,P〈0.05）;接受NIPPV后VT的增高很迅速,第一呼吸周期时即明显增高。SB时的跨膜压（Pdi）为14.04cmH2O,而NIPPV时为10.98cmH2O,比SB时约减少22%（P〈0.05）。NIPPV时Pdi的下降从第一个呼吸周期即开始,然后进一步迅速下降,治疗至第5个呼吸周期时与SB时相比开始有显著差异（P〈0.05）。SB时的呼吸肌做功（Wp）分别为0.47J/breath和0.95J/L;而NIPPV时分别为0.34J/breath和0.69J/L,比SB时分别减少28%和27%（P〈0.05）。NIPPV时Wp的下降也是从第一个呼吸周期即开始,然后进一步迅速下降,治疗至第5个呼吸周期时与SB时相比开始有显著差异（P〈0.05）。结论本实验证实了NIPPV治疗COPD急性加重期患者时吸气肌肉活动的非化学性抑制作用的存在;这种非化学性抑制作用的产生与NIPPV治疗的开始基本同步,能有效改善患者的呼吸肌肉疲劳。

Objective To investigate the mechanism of inspiratory muscle activity inhibition during noninvasive positive pressure ventilation （NIPPV） in the patients for acute exacerbation of chronic obstructive pulmonary disease（COPD）. Methods 12 patients with acute exacerbation of COPD were recruit for the study. NIPPV pressure settings were titrated to the highest level that the patients could comfortably tolerance during the adaptation process and then the change of inspiratory muscle effort and breathing pattern of the patients were measured. Results As compared with spontaneous breathing, NIPPV significantly increased tidal volume（from 408 ml to 462 ml, P〈0.05）; the transdiaphragrnatic pressure decreased from 14.04 cm H2O to 10.98 cm H2O and work of breathing decreased from 0.47 J/breath and 0.95 J/L to 0.34 J/breath and 0.69 J/L （decreased 22%,28% and 27% respectively, P 〈0.05）. After NIPPV started, tidal volume increased rapidly, while the transdiaphragrnatic pressure and work of breathing decreased rapidly from the first breath. Conclusions The present study confirms the existence of nonchemical inhibition of inspiratory activity during NIPPV in the patients for acute exacerbation of COPD. The nonchemical inhibition of inspiratory activity took effect and improved inspiratory muscles fatigue as soon as NIPPV stared.