Objective: To compare the trigger delay and work of trigger between neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients with intrinsic positive end-expiratory pressure (PEEP) during mechanical ventilation. Methods: AECOPD patients with intrinsic PEEP (PEEPi) greater than or equal to 3 cmH(2)O (1 cmH(2)O=0.098 kPa) were enrolled during invasive mechanical ventilation. Subjects were ventilated with low, medium and high pressure under either NAVA or PSV mode. Servo Tracker software continuously recorded the waveform of ventilator and respiratory mechanics indexes (including respiratory frequency, inspiratory tidal volume (Vti), minute ventilation volume (VE), peak airway pressure (PIP), inspiratory time), and calculated trigger and expiratory conversion delay time, work of trigger and total work of breath. Results: A total of 14 AECOPD patients were enrolled with the average PEEPi (4.3±1.3) cmH(2)O. PSV inspiratory trigger delay time was positively correlated with PEEPi (r=0.913, P<0.05). Compared with PSV, NAVA significantly decreased trigger delay time in low, medium and high pressure level groups [(48±17) ms vs. (167±86) ms, (63±65) ms vs. (247±240) ms, (63±49) ms vs. (342±192) ms,respectively all P<0.05]. Similar results were shown as to work of trigger [(0.92±0.36) μV∙s vs. (1.22±0.70) μV∙s, (1.08±0.51) μV∙s vs. (1.62±1.25) μV∙s, (1.20±0.96) μV∙s vs. (2.29±1.02) μV∙s, all P<0.05]. Trigger delay time increased according to the increase of pressure level in PSV mode. Conclusion: The presence of PEEPi in AECOPD patients leads to obvious trigger delay under PSV mode, which is positively correlated with PEEPi level. NAVA significantly reduces trigger delay time and work of trigger compared with PSV mode.
目的： 比较神经调节辅助通气（NAVA）和压力支持通气（PSV）对存在内源性呼气末正压（PEEP）的慢性阻塞性肺疾病急性加重（AECOPD）患者机械通气时触发延迟和触发功的影响。 方法： 纳入内源性PEEP≥3 cmH(2)O（1 cmH(2)O=0.098 kPa）且进行有创机械通气的AECOPD患者，分别在NAVA和PSV模式下采用低、中、高3种通气压力支持水平。Servo Tracker软件持续记录呼吸机波形、呼吸力学指标[包括呼吸频率、吸气潮气量（Vti）、分钟通气量（VE）、气道峰压（PIP）、吸气时间]，计算触发和吸呼气转换延迟时间、触发功和总呼吸功。 结果： 共纳入14例AECOPD患者，内源性PEEP为（4.3±1.3）cmH(2)O。PSV模式吸气触发延迟时间与内源性PEEP呈正相关（r=0.913，P<0.05）。与PSV比，NAVA在低、中、高通气压力支持水平时均能降低触发延迟时间[（48±17）ms比（167±86）ms，（63±65）ms比（247±240）ms，（63±49）ms比（342±192）ms，P值均<0.05]和触发功[（0.92±0.36）μV∙s比（1.22±0.70）μV∙s，（1.08±0.51）μV∙s比（1.62±1.25）μV∙s，（1.20±0.96）μV∙s比（2.29±1.02）μV∙s，P值均<0.05]。PSV模式时，随着通气压力支持水平的升高，触发延迟时间明显延长[（167±86）ms，（247±240）ms，（342±192）ms，P<0.05]。 结论： 存在内源性PEEP的AECOPD患者，在PSV模式下存在明显的触发延迟，且与内源性PEEP水平呈正相关。NAVA可显著缩短触发延迟时间，并减少触发功。.
Keywords: Acute exacerbation of chronic obstructive pulmonary disease; Intrinsic positive end-expiratory pressure; Neurally adjusted ventilatory assist; Pressure support ventilation; Trigger delay; Work of trigger.