Chin Med J (Engl). 2005 Dec 20;118(24):2034-40.
Respiratory muscle fatigue plays an important role in acute exacerbations of chronic obstructive pulmonary disease (AECOPD). In previous clinical studies, non-invasive positive pressure ventilation (NPPV) was proved to be successful only for AECOPD patients with severe respiratory failure. We hypothesized that, the outcomes of AECOPD would be improved if NPPV is early (within 24 to 48 hours of admission) administered in those patients with respiratory muscle fatigue and mild respiratory insufficiency, especially in patients without fulfilling the conventional criteria of mechanical ventilatory support.
A prospective multicentre randomized controlled trial was conducted in 19 hospitals in China over 16 months. Three hundred and forty-two AECOPD patients with pH > or = 7.25 and PaCO2 > 45 mmHg were recruited on general ward and randomly assigned to standard medical treatment (control group) or early administration of additional NPPV (NPPV group).
The characteristics of two groups on admission were similar. The number of AECOPD patients requiring intubations in NPPV group was much fewer than that of the control group (8/171 vs 26/71, P = 0.002). Subgroup analysis showed the needs for intubation in mildly (pH > or = 7.35) and severe (pH < 7.30) acidotic patients in NPPV group were both decreased (9/80 vs 2/71, P = 0.047 and 8/30 vs 3/43, P = 0.048, respectively). The mortality in hospital was reduced slightly by NPPV but with no significant difference (7/171 vs 12/171, P = 0.345). Respiratory rate (RR), scale for accessory muscle use and arterial pH improved rapidly at the first 2 hours only in patients of NPPV group. After 24 hours, the differences of pH, PaO2, scale for accessory muscle use and RR in NPPV group [(7.36 +/- 0.06) mmHg, (72 +/- 22) mmHg, (2.5 +/- 0.9)/min, (22 +/- 4)/min] were statistically significant compared with control group (7.37 +/- 0.05) mmHg, (85 +/- 34) mmHg, (2.3 +/- 1.1)/min, (21 +/- 4)/min, P < 0.01 for all comparisons].
The early use of NPPV on general ward improves arterial blood gas and respiratory pattern, decreases the rate of need for intubation in AECOPD patients. NPPV is indicative for alleviating respiratory muscle fatigue and preventing respiratory failure from exacerbation.
呼吸肌疲劳在慢性阻塞性肺疾病急性加重期（AECOPD）中起重要作用。在以往的临床研究中，无创正压通气（NPPV）仅被证明对严重呼吸衰竭的AECOPD患者有效。我们假设，如果对有呼吸肌疲劳和轻度呼吸功能不全的患者早期（入院后24至48小时内）给予NPPV，尤其是对那些不符合机械通气支持常规标准的患者，AECOPD的结局将会改善。
在中国19家医院进行了一项为期16个月的前瞻性多中心随机对照试验。342例pH≥7.25且PaCO2>45 mmHg的AECOPD患者在普通病房入选，并随机分为标准药物治疗组（对照组）或早期加用NPPV组（NPPV组）。
两组入院时的特征相似。NPPV组需要插管的AECOPD患者数量远少于对照组（8/171对26/71，P = 0.002）。亚组分析显示，NPPV组轻度（pH≥7.35）和重度（pH<7.30）酸中毒患者的插管需求均降低（分别为9/80对2/71，P = 0.047；8/30对3/43，P = 0.048）。NPPV使住院死亡率略有降低，但差异无统计学意义（7/171对12/171，P = 0.345）。仅NPPV组患者在最初2小时呼吸频率（RR）、辅助肌使用评分和动脉pH迅速改善。24小时后，NPPV组的pH、PaO2、辅助肌使用评分和RR差异[（7.36±0.06）mmHg，（72±22）mmHg，（2.5±0.9）/min，（22±4）/min]与对照组[（7.37±0.05）mmHg，（85±34）mmHg，（2.3±1.1）/min，（21±4）/min]相比有统计学意义（所有比较P<0.01）。
在普通病房早期使用NPPV可改善动脉血气和呼吸模式，降低AECOPD患者的插管率。NPPV有助于缓解呼吸肌疲劳并防止呼吸衰竭加重。
