Physiological effects of high-intensity versus low-intensity noninvasive positive pressure ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease: a randomised controlled trial

Background High-intensity noninvasive positive pressure ventilation (NPPV) is a novel ventilatory approach to maximally decreasing elevated arterial carbon dioxide tension (PaCO 2 ) toward normocapnia with stepwise up-titration of pressure support. We tested whether high-intensity NPPV is more effective than low-intensity NPPV at decreasing PaCO 2 , reducing inspiratory effort, alleviating dyspnoea, improving consciousness, and improving NPPV tolerance in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods In this physiological, randomised controlled trial, we assigned 24 AECOPD patients to undergo either high-intensity NPPV ( n = 12) or low-intensity NPPV ( n = 12). The primary outcome was PaCO 2 24 h after randomisation. Secondary outcomes included gas exchange other than PaCO 2 24 h after randomisation, inspiratory effort, dyspnoea, consciousness, NPPV tolerance, patient–ventilator asynchrony, cardiac function, ventilator-induced lung injury (VILI), and NPPV-related adverse events. Results Inspiratory positive airway pressure 24 h after randomisation was significantly higher (28.0 [26.0–28.0] vs. 15.5 [15.0–17.5] cmH 2 O; p = 0.000) and NPPV duration within the first 24 h was significantly longer (21.8 ± 2.1 vs. 15.3 ± 4.7 h; p = 0.001) in the high-intensity NPPV group. PaCO 2 24 h after randomisation decreased to 54.0 ± 11.6 mmHg in the high-intensity NPPV group but only decreased to 67.4 ± 10.6 mmHg in the low-intensity NPPV group (p = 0.008). Inspiratory oesophageal pressure swing, oesophageal pressure–time product (PTPes)/breath, PTPes/min, and PTPes/L were significantly lower in the high-intensity group. Accessory muscle use and dyspnoea score 24 h after randomisation were also significantly lower in that group. No significant between-groups differences were observed in consciousness, NPPV tolerance, patient–ventilator asynchrony, cardiac function, VILI, or NPPV-related adverse events. Conclusions High-intensity NPPV is more effective than low-intensity NPPV at decreasing elevated PaCO 2 , reducing inspiratory effort, and alleviating dyspnoea in AECOPD patients. Trial registration : ClinicalTrials.gov (NCT04044625; registered 5 August 2019).