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Table 1 Characteristics of included studies

From: Noninvasive ventilation with helium–oxygen mixture in hypercapnic COPD exacerbation: aggregate meta-analysis of randomized controlled trials

RCT Sample size Baseline FEV1 (ml/s) He/O2 mixture Ventilator type/helium canister connection Ventilation mode/daily duration/study duration Interface Between NIV sessions gas NIV failure criteria Baseline pH Baseline PaCO2 (mmHg) Predicted mortality rate (%) SMR Predicted NIV failure rate (%) Observed NIV failure rate (%)
He/O2 Air/O2 He/O2 Air/O2 He/O2 Air/O2 He/O2 Air/O2
Jolliet_2003 59 64 740 ± 362 78/22 ICU ventilator with connection to the air inlet NIPSV/≥ 6H/until recovery Oronasal mask Air/O2 Intubation 7.32 ± 0.06 7.30 ± 0.07 65 ± 13 63 ± 15 24 0.33 45 13.5 20.3
Maggiore_2010 102 102 900 ± 400 65/35 ICU ventilator with connection to the O2 inlet NIPSV/≥ 6H/until recovery Facial full mask Air/O2 Intubation 7.28 ± 0.07 7.28 ± 0.06 73 ± 18 72 ± 15 15 0.67 40 24.5 30.4
Jolliet_2016 225 220 785 ± 360 78/22 ICU ventilator with dedicated connection NIPSV/≥ 6H/≤ 72H Oronasal mask He/O2 Intubation or death in the ICU 7.29 ± 0.05 7.30 ± 0.06 71 ± 16 68 ± 17 15 0.37 25 14.7 14.5
  1. FEV1 forced expiratory volume in 1 s, NIPSV noninvasive pressure support ventilation, SMR standardized mortality ratio