Table 1 Baseline characteristics of the patients
Characteristic | High-intensity NPPV (n = 12) | Low-intensity NPPV (n = 12) | p value |
|---|---|---|---|
Demographics | |||
 Age, years | 72.3 ± 9.0 | 70.8 ± 8.2 | 0.608 |
 Male, n (%) | 8 (66.7) | 8 (66.7) |  > 0.999 |
 Height, cm | 169.0 (165.0–170.0) | 165.0 (160.0–172.8) | 0.906 |
 Predicted body weight, kg | 63.7 (57.2–66.0) | 61.5 (53.1–68.5) | 0.838 |
 Actual body weight, kg | 64.6 ± 13.0 | 67.8 ± 16.3 | 0.605 |
 Body mass index, kg/cm2 | 23.0 ± 4.3 | 24.3 ± 5.4 | 0.538 |
Smoking history | |||
 Former smoker, n (%) | 5 (41.7) | 9 (75.0) | 0.214 |
 Current smoker, n (%) | 3 (25.0) | 3 (25.0) |  > 0.999 |
 Smoking index, pack·year | 30.0 (12.5–54.4) | 25.0 (10.0–38.1) | 0.663 |
Lung function | |||
 FEV1, L | 0.5 ± 0.1 | 0.6 ± 0.2 | 0.087 |
 FEV1, % of predicted value | 21.8 ± 6.5 | 27.1 ± 10.2 | 0.145 |
 FVC, L | 1.4 ± 0.3 | 1.7 ± 0.6 | 0.129 |
 FVC, % of predicted value | 43.9 ± 8.3 | 53.7 ± 15.2 | 0.066 |
 FEV1/FVC, % | 38.0 ± 14.4 | 38.9 ± 14.9 | 0.888 |
 FEV1/FVC, % of predicted value | 54.0 ± 18.9 | 51.8 ± 22.1 | 0.792 |
 Within the previous 1 year, n (%) | 2 (16.7) | 5 (41.7) | 0.371 |
 At ICU discharge, n (%) | 10 (83.3) | 7 (58.3) | 0.371 |
Reason for acute exacerbation | |||
 Respiratory infection, n (%) | 7 (58.3) | 7 (58.3) |  > 0.999 |
 Acute heart failure, n (%) | 2 (16.7) | 1 (8.3) |  > 0.999 |
 Exposure to air pollutants, n (%) | 1 (8.3) | 1 (8.3) |  > 0.999 |
 Undetermined, n (%) | 2 (16.7) | 3 (25.0) |  > 0.999 |
Arterial blood gas at ICU admission | |||
 pH | 7.26 ± 0.07 | 7.29 ± 0.04 | 0.220 |
 PaCO2, mmHg | 90.7 ± 12.8 | 87.2 ± 17.9 | 0.584 |
 PaO2/FiO2, mmHg | 214 ± 46 | 189 ± 54 | 0.219 |
 Bicarbonates, mmol/L | 35.6 ± 5.9 | 36.0 ± 5.4 | 0.881 |
Arterial blood gas at randomisation | |||
 pH | 7.31 ± 0.07 | 7.33 ± 0.06 | 0.441 |
 PaCO2, mmHg | 83.4 ± 12.3 | 78.6 ± 11.3 | 0.331 |
 PaO2/FiO2, mmHg | 231 ± 63 | 240 ± 60 | 0.701 |
 Bicarbonates, mmol/L | 37.2 ± 7.6 | 37.2 ± 5.7 | 0.993 |