Characteristics of the study population
| Subjects n | 38 |
| Males | 30 |
| Age yrs | 70±12 |
| Diagnosis# | |
| COPD | 28 |
| Post-cardiosurgical event | 5 |
| Neuromuscular | 2 |
| Chest wall diseases | 3 |
| Causes of ICU admission | |
| Pneumonia | 15 |
| COPD exacerbations | 10 |
| Cardiogenic pulmonary oedema | 3 |
| Sepsis | 3 |
| Acute respiratory failure | 7 |
| Time from tracheotomy days# | 16±3 |
| Length of ICU stay days# | 24±4 |
| Duration of MV days¶ | 29±4 |
| Cannula diameter at admission cm¶ | 7.5±0.75 |
| Type of cuffed cannula at study entry¶ | |
| Mallinkrodt | 9 |
| Shiley | 6 |
| Portex blue line | 22 |
| Bivona | 1 |
| FEV1 % pred+ | 28±6 |
| FVC % pred+ | 34±7 |
| pH¶ | 7.38±0.02 |
| Pa,O2/FI,O2¶ | 267±45 |
| Pa,CO2 mmHg¶ | 50±5 |
Data are presented as mean±sd or n. COPD: chronic obstructive pulmonary disease; ICU: intensive care unit; MV: mechanical ventilation; FEV1: forced expiratory volume in one second; FVC: forced vital capacity; Pa,O2: arterial oxygen tension; FI,O2: inspiratory oxygen fraction; Pa,CO2: carbon dioxide arterial tension. #: at weaning centre admission; ¶: at the time of the study; +: pre-ICU admission, or before rehabilitative hospital discharge. mmHg = 0.133 kPa.