Table 5.
Correlations Between Inhaler-Specific and Inhaler-Independent Inhalation Characteristics (All Participants)
| Data genre | Variable | Peak pressure drop | PIFR (Inhaler) | Inhaled volume |
|---|---|---|---|---|
| All participants | ||||
| Spirometry | FEV1 | – | 0.69 (p < 0.0001) | 0.73 (p < 0.0001) |
| FVC | – | – | 0.80 (p < 0.0001) | |
| PEFR | – | 0.76 (p < 0.0001) | – | |
| PIFR (spirometry) | – | 0.80 (p < 0.0001) | – | |
| Whole-body plethysmography | FRC | – | – | –0.29 (p = 0.0013) |
| Residual volume | – | – | –0.39 (p < 0.0001) | |
| TLC | – | 0.02 (p = 0.8453) | 0.23 (p = 0.0104) | |
| RAW | –0.55 (p < 0.0001) | – | – | |
| Diffusion | VA | – | – | 0.76 (p < 0.0001) |
| DLCO | – | 0.71 (p < 0.0001) | 0.74 (p < 0.0001) | |
| Krogh factor | – | 0.59 (p < 0.0001) | 0.48 (p < 0.0001) | |
| Asthma patients | ||||
| Spirometry | FEV1 | – | 0.52 (p = 0.0003) | 0.60 (p < 0.0001) |
| FVC | – | 0.62 (p < 0.0001) | ||
| PEFR | – | 0.66 (p < 0.0001) | ||
| PIFR (spirometry) | – | 0.69 (p < 0.0001) | ||
| Whole-body plethysmography | FRC | – | 0.15 (p = 0.3344) | |
| Residual volume | – | –0.08 (p = 0.5947) | ||
| TLC | – | 0.25 (p = 0.1021) | 0.44 (p = 0.0026) | |
| RAW | –0.21 (p = 0.1589) | |||
| Diffusion | VA | – | 0.56 (p < 0.0001) | |
| DLCO | – | 0.49 (p = 0.0007) | 0.64 (p < 0.0001) | |
| Krogh factor | – | 0.30 (p = 0.0436) | 0.23 (p = 0.1326) | |
| COPD patientsa | ||||
| Spirometry | FEV1 | – | 0.73 (p < 0.0001) | 0.84 (p < 0.0001) |
| FVC | – | – | 0.85 (p < 0.0001) | |
| PEFR | – | 0.80 (p < 0.0001) | – | |
| PIFR (spirometry) | – | 0.85 (p < 0.0001) | – | |
| Whole-body plethysmography | FRC | – | – | –0.29 (p = 0.0289) |
| Residual volume | – | – | –0.40 (p = 0.0018) | |
| TLC | – | 0.27 (p = 0.0398) | 0.39 (p = 0.0022) | |
| RAW | –0.65 (p < 0.0001) | – | – | |
| Diffusion | VA | – | – | 0.88 (p < 0.0001) |
| DLCO | – | 0.79 (p < 0.0001) | 0.84 (p < 0.0001) | |
| Krogh factor | – | 0.67 (p < 0.0001) | 0.65 (p < 0.0001) | |
COPD, chronic obstructive pulmonary disease; DLCO, diffusing capacity of the lung for carbon monoxide; FEV1, forced expiratory volume in 1 second; FRC, functional residual capacity; FVC, forced vital capacity; PEFR, peak expiratory flow rate; PIFR, peak inspiratory flow rate; RAW, airways resistance; TLC, total lung capacity; VA, alveolar volume.
a
Includes all COPD patients from Study 1 and Study 2. Values in bold showed strong correlation (R > 0.7) and are statistically significant (p < 0.05).