Table 4.
Plethysmography and Diffusion Parameters (All Participants)
| Study 1 | Study 2 | Studies 1 & 2 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Healthy subjects | Mild asthma | Moderate asthma | Severe asthma | Mild COPD | Moderate COPD | Severe COPD | Very-severe COPD | Very-severe COPD | Very-severe COPD | |
| n = 15 | n = 15 | n = 15 | n = 15 | n = 15 | n = 15 | n = 10 | n = 5 | n = 15 | n = 18a | |
| Plethysmography | ||||||||||
| TLC (L) | 6.2 (5.6, 6.9) | 6.8 (6.0, 7.6) | 6.6 (5.8, 7.4) | 6.3 (5.8, 6.8) | 7.7 (7.1, 8.3) | 7.6 (6.9, 8.3) | 7.7 (6.6, 8.8) | 7.4 (6.1, 8.8) | 8.0 (7.1, 8.9) | 8.0 (7.2, 8.7) |
| RV (L) | 1.7 (1.5, 2.0) | 2.5 (2.0, 2.9) | 2.1 (1.7, 2.5) | 2.6 (2.1, 3.1) | 3.1 (2.8, 3.4) | 3.7 (3.2, 4.2) | 4.3 (3.5, 5.1) | 5.1 (3.6, 6.7) | 5.7 (5.0, 6.4) | 5.7 (5.1, 6.3) |
| FRC (L) | 2.9 (2.5, 3.3) | 3.6 (3.1, 4.1) | 2.9 (2.5, 3.3) | 3.5 (3.0, 4.0) | 4.1 (3.7, 4.4) | 4.8 (4.3, 5.3) | 5.4 (4.6, 6.3) | 5.8 (4.4, 7.1) | 6.4 (5.6, 7.2) | 6.4 (5.7, 7.0) |
| Airway resistance (kPa.s/L) | 0.3 (0.2, 0.3) | 0.5 (0.3, 0.7) | 0.3 (0.3, 0.4) | 0.5 (0.4, 0.7) | 0.3 (0.3, 0.4) | 0.4 (0.4, 0.5) | 0.9 (0.6, 1.2) | 1.3 (0.7, 1.9) | 1.2 (1.0, 1.5) | 1.3 (1.1, 1.5) |
| Specific airways resistance (kPa.s) | 0.9 (0.8, 1.0) | 2.0 (1.2, 2.9) | 1.1 (0.8, 1.3) | 2.1 (1.2, 3.1) | 1.5 (1.2, 1.9) | 2.3 (1.8, 2.8) | 5.4 (3.2, 7.5) | 8.1 (3.0, 13.2) | 8.5 (7.0, 9.9) | 8.8 (7.4, 10.2) |
| Diffusion | ||||||||||
| Alveolar volume (L) | 5.4 (4.8, 6.0) | 5.7 (5.0, 6.3) | 5.7 (5.0, 6.4) | 5.1 (4.8, 5.5) | 6.3 (5.8, 6.9) | 5.7 (5.0, 6.4) | 4.9 (3.9, 5.9) | 4.0 (3.4, 4.7) | 4.0 (3.7, 4.3) | 4.0 (3.7, 4.2) |
| DLCO (mmol/min.kPa) | 8.9 (7.9, 9.9) | 8.9 (7.4, 10.4) | 8.4 (7.4, 9.4) | 8.1 (7.4, 8.8) | 7.5 (6.1, 8.8) | 5.7 (4.3, 7.1) | 4.0 (3.2, 4.8) | 2.4 (1.3, 3.4) | 1.9 (1.3, 2.5) | 1.9 (1.4, 2.4) |
| Krogh factor (mmol/min.kPa.L) | 1.7 (1.6, 1.8) | 1.6 (1.4, 1.7) | 1.5 (1.4, 1.6) | 1.6 (1.5, 1.6) | 1.2 (1.0, 1.3) | 1.0 (0.8, 1.1) | 0.8 (0.7, 1.0) | 0.6 (0.4, 0.8) | 0.5 (0.3, 0.6) | 0.5 (0.4, 0.6) |
Data are mean (95% CI) unless otherwise stated.
CI, confidence interval; COPD, chronic obstructive pulmonary disease; DLCO, diffusing capacity of the lung for carbon monoxide; FRC, functional residual capacity; RV, residual volume; TLC, total lung capacity.
a
Includes all patients from Study 2, and three patients from Study 1 who also met the Study 2 eligibility criteria.