Insufficient lung emptying before the inhalation of aerosol drugs is considered a common mistake. However, its effect on the rest of the manoeuvre and drug deposition is not fully explored. The aim of this work was to conduct spirometry measurements using six DPIs to quantify the effect of lung emptying on the peak inhalation flow (PIF) and inhaled volume (IV). Thirty healthy adults participated in the inhalation experiments.
Forceful exhalation increased the values of PIF and IV. The extent of the increase depended on the strength of breath-out and it was patient and inhaler specific. For different inhalers, the mean value of the relative increase in PIF due to forceful exhalation was 15.3-38.4%, compared to tidal exhalation. The relative increase of IV was 36.4-57.1%. Since the inhaled dose increases with the increase of this two parameters, higher amount of drug is expected to be available for deposition in the airways.
Table 1. Average values, standard deviations and ranges of the measured PIF and IV values after tidal and forced exhalations
| PIF (L/min) | IV (L) | |||
| tidal | forced | tidal | forced | |
| Breezhaler® | 86.0 (31.1) | 119.0 (29.8) | 2.3 (0.6) | 3.3 (1.0) |
| 38.5-149.8 | 62.2-197.1 | 1.2-4.0 | 1.3-5.2 | |
| Easyhaler® | 51.6 (14.4) | 59.5 (13.0) | 2.0 (0.7) | 3.1 (1.0) |
| 28.1-84.2 | 38.9-91.9 | 1.1-3.9 | 1.4-5.1 | |
| Ellipta® | 74.3 (26.2) | 91.7 (26.2) | 2.2 (0.7) | 3.2 (1.0) |
| 39.1-153.4 | 52.6-158.0 | 1.1-3.6 | 1.1-5.2 | |
| Genuair® | 60.2 (20.5) | 73.3 (20) | 2.1 (0.7) | 3.1 (1.0) |
| 32.4-114.3 | 42.5-123.3 | 0.9-3.4 | 0.7-4.8 | |
| NEXThaler® | 67.0 (21.4) | 77.8 (20.4) | 2.2 (0.7) | 3.0 (0.9) |
| 33.0-118.4 | 30.1-119 | 1.1-3.7 | 1.6-4.9 | |
| Turbuhaler® | 64.8 (19.8) | 78.8 (21.1) | 2.1 (0.7) | 3.3 (1.0) |
| 31.1-127.6 | 48.2-134.1 | 0.8-3.4 | 1.0-5.0 |