| Group | t1 (min) | t2 (min) | The number of sputum aspiration |
| Group I (n = 24) | 132.71 ± 24.54 | 8.83 ± 1.99 | 46.94 |
| Group II (n = 24) | 135.83 ± 18.98 | 7.54 ± 1.87 | 37.75 |
| Group III (n = 24) | 128.17 ± 25.92 | 6.04 ± 1.37ab | 24.81ab |
| F/χ2 values | 0.655 | 15.087 | 17.739 |
| P values | 0.523 | 0.000 | 0.000 |