Tidal flow–volume loop parameters in the awake and sleeping state (n=91). The mean of the individual standard deviation is given to demonstrate variability related to arousal state and number of breaths
Awake | Sleeping | p-value# | |
Lung function parameters | |||
Number of loops included | 21 (18–24) | 33 (30–37) | <0.001 |
Respiratory rate (breaths·min−1) | 53 (51–56) | 38 (37–40) | <0.001 |
Standard deviation | 5.93 (5.26–6.61) | 4.27 (3.74–4.81) | <0.001 |
PTEF (mL) | 110 (105–116) | 84.1 (80.0–88.2) | <0.001 |
Standard deviation | 17.2 (15.3–19.0) | 12.1 (10.9–13.4) | 0.006 |
Time parameters | |||
tPTEF/tE ratio | 0.39 (0.37–0.41) | 0.28 (0.27–0.29) | <0.001 |
Standard deviation | 0.06 (0.05–0.06) | 0.05 (0.05–0.05) | 0.006 |
tPTEF (s) | 0.24 (0.23–0.26) | 0.25 (0.24–0.26) | 0.402 |
Standard deviation | 0.04 (0.04–0.04) | 0.04 (0.04–0.04) | 0.332 |
tE (s) | 0.65 (0.61–0.68) | 0.93 (0.88–0.98) | <0.001 |
Standard deviation | 0.08 (0.07–0.09) | 0.13 (0.12–0.14) | <0.001 |
Volume parameters | |||
VPTEF/VE ratio | 0.38 (0.36–0.40) | 0.29 (0.28–0.30) | <0.001 |
Standard deviation | 0.53 (0.48–0.58) | 0.52 (0.48–0.56) | 0.675 |
VPTEF (mL) | 18.4 (17.2–19.6) | 14.2 (13.5–15.0) | <0.001 |
Standard deviation | 4.07 (3.69–4.45) | 2.89 (2.68–3.10) | <0.001 |
VE (mL) | 49.1 (46.4–51.7) | 49.7 (47.4–51.9) | 0.834 |
Standard deviation | 8.16 (7.46–8.86) | 6.17 (5.60–6.73) | <0.001 |
VT (mL) | 49.4 (46.7–52.1) | 50.5 (48.2–52.8) | 0.598 |
Standard deviation | 7.76 (7.07–8.46) | 6.00 (5.41–6.59) | <0.001 |
Data are presented as mean (95% CI), unless otherwise stated. PTEF: peak tidal expiratory flow; tPTEF: time to peak tidal expiratory flow; tE: expiratory time; VPTEF: volume at peak tidal expiratory flow; VE: expiratory volume; VT: tidal volume. Bold type represents statistical significance. #: Wilcoxon signed-rank test of paired samples.