TABLE 3

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

AwakeSleepingp-value#
Lung function parameters
 Number of loops included21 (18–24)33 (30–37)<0.001
 Respiratory rate (breaths·min−1)53 (51–56)38 (37–40)<0.001
  Standard deviation5.93 (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 deviation17.2 (15.3–19.0)12.1 (10.9–13.4)0.006
Time parameters
tPTEF/tE ratio0.39 (0.37–0.41)0.28 (0.27–0.29)<0.001
  Standard deviation0.06 (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 deviation0.04 (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 deviation0.08 (0.07–0.09)0.13 (0.12–0.14)<0.001
Volume parameters
VPTEF/VE ratio0.38 (0.36–0.40)0.29 (0.28–0.30)<0.001
  Standard deviation0.53 (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 deviation4.07 (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 deviation8.16 (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 deviation7.76 (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.