Table 2—

Breathing pattern at rest and at peak exercise of 23 non-flow limited (non-FL) and 29 flow limited (FL) chronic obstructive pulmonary disease patients

RestPeak exercise
non-FLFLp-valuenon-FLFLp-value
VE L·min−110.3±0.710.9±0.4ns37.7±1.725.9±1.1<0.001
VE % pred64±441±2<0.001
VE MVV, %24±241±2<0.00187±596±5ns
VT L0.64±0.050.67±0.05ns1.25±0.041±.04±0.05<0.02
VT % pred62±247±3<0.001
fR breaths·min−116±0.816±1ns30±126±1<0.02
fR % pred103±488±3<0.03
tI s1.25±0.061.14±0.06ns0.74±0.040.81±0.03ns
tE s2.61±0.22.51±0.2ns1.31±0.051.65±0.09<0.02
ttot s3.79±±0.213.65±0.21ns2.05±0.082.45±0.11<0.03
VT/tI L·s−10.53±0.040.59±0.03ns1.75±0.081.32±0.06<0.001
VT/TE L·s−10.25±0.020.27±0.01ns0.99±0.050.65±0.03<0.001
tI/ttot0.34±0.020.32±0.02ns0.36±0.010.33±0.01ns
  • Values are presented as mean±sem.

  • VE: minute volume

  • MVV: maximal voluntary ventilation

  • VT: tidal volume

  • fR: breathing frequency

  • tI : inspiratory time

  • tE : expiratory time

  • ttot : total breathing cycle time

  • VT/tI : mean inspiratory flow

  • VT/tE : mean expiratory flow

  • tI/ttot : duty cycle