M. Inoue et al., EFFECT OF RESPIRATORY RATE ON RESPIRATORY PATTERNS IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE, Internal medicine, 36(11), 1997, pp. 771-775
We enrolled 22 patients with chronic obstructive pulmonary disease (CO
PD) and 20 normal subjects as controls. Using a hot-wire flow meter, m
e obtained tidal volume (V-T), duty ratio (Ti/Ttot), and mean inspirat
ory flow (V-T/Ti) as measures of respiratory pattern at two different
respiratory rates; 0.5 Hz and 1.5 Hz, At 0.5 Hz, there were significan
t differences in Ti/Ttot and V-T/Ti. At 1.5 Hz, patients with COPD had
significantly lower values of V-T and V-T/Ti. Furthermore, we calcula
ted the change ratios from 0.5 Hz to 1.5 Hz in these parameters as new
parameters of respiratory pattern change by respiratory rate, V-T0.5/
1.5 and V-T/Ti-0.5/1.5 significantly correlated with FEV1.0/FVC. The f
indings suggest that the parameters of the respiratory pattern may cha
nge depending on respiratory rates, and that the ratios of those param
eters obtained at two different rates could be helpful in diagnosing a
irflow obstruction.