EFFECT OF RESPIRATORY RATE ON RESPIRATORY PATTERNS IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

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.