Simplified detection of dynamic hyperinflation.
OBJECTIVE
To detect dynamic hyperinflation by comparing reduction in inspiratory capacity (IC) during both paced hyperventilation and cycle ergometry in patients with moderate-to-severe COPD, studied before and after acute bronchodilation.


METHODS
IC and FEV(1) were measured before and after metronome-paced hyperventilation at twice the resting respiratory rate for 20 s in 16 patients with COPD before and after 54 microg aerosolized ipratropium bromide (IB). We also studied the same 16 patients before and after administration of 54 microg aerosolized IB during symptom-limited incremental cycle ergometry when the final respiratory rate was also twice the resting rate.


RESULTS
Resting IC was 2.23 +/- 0.53 L (mean +/- SD), and the mean decrease in IC from baseline was 0.36 +/- 0.25 L after exercise (p < 0.001), and not significantly different (p = 0.64) from mean decrease in IC of 0.40 +/- 0.29 L following hyperventilation. Results following hyperventilation and exercise were similar after bronchodilator. The mean difference for decrease of IC between hyperventilation and exercise was 0.138 L (95% confidence interval, - 0.347 to 0.622; r = 0.66, p = 0.006). The decrease in FEV(1) was 0.01 +/- 0.13 L after exercise and 0.06 +/- 0.18 L after hyperventilation. Separately, baseline and peak end-expiratory and end-inspiratory lung volumes were similar with hyperventilation vs exercise both before and after bronchodilator.


CONCLUSIONS
Both metronome-paced hyperventilation and incremental cycle ergometry, when resting respiratory rate was doubled, provoked similar significant decrease in IC, even after administration of 54 microg aerosolized IB. The noninvasive simplicity of hyperventilation for 20 s provides a clinically useful screening surrogate to monitor changes in IC following exercise.
Gelb
Arthur F
AF
Pulmonary Division, Department of Medicine, Lakewood Regional Medical Center, 3650 E South St, Suite 308, Lakewood, CA 90712, USA. afgelb@msn.com
Gutierrez
Carlos A
CA
Weisman
Idelle M
IM
Newsom
Randy
R
Taylor
Colleen Flynn
CF
Zamel
Noe
N
D000280:Administration, Inhalation; D000328:Adult; D000336:Aerosols; D000368:Aged; D001993:Bronchodilator Agents / Q000008:administration & dosage; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology; D007320:Inspiratory Capacity; D009241:Ipratropium / Q000008:administration & dosage; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012129:Respiratory Function Tests
D000336:Aerosols; D001993:Bronchodilator Agents; D009241:Ipratropium