Determining the Role of Dynamic Hyperinflation in Patients with Severe Chronic Obstructive Pulmonary Disease

Abstract

Background: Dynamic hyperinflation due to increased respiratory frequency during exercise is associated with limitations in exercise capacity in patients with moderately severe chronic obstructive pulmonary disease (COPD). Objectives: The present study assessed whether the manually paced tachypnea (MPT) test, sitting at rest, induces dynamic hyperinflation correlating with exercise capacity in patients with very severe COPD. Methods: Dynamic hyperinflation was induced by the MPT test, using a breathing frequency of 40/min for 1 min. Dynamic hyperinflation was defined as a ‘change' in inspiratory capacity (IC) before and directly after the MPT test. At baseline, static hyperinflation by body plethysmography was measured, as well as the 6-min walking test and spirometry. Results: We studied 74 patients with severe COPD (age 59 ± 9 years, FEV₁ 28 ± 10% predicted). All patients tolerated the MPT test well. It induced a significant decrease in IC: -0.65 ± 0.33 liters, p < 0.001, correlating with the 6-min walking distance (rho = -0.246, p = 0.034). Static hyperinflation [IC/total lung capacity (TLC)] at baseline correlated stronger with the 6-min walking distance (r = 0.582, p < 0.001). Multiple regression analysis showed that IC/TLC, but not dynamic hyperinflation, was the only independent predictor of walking distance. Conclusions: In patients with very severe COPD, dynamic hyperinflation measurement by the MPT test is feasible and contributes less importantly to exercise performance than static hyperinflation.

Effects of inspiratory muscle training in COPD patients: A systematic review and meta‐analysis

“…Petrovic et al evaluated effects of IMT on inspiratory capacity (IC) and inspiratory fraction (IC/TLC) which are two clinical parameters reflecting hyperinflation. They demonstrated that in comparison with usual care, IMT improved more hyperinflation which is an important mechanism explaining dyspnea in COPD . It provides a novel and interesting hypothesis about the mechanisms explaining efficacy of IMT on dyspnea.…”

Is the Metronome-Paced Tachypnea Test (MPT) Ready for Clinical Use? Accuracy of the MPT in a Prospective and Clinical Study

“…The MPT test was first used by Gelb et al [1], in 16 chronic obstructive pulmonary disease (COPD) patients. Gelb et al [1] showed that DH with MPT was similar to DH with a CPET, if a subject breathed at twice the resting respiratory rate for 20 s. Since, the MPT test has been used in multiple studies to investigate the response to various bronchodilators [1-4], the development of DH during exacerbations [5], the role of DH in COPD [6], and the development of DH over the course of years [7]. Despite its increasing use as a valid measurement tool, only little is known about the accuracy of the MPT.…”

Static and dynamic hyperinflation during severe acute exacerbations of chronic obstructive pulmonary disease

“…Finally, one could discuss whether the test used in the current trial is the optimal standard to detect dynamic hyperinflation. 13 , 31 Based upon ethical arguments, the study team chose not to perform the more commonly used and better validated exercise test during the acute distress of severe exacerbation requiring admission.…”