Background: Tidal expiratory flow limitation (EFLT) is frequently found in patients with COPD and can be detected by forced oscillations when within-breath reactance of a single-breath is ≥0.28 kPa·s·L-1. The present study explored the association of within-breath reactance measured over multiple breaths and EFLT with 6-minute walk distance (6MWD), exacerbations, and mortality. Methods: In 425 patients, spirometry and forced oscillation technique measurements were obtained on eight occasions over 3 years. 6MWD was assessed at baseline and at the 3-year visit. Respiratory symptoms, exacerbations, and hospitalizations were recorded. A total of 5-year mortality statistics were retrieved retrospectively. We grouped patients according to the mean within-breath reactance (Δ(Formula Presented.)), measured over several breaths at baseline, calculated as mean inspiratory-mean expiratory reactance over the sampling period. In addition to the established threshold of EFLT, an upper limit of normal (ULN) was defined using the 97.5th percentile of Δ(Formula Presented.) of the healthy controls in the study; 6MWDs were compared according to Δ(Formula Presented.), as normal, ≥ ULN < EFLT, or ≥ EFLT. Annual exacerbation rates were analyzed using a negative binomial model in the three groups, supplemented by time to first exacerbation analysis, and dichotomizing patients at the ULN. Results: In patients with COPD and baseline Δ(Formula Presented.) below the ULN (0.09 kPa·s·L-1), 6MWD was stable. 6MWD declined significantly in patients with Δ(Formula Presented.) ≥ ULN. Worse lung function and more exacerbations were found in patients with COPD with Δ(Formula Presented.) ≥ ULN, and patients with Δ(Formula Presented.) ≥ ULN had shorter time to first exacerbation and hospitalization. A significantly higher mortality was found in patients with Δ(Formula Presented.) ≥ ULN and FEV1.50%. Conclusion: Patients with baseline Δ(Formula Presented.) ≥ ULN had a deterioration in exercise performance, more exacerbations, and greater hospitalizations, and, among those with moderate airway obstruction, a higher mortality. Δ(Formula Presented.) is a novel independent marker of outcome in COPD.

The association of tidal EFL with exercise performance, exacerbations, and death in COPD

DELLACA', RAFFAELE;
2017-01-01

Abstract

Background: Tidal expiratory flow limitation (EFLT) is frequently found in patients with COPD and can be detected by forced oscillations when within-breath reactance of a single-breath is ≥0.28 kPa·s·L-1. The present study explored the association of within-breath reactance measured over multiple breaths and EFLT with 6-minute walk distance (6MWD), exacerbations, and mortality. Methods: In 425 patients, spirometry and forced oscillation technique measurements were obtained on eight occasions over 3 years. 6MWD was assessed at baseline and at the 3-year visit. Respiratory symptoms, exacerbations, and hospitalizations were recorded. A total of 5-year mortality statistics were retrieved retrospectively. We grouped patients according to the mean within-breath reactance (Δ(Formula Presented.)), measured over several breaths at baseline, calculated as mean inspiratory-mean expiratory reactance over the sampling period. In addition to the established threshold of EFLT, an upper limit of normal (ULN) was defined using the 97.5th percentile of Δ(Formula Presented.) of the healthy controls in the study; 6MWDs were compared according to Δ(Formula Presented.), as normal, ≥ ULN < EFLT, or ≥ EFLT. Annual exacerbation rates were analyzed using a negative binomial model in the three groups, supplemented by time to first exacerbation analysis, and dichotomizing patients at the ULN. Results: In patients with COPD and baseline Δ(Formula Presented.) below the ULN (0.09 kPa·s·L-1), 6MWD was stable. 6MWD declined significantly in patients with Δ(Formula Presented.) ≥ ULN. Worse lung function and more exacerbations were found in patients with COPD with Δ(Formula Presented.) ≥ ULN, and patients with Δ(Formula Presented.) ≥ ULN had shorter time to first exacerbation and hospitalization. A significantly higher mortality was found in patients with Δ(Formula Presented.) ≥ ULN and FEV1.50%. Conclusion: Patients with baseline Δ(Formula Presented.) ≥ ULN had a deterioration in exercise performance, more exacerbations, and greater hospitalizations, and, among those with moderate airway obstruction, a higher mortality. Δ(Formula Presented.) is a novel independent marker of outcome in COPD.
2017
6-minute walk test; COPD; Exacerbations; Forced oscillation technique; Mortality; Reactance; Pulmonary and Respiratory Medicine; Health Policy; Public Health, Environmental and Occupational Health
File in questo prodotto:
File Dimensione Formato  
11311-1032318_Dellaca'.pdf

accesso aperto

: Publisher’s version
Dimensione 1.61 MB
Formato Adobe PDF
1.61 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1032318
Citazioni
  • ???jsp.display-item.citation.pmc??? 7
  • Scopus 17
  • ???jsp.display-item.citation.isi??? 14
social impact