TITLE:
Expiratory Flow Limitation and Its Relation to Dyspnea and Lung Hyperinflation in Patients with Chronic Obstructive Pulmonary Disease: Analysis Using the Forced Expiratory Flow-Volume Curve and Critique
AUTHORS:
Billy Peng, Matthew Miller, Mark Slootsky, Ravi Patel, Ahmet Baydur
KEYWORDS:
Air Trapping, Asthma, Chronic Obstructive Pulmonary Disease, Dyspnea, Forced Expiratory Flow-Volume Curve, Hyperinflation, Tidal Expiratory Flow Limitation
JOURNAL NAME:
Open Journal of Respiratory Diseases,
Vol.11 No.3,
August
24,
2021
ABSTRACT: Background: Tidal expiratory flow limitation (tEFL) is defined as absence of
increase in air flow during forced expiration compared to tidal breathing and
is related to dyspnea at rest and minimal exertion in patients with chronic
airflow limitation (CAL). Tidal EFL has not been expressed as a continuous
variable (0% - 100%) in previous analyses. Objective: To relate the
magnitude of tEFL to spirometric values and Modified Medical Research Council
(MMRC) score and Asthma Control Test (ACT). Methods: Tidal EFL was computed as percent of the tidal
volume (0% - 100%) spanned (intersected) by the forced expiratory-volume curve. Results: Of 353 patients
screened, 192 (114 M, 78 F) patients (136 with COPD, 56 with asthma) had CAL.
Overall characteristics: (mean ± SD) age 59 ± 11 years, BMI 28 ± 7, FVC (%
pred) 85 ± 20, FEV1 (% pred) 66 ± 21, FEV1/FVC 55% ± 10%, RV (% pred) 147 ± 42.
Tidal EFL in patients with tEFL was 53% ± 39%. Using univariate analysis,
strongest correlations were between tEFL and FVC and between tEFL and RV in
patients with BMI 2. In patients with nonreversible CAL,
tEFL was positively associated with increasing MMRC, negatively with
spirometric measurements, and positively with RV/TLC. In asthmatics, ACT scores
were higher in patients with mean BMI ≥ 28 kg/m2 (p 40% (p Conclusions: Dyspnea is strongly associated with tEFL and
lung function, particularly in patients with nonreversible CAL. Air trapping
and BMI contribute to tEFL.