[Show abstract][Hide abstract]ABSTRACT: Background
ATS/ERS Task Force has highlighted that special attention must be paid when FEV1 and FVC are concomitantly decreased (<5th percentile) and the FEV1/FVC ratio is normal (>5th percentile) because a possible cause of this non specific pattern (NSP) is collapse of small airways with normal TLC measured by body plethysmography (>5th percentile). Our objectives were to determine the main lung diseases associated with this pattern recorded prospectively in a lung function testing (LFT) unit, the prevalence of this pattern in our LFT and among the diseases identified, and its development.
Observational study of routinely collected data selected from our Clinical Database Warehouse.
The prevalence of NSP was 841/12 775 tests (6.6%, 95% CI: 6.2 to 7.0%). NSP was mainly associated with seven lung diseases: asthma (prevalence of NSP among asthmatics: 12.6%), COPD/emphysema (prevalence 8.6%), bronchiectasis (12.8%), sarcoidosis (10.7%), interstitial pneumonia (4.0%), pulmonary hypertension (8.9%) and bilateral lung transplantation for cystic fibrosis (36.0%). LFT measurements were described in 185 patients with NSP and indisputable nonoverlapping causes. A moderate defect (FEV1: 66 ± 9% predicted) with mild lung hyperinflation (FRC: 111 ± 27%, RV: 131 ± 33% predicted: suggesting distal airway obstruction) was evidenced whatever the underlying cause. A long term stability of NSP was evidenced in 130/185 patients (70% 95% CI: 64 to 77%).
NSP is observed in asthma, COPD/emphysema, bronchiectasis, sarcoidosis, pulmonary hypertension, interstitial pneumonia and after bilateral lung transplantation and remains stable in the majority of patients.
Full-text Article · Sep 2014 · BMC Pulmonary Medicine
[Show abstract][Hide abstract]ABSTRACT: Objectives:
The first objective of our study was to assess whether patients diagnosed with cardio-respiratory disorders report overestimation or underestimation on recall (Medical Research Council (MRC) dyspnea scale) of their true functional capacity (walked distance during a 6-minute walk test (6MWT)). The second objective was to assess whether the measurement of breathlessness at the end of a 6MWT (Borg score) may help to identify dyspneic patients on recall.
The 6MWTs of 746 patients aged from 40 to 80 years who were diagnosed with either chronic obstructive pulmonary disease (COPD, n = 355), diffuse parenchymal lung disease (n = 140), pulmonary vascular diseases (n = 188) or congestive heart failure (n = 63) were selected from a prospective Clinical Database Warehouse.
The percentage of patients who overestimated (MRC ≤ 2 with distance < lower limit of normal (LLN), 61/746, 8%; 95% confidence interval (CI): 6 to 10%) or underestimated (MRC > 2 with distance ≥LLN, 121/746, 16%; 95%CI: 14 to 19%) on recall their capacity was elevated. The overestimation seemed related to self-limitation, while the underestimation seemed related to patients who "work through" their breathing discomfort. These two latter groups of patients were mainly diagnosed with COPD. A Borg dyspnea score >3 (upper limit of normal) at the end of the 6MWT had 84% specificity for the prediction of a MRC score >1.
Almost one fourth of patients suffering from cardio-pulmonary disorders overestimate or underestimate on recall their true functional capacity. An elevated Borg dyspnea score at the end of the 6MWT has a good specificity to predict dyspnea on recall.
Article · May 2014 · COPD Journal of Chronic Obstructive Pulmonary Disease
[Show abstract][Hide abstract]ABSTRACT: Objectives:
Obesity has been associated with a lesser degree of asthma control that may be biased by other comorbidities. The objectives of this cross-sectional study were to describe resting and activity-related dyspnea complaints according to the presence of obesity-related comorbidities (asymptomatic airway hyperresponsiveness (AHR), asthma, gastroesophageal reflux disease (GERD) and sleep-disordered breathing (SDB)). We hypothesized that obese women can exhibit both resting and activity-related dyspnea, independently of the presence of asthma.
Severely obese (body mass index (BMI) > 35 kg m(-2)) women prospectively underwent description of resting and activity-related dyspnea (verbal descriptors and Medical Research Council (MRC) scale), pulmonary function testing (spirometry, absolute lung volumes, and methacholine challenge test), oesogastro-duodenal fibroscopy, and overnight polygraphy. Thirty healthy lean women without airway hyperresponsiveness were enrolled.
Resting dyspnea complaints were significantly more prevalent in obesity (prevalence 41%) than in healthy lean women (prevalence 3%). Chest tightness and the need for deep inspirations were independently associated with both asthma and GERD while wheezing and cough were related to asthma only in obese women. Activity-related dyspnea was very prevalent (MRC score > 1, 75%), associated with obesity, with the exception of wheezing on exertion due to asthma. Asymptomatic AHR and SDB did not affect dyspneic complaints.
In severely obese women referred for bariatric surgery, resting dyspnea complaints are observed in association with asthma or GERD, while activity-related dyspnea was mainly related to obesity only. Consequently, asthma does not explain all respiratory complaints of obese women.
[Show abstract][Hide abstract]ABSTRACT: Obesity affects airway diameter and tidal ventilation pattern, which could perturb smooth muscle function. The objective was to assess the pathophysiology of airway hyperresponsiveness in obesity while controlling for gastro-oesophageal reflux disease. Obese women (n=118, mean±SD BMI 46.1±6.8kg/m(-2)) underwent pulmonary function testing (including tidal ventilation monitoring and methacholine challenge) and oesogastro-duodenal fibroscopy. Fifty-seven women (48%, 95% CI: 39% to 57%) exhibited hyperresponsiveness (dose-response slope ≥ 2.39% decrease/μmol) that was independently and positively correlated with predicted % FRC, Raw(0.5) and negatively correlated with sigh frequency during tidal ventilation. Obese women had an increased breathing frequency but a similar sigh frequency than healthy lean women (n=30). Twenty-two obese women (19%, 95% CI: 12% to 26%) were classified as asthmatics (hyperresponsiveness and suggestive symptoms) without confounding effect of gastro-oesophageal reflux disease. In conclusion, in women referred for bariatric surgery, unloading of bronchial smooth muscle (reduced airway caliber and sigh frequency) is associated with hyperresponsiveness.
Article · Jan 2013 · Respiratory Physiology & Neurobiology
[Show abstract][Hide abstract]ABSTRACT: Sensory (physiological) and affective (psychological) dimensions of dyspnea have been described but the usefulness of measuring psychological status in addition to ventilatory capacity (spirometry, lung volumes) in the assessment of exertional dyspnea remains controversial. We hypothesized that activity-related dyspnea would not be modified by psychological status. Principal component analysis (PCA) was used to reduce the number of parameters (psychological or functional) to fewer independent dimensions in 328 patients with altered ventilatory capacity: severe obesity (BMI ≥ 35, n = 122), COPD (n = 128) or interstitial lung disease (n = 78). PCA demonstrated that psychological status (Hospital Anxiety-Depression, Fatigue Impact scales) and dyspnea (Medical Research Council [MRC] scale) were independent dimensions. Ventilatory capacity was described by three main dimensions by PCA related to airways, volumes, and their combination (specific airway resistance, FEV(1)/FVC), which were weakly correlated with dyspnea. In conclusion, in patients with COPD, interstitial lung disease or severe obesity, psychological status does not modify activity-related dyspnea rating as evaluated by the MRC scale.
Article · Feb 2012 · Respiratory Physiology & Neurobiology
[Show abstract][Hide abstract]ABSTRACT: Dyspnea is deemed to result from an imbalance between ventilatory demand and capacity. The single-breath diffusing capacity for carbon monoxide (DLCO) is often the best correlate to dyspnea in COPD. We hypothesized that DLCO contributes to the assessment of ventilatory demand, which is linked to physiological dead space /tidal volume (V(D)/V(T)) ratio. An additional objective was to assess the validity of non-invasive measurement of transcutaneous P(CO2) allowing the calculation of this ratio. Forty-two subjects (median [range] age: 66 [43-80] years; 12 females) suffering mainly from moderate-to-severe COPD (GOLD stage 2 or 3: n = 36) underwent pulmonary function and incremental exercise tests while taking their regular COPD treatment. DLCO% predicted correlated with both resting and peak physiological V(D)/V(T) ratios (r = -0.55, p = 0.0015 and r = -0.40, p = 0.032; respectively). The peak physiological V(D)/V(T) ratio contributed to increase ventilation (increased ventilatory demand), to increase dynamic hyperinflation and to impair oxygenation on exercise. Indirect (MRC score) and direct (peak Borg score/% predicted VO(2)) exertional dyspnea assessments were correlated and demonstrated significant relationships with DLCO% predicted and physiological V(D)/V(T) at peak exercise, respectively. The non-invasive measurement of transcutaneous P(CO2) both at rest and on exercise was validated by Bland-Altman analyses. In conclusion, DLCO constitutes and indirect assessment of ventilatory demand, which is linked to exertional dyspnea in COPD patients. The assessment of this demand can also be non invasively obtained on exercise using transcutaneous PCO(2) measurement.
Article · Feb 2012 · COPD Journal of Chronic Obstructive Pulmonary Disease
[Show abstract][Hide abstract]ABSTRACT: To assess whether different indices of dyspnea can be obtained from cardiopulmonary exercise test and whether these indices correlate with distinct physiological parameters in COPD. Forty-two COPD patients (12 females, median [IQ] age 66 [56-70] years; FEV(1)% predicted: 51 [38-65]) underwent pulmonary function and incremental exercise tests. A power law function described the oxygen consumption (V(O₂)-Dyspnea relationship from which two indices correlated with MRC score: dyspnea score measured at 50% of predicted V(O₂) (too much breathless for that effort) and tangent measured at 50% of peak dyspnea (too rapid increase in dyspnea at this time point). The former independently correlated with ventilation on exercise, while the latter independently correlated with baseline hyperinflation. An upward shift of both (iso)-V(O₂) and -ventilation was evidenced in patients with higher levels of dyspnea (MRC score ≥ 3) and their tangents were significantly different. In conclusion, baseline hyperinflation is associated with the perception of a too rapid increase in dyspnea on exercise in COPD.
[Show abstract][Hide abstract]ABSTRACT: Dynamic hyperinflation (DH) develops in patients with COPD during incremental exercise with a cycle ergometer. The aims of this study were to determine whether DH can be evidenced after walking with a handheld spirometer and to determine its functional consequences.
Fifty patients with COPD (39 men; median age, 60 years [interquartile range (IQR), 54 to 69 years]; FEV(1), 45% predicted [IQR, 31 to 67% predicted]) underwent pulmonary function tests and a 6-min walk test (6MWT). Inspiratory capacity (IC) was measured with the patient in the standing position at rest and immediately after the 6MWT with a portable spirometer. Dyspnea was evaluated directly (change in Borg score during 6MWT) and indirectly (Medical Research Council scale). The first 20 patients performed an incremental exercise test with cycle ergometer that allowed for the measurement of IC at peak exercise and repeatedly during the first 3 min of recovery.
The median change in IC during the 6MWT was -210 mL (IQR, 55 to -440; n = 50), whereas the median change in IC during the exercise test was -295 mL (IQR, -145 to -515; n = 20). Both the IC and IC changes after 6MWT correlated to values after the exercise test. DH decreased rapidly after the end of the exercise test but was nonsignificantly different from the baseline value after 75 s of recovery. The percentage of decrease in IC during the 6MWT correlated with dyspnea (change in Borg score during 6MWT: r(2) = 0.21; p = 0.0006).
DH can be measured during a 6MWT with a handheld spirometer to allow for its evaluation in daily practice and its contribution to dyspnea while walking.