Detection and prevalence of chronic obstructive pulmonary disease in a cardiovascular clinic: evaluation using a hand held FEV₁/FEV₆ meter and questionnaire

Background and objective: COPD is one of the leading causes of morbidity and mortality worldwide, and its prevalence continues to increase. Although spirometry is indispensable for the diagnosis of COPD, other simple and reliable tools are necessary for screening of COPD because spirometry is not widely available. This study investigated the usefulness of a combination of an electronic FEV₁/FEV₆ meter (PiKo‐6) with a COPD questionnaire as a screening method in patients with cardiovascular diseases. Methods: The PiKo‐6 and the COPD questionnaire of the International Primary Care Airways Group were used to screen patients attending a cardiovascular outpatient clinic. Patients with FEV₁/FEV₆ < 70% were defined as having airflow limitation. Patients diagnosed with airflow limitation underwent spirometry. Using data from the PiKo‐6 and the COPD questionnaire, patients were assigned to a COPD group or a non‐COPD group. The relationship between PiKo‐6 measurements and spirometry was also evaluated. Results: Among 753 patients, 82 (10.9%) showed airflow limitation when assessed with the PiKo‐6. Of these patients, 79 (10.5%) were assigned to the COPD group. FEV₁, FEV₆ and FEV₁/FEV₆, as measured with the PiKo‐6, correlated significantly with FEV₁, FVC and FEV₁/FVC, respectively, as measured by spirometry (r = 0.865, 0.751 and 0.57). Among the cardiovascular comorbidities, heart failure and ischaemic heart disease showed slightly stronger associations with airflow limitation (13.8% and 12.5%, respectively). Conclusions: Combination of the PiKo‐6 with a COPD questionnaire may be a useful and feasible method of identifying undiagnosed COPD patients attending a cardiovascular outpatient clinic.     

High Expression of Cathepsin E is Associated with the Severity of Airflow Limitation in Patients with COPD

Background: It was reported that Cathepsin E (Cat E) plays a critical role in antigen processing and in the development of pulmonary emphysema. The aim of this study was to investigate the role of Cat E and airflow limitation in the pathogenesis of COPD. Methods: Sixty-five patients with COPD, 20 smoking control subjects without COPD and 15 non-smoking healthy control subjects were enrolled. Cat E and EIC (Elastase inhibitory capacity) expressions were measured by ELISA in sputum and serum samples and compared according to different subgroups. Results: Cat E concentrations were significantly higher in patients with COPD than smoking control and non-smoking control subjects (P < 0.01). The levels of CatE were inversely correlated with FEV₁% predicted in COPD patients (r = ?0.95, P < 0.01). The levels of EIC were inversely positively correlated with FEV₁% predicted in COPD patients (r = 0.926, P < 0.01). Levels of Cat E were also inversely correlated with the levels of EIC (r = ?0.922, P < 0.01). Conclusions: Cat E contributes to the severity of airflow limitation during progression of COPD.     

Postoperative outcome after coronary artery bypass grafting in chronic obstructive pulmonary disease

BACKGROUND:

It is uncertain if the presence and severity of airflow obstruction in chronic obstructive pulmonary disease (COPD) is predictive of surgical morbidity and mortality after coronary artery bypass grafting (CABG).

METHODS:

Retrospective study of patients who underwent CABG between 1998 and 2003 in a university-affiliated hospital for whom a preoperative spirometry was available. COPD was diagnosed in smokers or ex-smokers 50 years of age or older in the presence of irreversible airflow obstruction. Patients were divided into three groups depending on the spirometry: controls (forced expiratory volume in 1 s [FEV₁] 80% or more, FEV₁/forced vital capacity [FVC] greater than 0.7), mild to moderate COPD (FEV₁ 50% or more and FEV₁/FVC 0.7 or less) and severe COPD (FEV₁ less than 50% and FEV₁/FVC 0.7 or less).

RESULTS:

Among the 411 files studied, 322 (249 men, 68±8 years of age) were retained (controls, n=101; mild to moderate COPD, n=153; severe COPD, n=68). The mortality rate (3.0%, 2.6% and 0%, respectively) was comparable among the three groups. Patients with severe COPD had a slightly longer hospital stay than controls (mean difference 0.7±1.4 days, P<0.05). Pulmonary infections were more frequent in severe COPD (26.5%) compared with mild to moderate COPD (12.4%) and controls (12.9%), P<0.05. Atrial fibrillation tended to be more frequent in severe COPD than in the other two groups.

CONCLUSION:

Mortality rate associated with CABG surgery is not influenced by the presence and severity of airflow obstruction in patients with COPD. The incidence of pulmonary infections and length of hospital stay were increased in patients with severe COPD.     

A meta-analysis on the efficacy of oral theophylline in patients with stable COPD

Background

Theophylline is a nonspecific inhibitor of phosphodiesterases that, despite exerting bronchodilator and anti-inflammatory effects, is a third-line therapy rarely used to treat chronic airflow limitation. We wished to evaluate the efficacy of oral theophylline as measured by improvements in trough (pre-dose) or peak (post-dose) FEV₁ and FVC in patients with clinically stable COPD.

Design

Meta-analysis of randomized, placebo-controlled trials reported as of June 2005 in which theophylline was orally administered to stable COPD patients and the functional evaluations included pre- and post-theophylline values for FEV₁ and FVC.

Results

A total of 18 trials were included in the meta-analysis. The weighted mean differences (WMD) with 95% confidence intervals (95% CI) for improvement over placebo in trough FEV₁ and FVC were 0.108L (0.053–0.163) and 0.186L (0.036–0.336), respectively, while peak FEV₁ and FVC improved by 0.096L (0.044–0.147) and 0.242L (0.11–0.374), respectively.

Conclusions

Treatment with oral theophylline improves both trough and peak FEV₁ and FVC in clinically stable COPD patients. These results support previously reported benefits of theophylline in COPD.     

Effect of Obesity on Asthma Phenotype is Dependent upon Asthma Severity

Background. We recently reported that obese and non-obese patients with asthma have similar airflow limitation and bronchodilator responsiveness, but obese patients have more symptoms overall. There is limited information on the effect of obesity on asthmatics of varying severity measured by objective physiological parameters. Understanding how obesity affects asthmatics of differing severity can provide insights into the pathogenesis of asthma in the obese and a rationale for the therapeutic approach to such patients. Methods. Participants with asthma from two American Lung Association—Asthma Clinical Research Center (ALA-ACRC) studies were grouped by tertiles of airflow obstruction (forced expiratory volume in one second (FEV₁%) predicted, FEV₁/forced vital capacity (FVC)) and methacholine reactivity (PC₂₀FEV₁). Within each tertile, we examined the independent effect of body mass index (BMI), divided into normal weight, overweight, and obese categories, on lung function, airway reactivity, and symptoms. Results. Overall, both FEV₁ and FVC decreased and symptoms worsened with increasing BMI; airway reactivity was unchanged. When stratified by the degree of airflow obstruction, higher BMI was not associated with greater airway reactivity to methacholine. Higher BMI was associated with more asthma symptoms only in the least obstructed FEV₁/FVC tertile. When stratified by degree of airway reactivity, BMI was inversely associated with FVC in all PC₂₀FEV₁ tertiles. BMI was directly associated with asthma symptoms only in those with the least airway reactivity. Conclusions. Obesity does not influence airway reactivity in patients with asthma and it is associated with more symptoms only in those with less severe disease.     

Case Identification of Subjects with Airflow Limitations Using the Handheld Spirometer “Hi-CheckerTM”: Comparison Against an Electronic Desktop Spirometer

Background: Systematic case identification has been proposed as a strategy to improve diagnosis rates and to enable the early detection of subjects with COPD. We hypothesized that case identification could be possible using the handheld spirometer Hi-Checker^TM. Aim: To determine how to modify the FEV₁/FEV₆ values obtained using the Hi-Checker ^TM to screen for cases with airflow limitation. Methods: Spirometry was performed with both an electronic desktop spirometer and with the Hi-Checker^TM in 312 male subjects. Results: The average FEV₁ (mean ± SD) measured using a conventional spirometer and the Hi-Checker^TM was 2.99 ± 0.56L and 3.07 ± 0.57L, respectively. These results were significantly different (P<0.001, paired t-test for both). This difference of ?0.08 ± 0.13L (95% confidence interval: ?0.094–0.066L) was normally distributed, and thought to be random. Statistically significant correlations were found for all measurements between the spirometer and the Hi-Checker^TM; the Pearson's correlation coefficient (R) between the FEV₁/FVC and FEV₁/FEV₆ values was 0.881. If one defines a FEV_1/FVC smaller than 0.7 measured by the spirometer as airflow limitation, then a FEV₁/FEV₆ smaller than 0.746 measured by the Hi-Checker^TM best matches this definition, and Cohen's kappa coefficient was 0.672. Conclusion: Although the Hi-Checker ^TM estimates resembled those from conventional spirometry, it should be emphasized that the two methods did not produce identical results due to random measurement error. Although one must be careful about overinterpreting these results, since the Hi-Checker ^TM is small and inexpensive, it could make a significant contribution in facilitating the case selection of patients with airflow limitation.     

What is the difference between FEV1 change in percentage predicted value and change over baseline in the assessment of bronchodilator responsiveness in patients with COPD?

Background

Several criteria are clinically applied in the assessment of significant bronchodilator responsiveness in chronic obstructive pulmonary disease (COPD). The present study aimed to investigate the differences in various degree of severity of COPD among these criteria.

Methods

After 400 micrograms of salbutamol administered via spacer by metered dose inhaler (MDI), forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) changes (including percentage change, absolute change and absolute change in percentage predicted value) were retrospectively analysed in 933 stable patients with mild-to-very-severe COPD. Significant bronchodilator responsiveness was assessed using American Thoracic Society and European Respiratory Society (ATS-ERS) criterion based on FEV₁ or/and FVC (both ≥12% increase over baseline and ≥200 mL) and FEV₁ percentage predicted criterion (≥10% absolute increase in percentage predicted FEV₁) in different grades of COPD.

Results

Of the patients [age 66.8 years, baseline FEV₁ 974 mL (39.3% predicted) and FVC 2,242 mL], mean improvements were 126 mL in FEV₁ and 265 mL in FVC; 21.4% and 45.3% met ATS-ERS criterion based on FEV₁ and FVC, respectively; and 13.5% met FEV₁ percentage predicted criterion. The responsive ratios of ATS-ERS criterion based on FEV₁ to FEV₁ percentage predicted criterion in grade I, II, III and IV of COPD were 0.95^:1.26^:2.53^:6.00, respectively (P<0.01 in grade II and P<0.001 in grade III). As the degree of severity increased, the mean improvement of FEV₁ was reduced; on the contrary, that of FVC was increased.

Conclusions

Compared with FEV₁ percentage predicted criterion, ATS-ERS criterion based on FEV₁ as well as FVC, the later in particular, detected a larger percentage of patients with significant responsiveness. The increasing difference was relevant as a function of the severity of airflow obstruction.KEY WORDS : Airflow obstruction, bronchodilator responsiveness, chronic obstructive pulmonary disease (COPD), forced vital capacity (FVC), forced expiratory volume in one second (FEV₁)     

Acute bronchodilator responsiveness in subjects with and without airflow obstruction in five Latin American cities: The PLATINO study

BackgroundAcute bronchodilator responsiveness is an area of discussion in COPD. No information exists regarding this aspect of the disease from an unselected COPD population. We assessed acute bronchodilator responsiveness and factors influencing it in subjects with and without airway obstruction in an epidemiologic sample.MethodsCOPD was defined by GOLD criteria (post-bronchodilator FEV₁/FVC < 0.70). In this analysis, subjects with pre-bronchodilator FEV₁/FVC <0.70 but ≥0.70 post-bronchodilator were considered to have reversible obstruction. Bronchodilator responsiveness after albuterol 200 μg was assessed using three definitions: a) FVC and/or FEV₁ increment ≥12% plus ≥200 mL over baseline; b) FEV₁ ≥ 15% increase over baseline; and c) FEV₁ increase ≥10% of predicted value.ResultsThere were 756 healthy respiratory subjects, 481 subjects with reversible obstruction and 759 COPD subjects. Depending on the criterion used the proportion of person with acute bronchodilator responsiveness ranged between 15.0–28.2% in COPD, 11.4–21.6% in reversible obstructed and 2.7–7.2% in respiratory healthy. FEV₁ changes were lower (110.6 ± 7.40 vs. 164.7 ± 11.8 mL) and FVC higher (146.5 ± 14.2 mL vs. ?131.0 ± 19.6 mL) in COPD subjects compared with reversible obstructed. Substantial overlap in FEV₁ and FVC changes was observed among the groups. Acute bronchodilator responsiveness in COPD persons was associated with less obstruction and never smoking.ConclusionsOver two-thirds of persons with COPD did not demonstrate acute bronchodilator responsiveness. The overall response was small and less than that considered as significant by ATS criteria. The overlap in FEV₁ and FVC changes after bronchodilator among the groups makes it difficult to determine a threshold for separating them.     

Association between airflow limitation and prognosis in patients with chronic pulmonary aspergillosis

BackgroundPrevious studies have shown that reduced levels of lung function, characterized by forced expiratory volume in 1 second (FEV₁), are associated with higher respiratory events and mortality in general population and some chronic lung diseases. Chronic pulmonary aspergillosis (CPA) is a destructive, fatal lung disease caused by Aspergillus infection in non-immunocompromised patients with suboptimal pulmonary function. However, there is limited information on the status and features of CPA according to FEV₁.MethodsWe performed a retrospective observational study to investigate the FEV₁ and airflow limitation in patients with CPA between March 2017 and February 2019 at a tertiary hospital in South Korea.ResultsOf the 144 CPA patients, 104 underwent spirometry, demonstrating median forced vital capacity (FVC) and FEV₁ of 2.35 L (68%) and 1.43 L (62%), respectively. Among them, 56 patients had airflow limitation on PFT, with median FVC, and FEV₁ of 2.47 L (73%) and 1.11 L (47%), respectively. Low body mass index (BMI) (20.1 vs. 22.1 kg/m²; P=0.011), breathlessness (60% vs. 20%; P=0.002), and bilateral pulmonary lesions (33.3% vs. 4%; P=0.006) were more common in patients with moderate to very severe airflow limitation than in those with normal to mild airflow limitation.ConclusionsModerate to very severe airflow limitation was observed in 43.3% of patients with CPA. Additionally, low BMI, breathlessness, and bilateral pulmonary lesions contributing to poor prognosis were more common in patients with moderate to very severe airflow limitation than in those with normal to mild airflow limitation. Our findings suggest that airflow limitation can be associated with the prognosis of CPA. Further investigations are needed to demonstrate the clinical significance of this association.     

Modifying the Course of Chronic Obstructive Pulmonary Disease: Looking Beyond the FEV1

Abstract

COPD is defined by airflow limitation that is not fully reversible and is usually progressive. Thus, airflow obstruction (measured as FEV₁) has traditionally been used as the benchmark defining disease modification with therapy. However, COPD exacerbations and extrapulmonary effects are common and burdensome and generally become more prominent as the disease progresses. Therefore, disease progression should be broader than FEV₁ alone. Interventions that reduce the frequency or severity of exacerbations or ameliorate extrapulmonary effects should also be considered disease modifiers. A narrow focus on FEV₁ will fail to capture all the beneficial effects of therapy on disease modification. Although smoking cessation has been unequivocally demonstrated to slow the rate of FEV₁ decline, inhaled corticosteroid–long-acting bronchodilator therapy may also have modest effects according to post hoc analysis. Maintenance pharmacotherapy with inhaled long-acting anti-muscarinic or ®-adrenergic agents or combined ®-adrenergic—inhaled corticosteroid reduces symptoms, improves lung function, reduces the frequency of exacerbations, and improves exercise capacity and HRQL. Pulmonary rehabilitation reduces symptom burden, increases exercise capacity, improves HRQL, and reduces health care utilization, probably through reducing the severity of exacerbations. Smoking cessation, lung volume reduction surgery, inhaled maintenance pharmacotherapy, and pulmonary rehabilitation administered in the post-exacerbation period may reduce mortality in COPD. These improvements over multiple outcome areas and over relatively long durations suggest that disease modification is indeed possible with existing therapies for COPD. Therefore, therapeutic nihilism in COPD is no longer warranted.     

The prognostic significance of lung function in stable heart failure outpatients

Background

This study investigated the impact on all‐cause mortality of airflow limitation indicative of chronic obstructive pulmonary disease or restrictive spirometry pattern (RSP) in a stable systolic heart failure population.

Hypothesis

Decreased lung function indicates poor survival in heart failure.

Methods

Inclusion criteria: NYHA class II‐IV and left ventricular ejection fraction (LVEF) < 45%. Prognosis was assessed with multivariate Cox proportional hazards models. Two criteria of obstructive airflow limitation were applied: FEV₁/FVC < 0.7 (GOLD), and FEV₁/FVC < lower limit of normality (LLN). RSP was defined as FEV₁/FVC > 0.7 and FVC<80% or FEV₁/FVC > LLN and FVC <LLN.

Results

There where 573 patients in the cohort (85% of eligible patients in study period). Median follow‐up was 4.7 years and 176 patients died (31%). Age, NYHA class, smoking, body mass index and LVEF were independent prognostic factors (p<0.01). Obstructive airflow limitation increased mortality using both criteria (HR_GOLD 2.07 [95% CI 1.45–2.95] p<0.01 and HR_LLN 2.00 [1.40–2.84] p<0.01) and was an independent marker when using LLN criteria (HR 1.74 [1.17‐2.59] p=0.006). RSP was independently associated with mortality when defined as FVC < LLN (HR 1.54 [1.01–2.35] p=0.04) but not as FVC < 80%. Multivariate hazard ratios for a 10% decrease in predicted value of FEV1 or FVC were 1.42 (p<0.001) and 1.33 (p<0.001) in patients exhibiting airflow obstruction, and 1.36 (p=0.031) and 1.38 (p=0.041) in RSP.

Conclusions

Presence of obstructive airflow limitation indicative of COPD or RSP were associated with increased all‐cause mortality, however only independently when using the LLN definition.

     

Severity of Airflow Obstruction in Chronic Obstructive Pulmonary Disease (COPD): Proposal for a New Classification

Current classifications of Chronic Obstructive Pulmonary Disease (COPD) severity are complex and do not grade levels of obstruction. Obstruction is a simpler construct and independent of ethnicity. We constructed an index of obstruction severity based on the FEV₁/FVC ratio, with cut-points dividing the Burden of Obstructive Lung Disease (BOLD) study population into four similarly sized strata to those created by the GOLD criteria that uses FEV₁. We measured the agreement between classifications and the validity of the FEV₁-based classification in identifying the level of obstruction as defined by the new groupings. We compared the strengths of association of each classification with quality of life (QoL), MRC dyspnoea score and the self-reported exacerbation rate. Agreement between classifications was only fair. FEV₁-based criteria for moderate COPD identified only 79% of those with moderate obstruction and misclassified half of the participants with mild obstruction as having more severe COPD. Both scales were equally strongly associated with QoL, exertional dyspnoea and respiratory exacerbations. Severity assessed using the FEV₁/FVC ratio is only in moderate agreement with the severity assessed using FEV₁ but is equally strongly associated with other outcomes. Severity assessed using the FEV₁/FVC ratio is likely to be independent of ethnicity.     

Analysis of FEV1 Decline in Relatively Healthy Heavy Smokers: Implications of Expressing Changes in FEV1 in Relative Terms

Progressive decline in lung function has been widely accepted as the hallmark of chronic obstructive pulmonary disease (COPD); however, recent evidence indicates that the rate of decline measured as decline in forced expiratory volume in one second (FEV₁) is higher in mild to moderate COPD than in severe COPD. Usually changes in FEV₁ are measured in ml that is “absolute”; however, changes can also be measured “relative” as a percentage of the actual FEV₁. We hypothesize that relative measurements could be more appropriate than absolute measurements for describing changes in lung function. We analyzed data from 3,218 relatively healthy heavy smokers who participated in the Danish Lung Cancer Screening Trial. The influences of age, sex, height, body mass index, smoking, and severity of airflow limitation on FEV₁ were analyzed in mixed effects models. In absolute terms those with the best lung function consistently showed the steepest decline, whereas in relative terms most fast decliners are found among those with low lung function. Measuring changes in relative terms implied statistically significant acceleration of decline with advancing age, smoking (pack-years) and severity of airflow limitation. Relative measurements may lead to a better understanding of changes in lung function. Smoking and severity of airflow limitation speed up the loss of lung function, and this emphasizes the importance of abstaining from smoking the sooner the better. Measuring changes in relative terms could have important implications for the interpretation of results from clinical trials where FEV₁ is the primary outcome. DLCST; www.ClinicalTrials.org, registration number: NCT00496977.     

Lung Dysfunction of Chronic Smokers with No Signs of COPD

Cigarette smoking causes airflow limitation with lung hyperinflation being the primary causes of COPD. Fifty chronic smokers (CSs) with no signs of GOLD-adjusted COPD with smoking habit at least ≥10 pack-years (p/yrs) were divided into CS-mild (n = 24) with smoking history from ≥10 to ≤20 p/yrs and CS-heavy groups (n = 26) with smoking history ≥21 p/yrs. Spirometry, plethysmography and diffusing capacity were measured and lung computed tomography (CT) was performed. Residual volume (RV) (L) and RV/TLC (total lung capacity) ratio were significantly increased in CS-heavy when compared to CS-mild (p = 0.001, p = 0.03). A significant reduction of forced expiratory volume in 1 second/forced vital capacity (FEV₁/FVC) ratio and airway specific conductance was shown in CS-heavy (p = 0.02, p = 0.03). Lung emphysema signs at CTs were revealed in 17 CSs and ten of them had declined diffusing capacity below 70% of predicted. The percentage of emphysematous lesions inversely and significantly correlated with measured diffusing capacity (p = 0.0009, r = ?0.72). Study groups’ smoking intensity inversely correlated the declined airway specific conductance (p = 0.004, r = ?0.39) and increase of the RV (L) (p = 0.0004, r = 0.46). Multiple regression analysis determined that smoking intensity regardless of the subjects’ age was significant factor for decline of airway specific conductance and increase of RV (L). Here we conclude that lung function deviation and lung structural changes are present in CSs before the clinical signs of airway obstruction reveal. Body plethysmography and diffusing capacity measurement with routine spirometry can provide valuable information for detection of changes reflecting to the early onset of COPD in CSs.     

Reduced level of physical activity in Japanese patients with chronic obstructive pulmonary disease

BackgroundThere is increasing interest in the quantification of physical activity (PA) with an accelerometer for the management of chronic obstructive pulmonary disease (COPD). However, a detailed understanding of the PA in Japanese patients with COPD is lacking. We evaluated the levels of PA in terms of intensity in Japanese patients with COPD and evaluated the factors, which could influence the PA.MethodsForty-three outpatients with COPD and 21 age-matched healthy subjects were monitored with a triaxial accelerometer, and their PA was compared. Furthermore, the effects of pulmonary function, ADO index (age, dyspnea, and airflow obstruction) and modified BODE index (body mass index, airflow obstruction, dyspnea, and exercise capacity) on the PA were evaluated.ResultsThe PA in COPD was significantly reduced at all intensities. The reduced levels of PA in COPD were 23.1% at ≥2.0 metabolic equivalents (METs), 33.0% at ≥2.5 METs, 50.9% at ≥3.0 METs, and 66.9% at ≥3.5 METs, compared with that of healthy subjects, and the reduction was significant at GOLD stage III. The values of FVC, FEV_1.0, and DLCO/VA were correlated with that of the PA, but the lung volume parameters were not. The ADO and modified BODE indices were also well correlated with the PA.ConclusionsThe reduced levels of PA in Japanese patients with COPD were objectively demonstrated in terms of intensity that could provide us a new target for the management of COPD.     

COPD Assessment Test: A Simple Tool to Evaluate Disease Severity and Response to Treatment

The COPD assessment test (CAT) is a short questionnaire designed to assess the impairment in health status of COPD patients. We aimed to determine the change of the CAT in COPD patients after 1 year of treatment and test the association between the score and clinical and lung function variables. Methods A cohort of 111 newly diagnosed COPD patients in primary care was evaluated at baseline and one year after the implementation of the recommended treatment according to the Global Initiative for the management of COPD (GOLD). Results Most of the patients (82%) were diagnosed with mild to moderate airflow limitation (mean FEV₁ 72 ± 21.5% predicted) and the CAT score increased in proportion with the GOLD stage of severity. The CAT significantly correlated with the number of exacerbations, visits to general practitioners and days of hospitalization both at the beginning and at 1 year follow-up. A strong negative correlation between the CAT score and FEV₁ predicted was also observed. The CAT was responsive to the application of treatment with a significant improvement in the mean score (95% confidence interval) following 12 months of treatment by –2.4 (–2.9, –1.9) despite the small decline in lung function indices. The number of exacerbations in the preceding year and FEV₁ were independent predictors of the CAT score in the general linear model. Conclusion The CAT questionnaire may serve as a simple, measurable tool complementary to spirometry in the assessment of severity and of response to treatment in unselected COPD patients in primary care.     

Dynamic Hyperinflation Correlates with Exertional Oxygen Desaturation in Patients with Chronic Obstructive Pulmonary Disease

Background

Dynamic hyperinflation (DH) causes exercise limitation and exertional dyspnea in patients with chronic obstructive pulmonary disease (COPD). Exertional desaturation (ED) also occurs commonly in COPD but neither routine physiologic parameters nor imaging predict ED accurately. In this study we evaluated the relationship between DH and ED during 6-min walk testing (6MWT).

Methods

We measured ED and DH in patients with stable COPD. SpO₂ was measured by continuous pulse oximetry during 6MWT. ED was defined as a decline in SpO₂ (ΔSpO₂) ≥4 %. DH was determined by measuring inspiratory capacity (IC) before and after the 6MWT using a handheld spirometer. DH was defined as ΔIC >0.0 L. We correlated DH and ED with clinical and pulmonary physiologic variables by regression analysis, χ ², and receiver operator curve (ROC) analysis.

Results

Thirty males [age = 65 ± 9.4 years, FEV₁ % predicted = 48 ± 14 %, and DLCO % predicted = 50 ± 21 % (mean ± SD)] were studied. ΔSpO₂ correlated with ΔIC (r = 0.49, p = 0.005) and age (r = 0.39, p = 0.03) by univariate analysis; however, only ΔIC correlated on multivariate regression analysis (p = 0.01). ΔSpO₂ did not correlate with FEV₁, FVC, FEF_25–75, RV, DLCO % predicted, BMI, smoking, BORG score, or distance covered in 6MWT. DH strongly correlated with ED (p = 0.001). On ROC analysis, DH had an area under the curve of 0.92 for the presence of ED (sensitivity = 90 %; specificity = 77 %, p < 0.001).

Conclusion

Routine pulmonary function test results and clinical variables did not correlate with ED in patients with stable COPD. Dynamic hyperinflation strongly correlates with exertional desaturation and could be a reason for this desaturation.     

Tidal Expiratory Flow Limitation at Rest as a Functional Marker of Pulmonary Emphysema in Moderate-to-Severe COPD

Background: Tidal expiratory flow limitation (EFL) is a step of paramount importance in the functional decline in COPD. Among mechanisms contributing to EFL, loss of airway-parenchymal interdependence could mostly be involved. Aim: To assess if EFL is a functional marker more frequently linked to prevalent pulmonary emphysema rather than to prevalent chronic bronchiolitis in COPD patients with moderate-to-severe airflow obstruction. Methods: Forty consecutive stable COPD patients with FEV₁ between 59 and 30% of predicted were functionally evaluated by measuring spirometry, maximal flow-volume curve and lung diffusion capacity (DL_CO) and coefficient of diffusion (K_CO). EFL was assessed by the negative expiratory pressure (NEP) method both in sitting and supine position. Chronic dyspnea was also scored by modified Medical Research Council (mMRC) scale. Results: In sitting position 13 patients (33%) were flow limited (FL) and 27 were non-flow limited (NFL). Only FEV₁/FVC, FEV₁ and MEF_25–75% were different between FL and NFL patients (p < 0.01). In supine position, however, among NFL patients in sitting position those who developed EFL, had significantly lower values of DL_CO and K_CO (p < 0.05) and higher mMRC score (p < 0.01), but similar values of FEV₁ as compared to those who did not have EFL. Conclusions: In COPD EFL in sitting position is highly dependent by the severity of airflow obstruction. In contrast, the occurrence of EFL in supine position is associated with worse DL_CO and K_CO and greater chronic dyspnea, reflecting a prevalent emphysematous phenotype in moderate-to-severe COPD patients.     

Lack of Benefit of Continuous Positive Airway Pressure on Lung Function in Patients with Overlap Syndrome

Obstructive sleep apnea (OSA) has been shown to be an inflammatory stimulus and may potentially result in a deterioration in the respiratory status of patients with coexistent chronic obstructive pulmonary disease (COPD) (overlap syndrome). We hypothesized that with treatment of OSA, there would be an improvement in coexistent COPD in overlap patients. We also sought to characterize overlap patients by comparing them with patients with either OSA or COPD alone. We performed a retrospective study of patients who attended a university-affiliated Veterans Affairs hospital. Demographic and clinical data were obtained from the medical charts and pharmacy records for the preceding two years and for the two years following the initiation of continuous positive airway pressure (CPAP) therapy. Overlap patients had moderately severe sleep apnea (AHI 28.6 ± 4.2) and moderately severe COPD (FEV₁= 1.94 ± 0.10 L). The prevalence of overlap syndrome in COPD patients was 11.9%, and 41% in OSA patients. Overlap patients who were compliant with CPAP therapy experienced a greater decrease in FEV₁, percent predicted FEV₁, percent decrease in FEV₁, FVC, percent predicted FVC, and percent decrease in FVC when compared with noncompliant patients. A very strong correlation was found between the average hours of CPAP use per day and the percent decrease in FEV₁ (r = 0.69, p = 0.003). There was a similar strong correlation for the decrease in FEV₁ and percent predicted FEV₁. OSA is common in COPD patients; similarly, COPD is common in OSA patients. Treatment of OSA with CPAP therapy in patients with overlap syndrome may not lead to an improvement in the coexistent COPD.