Inspiratory Capacity in Chronic Obstructive Pulmonary Disease: A Measure of Hyperinflation and Relation with Other Parameters – A Cross-Sectional Study (original) (raw)
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International Journal of Chronic Obstructive Pulmonary Disease, 2019
Background: Severe hyperinflation causes detrimental effects such as dyspnea and reduced exercise capacity and is an independent predictor of mortality in COPD patients. Static lung volumes are required to diagnose severe hyperinflation, which are not always accessible in primary care. Several studies have shown that the area under the forced expiratory flow-volume loop (AreaFE) is highly sensitive to bronchodilator response and is correlated with residual volume/ total lung capacity (RV/TLC), a common index of air trapping. In this study, we investigate the role of AreaFE% (AreaFE expressed as a percentage of reference value) and conventional spirometry parameters in indicating severe hyperinflation. Materials and methods: We used a cohort of 215 individuals with COPD. The presence of severe hyperinflation was defined as elevated air trapping (RV/TLC .60%) or reduced inspiratory fraction (inspiratory capacity [IC]/TLC ,25%) measured using body plethysmography. AreaFE% was calculated by integrating the maximal expiratory flow-volume loop with the trapezoidal rule and expressing it as a percentage of the reference value estimated using predicted values of FVC, peak expiratory flow and forced expiratory flow at 25%, 50% and 75% of FVC. Receiver operating characteristics (ROC) curve analysis was used to identify cutoffs that were used to indicate severe hyperinflation, which were then validated in a separate group of 104 COPD subjects. Results: ROC analysis identified cutoffs of 15% and 20% for AreaFE% in indicating RV/ TLC .60% and IC/TLC ,25%, respectively (N=215). On validation (N=104), these cutoffs consistently registered the highest accuracy (80% each), sensitivity (68% and 75%) and specificity (83% and 80%) among conventional parameters in both criteria of severe hyperinflation. Conclusion: AreaFE% consistently provides a superior estimation of severe hyperinflation using different indices, and may provide a convenient way to refer COPD patients for body plethysmography to address static lung volumes.
American Journal of Respiratory and Critical Care Medicine, 2005
Static lung hyperinflation has important clinical consequences in patients with chronic obstructive pulmonary disease. We analyzed the power of lung hyperinflation as measured by the inspiratory capacity-to-total lung capacity ratio (IC/TLC) to predict mortality in a cohort of 689 patients with chronic obstructive pulmonary disease (95% males; FEV 1 , 1.17 L) with a mean follow-up of 34 months. We also compared the predictive value of IC/TLC with that of the BODE (body mass index, airflow obstruction, dyspnea, exercise performance) Index. Subjects who died (183; 27%) were older; had lower body mass index, FEV 1 , and IC/TLC ratio; walked less in the 6-minute walking distance; and had more dyspnea, a higher BODE Index, and comorbidity (p Ͻ 0.001). On the basis of logistic regression analysis, IC/TLC was found to be a good and independent predictor of all-cause and respiratory mortality. On the basis of receiver operating characteristic Type II curves, IC/TLC compared favorably with FEV 1 and predicted mortality independently of the BODE Index. We conclude that IC/TLC is an independent risk factor for mortality in subjects with chronic obstructive pulmonary disease. We propose that this ratio be considered in the assessment of patients with chronic obstructive pulmonary disease.
Inspiratory capacity predicts mortality in patients with chronic obstructive pulmonary disease
Respiratory Medicine, 2008
Background: Chronic obstructive pulmonary disease (COPD) severity is usually graded upon the FEV 1 reduction and FEV 1 has been considered the most important mortality predictor with age in COPD. Recent studies suggest other factors as more powerfully related to mortality than FEV 1 in COPD patients. Aim: To assess the impact of inspiratory capacity (IC) on mortality and morbidity in COPD patients during a 5-year follow-up period. Methods: We recruited 222 patients with mild-to-moderate COPD from January 1995 to December 2001 with an average follow-up period of 60 months (range 30-114 months). Among different respiratory parameters measured in stable conditions FEV 1 , FEV 1 /FVC%, IC and PaO 2 , PaCO 2 and BMI were chosen and their relationships with all-cause and respiratory mortality and with morbidity were assessed. Results: All these variables were associated with mortality at the univariate analysis. However, in a multivariate regression analysis (Cox proportional hazards model) for all-cause mortality age (year), IC (%pred.) and PaO 2 (mmHg) remained the only significant, independent predictors (HR ¼ 1.056, 95%CI: 1.023-1.091; HR ¼ 0.981, 95%CI: 0.965-0.998; HR ¼ 0.948, 95%CI: 0.919-0.979, respectively). According to the same analysis, IC (%pred.) and PaO 2 (mmHg) were significant independent predictors for respiratory mortality (HR ¼ 0.967, 95%CI: 0.938-0.997; HR ¼ 0.919, 95%CI: 0.873-0.969) together with FEV 1 /FVC% and BMI (kg/m 2 ) (HR ¼ 0.967, 95%CI: 0.933-1.022; HR ¼ 0.891, 95%CI: 0.807-0.985, respectively). IC (%pred.), FEV 1 /FVC%, and PaO 2 (mmHg) were also significantly related to morbidity, as independent predictors of hospital admissions because of exacerbations OR ¼ 0.980, 95%CI: 0.974-0.992; OR ¼ 0.943, 95%CI: 0.922-0.987; OR ¼ 0.971, 95%CI: 0.954-0.996, respectively). (C. Tantucci). Respiratory Medicine (2008) 102, 613-619
Respiratory Research, 2011
Background: Dyspnea while performing the activities of daily living has been suggested to be a better measurement than peak dyspnea during exercise. Furthermore, the inspiratory capacity (IC) has been shown to be more closely related to exercise tolerance and dyspnea than the FEV 1 , because dynamic hyperinflation is the main cause of shortness of breath in patients with COPD. However, breathlessness during exercise is measured in most studies to evaluate this relationship. Purpose: To evaluate the correlation between breathlessness during daily activities and airflow limitation or static hyperinflation in COPD. Methods: We examined 167 consecutive outpatients with stable COPD. The Baseline Dyspnea Index (BDI) was used to evaluate dyspnea with activities of daily living. The relationship between the BDI score and the clinical measurements of pulmonary function was then investigated. Results: The Spearman rank correlation coefficients (Rs) between the BDI score and the FEV 1 (L), FEV 1 (%pred) and FEV 1 /FVC were 0.60, 0.56 and 0.56, respectively. On the other hand, the BDI score also correlated with the IC, IC/ predicted total lung capacity (TLC) and IC/TLC (Rs = 0.45, 0.46 and 0.47, respectively). Although all of the relationships studied were strongly correlated, the correlation coefficients were better between dyspnea and airflow limitation than between dyspnea and static hyperinflation. In stepwise multiple regression analyses, the BDI score was most significantly explained by the FEV 1 (R 2 = 26.2%) and the diffusion capacity for carbon monoxide (R 2 = 14.4%) (Cumulative R 2 = 40.6%). Static hyperinflation was not a significant factor for clinical dyspnea on the stepwise multiple regression analysis. Conclusion: Both static hyperinflation and airflow limitation contributed greatly to dyspnea in COPD patients.
Respiratory Care, 2012
BACKGROUND: Dynamic hyperinflation (DH) and exercise limitation develop in patients with COPD; however, there is lack of knowledge about their long-term clinical consequences. We aimed to assess the impact of DH and exercise capacity in predicting mortality and also morbidity, as evaluated by emergency visits and hospital admissions in COPD patients during a 4-year period. METHODS: We recruited 73 stable COPD patients. The relationships of different respiratory parameters (FEV 1 %, body mass index, 6 min walk test distance [6MWD], static hyperinflation as measured by the ratio of inspiratory capacity to total lung capacity (IC/TLC) at rest, DH as measured by the change between the post-and pre-exercise values of IC/TLC [⌬IC/TLC], P aO 2 , and P aCO 2) with emergency visits and hospital admissions because of exacerbations and also with respiratory and all-cause mortality were assessed. RESULTS: The median follow-up period was 47 months (IQR 45-48 months, n ؍ 73). During the follow-up there were 8 (11%) deaths. The ⌬IC/TLC value was 3.9 ؎ 4.6%. The Kaplan-Meier survival curve showed that the cumulative survival rate was significantly lower in the patients with ⌬IC/TLC > 4 and with 6MWD < 439.56 m, using these values as thresholds. (The rates for sensitivity were 100% and 87.5%, and for specificity were 56.92% and 87.69%, respectively). The Cox proportional hazards model showed that DH (hazard ratio ؍ 1.4, 95% CI ؍ 1.09-1.84, P ؍ .009) and 6MWD (hazard ratio ؍ 0.98, 95% CI ؍ 0.97-0.99, P ؍ .006) were independent predictors of all-cause and respiratory mortality. 6MWD, FEV 1 %, IC/TLC, and ⌬IC/TLC were found to be significantly related to emergency visits (r ؍ ؊0.28, r ؍ ؊0.41, r ؍ ؊0.24, and r ؍ 0.38, respectively) and hospital admissions (r ؍ ؊0.41, r ؍ ؊0.45, r ؍ ؊0.36, and r ؍ 0.28, respectively). CONCLUSIONS: DH and exercise capacity are reliable and independent predictors for mortality and morbidity in COPD patients. We propose that DH and exercise capacity be considered in the assessment of long-term clinical consequences of COPD patients.
Background: Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease characterized by partially reversible airflow limitation. BODE index is amultidimensional tool stands as pneumonic composing the four individual variables {B-the body mass index (BMI), O-the degree of airway obstruction (post-bronchodilator FEV1% predicted), D-Dyspnea scale and E-exercise capacity measured by 6-minute walk distance test (6MWDT)}; giving the total points of 10; divided into four quartiles. It is used to diagnose, grade the severity, evaluate systemic comorbidities, evaluate the response to intervention and predict the mortality due to the disease. Purpose: To assess the severity of COPD by using BODE index and its individual variables, and GOLD stage; correlate their values to each other and determine their validity in stratifying the severity of COPD. Patients and methods: A hospital based cross-sectional study was conducted among a sampled 80 consecutive COPD patients visiting chest clinic of Jimma University Medical Center (JUMC) located at Jimma town, South west Ethiopia; from May 18 to August 18, 2017 G.C; and the measurement of all individual variables of BODE index were performed according to the American Thoracic Society (ATS), their results were entered into EPI data (3.1) and exported to SPSS (20) for further analysis. Chi square (X 2 ) test, Spearman correlation, kappa measure of agreement, receiver operator characteristic (ROC) and area under curve (AUC) was applied to determine the correlation and validity of variables/tools in grading the severity of the disease. Results: 80 COPD patients were enrolled in the study, Mean of age (55.1±13.66), BMI(19.98±3.43), 6MWDT (283±84.5), BODE index point (6.17±2.55), FEV1% predicted (42.5±15.6) and Dyspnea scale (2.2±0.7) were achieved. Majority of COPD patients were belonged to quartile IV, relatively increased through the stages if classification was made by BODE index and its components (FEV1% predicted and 6MWDT) but was higher among stage 3/severe if it was based on GOLD stage and dyspnea score. All variables used to grade COPD were positively correlated with each other except with BMI score (inversely correlated). The validity of the variables/tools used in grading severity of the disease was ranked as BODE index, 6MWDT, FEV1%, GOLD stage and dyspnea score in descending order while BMI score had the least/poor validity to predict the aim of the study based on specific results of their sensitivity, specificity, AUC with 95% CI and p-value. Conclusion: All variables except BMI score were valid to predict severity of COPD.
Clinical relevance of maximal inspiratory pressure: determination in COPD exacerbation
International Journal of Chronic Obstructive Pulmonary Disease, 2010
Muscle dysfunction represents a pathophysiological feature of chronic obstructive pulmonary disease (COPD). Muscle impairment contributes to decreased effort capacity in these patients at least in the same proportion as pulmonary function limitation. Maximal inspiratory pressure (MIP) is a reliable, noninvasive parameter for assessing the respiratory muscle capacity. The aim of the present study was to determine the role of MIP in effort capacity decrease in COPD patients. MIP was measured in 121 COPD patients without hyperinflation (RV , 150%) together with the following investigations: body plethysmography, body impedance analysis, dynamometry, 6-minute walking test (6MWT), determination of SaO 2 and serum levels of highly sensitive C-reactive protein (hsCRP). MIP (kPa) was significantly decreased in moderate-severe stages (6.19 ± 2.42, COPD II; 5.35 ± 2.49, COPD III; 4.56 ± 1.98, COPD IV vs 7.90 ± 2.61 in controls, P , 0.001), whereas the muscle force assessed by dynamometry was decreased only in advanced stages of disease (0.47 ± 0.12, COPD III; 0.41 ± 0.07, COPD IV vs 0.71 ± 0.16 in controls, P , 0.001). The values of MIP correlated (r = 0.53, P = 0.0003) with the distance walked in 6MWT. MIP may provide additive information concerning the general profile of muscle dysfunction in COPD patients.
Inspiratory fraction and exercise impairment in COPD patients GOLD stages II-III
European Respiratory Journal, 2006
The inspiratory-to-total lung capacity ratio or ''inspiratory fraction'' (inspiratory capacity(IC)/total lung capacity (TLC)) may be functionally more representative than traditional indices of resting airflow limitation and lung hyperinflation in patients with chronic obstructive pulmonary disease (COPD).