Inspiratory fraction and exercise impairment in COPD patients GOLD stages II-III

Abstract

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).In the present retrospective study, a comparison was made of the individual performance of post-bronchodilator IC, IC/TLC and forced expiratory volume in one second (FEV1) in predicting a severely reduced peak oxygen uptake (V9O 2 ; ,60% predicted) in 44 COPD patients Global Initiative for Chronic Obstructive Lung Disease stages II-III (post-bronchodilator FEV1 ranging from 31-79% pred).Patients with lower IC/TLC values (f0.28) showed increased lung volumes and reduced exercise capacity as compared with other subjects. Following a multiple linear regression analysis, only IC/TLC and FEV1 remained as independent predictors of V9O 2 (r 2 50.33). A receiver operating characteristic (ROC) curve analysis revealed that an IC/TLC f0.28 had the highest specificity (89.6%), positive predictive value (80%) and overall accuracy (86.3%) in identifying patients with V9O 2 ,60% pred. In addition, the area under the ROC curve tended to be higher for IC/TLC than IC.In conclusion, post-bronchodilator total lung capacity-corrected inspiratory fraction provides useful information in addition to forced expiratory volume in one second and inspiratory capacity, to estimate the likelihood of chronic obstructive pulmonary disease patients to present with severely reduced maximal exercise capacity.

Lung-Heart Clinical Crosstalk in the Course of Copd Exacerbation

“…As expected, IC has not revealed the degree of hyperinflation, whereas RV%TLC, as one of the most accurate methods of measuring hyperinflation, could reflect static hyperinflation changes [27,29]. That is why, in contrast to what was previously established [30], in the authors' opinion, COPD exacerbation itself is not enough to induce dynamic lung hyperinflation. The results of the study suggest that during the first phase of COPD exacerbation (hospital treatment) the reduction of dyspnoea at rest is probably caused by a decrease in lung volume (RV% TLC) and increase in bronchial patency (FEV 1 ).…”

Inspiratory Fraction Correlates With Exercise Capacity in Patients With Stable Moderate to Severe COPD

“…4 Also, Vassaux et al found that COPD subjects with an IF Ͻ 0.25 possessed worse percent-of-predicted peak V O 2 and peak O 2 pulse than subjects with an IF Ͼ 0.25. 26 Another study found that IF was an independent predictor of mortality risk in COPD subjects, and that COPD subjects with an IF Ͻ 0.25 had worse pulmonary function and higher mortality risk.…”

“…3 IC reflects the level of lung hyperinflation and is associated with the functional reserve in patients with COPD. Moreover, the ratio of IC to total lung capacity (IC/TLC, called the inspiratory fraction or IF) provides a better characterization of the volume fraction available for inspiration than does IC alone, 4 and IF predicts exercise capacity in patients with moderate to severe COPD. In the current study we compared the functional parameters of ventilation, gas exchange, and exercise capacity in patients with stable moderate to severe COPD.…”

Hiperinsuflação dinâmica no esforço: ainda muito a ser esclarecido

“…In COPD, although various mechanisms can act on exercise intolerance, mechanisms such as decreased peripheral strength and cardiovascular dysfunction, airflow limitation with dynamic air trapping has unique significance. (1)(2)(3)(4) The development of dynamic hyperinflation during exercise is highly prevalent in patients with moderate to severe COPD, reaching 80-85%, (1,2) but it also occurs in those with mild disease. (5) Dynamic hyperinflation on exertion is the result of expiratory flow limitation in response to reduced expiratory time, because of an increased ventilatory demand.…”

“…(7) In their study, Vogiatzis et al also defined two patterns of Editorial reduce airway resistance or ventilatory demand, or both. (4,11) Despite the major medical and therapeutic advances resulting from studies on dynamic hyperinflation in COPD, especially in the last two decades, there are still some limitations. The amount of reduction in IC during exertion that defines the presence of dynamic hyperinflation has yet to be established.…”