Lung Volume Abnormalities and its Correlation to Spirometric and Demographic Variables in Adult Asthma

Abstract

A significant proportion of asthmatic patients have elevated residual volume and abnormal RV/TLC ratio in the presence of normal FEV1/FVC ratio and absence of significant bronchodilator response. The clinical significance of these findings in asthma needs further prospective study.

Prevalence and reversibility of lung hyperinflation in adult asthmatics with poorly controlled disease or significant dyspnea

“…We did not observe this inverse relationship in our study population. In fact, our data tend to confirm Jain et al's observation of a weak relationship between FEV1 (% pred) and lung volumes. In a recent observational study, 51% of patients with symptomatic or nonsymptomatic persistent asthma treated with a fixed ICS/LABA combination displayed HI; furthermore, the RV/TLC ratio was correlated (albeit weakly) with the level of dyspnea .…”

“…Moreover, half of the children with HI had no signs of airflow obstruction . A recent study of 321 asthmatic adults also found a high prevalence of HI (52% for RV‐HI), although the cutoff for HI was rather low (>100% pred for RV) and lung volume reversibility was not assessed.…”

Longer duration of asthma is significantly associated with increased RV/TLC ratio

“…A recent study with simultaneously measured lung volumes and spirometry in subjects with asthma showed that there were significantly more frequency of abnormal residual volume (RV) and RV/TLC ratio (residual volume/Total lung capacity) than the frequency of abnormal FEV1/FVC ratios, percent predicted FEV1 values or the FEV1 reversibility [9,10]. These findings are consistent with previous observation that spirometric criteria may be used to guide, but not to diagnose airflow obstruction in subjects with asthma [9]. A cross sectional study of non-smoking subjects with asthma over the age of sixty, showed a significant association between increased FRC in subjects with longer duration of asthma [11].…”

“…However, Sorkness and associates observed an association between abnormal lung volumes and severe asthma [8]. A recent study with simultaneously measured lung volumes and spirometry in subjects with asthma showed that there were significantly more frequency of abnormal residual volume (RV) and RV/TLC ratio (residual volume/Total lung capacity) than the frequency of abnormal FEV1/FVC ratios, percent predicted FEV1 values or the FEV1 reversibility [9,10]. These findings are consistent with previous observation that spirometric criteria may be used to guide, but not to diagnose airflow obstruction in subjects with asthma [9].…”

Flow Dynamics and PM2.5 Deposition in Healthy and Asthmatic Airways at Different Inhalation Statuses

“…Asthma occurs as a result of chronic inflammation of airways, especially on small bronchioles, which leads to increased contractibility of the surrounding smooth muscles (Macklem, 1996). Since the walls in asthmatic airways are significantly thickened, the airway obstruction results in breathing difficulties (Jain et al, 2013). Studies had shown that elevated levels of PM 2.5 and rhinovirus infection could exacerbate asthma Tang et al, 2017).…”