Cui L, et al. - This investigation was undertaken to determine the role of inspiratory capacity (IC) on dyspnea assessment among COPD patients with or without emphysematous lesions. IC showed potential for being an effective complement to forced expiratory volume in 1 second (FEV₁) for post-treatment assessment of dyspnea in COPD patients. Furthermore, an increase in IC versus FEV₁ more suitably explained dyspnea relief for COPD patients with predominant emphysematous lesions.

Methods

• Researchers performed this prospective study on 124 patients with stable COPD.
• Patients performed pulmonary function tests and dyspnea evaluation using the modified Medical Research Council (mMRC) scale during the baseline visit.
• As per physicians’ recommendations, quantitative computerized tomography was performed on partial patients and, the emphysema index (EI; low attenuation area [LAA]% -950) was used to evaluate emphysematous changes.
• Thereafter, participants were categorized into the emphysema-predominant group (LAA% -950≥9.9%) and the non-emphysema-predominant group (LAA% -950<9.9%).
• A reevaluation was also performed ~1 month post-treatment in order to re-assess both pulmonary function parameters and dyspnea severity.
• In addition, correlation analysis between the change in IC (ΔIC) and dyspnea (ΔmMRC) was performed.

Results

• Researchers found that a negative correlation of ΔIC with ΔmMRC (correlation coefficient [cc], -0.490, P<0.001) was evident in the total study population in correlation analysis, which was stronger than that between ΔFEV₁ and ΔmMRC (cc, -0.305, P=0.001).
• A marked increase in IC (≥300 mL) was more likely in patients with absolute ΔmMRC >1 versus those with absolute ΔmMRC ≤ 1 (74.36% versus 35.29%; odds ratio [OR], 5.317; P<0.001).
• Findings demonstrated that in the emphysema-predominant group, only ΔIC strongly correlated with ΔmMRC (cc, -0.459, P=0.005), while ΔFEV₁ did not (P>0.05).