Influence of the distribution of emphysema on diaphragmatic motion in patients with chronic obstructive pulmonary disease

Abstract

We investigated whether the distribution of emphysema on computed tomography (CT) images can affect chest wall motion in patients with chronic obstructive lung disease (COPD). The subjects were 35 male patients with COPD (age, 69.7 ± 6.2 years). The RA-950 (the ratio of lung volume under -950 HU to total lung volume on CT) was measured separately for the upper and lower halves of the lung. We analyzed the flatness of the diaphragm (Kdome) and its motion (ΔLappo) using dynamic magnetic resonance imaging. Paradoxical motion (Mpr) represented the ratio of the paradoxical diaphragmatic movement (downward or upward) when the lung area decreased or increased, respectively, to he total diaphragm movement (expressed as a percent). These parameters were analyzed in correlation with pulmonary function tests and St. George Respiratory Questionnaire (SGRQ) scores. The RA-950 of the lower lung zone correlated significantly with the Kdome (P = 0.033), ΔLappo (P = 0.006), Mpr (%) (P = 0.001), forced expiratory volume at 1 s (% predicted; P < 0.001), and activity score of the SGRQ (p = 0.017). The RA-950 of the upper lung zone did not correlate with these parameters. In COPD patients, the distribution of emphysema on CT correlates with airflow obstruction and abnormal diaphragmatic motion.