Abstract
Although it is known that in patients with COPD hyperinflation determines shortening of the inspiratory muscles, its effects on DI and RC morphology are still to be investigated. Therefore, the relationships between hyperinflation, DI and RC geometry were studied in 5 severe COPD patients (3F, 2M, age 62±6, FEV1%pred 18±4, %Low Attenuation Areas 43±10) and 5 healthy subjects (3F, 2M, age 48±4, FEV1%pred 114±20) by a custom software able to automatically obtain DI and RC 3D reconstruction from CT scans taken at TLC and RV. Dome surface area (Ado), length (Ld), radius of curvature and position (referred to xiphoid level) of DI and antero-posterior (A-P) and transverse (T) diameters of RC (at the level of the Louis angle) were calculated at both volumes. In COPD the range of DI position was invariantly below the xiphoid level, while in controls the top of DI dome was in average ∼80 mm above it. Ado and Ld were similar in COPD and controls when compared at similar absolute lung volumes. Radius of curvature was significantly higher in COPD than in controls only at TLC (P<0.001). RC diameters were not different at TLC (A-P:114±14 and 102±13 mm; T: 225±19 and 241±8 mm, respectively in COPD and healthy). At RV, A-P diameter was greater in COPD than controls (110±14 vs 87±18 mm), while T diameters were similar (223.26±19.12 and 235.69±9.84 mm).
CT images taken at different lung volumes allow detailed RC and DI morphometry. In severe COPD, DI and RC geometry is altered at RV. The lower DI position is associated to smaller A-P, but not T diameters of RC, which adopts a more circular shape. How and why these alterations influence the action of inspiratory muscles remains to be investigated.
- © 2014 ERS