The general morphometric characteristics of the external intercostal muscle (EIM) of patients with chronic respiratory disease have been well described. Because this muscle is highly acccssibile, it can provide an ideal model for longitudinal studies using consecutive biopsies of both sides. Whether or not the EIM fiber phenotype is homogeneous on dominant (D) and non dominant (ND) sides is unknown, however. To evaluate possible stuctural differences in right and left EIM in patients with COPD, eight patients (63 ±7 years of age) were enrolled. Lung function, respiratory muscle power, general muscle power and nutritional state were evaluated. Biopsies of the fifth EIM were taken from both sides. Specimens were processed in parallel manner to determine conventional morphometry (hematoxyllin-cosin staining), including minimum diameter (Dm) and fiber area (Ar) in cross sections. Fibers were typed by ATPase (at pH 4.2,4.6 and 9.4) and NADH-TR staining. Nutrition was normal in all patients. All patients had severe COPD (FEV, 27 ±7% of reference, limits 13 to 38% of reference) with air entrapment (RV 163 ±36% of reference, limits 181 to 276% of reference). None of the patients showed respiratory insufficiency at rest (PaO2, 72 ±7 mmHg). Peripheral musculoskeletal power measured by manual dynamometer showed no significant right-left differences: D 29 ± 2 and ND 28 ± 3 dynes. Morphometric study of 16 muscle specimens showed no significant differences between fiber size on D and ND sides. DmD was 47 ±10 μm and ArD was 2,595 ± 1,249 μm2. DmND was 49 ± 9 μm and ArND was 2,636 ± 953 μm22. Likewise, no significant differences were found between D and ND fiver types: type ID 51 ± 4% and type IID 49 ± 5% versus type IND 52 ± 4% and type IIND 48 ± 4%. EIM on N and ND sides is homogeneous at the fifth intercostal space. This finding, along with the scarcely invasive nature of the technique for collecting specimens leads us to suggest that longitudinal studies might be performed on the structural effects of various pharmacological or physical treatments followed by COPD patients.
|Journal||Archivos de Bronconeumologia|
|Publication status||Published - 1 Jan 1998|
- Respiratory muscles