[Obtaining samples of the human diaphragm during upper laparotomy. A structural analysis].

UNLABELLED: The diaphragm seems to undergo adaptive structural change in chronic obstructive pulmonary disease. The possibility of obtaining muscle specimens is limited, however, particularly when respiratory function is severely affected.

OBJECTIVE

To assess the viability of a new technique for obtaining diaphragm muscle samples appropriate for structural assessment even from patients with severe functional change, and to study the size of fibers in relation to severity of disease.

METHODS

Fifteen muscle specimens were obtained from patients (aged 57 +/- 15 years) by abdominal laparotomy. All had undergone full lung function testing. Muscle samples were taken during surgery using a new technique involving formation of a tobacco pouch with dome biopsy. The method had been previously validated in animal models. Later, the biopsies were processed to evaluate fiber proportions and sizes (ATPase dyes at different levels of pH).

RESULTS

The 15 patients had a wide range of lung function results (FEV1 22-120% ref); 4 were severely affected (FEV1 < or = 50% ref). Nutritional status was normal in all cases; FEV1/FVC was 67 +/- 13%, RV was 134 +/- 55% ref, maximal mouth pressure (PImmax) was -75 +/- 27 cmH2O, transdiaphragmatic pressure (PIdimax) was 96 +/- 26 cmH2O, DLCO was 87 +/- 26% ref and PaO2 was 89 +/- 14 mmHg. We were able to obtain specimens valid for structural analysis from all patients with no complications. Light type I fibers predominated (54 +/- 9%) and size was normal overall (57 +/- 9 microns minimum diameter [Dm] atrophy index 195 +/- 243, and hypertrophy index 66 +/- 78), with no differences between the two fiber subtypes (Dm 58 +/- 8 microns for type I and 61 +/- 8 microns for type II). Overall size correlated inversely with static volumes (e.g. Dm with RV, r = -0.729, p < 0.01).

CONCLUSIONS

The laparoscopic technique described is simple and safe for use in humans to obtain diaphragm muscle specimens that are valid for morphometric analysis, allowing us to enlarge the range of subjects that can be enrolled for this type of study. The fiber muscles studied are smaller when functional involvement is greater in chronic obstructive pulmonary disease.