Background: Diaphragmatic excursion during spontaneous ventilation (SV) in normal supine volunteers is greatest in the dependent regions (bottom). During positive pressure ventilation (PPV) after anesthesia and neuromuscular blockade and depending on tidal volume, the nondependent region (top) undergoes the greatest excursion, or the diaphragm moves uniformly. The purpose of this study was to compare diaphragmatic excursion (during SV and PPV) in patients with chronic obstructive pulmonary disease (COPD) with patients having normal pulmonary function.
Methods: Twelve COPD patients and 12 normal control subjects were compared. Cross-table diaphragmatic fluoroscopy was performed while patients breathed spontaneously. After anesthetic induction and pharmacologic paralysis and during PPV, diaphragmatic fluoroscopy was repeated. For analytic purposes, the diaphragm was divided into three segments: top, middle, and bottom. Percentage of excursion of each segment during SV and PPV in normal subjects was compared with the percentage of excursion of each segment in patients with COPD.
Results: There was no significant difference in the pattern of regional diaphragmatic excursion (as a percentage of total excursion)-top, middle, bottom-when comparing COPD patients with control subjects during SV and PPV. In the control subjects, regional diaphragmatic excursion was 16 +/- (5), 33 +/- (5), 51 +/- (4) during SV and 49 +/- (13), 32 +/- (6), 19 +/- (9) during PPV. In COPD patients, regional diaphragmatic excursion was 18 +/- (7), 34 +/- (5), 49 +/- (7) during SV and 47 +/- (10), 32 +/- (6), 21 +/- (9) during PPV.
Conclusion: Regional diaphragmatic excursion in patients with COPD during SV and PPV is similar to that in persons with normal pulmonary function.