Neural drive to the diaphragm after lung volume reduction surgery.
OBJECTIVE
The aim of this study was to investigate prospectively the changes in neural drive to the diaphragm in the first year after lung volume reduction surgery (LVRS) in patients with COPD.


METHODS
In 14 patients with severe emphysema (mean +/- SD; age, 53.7 +/- 8.3 years; FEV(1), 0.64 +/- 0. 18 L; residual volume [RV], 5.33 +/- 1.25 L; PaO(2), 62.3 +/- 9.0 mm Hg; PaCO(2), 39.0 +/- 6.0 mm Hg), we assessed lung function, arterial blood gases, maximal exercise capacity (Wmax), and oxygen uptake (f1.gif" BORDER="0">O(2)max); intrinsic positive end-expiratory pressure (PEEPi); diaphragmatic strength (transdiaphragmatic pressure, Pdisniff) and endurance capacity (tlim); central diaphragmatic drive assessed by root mean square analysis of the esophageal electromyogram (rmsdia); and isotime dyspnea during loaded breathing tests (BS).


RESULTS
Despite a significant increase (expressed as a percentage of baseline) in FEV(1) (40.6%) and a decrease in RV (30.0%) and PEEPi (75.7%) 1 month after LVRS, the improvements in Wmax (31.2%) and f1.gif" BORDER="0">O(2)max (13.7%); Pdisniff (25.4%) and tlim (64.9%); rmsdia (34.6%); and BS (21.7%) did not reach statistical significance (p < 0.05) until 6 months after LVRS. Arterial blood gases did not change significantly. Significant correlations were found between decrease in rmsdia and changes in PEEPi (r = 0.69), Wmax (r = -0.56), Pdisniff (r = -0.65), tlim (r = -0.59), and BS (r = 0.71) 6 months after LVRS.


CONCLUSIONS
Our results show that LVRS is able to increase the efficacy of the respiratory pump and by this way reduce ventilatory drive and respiratory effort sensation.
Lahrmann
H
H
Neurological Department Kaiser Franz Josef Hospital, Vienna, Austria.
Wild
M
M
Wanke
T
T
Tschernko
E
E
Wisser
W
W
Klepetko
W
W
Zwick
H
H
D003964:Diaphragm / Q000294:innervation*; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011013:Pneumonectomy; D011446:Prospective Studies; D015656:Respiratory Mechanics; D012132:Respiratory Muscles / Q000503:physiopathology