Neural respiratory drive and neuromuscular coupling during CO2 rebreathing in patients with chronic interstitial lung disease.
In 12 patients with CILD and 18 age-matched normal subjects we assessed the ventilatory control system at three levels: (a) neural, as assessed by EMGd (XP/Ti) and EMGint muscles via surface electrodes; (b) muscular, as assessed by mouth occlusion pressure (P0.1); and (c) ventilatory, as assessed by both ventilation (VE) and the related parameters, tidal volume (VT) and respiratory frequency (f). Compared with a normal control group, patients exhibited a significant decrease in lung volumes and in MIP; VT and inspiratory time (Ti) were significantly lower, while VT/Ti, P0.1, and both EMGd and EMGint were significantly greater in patients. During a CO2 rebreathing test, patients exhibited significantly greater EMGd, EMGint, and P0.1 responses to increasing PETCO2 than the control group. VE response slopes were similar in the two groups. For a given EMGd response slope (delta XP/Ti/delta PETCO2), the average P0.1 response slope (delta P0.1/delta PETCO2) was found to be significantly lower in patients than in the normal control group. Compared with normal subjects, CILD patients have a normal or increased neural component of respiratory activity and relatively low neuromuscular coupling (delta P0.1/delta XP/Ti). The decreased neuromuscular coupling could be explained in these patients by a reduced inspiratory muscle strength.
Gorini
M
M
Istituto di Clinica Medica III, Universita' degli Studi, Florence, Italy.
Spinelli
A
A
Ginanni
R
R
Duranti
R
R
Gigliotti
F
F
Arcangeli
P
P
Scano
G
G
D000368:Aged; D004576:Electromyography; D005260:Female; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000175:diagnosis / Q000503:physiopathology*; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000294:innervation*