Breathing pattern assessment in normocapnic and hypercapnic patients in chronic obstructive pulmonary disease.
Thirty-six patients, 24 normocapnic (mean age +/- SD: 60 +/- 10) and 12 hypercapnic (mean age +/- SD: 64 +/- 9) were compared with a control group (10 volunteers, mean age +/- SD: 46 +/- 8) for the following patterns of respiratory drive and respiratory timing: (1) mean inspiratory flow (Vt/Ti); (2) mouth occlusion pressure 100 ms after the onset of inspiration (P 0.1) and minute ventilation (Ve); (3) inspiratory duty cycle Ti/Tt). The data suggest COPD "respiratory patterns" which may be characterized by the following features: (1) increased mean inspiratory flow (Vt/Ti); (2) increased P 0.1 (in absolute values), P 0.1/Ve and P 0.1/Vt/Ti; (3) reduction in inspiratory duty cycle (Ti/Tt). Changes are more evident in inspiratory duty cycle among hypercapnic pts. When respiratory obstruction becomes worse and hypercapnia appears, the Ti/Tt decrease could be explained by a reduction in diaphragm muscle work, that can prevent the failure of diaphragmatic contractility.
Vignale
L
L
Moretti
A
A
Rossi
P C
PC
Parentini
G C
GC
D000328:Adult; D003964:Diaphragm / Q000503:physiopathology; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000150:complications / Q000503:physiopathology*; D008875:Middle Aged; D009119:Muscle Contraction; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics