The diaphragm in emphysema.
Because of hyperinflation, the diaphragm of emphysematous patients operates at a disadvantageous position which affects its mechanical arrangement, modifies the configuration of its zone of apposition, increases its radius of curvature, and decreases its muscle fiber length below optimal configuration. The diaphragm in emphysema therefore displays a suboptimal configuration limiting its ability to function properly but shows no inherent structural insufficiency, unless its contractility is impaired by significant arterial blood gas anomalies or severe malnutrition. The demand imposed on the diaphragm in emphysema is increased by both hyperinflation and air-flow obstruction. With altered performance of the diaphragm and increased demand, force reserve is diminished and diaphragmatic fatigue may occur; this imbalance is targeted in some treatment modalities of emphysema such as pulmonary rehabilitation programs and lung volume reduction surgery.
Ruel
M
M
Thoracic Surgery Division, Centre de Penumologie de l'Hôpital Laval, Sainte-Foy, Quebec, Canada.
Deslauriers
J
J
Maltais
F
F
D001696:Biomechanical Phenomena; D003964:Diaphragm / Q000098:blood supply / Q000503:physiopathology*; D005652:Functional Residual Capacity; D006801:Humans; D016040:Lung Transplantation; D011013:Pneumonectomy; D011312:Pressure; D011656:Pulmonary Emphysema / Q000503:physiopathology*; D012039:Regional Blood Flow