Flow–volume loops of test breaths and preceding control breaths of a representative chronic obstructive pulmonary disease patient with different degrees of flow limitation in seated and supine posture: a) the patient was not flow limited in the seated posit... Flow–volume loops of test breaths and preceding control breaths of a representative chronic obstructive pulmonary disease patient with different degrees of flow limitation in seated and supine posture: a) the patient was not flow limited in the seated position and b) was flow limited in the supine position. Arrows indicate points at which manual compression of the abdomen was applied. Exp: expiration. Reproduced and modified from [57] with permission from the publisher. N.G. Koulouris, and G. Hardavella Eur Respir Rev 2011;20:147-155 ©2011 by European Respiratory Society