title: Exponential analysis of the lung pressure-volume curve in patients with chronic pigeon-breeder's lung.
abstract: Pigeon-breeder's lung (PBL) is extremely common in Mexico City and often progresses to irreversible pulmonary fibrosis. The exponential analysis of the lung pressure-volume (PV) curve (V = A - Be-kp) has been suggested as a method to separate the lung restriction caused by inflammation from that caused by pulmonary fibrosis; a significantly decreased value for the exponential constant, k, suggests a change in the mechanical properties of the functioning lung parenchyma, while a normal value accompanied by restriction suggests subtraction of lung units without a change in the mechanical properties of the functioning units. We measured lung volumes and static PV curves in 29 patients who had persistent lung restriction following a biopsy-proven diagnosis of PBL. Mean values in the 29 subjects were as follows: age, 43 +/- 13 years; TLC, 61 +/- 15 percent of predicted; VC, 46 +/- 19 percent of predicted; and k, 55 +/- 17 percent of predicted. Twenty-four of the 29 patients had values for k that were below the 95 percent confidence level, and five had "normal" values. There was no difference in TLC and VC (percent of predicted) between those with or without a decreased value for k. Four of five patients with a normal value for k improved subsequent to diagnosis, while only one of 21 patients with a decreased k improved. We conclude that increased lung elasticity manifested by a low value for k is common in patients with chronic PBL. These results support the observation of frequent irreversible lung fibrosis in these patients. Measurements of k could prove a good prognostic indicator at the time of initial diagnosis.
authors.affiliation: Departamento de Fisiologia Pulmonar, Instituto Nacional de Enfermedades Respiratorias (INER), Mexico City.
authors.forename: R
authors.initials: R
authors.lastname: Sansores
authors.forename: R
authors.initials: R
authors.lastname: Perez-Padilla
authors.forename: P D
authors.initials: PD
authors.lastname: Paré
authors.forename: M
authors.initials: M
authors.lastname: Selman
mesh_terms: D000328:Adult; D001716:Bird Fancier's Lung / Q000503:physiopathology*; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D004548:Elasticity; D006801:Humans; D008875:Middle Aged; D011312:Pressure; D012123:Pulmonary Ventilation; D014109:Total Lung Capacity; D014797:Vital Capacity