Mechanical properties of normal and emphysematous canine lungs

The right or left lung from 6 normal dogs (ME) and 6 dogs with chronic, bilateral papain-induced emphysema (E) were removed, degassed, and weighed. Transpulmonary pressure (P)-volume relationships were determined from 0 to 25cmH20 (TLC). At 10 cmH20, 3 alveolar capsules were attached. Isolated lungs were placed in a flow-type plethysmograph, and attached at a 3 way valve to positive end-expiratory pressure (PEEP), a constant flow air source, or a modified Harvard ventilator. After inflation to 20 cm HzO, lungs were deflated to 2.5, 5.0 or 7.5 cm HzO PEEP and ventilated sinusoidally at a fixed tidal volume (10%TLC) between 10 and 50 breaths/min. Capsule and bronchial pressures, and the volume and flow delivered to the bronchus were recorded on computer. End-expiratory volume (V) was determined from the P-volume relationships, and normalized compliance (C/V), airway resistance (Rair V), tissue resistance (Rtiss V), and hysteresivity (r|) were computed by linear regression between the P, volume and flow signals. E did not affect the frequency- or V-dependence of SHE c/v Mfv Rflu'v ; n Rtiss V, Rair V or C/V,Eof Rtiss V and Rair V increased, C/V decreased, but r| was not significantlyaffected. These data are consistent with the hypotheses that chronic papaininstillation decreases the airway-parenchymal interdependence, and increasesboth the elastic and viscous components of the lung, such that their ratio, n.,remains constant. This work was funded by The Whitaker Foundation.