Lobar variations in collateral ventilation in excised dog lungs.
Lobar differences in the mechanics of collateral ventilation were investigated in sublobar segments of excised dog lungs using a wedged-catheter technique. At a transpulmonary pressure of 5 cm H2O, the collateral time constant was longest in segments from the right middle lobe, less in segments from the left upper lobe, and least in segments from the right and left lower and right upper lobes. The longer time constants for the right middle and left upper lobes were due to high collateral resistance. At a transpulmonary pressure of 2 cm H2O, the collateral time constant was longest in the right middle and left upper lobes primarily because of higher segment compliance, which reflected a lack of interdependence between segment and lobe. Lobar segments with long collateral time constants (right middle and left upper lobes) had large ratios of pleural surface area to volume. If this ratio is inversely related to the area of parenchymal contact between segment and lobe, then segments with a high ratio of pleural surface area to volume may be more prone to atelectasis after airway obstruction.
D000818:Animals; D004285:Dogs; D066298:In Vitro Techniques; D008168:Lung / Q000033:anatomy & histology / Q000502:physiology*; D008170:Lung Compliance; D008176:Lung Volume Measurements; D010994:Pleura / Q000033:anatomy & histology; D012119:Respiration; D013499:Surface Properties