title: NO diffusing capacity of rabbit lungs increases with ventilator-driven lung expansion.
abstract: In this animal study we evaluated the dependence of the pulmonary diffusing capacity (DL) of nitric oxide (DL,NO) on ventilator-driven increases in alveolar volume. According to the common hypothesis as to whether DL,NO reflects the diffusive properties of the alveolar-capillary membrane, DL,NO should be improved by lung expansion. However, the influence of a simultaneous raise in intrapulmonary pressure is unknown. DL,NO was determined by applying the single-breath method to four anaesthetised paralysed rabbits (weight 3.2-3.5 kg) at various alveolar volumes (38-69 ml) and intrapulmonary pressures (0.15-12.5 mmHg). The animals were ventilated with room air, using a computerised ventilatory servo-system that was also employed to perform the single-breath manoeuvres. Inflation procedures were always started from residual volume (12-13.7 ml), using 0.05% NO in N2 as the indicator gas mixture. End-tidal PNO was determined by respiratory mass spectrometry. DL,NO increased simultaneously with lung expansion and with increasing intrapulmonary pressure (P<0.001). We conclude that the DL,NO provides a measure of the pulmonary diffusive properties that is not influenced by a pressure-induced impairment of pulmonary capillary blood flow.
authors.affiliation: Department of Physiology, University of Bonn, Nussallee 11, 53115 Bonn, Germany. h.heller@uni-bonn.de
authors.forename: H
authors.initials: H
authors.lastname: Heller
authors.forename: K D
authors.initials: KD
authors.lastname: Schuster
mesh_terms: D000818:Animals; D008168:Lung / Q000502:physiology*; D008954:Models, Biological; D009569:Nitric Oxide; D011312:Pressure; D011650:Pulmonary Alveoli / Q000502:physiology; D011653:Pulmonary Diffusing Capacity; D011817:Rabbits; D012121:Respiration, Artificial
chemical_list: D009569:Nitric Oxide