| Abstract: | Regionalpulmonary blood flow was investigated with radiolabeled microspheres infour supine lambs during the transition from conventional mechanicalventilation (CMV) to partial liquid ventilation (PLV) and withincremental dosing of perfluorocarbon liquid to a cumulative dose of 30 ml/kg. Four lambs supported with CMV served as controls.Formalin-fixed, air-dried lungs were sectioned according to a grid;activity was quantitated with a multichannel scintillation counter,corrected for weight, and normalized to mean flow. During CMV, flow inapical and hilar regions favored dependent lung(P < 0.001), with no gradient acrosstransverse planes from apex to diaphragm. During PLV the gradientwithin transverse planes found during CMV reversed, most notably in thehilar region, favoring nondependent lung(P = 0.03). Also during PLV, flow wasprofoundly reduced near the diaphragm(P < 0.001), and across transverse planes from apex to diaphragm a dose-augmented flow gradient developed favoring apical lung (P < 0.01). Weconclude that regional flow patterns during PLV partially reverse thosenoted during CMV and vary dramatically within the lung from apex todiaphragm. |
