[Effect of dopamine on lung vascular mechanics. Its study in the isolated canine lobe model embolized with gel foam]

After inducing an increase in pulmonary vascular resistance (Rp) in an isolated in situ lobe (LAIS) embolized with gelfoam (GE), the effect of dopamine infused at 12 mcg/kg/min in eight mongrel dogs was evaluated. We studied the rectilinear pressure-flow (QL/PL) relationship, the hemodynamic and blood gas before (condition A), 15 minutes later GE (condition B) and after dopamine infusion (condition C). After GE a decrease in QL and an increase in inflow (PL) and mean critical closing pressures (PLi) were noticed (p less than 0.01). Also decrease in pulmonary vascular conductance (1/Rp) was noted. At condition C a rise in QL and PL were noticed (p less than 0.01), but 1/Rp and PLi did not change. We concluded that dopamine in the LAIS with increased Rp at the used doses does not have vasoactive action for those vessels responsible for the phenomenons where flow resistance or mean critical closing pressure occurs.