title: Distribution of pulmonary vascular resistance during lactic acid infusion in dogs.
abstract: We sought to determine the longitudinal distribution of pulmonary vascular resistance (PVR) in acute lactic acidosis utilizing pulmonary artery and vein balloon occlusion techniques (Holloway et al. J. Appl. Physiol. 54: 840-851, 1983). In anesthetized dogs, both a systemic vein (I-V) infusion and systemic artery (I-A) infusion of L-lactic acid were studied to control for potential effects of factors other than pH on PVR. During progressive I-A infusion (n = 9) to a pH of 6.94 +/- 0.06 there was no significant change in PVR or its distribution. In contrast, I-V infusion (n = 9) to a pH of 7.08 +/- 0.09 increased median PVR from 3.6 to 21.7 mmHg.1(-1).min (P less than 0.001), due to an increase in middle segment resistance (0.0-15.4 mmHg.1(-1).min, P less than 0.02). Examination by light and electron microscopy demonstrated pulmonary capillary obstruction with hemolyzed erythrocyte (RBC) membranes with I-V infusion, but representative I-A animals did not demonstrate these findings. Conceivably, the systemic vascular bed filtered the fragmented RBC membranes in the I-A model, but this microvascular obstruction with altered RBCs and RBC fragments caused the pulmonary hypertension observed in the I-V infusion. We conclude that lactic acidosis does not increase pulmonary vascular tone in dogs, a finding compatible with most previous studies in which observed increases in PVR may be attributed to other effects from I-V acid infusion on circulating blood elements.
authors.affiliation: Section of Pulmonary and Critical Care Medicine, University of Chicago, Illinois.
authors.forename: K W
authors.initials: KW
authors.lastname: Presberg
authors.forename: J I
authors.initials: JI
authors.lastname: Sznajder
authors.forename: J
authors.initials: J
authors.lastname: Melendres
authors.forename: T
authors.initials: T
authors.lastname: Lewis
authors.forename: C
authors.initials: C
authors.lastname: Abrahams
authors.forename: L D
authors.initials: LD
authors.lastname: Wood
mesh_terms: D000140:Acidosis, Lactic / Q000139:chemically induced / Q000503:physiopathology*; D000818:Animals; D001794:Blood Pressure; D002196:Capillaries / Q000473:pathology; D002302:Cardiac Output; D004285:Dogs; D004910:Erythrocyte Membrane / Q000473:pathology; D004912:Erythrocytes / Q000473:pathology; D006863:Hydrogen-Ion Concentration; D007261:Infusions, Intra-Arterial; D007262:Infusions, Intravenous; D007773:Lactates / Q000008:administration & dosage; D019344:Lactic Acid; D008168:Lung / Q000098:blood supply*; D008297:Male; D008854:Microscopy, Electron; D011651:Pulmonary Artery / Q000503:physiopathology; D011667:Pulmonary Veins / Q000503:physiopathology; D014655:Vascular Resistance
chemical_list: D007773:Lactates; D019344:Lactic Acid