title: Arteriovenous differences in plasma dilution and the distribution kinetics of lactated ringer's solution.
abstract: BACKGROUND
  Conventional concept suggests that infused crystalloid fluid is first distributed in the plasma volume and then, since the capillary permeability for fluid is very high, almost instantly equilibrates with the extracellular fluid space. We challenge whether this view is consistent with findings based on volume kinetic analysis.
  
  
  METHODS
  Fifteen volunteers received an IV infusion of 15 mL/kg of lactated Ringer's solution during 10 min. Simultaneous arterial and venous blood hemoglobin (Hgb) samples were obtained and Hgb concentrations measured. The arteriovenous (AV) difference in Hgb dilution in the forearm was determined and a volume kinetic model was fitted to the series of Hgb concentrations in arterial and venous blood.
  
  
  RESULTS
  The AV difference in plasma dilution was only positive during the infusion and for 2.5 min thereafter, which represents the period of net flow of fluid from plasma to tissue. Kinetic analysis showed that volume expansion of the peripheral fluid space began to decrease 14 min (arterial blood) and 20 min (venous blood) after the infusion ended. Distribution of lactated Ringer's solution apparently occurs much faster in the forearm than in the body as a whole. Therefore, the AV difference in the arm does not accurately reflect the distribution of Ringer's solutions or whole-body changes in plasma volume.
  
  
  CONCLUSIONS
  The relatively slow whole-body distribution of lactated Ringer's solution, which boosts the plasma volume expansion during and for up to 30 min after an infusion, is probably governed by a joint effect of capillary permeability and differences in tissue perfusion between body regions.
authors.affiliation: Clinical Research Center, Södertalje Hospital, Södertalje, Sweden.
authors.forename: Christer H
authors.initials: CH
authors.lastname: Svensen
authors.forename: Peter M
authors.initials: PM
authors.lastname: Rodhe
authors.forename: Joel
authors.initials: J
authors.lastname: Olsson
authors.forename: Elisabet
authors.initials: E
authors.lastname: Børsheim
authors.forename: Asle
authors.initials: A
authors.lastname: Aarsland
authors.forename: Robert G
authors.initials: RG
authors.lastname: Hahn
mesh_terms: D000328:Adult; D002199:Capillary Permeability; D045604:Extracellular Fluid / Q000378:metabolism; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006438:Hemodilution; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007262:Infusions, Intravenous; D007552:Isotonic Solutions / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D008954:Models, Biological; D010953:Plasma Volume; D017534:Radial Artery / Q000378:metabolism; D000077325:Ringer's Lactate; D014018:Tissue Distribution; D014680:Veins / Q000378:metabolism; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D007552:Isotonic Solutions; D000077325:Ringer's Lactate