title: Effect of crystalloid infusion on hematocrit and intravascular volume in healthy, nonbleeding subjects.
abstract: We evaluated the effect of IV crystalloid administration on hematocrit in 28 healthy, nonbleeding volunteers. Normal saline boluses of 10, 20, and 30 mL/kg were delivered at a mean rate of 115 +/- 4 mL/min, followed by a continuous infusion of either 1 or 5 mL/kg/hr. Hematocrit values determined immediately after bolus infusion declined from baseline a mean +/- SEM of 4.5 +/- 0.6 (P less than .001), 6.1 +/- 0.4 (P less than .001) and 6.3 +/- 0.6 points (P less than .001) in the 10, 20, and 30 mL/kg groups, respectively. Twenty minutes into the maintenance infusion, hematocrits had risen 1.5 +/- 0.8 (P = .03), 2.4 +/- 0.4 (P = .004) and 2.3 +/- 0.7 points (P = .005) when compared with post-bolus hematocrits in the 10, 20, and 30 mL/kg groups, respectively. These data show that in healthy, nonbleeding subjects, crystalloid infusion may cause significant changes in hematocrit. Calculations reveal that approximately 60% of infused saline, when delivered as a bolus, will diffuse from the intravascular space within 20 minutes of administration.
authors.affiliation: Department of Emergency Medicine, Harbor-UCLA Medical Center, Torrance 90509.
authors.forename: R H
authors.initials: RH
authors.lastname: Greenfield
authors.forename: H A
authors.initials: HA
authors.lastname: Bessen
authors.forename: P L
authors.initials: PL
authors.lastname: Henneman
mesh_terms: D000328:Adult; D001810:Blood Volume; D000077324:Crystalloid Solutions; D005260:Female; D006400:Hematocrit; D006470:Hemorrhage / Q000628:therapy; D006801:Humans; D007262:Infusions, Intravenous; D007552:Isotonic Solutions; D008297:Male; D010952:Plasma Substitutes / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010952:Plasma Substitutes