title: Isolated reduction of haematocrit does not compromise in vitro blood coagulation.
abstract: Low haematocrit values are generally well tolerated in terms of oxygen transport but a low haematocrit might interfere with blood coagulation. We thus sampled 60 ml of blood in 30 healthy volunteers. The blood was centrifuged for 30 min at 2000 g and separated into plasma, which contained the platelet fraction, and packed red blood cells. The blood was subsequently reconstituted by combining the entire plasma fraction with a mixture of packed red blood cells, 0.9% saline, so that the final haematocrit was either 40, 30, 20, or 10%. Blood coagulation was assessed by computerized Thrombelastograph analysis. Data were compared using repeated measures analysis of variance and post-hoc paired t-tests with Bonferroni correction. Decreasing the haematocrit from 40 to 10% resulted in a shortening of reaction time (r) and coagulation time (k), and an increase in angle alpha, maximum amplitude (MA) and clot strength (G) (all P<0.02). This pattern represents acceleration of blood coagulation with low haematocrit values. The isolated reduction in haematocrit, therefore, does not compromise in vitro blood coagulation.
authors.affiliation: Institute of Anaesthesiology, University Hospital Zurich, Switzerland.
authors.forename: B M
authors.initials: BM
authors.lastname: Iselin
authors.forename: P F
authors.initials: PF
authors.lastname: Willimann
authors.forename: B
authors.initials: B
authors.lastname: Seifert
authors.forename: M
authors.initials: M
authors.lastname: Casutt
authors.forename: T
authors.initials: T
authors.lastname: Bombeli
authors.forename: M P
authors.initials: MP
authors.lastname: Zalunardo
authors.forename: T
authors.initials: T
authors.lastname: Pasch
authors.forename: D R
authors.initials: DR
authors.lastname: Spahn
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001777:Blood Coagulation / Q000502:physiology*; D006400:Hematocrit; D006438:Hemodilution; D006801:Humans; D008875:Middle Aged; D011930:Reaction Time; D013916:Thrombelastography