Oncotic, hemodilutional, and hemostatic effects of isotonic saline and hydroxyethyl starch solutions in clinically normal ponies

Peyton A. Jones From the Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348-1692 (Jones, Tomasic); and the Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G2W1, Canada (Gentry).

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Michael Tomasic From the Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348-1692 (Jones, Tomasic); and the Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G2W1, Canada (Gentry).

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Patricia A. Gentry From the Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348-1692 (Jones, Tomasic); and the Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G2W1, Canada (Gentry).

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Abstract

Objective

To evaluate the oncotic, hemodilutional, and hemostatic effects of IV infusions of a large volume of isotonic saline solution and 2 doses of 6% hydroxyethyl starch (HES) in clinically normal ponies.

Animals

12 adult ponies.

Procedure

Ponies were assigned to 3 treatment groups and received the following IV infusions: 80 ml of 0.9% sodium chloride/kg; 10 ml of 6% HES (in 0.9% sodium chloride)/kg; or 20 ml of 6% HES (in 0.9% sodium chloride)/kg. Blood samples were collected for determination of colloid oncotic pressure (COP), PCV, plasma total protein concentration, platelet count, von Willebrand factor antigen (vWf:Ag) activity, fibrinogen concentration, prothrombin time, activated partial thromboplastin time (APTT), and factor VIII coagulant (FVIII:C) activity. A rocket immunoelectrophoretic procedure was used for determination of vWf:Ag activity. A modification of the APTT assay was used for determination of FVIII:C activity. Cutaneous bleeding time was determined, using a template method.

Results

Mean COP was persistently increased over baseline values in the face of hemodilution in HES-treated ponies. Prothrombin time, APTT, and fibrinogen concentrations decreased after infusions and vWf:Ag and FVIII:C activities were decreased in dosedependent manner in HES-treated ponies. Though cutaneous bleeding time was not significantly affected in ponies of any group, a trend toward prolongation of bleeding time was evident in ponies receiving 20 ml of HES/kg. This trend appeared to be associated with marked decrement in vWf:Ag activity at this dosage.

Conclusions and Clinical Relevance

Infusion of HES in clinically normal ponies increases COP, and exerts dose-dependent hemodilutional effects and dose-dependent effects on specific hemostatic variables. Thus, HES may be useful for resuscitative fluid treatment of horses. (Am J Vet Res 1997;58:541–548)

Abstract

Objective

To evaluate the oncotic, hemodilutional, and hemostatic effects of IV infusions of a large volume of isotonic saline solution and 2 doses of 6% hydroxyethyl starch (HES) in clinically normal ponies.

Animals

12 adult ponies.

Procedure

Ponies were assigned to 3 treatment groups and received the following IV infusions: 80 ml of 0.9% sodium chloride/kg; 10 ml of 6% HES (in 0.9% sodium chloride)/kg; or 20 ml of 6% HES (in 0.9% sodium chloride)/kg. Blood samples were collected for determination of colloid oncotic pressure (COP), PCV, plasma total protein concentration, platelet count, von Willebrand factor antigen (vWf:Ag) activity, fibrinogen concentration, prothrombin time, activated partial thromboplastin time (APTT), and factor VIII coagulant (FVIII:C) activity. A rocket immunoelectrophoretic procedure was used for determination of vWf:Ag activity. A modification of the APTT assay was used for determination of FVIII:C activity. Cutaneous bleeding time was determined, using a template method.

Results

Mean COP was persistently increased over baseline values in the face of hemodilution in HES-treated ponies. Prothrombin time, APTT, and fibrinogen concentrations decreased after infusions and vWf:Ag and FVIII:C activities were decreased in dosedependent manner in HES-treated ponies. Though cutaneous bleeding time was not significantly affected in ponies of any group, a trend toward prolongation of bleeding time was evident in ponies receiving 20 ml of HES/kg. This trend appeared to be associated with marked decrement in vWf:Ag activity at this dosage.

Conclusions and Clinical Relevance

Infusion of HES in clinically normal ponies increases COP, and exerts dose-dependent hemodilutional effects and dose-dependent effects on specific hemostatic variables. Thus, HES may be useful for resuscitative fluid treatment of horses. (Am J Vet Res 1997;58:541–548)

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