The influence of crystalloid type on acid–base and electrolyte status of cats with urethral obstruction

Authors

  • Kenneth J. Drobatz DVM, MSCE, DACVIM (Medicine), DACVECC,

    1. Section of Critical Care, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA
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  • Steven G. Cole DVM, DACVECC, DACVIM (Cardiology)

    1. Section of Critical Care, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA
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  • Portions of these data were presented in abstract form at the IVECCS Forum in New Orleans, LA, September, 2003.

Address correspondence and reprint requests to:
Kenneth J. Drobatz, School of Veterinary Medicine, University of Pennsylvania, Matthew J. Ryan Veterinary Hospital, 3900 Delancey Street, Philadelphia, PA 19104-6010.
E-mail: drobatz@vet.upenn.edu

Abstract

Objective: To compare the effect of a balanced isotonic crystalloid solution with that of 0.9% sodium chloride on the acid–base and electrolyte status of cats with urethral obstruction.

Design: Randomized prospective clinical trial.

Setting: Academic veterinary emergency room.

Animals: Sixty-eight cats with naturally occurring urethral obstruction.

Interventions: Cats were randomized to receive either a balanced isotonic crystalloid solution (Normosol-R, n=39) or 0.9% sodium chloride (n=29) for fluid therapy. Baseline venous blood gas and blood electrolyte values were obtained at the time of admission and at intervals during the course of therapy.

Measurements and main results: Baseline values were similar between groups. Cats receiving Normosol-R had a significantly higher blood pH at 12 hours, a significantly greater increase in blood pH from baseline at 6 and 12 hours, as well as a significantly higher blood bicarbonate concentration at 12 hours and a significantly greater increase in blood bicarbonate from baseline at 6 and 12 hours. Conversely, the increase in blood chloride from baseline was significantly higher at 2, 6, and 12 hours in cats receiving 0.9% sodium chloride. There were no significant differences in the rate of decline of blood potassium from baseline between groups. Subgroup analysis of hyperkalemic cats (K+>6.0 mmol/L) and acidemic cats (pH<7.3) yielded similar findings.

Conclusions: While both crystalloid solutions appear safe and effective for fluid therapy in cats with urethral obstruction, the use of a balanced electrolyte solution may allow more rapid correction of blood acid–base status within the first 12 hours of fluid therapy. The use of a potassium-containing balanced electrolyte solution does not appear to affect the rate of normalization of blood potassium in treated cats with urethral obstruction.

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