Assessment of the effect of dilution of blood samples with sodium heparin on blood gas, electrolyte, and lactate measurements in dogs.
OBJECTIVE
To evaluate the effect of dilution of blood samples with sodium heparin on blood gas, electrolyte, and lactate measurements in dogs. Sample Population-Venous blood samples collected from 6 adult dogs of various breeds.


METHODS
Syringes were prepared with anticoagulant via 1 of 4 techniques, and the residual volume of liquid heparin in each type of prepared syringe was determined. Blood gas values and other selected clinicopathologic variables were measured in whole blood samples after collection (baseline) and after aliquots of the samples were diluted with heparin via 1 of the 4 manual syringe techniques. By use of a tonometer, whole blood samples were adjusted to 1 of 3 oxygen concentrations (40, 100, or 600 mm Hg) and the PO2 values were measured at baseline and subsequent to the 4 heparin dilutions.


RESULTS
The 4 syringe techniques resulted in 3.9%, 9.4%, 18.8%, and 34.1% dilutions of a 1-mL blood sample. Compared with baseline values, dilution of blood samples with liquid heparin significantly changed the measured values of PCO2, PO2, and base deficit and concentrations of electrolytes and lactate. Of the variables assessed, measurement of ionized calcium concentration in blood was most affected by heparin dilution.


CONCLUSIONS
These findings in dogs indicate that dilution of blood samples with heparin can be a source of preanalytical error in blood gas, electrolyte, and lactate measurements. Limiting dilution of blood samples with heparin to < 4% by volume via an evacuation technique of syringe heparinization is recommended.
Hopper
Kate
K
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Rezende
Marlis L
ML
Haskins
Steve C
SC
D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D001774:Blood Chemical Analysis / Q000379:methods / Q000662:veterinary; D001784:Blood Gas Analysis / Q000379:methods / Q000662:veterinary; D001800:Blood Specimen Collection / Q000379:methods* / Q000662:veterinary*; D002245:Carbon Dioxide / Q000097:blood; D004285:Dogs / Q000097:blood*; D006493:Heparin / Q000494:pharmacology*; D019344:Lactic Acid / Q000097:blood; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure
D000925:Anticoagulants; D002245:Carbon Dioxide; D019344:Lactic Acid; D006493:Heparin; D010100:Oxygen