In vitro comparison of the effects of two forms of hydroxyethyl starch solutions on platelet function in dogs

Objective - To evaluate the effect of 2 hydroxyethyl starch (HES) preparations (ie, HES solution with a molecular weight of 600 kd and a degree of substitution of 0.7 [HES 600/0.7] and a calcium-containing polyionic HES solution with a molecular weight of 670 kd and a degree of substitution of 0.75 [HES 670/0.75]) on canine platelet function. Sample Population - Blood samples from 10 healthy adult dogs. Procedures - Dilution of citrated whole blood was performed with saline (0.9% NaCl) solution, HES 600/0.7, and HES 670/0.75 at ratios of 1:9 (ie, 1 part saline solution or colloid to 9 parts whole blood) and 1:3. Measurements of time to platelet plug formation in a capillary tube (ie, closure time) were made by use of a bench-top platelet function analyzer with collagen and ADP platelet agonists. Results - Mean baseline closure time was 68.0 ± 15.3 seconds. A 1:3 dilution of whole blood with saline solution, HES 600/0.7, and HES 670/0.75 resulted in mean closure times of 85.8 ± 15.7 seconds, 100.6 ± 18.6 seconds, and 101.6 ± 16.2 seconds, respectively. Closure time following 1:3 dilution of whole blood with saline solution was significantly different from baseline and from 1:9 dilution with saline solution. Closure time following 1:3 dilution of whole blood with HES 670/0.75 was significantly different from baseline, 1:3 and 1:9 dilutions with saline solution, and 1:9 dilutions with HES 600/0.7 or HES 670/0.75. Conclusions and Clinical Relevance - Saline solution, HES 600/0.7, and HES 670/0.75 affect canine platelet function by prolonging closure times; HES solutions prolonged closure time to a greater extent than saline solution.