Effects of hypertonic saline hydroxyethyl starch solution on collagen-induced platelet aggregation and ATP secretion.

OBJECTIVE

The purpose of this study was to investigate the effect of hypertonic (NaCl 7.5%) hydroxyethyl starch (HES 6%, molecular weight 200,000) (HHES) as used for small-volume resuscitation on global coagulation parameters and platelet function.

DESIGN

Randomized, controlled clinical trial.

SETTING

Intraoperative volume loading after induction of general anesthesia.

PATIENTS

27 consecutive patients [mean age 59 (22-76) years, mean body weight 69.8 (46-98) kg] undergoing abdominal surgery were studied.

INTERVENTIONS

Global coagulation tests (aPTT: activated partial thromboplastin time; PT: prothrombin time; platelet count; thrombelastography: TEG), platelet aggregation and ATP release were measured before and 10 min after the application of 4 ml.kg-1 of HHES (study group H, n = 14) or HES (control group C, n = 13).

RESULTS

The aPTT was prolonged and platelet count was significantly reduced in both study groups. In contrast to the HES group, clot formation time in the TEG was significantly prolonged and the maximum amplitude was reduced in the HHES group. Furthermore, platelet aggregation was significantly slowed down, whereas ATP release significantly increased in the HHES group.

CONCLUSION

The changes in global coagulation parameters can be explained by dilutional effects of the infused solution. The hyperosmolar saline compound of the HHES solution obviously contributes to the slowing down of platelet aggregation. Osmotic stress and membrane pleating may aggravate HES-induced changes in membrane fluidity and microviscosity and thus explain this impaired interaction. The increase in ATP release suggests a change in receptor-second messenger interaction for delta granule release.