Effects of gelatin-based resuscitation fluids on platelet aggregation

Fluid resuscitation aims to maintain intravenous volume without significant effects on haemostasis. Several different types of i.v. fluid are available for use in a patient who has suffered trauma, but there is evidence that some resuscitation fluids may affect primary haemostasis. We have compared the effects of two resuscitation fluids, Haemaccel and Gelofusin, on platelet aggregation in vitro. These resuscitation fluids are both based on gelatin but Haemaccel contains a high concentration of Ca2+ whereas Gelofusin does not. Their effects on platelet aggregation in whole blood, induced by a range of different agents, were determined using a platelet-counting technique. Both Haemaccel and Gelofusin prevented platelet aggregation induced by ristocetin (P < 0.05, Mann-Whitney). In addition, Haemaccel proved to be a potent inhibitor of the platelet aggregation that occurred in response to all of the other agonists investigated: adenosine diphosphate, platelet-activating factor, collagen, a thromboxane A2 mimetic (U46619) and epinephrine. The additional inhibitory effects of Haemaccel were largely, but not completely, attributable to its high Ca2+ content. Inhibition of platelet aggregation by ristocetin may indicate a mechanism by which Haemaccel or Gelofusin may contribute to impaired haemostasis. The presence in Haemaccel of high concentrations of Ca2+, which is largely responsible for inhibition of the aggregation induced by other agents, may provide an additional means by which haemostasis could be impaired.