A head-to-head comparison of the in vitro coagulation effects of saline-based and balanced electrolyte crystalloid and colloid intravenous fluids.

Both fluid composition (e.g., type of hydroxyethyl starch) and formulation (e.g., saline or balanced salt carrier solution) may alter whole blood coagulation. We therefore enrolled 10 healthy volunteers to test ex vivo, thrombelastograph-based blood coagulation differences of eight crystalloid and colloid solutions at 20%, 40%, and 60% dilutions. Saline and lactated Ringer's solution produced a hypercoagulable state at 20%-40% dilutions. Saline, hetastarch in saline, pentastarch in saline, tetrastarch in saline, and human albumin solutions all produced a hypocoagulable state at 60% dilution. Hetastarch in saline also produced a hypocoagulable state at 40% dilution. The larger molecular weight starches produced more intense coagulation abnormalities than the medium molecular weight compounds formulated similarly (i.e., suspended in saline or balanced salt solution). The balanced salt solutions caused fewer coagulation abnormalities, especially pentastarch in balanced salt solution. This balanced salt pentastarch preparation produced the least derangement of coagulation of the colloid solutions at all dilutions, causing hypercoagulability at the lower dilutions and minimal coagulation derangement at 60% dilution. These data support the theory that smaller molecular weight hydroxyethyl starches and colloids suspended in balanced salt solutions preserve coagulation better than large molecular weight starches and saline-based colloids, as judged by thrombelastography.