Blood Products, Crystalloids, and Rapid Infusion: An Experimental Study With Magnesium.

ABSTRACT

OBJECTIVES: Calcium and magnesium are concentration-dependent pro- and anticoagulant cofactors, and magnesium behaves similarly to calcium in the presence of citrate. The authors hypothesized that magnesium can cause clot formation (primary objective) when mixed with coagulation factor-containing blood products diluted with different crystalloids in a rapid- infuser reservoir. A secondary objective was the observation of any infuser alarms and stops in the event of clotting. DESIGN: An experimental in vitro study with blood products, crystalloids, magnesium, and calcium in a rapid infuser with a reservoir using a closed-loop system. SETTING: Anesthesia research laboratory at an urban academic tertiary medical center PARTICIPANTS: Not applicable. INTERVENTIONS: Exposure of fresh frozen plasma (FFP) and packed red blood cells alone (control) or in combination with either normal saline (NS), lactated Ringer's solution (LR), or Plasma-Lyte A (PL) to increasing concentrations of magnesium sulphate (MgSO4) up to 1 g. After each incremental MgSO4 change, the authors applied a specific pump-flow sequence in a closed-loop system with a rapid-infuser reservoir, and if no clot was observed, the authors incrementally added calcium chloride (CaCl2) up to 1 g. MEASUREMENTS AND MAIN RESULTS: Observation of macroscopic clot and time to event, as well as occurrence and type of any pump alarms or stops. LR experiments resulted in clot observation in the reservoir by a dedicated observer after MgSO4 275 ± 206 mg (95% confidence interval [CI], 9-541). Adding MgSO4 1 g in the NS, PL, or the control experiments did not result in clot observation. Only when CaCl2 166.7 ± 51.64 mg (95% CI, 112.0-22.01) was added to the combination of blood products alone or mixed with NS and PL, clotting occurred. The mean FFP volume was 281 ± 48.6 mL (range, 204-340 mL) and was not different between groups (p = 0.44). Pump alarms and stops were inconsistent. CONCLUSIONS: The addition of magnesium to a combination of LR with coagulation factor- containing blood products consistently resulted in a visible blood clot in the rapid-infuser reservoir in the authors' experimental setup. In addition to MgSO4 1 g in the control, NS, and PL experiments, CaCl2 is needed before a clot can be observed.