• Roman Schumann, Ina Zaimi, Kareen Shebaclo, and Anupriya Gupta.
• Department of Anesthesiology, VA Boston Healthcare System, West Roxbury, MA; Department of Anesthesiology and Perioperative Medicine, Tufts University School of Medicine, Boston, MA. Electronic address: rschum01@gmail.com.
• J. Cardiothorac. Vasc. Anesth. 2022 Apr 1; 36 (4): 1040-1046.

ObjectivesCalcium 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.DesignAn experimental in vitro study with blood products, crystalloids, magnesium, and calcium in a rapid infuser with a reservoir using a closed-loop system.SettingAnesthesia research laboratory at an urban academic tertiary medical center PARTICIPANTS: Not applicable.InterventionsExposure 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 ResultsObservation 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.ConclusionsThe 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.Published by Elsevier Inc.

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