Tetany following resuscitation after abruptio placentae.

BACKGROUND

Serum ionized calcium and magnesium are normally decreased during later stages of pregnancy. A further rapid decline may be caused by the rapid infusion of blood bank products in which citrate is used as an anticoagulant/preservative. Tetany, as reported here, may be precipitated by such infusions.

CASE: A gravid woman presented in hemorrhagic shock due to abruptio placentae. Rapid infusion of packed red blood cells and fresh frozen plasma precipitated signs of tetany, muscle rigidity, posturing, high airway pressure during mechanical ventilation, etc. Ionized calcium and magnesium blood levels were very low (0.58 mmol/L and 1.0 mg/dL, respectively), but responded to rapid electrolyte administration.

CONCLUSION

Binding of calcium and magnesium by citrate may lead to hypo-ionized calcemic and hypomagnesemic tetany after rapid replacement of blood products in the pregnant patient. This consequence is worsened when extreme alkalemia due to respiratory or metabolic causes is also present.