Management of prolonged QT interval during a massive transfusion: calcium,magnesium or both?

Purpose: This case report describes the intra-operative management of a pro longed QT interval in the setting of massive transfusion. Clinical Features: A previously healthy, 45-yr-old man presented for repair of a class IV thoraco-abdominal aneurysm. The initial stages of the operat ion were relatively uneventful, with the exception of an estimated blood lo ss of 5.0 L, At this point the patient's QT interval became markedly prolon ged, and subsequently narrowed in response to supplemental calcium and magn esium. A blood sample taken just before QT prolongation revealed an ionized calcium of 0.98 mmol.L-1 and an ionized magnesium of 0.37 mmol.L-1, indica ting, that low magnesium may have contributed to the QT interval prolongati on. Conclusion: This case illustrates the importance of following both ionized calcium and magnesium in the setting of a massive transfusion.