Monitoring of total and ionized magnesium in children undergoing liver transplantation

Study objective To describe the biochemical changes, correlation, and agreement between ionized magnesium (iMg) and total magnesium (tMg), and the relationship between iMg levels and clinical events in pediatric patients undergoing liver transplantation. Design Prospective observational study from July 2021 to December 2022. Setting Operating room, postoperative recovery area, Intensive Care Unit. Patients The study included 42 pediatric patients undergoing liver, multivisceral or liver-kidney transplantation. Interventions Clinical and analytical variables were monitored during surgery and the 24-h postoperative period. Measurements iMg, tMg, ionized and total calcium, pH, lactate, glucose, creatinine, total protein, anion gap, and Mg gap. Heart rate, temperature, diuresis, blood pressure, central venous pressure, electrocardiogram, drugs, fluids, and blood products administered. Main results 50 % females; 2 (0.26-8) years median (IQR) age. There was a very weak correlation between iMg and tMg levels (r = 0.02, p > 0.05). The iMg concentration progressively decreased during the dissection and anhepatic phases, whereas the tMg concentration showed an upward trend. A significant association was observed between most clinical variables with Mg gap, but not with iMg. The incidence of hypomagnesemia was 76 % for the iMg measurement compared to 29 % based on tMg. The diagnostic agreement of the two forms was 40.9 % (95 % CI 36 to 45.9). When iMg was low, the category agreements between the two forms (iMg/tMg) were 7 % low/low, 84 % low/normal, and 9 % low/high. When categorizing patients into those with and without ionized hypomagnesemia, there were no significant differences found in electrocardiogram abnormalities, prolonged QT or ICU stay. Conclusions tMg does not reflect the important changes that occur during liver transplantation. These results emphasize the significance of the use of iMg in pediatric liver transplantation, although the clinical impact of ionized hypomagnesemia warrants further investigation.