Decrease in blood magnesium and calcium concentration is associated with an increase in the incidence of arrhythmia, especially during the induction period. Therefore, it is important to evaluate the effects of propofol, pentothal sodium, and sevoflurane on calcium and magnesium concentration.

Thirty-six premedicated, ASA grade I patients were selected and randomly allocated into 3 groups. Six percent sevoflurane inhalation (sevo group), propofol 1.5 mg/kg (propofol group), and 5 mg/kg of pentothal sodium (pento group) were administered for anesthetic induction and anesthetic maintenance was done with end-tidal sevoflurane concentration at 3.5%. Blood sampling was performed during the pre-induction period (pre-induction), just before tracheal intubation (pre-intubation), and 2 min after intubation (post-intubation). pH corrected ionized magnesium and calcium were calculated and analyzed simultaneously.

Both total calcium and magnesium concentrations decreased significantly in all groups during the pre-intubation and post-intubation periods compared with the pre-induction period. Ionized calcium only decreased significantly during pre-intubation and post-intubation in the pento group, and did not change throughout the study period in the sevo and propofol groups. Ionized magnesium did not change throughout the study period in any of the groups. pH corrected ionized calcium decreased significantly only at post-intubation in the pento group.

All anesthetic induction agents administered in this study can be used safely in terms of magnesium-associated arrhythmia. However, ionized calcium concentration decreased in the pento group, but all values were within normal limits. This finding indicated that it is safe to use propofol, pentothal sodium, and sevoflurane for anesthetic induction