Effect of various anesthetic induction agents on blood magnesium and calcium concentration / 대한마취과학회지

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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

Electrophysiologic Effect of Desflurane on the Prolongation of Action Potential Duration in Ventricular Myocytes / 대한마취과학회지

BACKGROUND: Desflurane has been reported to prolong the QTc. Several ionic currents that contribute to the prolongation of the action potential (AP) duration were investigated using guinea pig (GP) and rat ventricular myocytes. METHODS: The normal APs were measured in isolated GP papillary muscles at 37 degrees C. Ventricular myocytes were obtained from GP and rat hearts. Both the delayed outward K+ current (I(K)) and the inward rectifier K+ current (I(KI)) were assessed using a voltage ramp protocol. A more detailed study on the I(K) was performed. The ICa, L was measured. In the rat ventricular myocytes, the transient outward K+ current (I(to)) was obtained. All the patch clamp experiments were carried out at room temperature. The values are presented as mean +/- SD. RESULTS: 0.91 mM desflurane significantly prolonged the APD in the GP ventricular myocytes. Using a linear voltage ramp protocol, the I(KI) at -130 mV and the peak outward I(KI) at -60 to -50 mV were not found to be significantly reduced by 0.78 and 1.23 mM desflurane, respectively. However, the peak outward I(K) at +60 mV was significantly reduced to 63 +/- 19% and 58 +/- 12% of the baseline by 0.78 and 1.23 mM desflurane, respectively. At a membrane potential of +60 mV, 0.78 and 1.23 mM desflurane reduced the Ito to 80 +/- 8% and 68 +/- 7%, respectively. A concentration-dependent reduction in the ICa, L was observed. CONCLUSIONS: The prolongation of the APD induced by clinically relevant concentrations of desflurane in GP and rat ventricular myocytes is most likely the result of I(K) and I(to) suppression.