ABSTRACT
Background; Tracheal intubation for cesarean section is usually performed with rapid sequence induction. Under this light stage of anesthesia, marked hypertensive changes of maternal hemodynamic responses following tracheal intubation may occur, which are the common cause of maternal and neonatal complications. We have studied the maternal cardiovascular blunting effect of magnesium sulfate following tracheal intubation in cesarean section. Methods; After obtaining the written informed consents, ninety ASA class I parturients scheduled for cesarean section were randomly allocated to one of three groups: group 1 received thiopental 4 mg/kg and succinylcholine 1.5 mg/kg, group 2 received fentanyl 1.5 microgramg/kg additionally, and group 3 received fentanyl 1.5 microgramg/kg and MgSO4 40 mg/kg additionally. Systolic, mean, diastolic blood pressure, and heart rate were measured before induction, immediately after intubation. Serum magnesium concentrations were measured before administering magnesium and near the end of surgery. Train of four ratio was monitored during whole period of anesthesia. Neonatal Apgar scores and neurologic and adaptive capacity scores (NACS) were checked. Results; Blood pressure changes were more stable in group 2 and group 3, especially group 3, than group 1 (p<0.05). No statistical differences were found in heart rate changes in all groups. No significant differences were noted in neuromuscular recoveries, neonatal Apgar scores and NACS. Conclusions; Magnesium sulfate may be successfully used for blunting the cardiovascular response to tracheal intubation in parturients undergoing general anesthesia for cesarean section.
Subject(s)
Female , Pregnancy , Anesthesia , Anesthesia, General , Blood Pressure , Cesarean Section , Fentanyl , Heart Rate , Hemodynamics , Intubation , Magnesium Sulfate , Magnesium , Succinylcholine , ThiopentalABSTRACT
BACKGROUND: Magnesium sulfate (MgSO4) is widely utilized in the treatment of preeclamptic hyperreflexia. It is well known that magnesium enhances nondepolarizing neuromuscular blockade. Eclamptic convulsions are almost always prevented by magnesium in plasma concentrations of 4 to 7 mEq/L. METHODS: The effects of various concentration of magnesium on the potency and reversibility of pipecuronium were investigated in vitro rat phrenic nerve-hemidiaphragm. The phrenic nerve-hemidiaphragm was dissected and suspended in organ bath containing modified Krebs' solution. Forty samples were divided into 4 groups (n=10 in each group). Group I was studied at the physiologic magnesium concentration(2.4 mEq/L, control group). Group II, III, IV were studied at the concentration of 4, 5.5, and 7 mEq/L, respectively. In each group, we added pipecuronium until twitch height decreased more than 90% of initial level. To compare the recovery, we added neostigmine and calcium, and then, measured TOF ratio. RESULTS: The amounts of added pipecuronium were 73.8+/-15.2 microgram (mean+/-S.D.) in Group I, 38.1+/-5.0 microgram in Group II, 33.0+/-4.1 microgram in Group III and 16.1+/-1.7 microgram in Group IV. The amounts of pipecuronium in Group II, III, IV were significantly less than Group I. After the addition of neostigmine, the values of TOF ratio were under 0.6 in all groups. But after the addition of calcium, all groups were recovered with TOF ratio over 0.85 except Group I. CONCLUSIONS: This study indicated that the increased magnesium concentration potentiated pipecuronium-induced neuromuscular blockade and at higher level, it was more apparent. Neostigmine was not significantly effective to reverse the pipecuronium-induced neuromuscular blockade potentiated with magnesium. But calcium was significantly effective.