Magnesium sulphate has beneficial effects as an adjuvant during general anaesthesia for Caesarean section.
BACKGROUND
The use of low concentrations of volatile anaesthetics with avoidance of opioids may induce intraoperative awareness and adverse haemodynamic responses during Caesarean section. Magnesium is well known to reduce anaesthetic requirements and to block noxious stimuli. We investigated whether i.v. magnesium sulphate modulates anaesthetic depth and analgesic efficacy during Caesarean section.


METHODS
Seventy-two patients undergoing Caesarean section were randomly assigned to receive i.v. saline (control group) or magnesium sulphate 30 mg kg(-1) bolus+10 mg kg(-1) h(-1) continuous infusion (Mg 30 group) or 45 mg kg(-1) bolus+15 mg kg(-1) h(-1) continuous infusion (Mg 45 group) after induction. Bispectral index (BIS) value, mean arterial pressure (MAP), and midazolam, fentanyl, and atracurium consumptions were recorded.


RESULTS
BIS values [mean (sd)] at 7.5 and 10 min after surgery and before delivery in the control [64 (9), 66 (8), 67 (8), P<0.001] and the Mg 30 groups [62 (8), P<0.01; 64 (7), 63 (9), P<0.001] were higher than in the Mg 45 group [56 (8), 55 (8), 55 (7)]. MAP was greater in the control group (P<0.05) than in the Mg 30 and Mg 45 groups during the pre-delivery period. The magnesium groups required less midazolam (P<0.05), fentanyl (Mg 30, P<0.05; Mg 45, P<0.01), and atracurium (P<0.001) vs the control group.


CONCLUSIONS
Preoperative i.v. magnesium sulphate attenuated BIS and arterial pressure increases during the pre-delivery period. Magnesium sulphate can be recommended as an adjuvant during general anaesthesia for Caesarean section to avoid perioperative awareness and pressor response resulting from inadequate anaesthesia, analgesia, or both.
Department of Anaesthesiology and Pain Medicine, College of Medicine, Yeungnam University, Daegu, Republic of Korea. dhlee415@ynu.ac.kr
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Lee
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Kwon
D000759:Adjuvants, Anesthesia / Q000494:pharmacology*; D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage; D000768:Anesthesia, General / Q000379:methods*; D000773:Anesthesia, Obstetrical / Q000379:methods*; D001279:Atracurium / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects; D002585:Cesarean Section; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D008278:Magnesium Sulfate / Q000494:pharmacology*; D008874:Midazolam / Q000008:administration & dosage; D016343:Monitoring, Intraoperative / Q000379:methods; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage; D011247:Pregnancy
D000759:Adjuvants, Anesthesia; D000701:Analgesics, Opioid; D006993:Hypnotics and Sedatives; D003473:Neuromuscular Nondepolarizing Agents; D001279:Atracurium; D008278:Magnesium Sulfate; D008874:Midazolam; D005283:Fentanyl