Effect of MgSO4 Pretreatment on Muscle Relaxation

General anesthesia is a drug-induced reversible state consisting of unconsciousness, amnesia, anti-nociception, and immobility, with maintenance of physiological stability. Balanced general anesthesia, the most common management strategy used in anesthesia care, entails administering a combination of different agents to create the anesthetic state. There is evidence that balanced general anesthesia uses less of each drug than if the drug were administered alone. This approach is believed to increase the likelihood of a drug's desired effects and reduce the likelihood of its side effects. With addition of adjuvants, Alpha-2 adrenoceptor agonists, such as dexmedetomidine, are known to possess amnesic, analgesic, sympatholytic, and antinociceptive properties, and therefore, can reduce the requirement of anesthetics and opioids intraoperatively. Administration of MgSO4 has also shown significant reduction in the perioperative requirement of propofol, opioids, and muscle relaxants. Magnesium sulphate has gained prominence as an adjuvant drug in multimodal anesthesia and pain medicine. It has several clinical indications including attenuation of the adrenergic response to tracheal intubation and improved peri-operative analgesia. Magnesium sulphate also enhances the action of non-depolarizing neuromuscular blocking drugs, resulting in potentiation of neuromuscular blockade (NMB).The site of magnesium potentiation of neuromuscular blocking drugs is the motor end plate, where magnesium reduces the release of prejunctional acetylcholine, thereby decreasing the muscle membrane excitability. However, limited data exist concerning the effect of magnesium sulphate on the duration of deep or intense NMB and on the period of no response to nerve stimulation.