Magnesium sulphate optimises surgical field

 without attenuation of the stapaedius reflex in paediatric cochlear implant surgery
Wahba Z Bakhet, Hassan A Wahba, Lobna M El Fiky, Hossam Debis

Indian Journal of Anaesthesia 2019 63(4):304-309

Background and Aims: The anaesthesia technique for paediatric cochlear implantation should be modified to achieve an optimised surgical field and allow neuromonitoring. Total intravenous anaesthesia (TIVA) provides good surgical condition without affecting intraoperative electrical stapaedial reflex threshold (ESRT). Though magnesium sulphate (MgSO4) is a cheap, readily available drug for controlled hypotension, it can decrease the amplitude of motor-evoked potentials. This study aimed to evaluate the effect of MgSO4 infusion on quality of surgical field, intraoperative ESRT, and anaesthetic requirements in paediatric cochlear implant surgery performed under TIVA. Methods: In this randomised controlled trial, 66 children (1-6 years) undergoing cochlear implant under TIVA were randomly assigned to control group or MgSO4 group. The primary outcome was quality of surgical field, and the secondary outcomes were mean arterial blood pressure (MAP), heart rate (HR), ESRT, and the intraoperative anaesthetic requirements. The incidence of adverse events was recorded as well. Results: The quality of surgical field was better in group M than group C, P < 0.02. The number of children who achieved optimum surgical conditions (scores ≤2) was significantly better in the group M (n = 23/33, 70%) compared with group C (n = 13/33, 39%), P < 0.001. MAP, HR, and anaesthetic requirements were significantly lower in group M, P < 0.05. There were no differences between both groups regarding ESRT response. Conclusion: Magnesium sulphate IV infusion optimised surgical field and decreased anaesthetic requirements without attenuating the ESRT in paediatric cochlear implant surgery performed under TIVA.