effect of propofol versus sevoflurane based anaesthesia on the electrically evoked stapedius reflex during cochlear implant surgery in paediatrics [comparative study]

ABSTRACT

Cochlear implantation is a widely used mean of treatment in deafness and severe hearing disorders in adults, children, and infants. Postoperative fitting of the externally worn speech processor is very important for successful use of the cochlear implant. In young children, this fitting process can be difficult because of limited communication capabilities. Investigators have used electrically evoked stapedius reflex threshold [ESRT] to predict maximum comfortable loudness [MCL]. During surgery the drugs used for general anaesthesia influence the values of the stapedius reflex. This study aims to compare two anesthetic regimens that can be used during cochlear implant surgery with the least effect on the evoked stapedius reflex threshold. This prospective r and om controlled study was done on 20 patients [n=20] ASA physical status I-II, scheduled for cochlear implant surgery. According to the maintenance agent patients were allocated randomly into two equal groups, each group is 10 patients. The propofol group [group Prop.], in which patients were maintained using propofol infusion [6mg.kg[1] hr[-1]]. The other group was maintained using sevoflurane [group Sevo.] at a concentration of 2%. Intra operative stapedius reflex testing was performed after implantation of prosthesis. The stimuli were generated by the nucleus diagnostic programming interface and reflex threshold was determined by observing the contraction of stapedius muscle. Two months later the MCL value was determined The mean amplitude of electric current [in mAm] used for induction of ESRT was significantly lower in the group Prop, than that required to induce the reflex in group Sevo. Regarding the ability of the electrically elicited stapedius reflex thresholds obtained under anaesthesia to predict the MCL in the post-operative setting. It was found that this was achievable in the propofol group and not sevoflurane. Compared to sevoflurane propofol has less inhibitory effect on the ESRT. The reflex threshold obtained under the effect of propofol can serve as a guide for postoperative MCL. This was not the case while using sevoflurane.