Butorphanol more effective than dexmedetomidine in reducing etomidate-induced myoclonus

Etomidate is a preferred intravenous (IV) induction drug because of its many benefits; however, these benefits are somewhat offset by a few unfavourable side effects, including injection pain, nausea and vomiting after surgery, adrenal suppression, superficial thrombophlebitis, and myoclonus. In individuals who were not treated, the incidence of myoclonus after etomidate injection has been observed to range from 50% to 80%.

A recent study assessed the relative effectiveness of butorphanol and dexmedetomide in reducing the frequency and intensity of myoclonus elicited by etomidate while maintaining hemodynamic stability.

After receiving approval from the institutional ethical committee and signed informed consent from sixty American Society of Anesthesiologists (ASA) I or II consenting patients, aged 18 to 60, of both sexes, who were scheduled for elective general anaesthesia surgeries, this randomised study was carried out. Patients were randomised to receive either butorphanol (0.015 mg/kg) or dexmedetomidine 0.5 μg/kg (Group D). Before inducing anaesthesia, both medications were administered as an infusion over the course of ten minutes. The frequency of myoclonic movements after etomidate was the main result, whereas the degree of myoclonus, alterations in the hemodynamic parameters, and frequency of airway problems were the secondary results. Student's t-test was used to compare regularly distributed data, while the Mann-Whitney U test was used to examine non-normally distributed variables. To assess qualitative data, Fisher's exact test and Chi-square were used. P-values less than 0.05 were regarded as significant.

Group B saw a considerably greater incidence of etomidate-induced myoclonus (P = 0.035) than group D. Patients in groups D and B had myoclonus grades of 0.00 (0.00–3.00) and 2.50 (0.00–3.00) respectively, with a median (interquartile range [IQR] of 0.00 (0.00–3.00) (P = 0.035). The groups' hemodynamics and problems associated to the airways were similar.

When dexmedetomidine was used instead of butorphanol to treat etomidate-induced myoclonus, a statistically significant decrease in both the incidence and median myoclonus grade severity was seen. With maintained hemodynamics, dexmedetomidine 0.5 μg/kg is more effective in lowering the occurrence and severity of myoclonus than butorphanol 0.015 mg/kg. Determining the ideal lowest dose of dexmedetomidine for preventing etomidate-induced myoclonus would become clearer with more research comparing various doses of the drug, either higher or lower than the one used in the current study to attenuate etomidate-induced myoclonus.

Reference-

Rautela, Rajesh S.; Gulabani, Michell; Kumar, Pramod; Salhotra, Rashmi; Mohta, Medha; Verma, Kshitiz. Comparative assessment of dexmedetomidine and butorphanol for attenuation of etomidate-induced myoclonus: A double-blind, randomised controlled study. Indian Journal of Anaesthesia 67(9):p 815-820, September 2023. | DOI: 10.4103/ija.ija_414_23