Effects of low‐dose remifentanil infusion on analgesic or antiemetic requirement during brain function mapping: A retrospective cohort study

Background Pain and discomfort during the awake phase in awake craniotomy should be relieved to facilitate brain mapping. Although some anaesthesiologists use low‐dose (0.01‐0.05 µg/kg/min) remifentanil infusion to provide analgesia during this phase, its efficacy and side effects have never been evaluated. Therefore, this study primarily aimed to investigate the effects of low‐dose remifentanil infusion on the need for antiemetic treatment during brain mapping and secondarily aimed to determine its effects on the need for additional analgesic treatment. Methods This retrospective study included 218 patients who underwent awake craniotomy at our centre from 2008 to 2018. The relationship between low‐dose remifentanil infusion during the awake phase and the requirement for analgesic or antiemetic treatment was examined. A multivariable competing risk regression analysis was performed to adjust for patient and operative variables. Results Sixty‐six patients (30.3%) received low‐dose (median rate: 0.01 µg/kg/min) remifentanil infusion during the awake phase. Forty‐nine patients (22.5%) received an antiemetic and 99 (45.4%) received additional analgesic treatment. The difference in additional analgesic treatment was not significant between patients who received low‐dose remifentanil infusion and those who did not (adjusted hazard ratio: 1.13; 95% confidence interval: 0.75‐1.70; P = .570); however, the use of antiemetics significantly increased in patients who received remifentanil (adjusted hazard ratio: 1.78; 95% confidence interval: 1.01‐3.15; P = .047). Conclusion Low‐dose remifentanil infusion during the awake phase in awake craniotomy significantly increased the need for antiemetics but did not decrease the need for additional analgesic treatment.