The effect of an eye mask on midazolam requirement for sedation during spinal anesthesia: a randomized controlled trial

BACKGROUND: Midazolam is frequently used for sedation during spinal anesthesia. However, external environmental factors, such as bright surgical lights, may hamper patient relaxation, which may lead to an increase in the dose of midazolam required and the likelihood of adverse drug effects. We investigated whether using an eye mask to block the external environment could reduce midazolam requirements during spinal anesthesia. METHODS: Participants aged 18–‒80 years, scheduled for elective surgery under spinal anesthesia, were randomly divided into a masked group (wearing eye masks during surgery, n = 20) and a control group (no mask, n = 18). The sedation level was assessed using a modified Observer Assessment of Alertness and Sedation (MOAA/S) scale. Midazolam (1 mg) was incrementally administered every 5 min until moderate sedation (MOAA/S score of 3) was achieved. The bispectral index (BIS) was monitored, and the onset and maintenance times of a BIS < 80 were recorded. RESULTS: The two groups had similar demographic characteristics. The midazolam requirements were significantly lower in the masked group than in the control group (2.8 mg vs. 3.7 mg, P = 0.024). However, the onset and maintenance times for a BIS < 80 were similar. In addition, there were no significant differences in the incidence of side effects or patient satisfaction between the two groups. CONCLUSIONS: Blocking the external environment with an eye mask during spinal anesthesia can reduce the requirement for sedatives, such as midazolam. TRIAL REGISTRATION: The trial was retrospectively registered with the Clinical Research Information Service (No. KCT0005528, 15/10/2020) entitled “Can we reduce an amount of sleeping pills just by blocking light?”.