Effect of earplugs on propofol requirement and awareness with recall during spinal anesthesia

Aim. Anxiety is an important perioperative issue, especially in patients undergoing spinal anesthesia. Intraoperative noise is potentially harmful to staff and patients and hinders continuous sedation. The primary goal was to test the hypothesis that patients wearing single-use paraffin wax earplugs while undergoing spinal anesthesia in an extremely noisy environment show a reduction in the amount of propofol necessary for bispectral guided sedation compared to patients without earplugs. The secondary goal was to evaluate whether earplugs could reduce the incidence of intraoperative awareness with recall. Methods. In this prospective, randomized study, 50 patients undergoing orthopedic surgery were included. After achieving a target sedation depth of bispectral score 70 using a propofol bolus followed by a continuous infusion, an independent investigator either placed or did not place earplugs into the patients' ears (PLUG or noPLUG groups, respectively). Propofol requirements for stable sedation guided by the bispectral index and incidence of postoperative recall of intraoperative events were assessed in a double-blinded fashion. Results. We found high but comparable propofol requirements in both groups (PLUG 4.4±1.2 vs. noPLUG 4.2±1.0 mg kg -1 h -1 , p=NS). The incidence of intraoperative awareness was lower in the PLUG compared to the noPLUG group (16 vs. 56%; P<0.001). Conclusion. Although no sedative-sparing effect could be found in patients who wore earplugs during elective orthopedic surgery under spinal anesthesia, we nevertheless recommend using single-use paraffin wax earplugs. Beside their beneficial effect against potential harmful intraoperative noise, they reduce the incidence of intraoperative awareness with recall.