• Supaporn Tharahirunchot, Suwanna Tatiyapongpinij, and Ketchada Uerpairojkit.
• Department of Anesthesiology, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok, Thailand. supabura@windowslive.com
• J Med Assoc Thai. 2011 Mar 1;94 Suppl 2:S103-7.

ObjectiveTo determine effect of noise block using earplugs on reducing propofol infusion needed to maintain a constant bispectral index (BIS) values in patients undergoing extracorporeal shock wave lithotripsy (ESWL).Material And MethodFifty-eight patients (18-65 years) with nephrolithiasis undergoing ESWL, having ASA physical status I or II and have normal hearing function tested by audiometry were enrolled in this randomized, double-blind, controlled trial. Patients were randomized and allocated into two groups: noise blocked group (earplugs inserted into both ears) and control group (earplugs not inserted). Sedation by target-controlled infusion was started with 1.2 mcg/mL of propofol and propofol target concentration was adjusted gradually by 0.2 mcg/ml every 5 minutes intraoperatively to achieve and maintain bispectral index (BIS) values within 75-80% until the procedure finished. Total amount of propofol (mg), BIS values (%), ambient noise level (dB) and patient satisfaction (1-5) were measured.ResultsThe amount of propofol infusion needed to maintain a constant BIS index value in patients undergoing ESWL in the noise blocked group was significantly lower than that in the control group (6.91 +/- 2.05 vs. 8.23 +/- 2.16 mg/kg/m2/hr, p = 0.021). Patient satisfaction was similar in both groups (4 [1] vs. 4 [1], p = 0.929).ConclusionNoise diminution in ambient operating room can reduce the amount of propofol needed to maintain light sedation during ESWL.

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