J Med Assoc Thai 2011; 94 (3):103

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Effect of Noise Block Using Earplugs on Propofol Sedation Requirement during Extracorporeal Shock Wave Lithotripsy
Tharahirunchot S Mail, Tatiyapongpinij S , Uerpairojkit K

Objective: To 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 Method: Fifty-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.

Results:
The 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).
Conclusion: Noise diminution in ambient operating room can reduce the amount of propofol needed to maintain light
sedation during ESWL.

Keywords: Noise, Bispectral index, Operating room noise, ESWL, Sedation, Propofol

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