Effect of Noise Block Using Earplugs on Propofol Sedation Requirement during Extracorporeal Shock Wave Lithotripsy
Supaporn Tharahirunchot MD*, Suwanna Tatiyapongpinij BN*, Ketchada Uerpairojkit MD**
Affiliation : * Department of Anesthesiology, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok, Thailand ** Department of Anesthesia, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
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
