Comparison of Cumulative Opioid Consumption Between Variable-Rate Feedback Infusion and Fixed-Rate Basal Infusion Modes of Intravenous PCA Following Mixed Surgery

All participants received a standardized PCA solution containing sufentanil (100 μg), ondansetron (16 mg), and normal saline with total volume 100 mL. In conventional fixed-rate basal infusion mode group, the PCA was set to administer a bolus of 2 mL with a lock out interval of 15 minutes and background infusion rate 2 mL/h.

All participants received a standardized PCA solution containing sufentanil (100 μg), ondansetron (16 mg), and normal saline with total volume 100 mL. In variable-rate feedback infusion mode group, a bolus of 2 mL with a lock out interval of 15 minutes and background infusion rate 2 mL/h, which increased to 2.5 mL/h, was used whenever the demand dose was administered within lock out interval. The background infusion rate automatically decreased by 0.5 mL/h when the bolus button was not pressed for 1 hour. The background infusion rate was limited to a maximum of 12.0 mL/h and a minimum of 1 mL/h. The specific variable-rate feedback infusion mode setting was based on previous research, and the opinions of manufacturers and researchers to ensure patient safety and to provide effective analgesia.