Beyond opioid dosage: temporal dynamics of intravenous patient-controlled analgesia use captured by electronic device logs-a post hoc analysis of three randomized controlled trials.

BACKGROUND

Intravenous patient-controlled analgesia (IV-PCA) is widely used for postoperative pain management. However, its temporal usage pattern remains poorly characterized.

METHODS

This secondary analysis included 332 patients from three randomized controlled trials investigating postoperative analgesia following robot-assisted laparoscopic prostatectomy, video-assisted thoracoscopic surgery, and minimally invasive distal gastrectomy (MIDG). Each trial compared two analgesic strategies, yielding six groups. Only the conventional MIDG group received IV-PCA alone without multimodal analgesia. Hourly fentanyl-based IV-PCA consumption and bolus attempts were obtained from electronic device logs. The primary outcome was the first time when 75% of patients reached an hourly IV-PCA consumption of ≤ 20 μg fentanyl/hr, predefined as the low-utilization threshold. The secondary outcomes included the first time when 75% of patients reached a bolus attempt rate ≤ 1/hr, temporal trajectories of PCA use, delivery-to-demand ratio, and correlations between pain scores and cumulative opioid consumption.

RESULTS

The low-utilization threshold was reached within 6-8 hours by 75% of patients in all groups, except for the conventional MIDG group. Similarly, bolus attempts declined to ≤ 1/hr after 7-9 hours postoperatively, again excluding the opioid-only group. Delivery-to-demand ratio was the lowest immediately after surgery and increased over time, showing higher values with multimodal analgesia. Pain intensity correlated significantly, but only weakly, with PCA consumption (r = 0.16-0.24, P < 0.05 for all comparisons).

CONCLUSIONS

Fentanyl-based IV-PCA use declined rapidly, indicating that its benefit is largely confined to the early postoperative phase and that its duration can be shortened when multimodal analgesia is well established.