Preoperative versus Postoperative Paravertebral Block on Postoperative Opioid Consumption in Patients Undergoing...

The optimal timing of paravertebral block (PVB) for metabolic and bariatric surgery (MBS) remains uncertain. Drawing on the concept of preemptive analgesia-which suggests that blocking nociceptive signals before surgical stimulus may limit central sensitization-we designed this study to test whether a preoperative PVB reduces 24-hour opioid consumption more effectively than a postoperative PVB in patients undergoing laparoscopic sleeve gastrectomy (LSG).

This single-center retrospective cohort study enrolled patients aged ≥18 years undergoing LSG with bilateral T8 PVB between January and October 2025. Patients were categorized into Pre (PVB before anesthesia induction) and Post (PVB after surgery) groups. The primary outcome was 24-hour postoperative opioid consumption (morphine milligram equivalents, MME). Secondary outcomes included time to first rescue analgesia, rescue analgesia requirement, postoperative nausea and vomiting (PONV), time to first ambulation, and length of hospital stay. Propensity score matching (PSM, 1:3 nearest-neighbor matching with a caliper width of 0.2) was performed to control for confounders.

After PSM, 233 patients were analyzed (Pre, n=168; Post, n=65). Median 24-hour MME consumption was 104.1 (IQR 64.8-147.3) in the Pre group and 91.2 (IQR 50.4-158.4) in the Post group (P=0.425). No significant differences were observed in any secondary outcomes, including time to first rescue analgesia (3h vs 4h, P=0.182), PONV incidence (70.2% vs 73.8%, P=0.585), time to first ambulation (2.5h vs 2.5h, P=0.681), or length of hospital stay (3 vs 4 days, P=0.865).

In patients undergoing LSG within a multimodal analgesic protocol, preoperative PVB was not associated with reduced 24-hour opioid consumption or improved early recovery outcomes compared to postoperative PVB in this retrospective cohort. These findings suggest that PVB timing may be guided by logistical considerations without compromising analgesic efficacy, but prospective studies are needed to confirm this observation.