Postoperative pain profiles and rebound pain following spinal anesthesia compared to general anesthesia: an observational study.

Background: Excessive pain during nerve block resolution after surgery under regional anesthesia has recently been referred to as rebound pain. The objective of this study was to detect differences in postoperative pain profiles of spinal and general anesthesia.

Methods: This single-center observational cohort study was conducted at University Hospital Marburg from January 2022 until July 2023. Main outcome measures were integrated pain scores (IPS), postoperative pain scores over 24 hours, cumulative morphine equivalents, and incidence of rebound pain according to the clinical definitions.

Results: We enrolled 328 patients scheduled for elective orthopedic, urological or gynecological surgery receiving either spinal or general anesthesia in this study. No statistically significant differences in IPS were observed apart from the PACU interval. Regarding pain scores on the Numerical Rating Scale (NRS), we found significantly lower NRS at the PACU, but significantly higher NRS after six hours following orthopedic surgery that was conducted under spinal anesthesia, but not for the other cohorts. The morphine equivalent consumption was very low for the entire study. The incidence for rebound pain according to clinical definitions, was highest for patients in the orthopedic cohort following spinal anesthesia.

Conclusions: Statistically significant and clinically relevant differences in pain scores were seen in orthopedic and orthopedic patients during the early postoperative period on resolution of spinal anesthesia. While the entity or rebound pain remains unclear, this phenomenon is a relevant problem in some clinical settings.