Association of rectus sheath block with fentanyl consumption and early postoperative outcomes after liver transplantation: a retrospective cohort study

Among liver transplant recipients, evidence for catheter-based rectus sheath block (RSB) remains limited. We evaluated the associations of a five-day, once-daily RSB regimen with fentanyl consumption, pain burden, and exploratory recovery outcomes over postoperative days (PODs) 1–5. This single-center retrospective cohort study included 135 adult liver transplant recipients during 2021 to 2024; 71 received conventional pain control (CPC) and 64 received RSB. The primary outcome was weight-adjusted fentanyl consumption during PODs 1–5. Secondary outcomes were pain burden, intensive care unit (ICU) and hospital length of stay, and ICU-recorded nutritional intake. Models were adjusted for age, sex, and Model for End-stage Liver Disease-Sodium category. On POD 1, observed median fentanyl consumption was 1.7 (0.0–4.0) µg kg⁻¹ day⁻¹ with RSB and 13.6 (9.5–18.2) µg kg⁻¹ day⁻¹ with CPC. Adjusted consumption was lower with RSB across PODs 1–5; the POD 1 adjusted RSB-to-CPC ratio was 0.13 (95% confidence interval [CI], 0.08–0.22; P < 0.001). Daily time-weighted pain scores were low in both groups, with no significant between-group difference. Among survivors, ICU length of stay was shorter with RSB (adjusted time ratio, 0.71; 95% CI, 0.55–0.92; P = 0.010), whereas hospital length of stay did not differ between groups. Calorie achievement rate and enteral nutrition ratio were higher with RSB during later ICU days. In adult liver transplant recipients, a five-day catheter-based RSB was associated with substantially lower early postoperative fentanyl consumption without higher measured pain burden. Associations with ICU-recorded nutritional intake and ICU stay were exploratory and hypothesis-generating. These findings support prospective evaluation of catheter-based RSB as part of multimodal opioid-sparing analgesia after liver transplantation. Not applicable.