Epinephrine-added Irrigation Shortens and Stabilizes Operative Time in Full-endoscopic Lumbar Decompression after Adjusting for the Learning Curve: An Interrupted Time Series Study.

OBJECTIVE: To evaluate whether epinephrine-added irrigation improves operative efficiency and visualization during uniportal full-endoscopic unilateral laminotomy for bilateral decompression (FESS-ULBD) after adjusting for the learning curve.

SUMMARY OF BACKGROUND DATA: Maintaining a clear operative field under continuous irrigation is a major challenge in full-endoscopic lumbar decompression. Epinephrine-added irrigation improves visualization in arthroscopy, but evidence in endoscopic spine surgery is limited and may be confounded by learning curve effects.

METHODS: Fifty consecutive single-level FESS-ULBD cases for degenerative lumbar spinal stenosis were analyzed (saline-only irrigation [SAL], n=24; epinephrine-added irrigation [EPI], n=26). Segmented regression ITS models were applied to evaluate operative time, endoscopic visibility, and hemostasis while adjusting for case sequence (learning curve), post-implementation slope change, and sex.

RESULTS: Mean operative time decreased from 99.3 minutes (SD 18.5) in SAL to 60.7 minutes (SD 9.4) in EPI (P<0.001). ITS analysis demonstrated a significant immediate reduction in operative time (level change -18.3 minutes, 95% CI -33.7 to -2.9; P=0.024) and reduced variability (residual SD 17.5 to 7.2 minutes; P=0.001). Visibility improved (median "Good" 44.4% vs. 100%; ITS OR 668.8; P=0.004), and the need for hemostasis decreased (ITS OR 0.021; P=0.032). Under routine monitoring, intraoperative hypertension events occurred at similar rates between groups (17% vs. 15%), and no antihypertensive medication was required.

CONCLUSION: After adjusting for learning curve effects using segmented regression ITS analysis, epinephrine-added irrigation during FESS-ULBD improved visualization and reduced hemostasis burden, resulting in shorter and more consistent operative times without clinically apparent hemodynamic instability under routine monitoring or increased postoperative bleeding.

STUDY DESIGN: Single-center, single-surgeon retrospective observational study using segmented regression interrupted time series (ITS) analysis.