Abstract
INTRODUCTION: Spread patterns of the erector spinae plane block (ESPB) in a larger cohort of living subjects remain inadequately understood. This study investigated the spread of local anaesthetics or saline with contrast in patients undergoing computed tomography-guided radiofrequency ablation of hepatic tumours. PATIENTS AND METHODS: Thirty patients participated in a double-blinded randomized controlled trial, 14 April 2021 and 18 January 2023. These patients were randomized into two groups: the ESPB group, which received local anaesthetic with contrast, and the sham group, which received saline with contrast. The spread of the drug was assessed regarding vertebral levels and its correlation with the patient characteristics. Pain intensity and morphine consumption were also evaluated. RESULTS: The ESPB consistently spread cranio-caudally to the dorsal erector spinae muscle in all patients, with a median (IQR) spread of 9 (8-11) vertebral levels, and to the intercostal space with a median (IQR) spread of 4 (3-6) vertebral levels. Paravertebral spread occurred in 90% of patients (27 out of 30) with a median (IQR) spread of 3 (2-5) vertebral levels, while epidural spread was observed in 36.7% of patients (11 out of 30) with a median (IQR) spread of 0 (0-2) vertebral levels. Cranio-caudal spread negatively correlated with back muscle thickness (r= -0.4; p = 0.035), and females exhibited significantly more intercostal spread levels than males (5.8 ± 1.0 vs. 4.3 ± 1.6 levels in females and males, respectively; p = 0.021). However, no significant difference was found in pain intensity and morphine consumption between the two study groups. CONCLUSION: This study provides insights into the drug spread patterns of ESPB in living subjects. However, a unilateral ESPB did not yield sufficient analgesic effects for radiofrequency ablation of hepatic tumours.