Bilateral Thoracic Paravertebral Blocks Compared to Thoracic Epidural Analgesia after Midline Laparotomy: A Pragmatic Noninferiority Clinical Trial

Abstract

BACKGROUND: Bilateral paravertebral block (PVB) is a suitable alternative to thoracic epidural analgesia (TEA) for abdominal surgeries. This randomized clinical trial aims to determine if PVB is noninferior to TEA in terms of analgesia after midline laparotomy. METHODS: Seventy American Society of Anesthesiologists (ASA) class I-III patients undergoing a laparotomy through a midline incision were randomized to receive either TEA (TEA group) or continuous bilateral PVB (PVB group) as a part of a multimodal analgesia regimen in an open-label design. Noninferiority was to be concluded if the mean between-group difference in pain on movement at the 24 postoperative hours was within a margin of 2 points on a 0-10 numerical rating scale (NRS). Pain score at rest and on movement, analgesic consumption, hemodynamics, and adverse events during the first 72 postoperative hours were the secondary outcome measures assessed for superiority. Postblock and steady-state plasma concentrations of ropivacaine and pattern of dye spread were also recorded in the PVB group. RESULTS: The primary outcome of pain scores on movement at 24 postoperative hours was noninferior in PVB group in comparison to TEA group (mean difference [95% confidence interval {CI}], 0.43 [-0.72-1.58]). The pain scores at rest and on movement at other time points of assessment were within clinically acceptable limits in both groups with no significant differences between the groups over time. Arterial plasma ropivacaine levels were within safe limits, while steady-state venous level was higher than an acceptable threshold in 9 of 34 cases. CONCLUSIONS: As a component of multimodal analgesia, bilateral PVB provides noninferior analgesia compared to TEA for midline laparotomy.