Comparison of Ultrasound-Assisted and Classic Approaches to Continuous Paravertebral Block for Video-Assisted Thoracoscopic Surgery: a Prospective Randomized Trial

Abstract

Background: Continuous paravertebral blocks (PVBs) are an established means of providing postoperative analgesia in thoracic surgery. While PVBs can be administered using multiple methods, no randomized clinical trial comparing the relative advantages of the ultrasound-assisted approach to the traditional landmark approach, the two most commonly-used approaches in our hospital, has been conducted to date. Our study thus sought to compare the efficacy of these two methods of PVB placement.

Methods: From July 1, 2013 to June 5, 2014, 45 patients scheduled for thoracic surgery consented to participate in the study. Each patient was randomized into a group receiving PVB placed with either the classic landmark-based (CL) or ultrasound-assisted (US) approach. Each group received 20 ml of ropivacaine 0.5% as the local anesthetic (LA). Onset time and spread of the block were then assessed by a blind observer. The main outcome was hydromorphone consumption 24 hours after initiation of patient-controlled analgesia (PCA). Secondary outcomes were the following: Pain Numeric Rating Scale (NRS) score after 24 hours at rest and during deep inspiration; requested PCA boluses in 24 hours; total LA consumption and number of boluses through the catheter; and changes between pre-and post-operative (24 hours after surgery) tidal volume, forced vital capacity, forced expiatory volume in 1 sec, and peak expiatory flow.

Results: Mean opiate consumption during the 24 hours after PCA initiation was 5.75 mg (4.23-7.26) for the CL group and 6.38 mg (4.51-8.25) for the US group (p= 0.643). None of the secondary outcomes statistically differed between the two groups.

Conclusions: Our data supports the concept that choice of continuous PVB approach does not affect the outcome. The expertise of the anesthesiologist performing the block remains a key factor in choosing which approach to use.