Transverse vs. parasagittal in-plane approaches in ultrasound-guided paravertebral block using a microconvex probe: A randomised controlled trial.

Abstract

Several approaches have been proposed for ultrasound-guided thoracic paravertebral block, but the best approach remains unclear. We compared two ultrasound-guided in-plane approaches using a microconvex probe, transverse and parasagittal. We assessed whether either approach would facilitate successful catheter placement in the paravertebral space. Randomised controlled trial. University hospital, July 2015 to March 2016. Sixty patients scheduled to undergo thoracotomy were randomly allocated into two groups. A microconvex probe was placed transversely between adjacent ribs (transverse) or sagittally between adjacent transverse processes (parasagittal). When the Tuohy needle reached the paravertebral space, a catheter was inserted to a depth of 4 cm. Then, 0.5-ml radiocontrast was injected through the catheter under fluoroscopy. The primary outcome was successful catheter placement in the paravertebral space; secondary outcomes were 0 to 100 mm visual analogue scale pain score and morphine consumption in the first 24 h. All patients received the allocated paravertebral block. Correct catheter placement occurred in 23 (77%) and 24 patients (80%) using the transverse (n=30) and parasagittal approaches (n=30), respectively (P = 1.00). Five patients were excluded due to changes in surgical procedure. Postoperative pain, represented by median [IQR] visual analogue scale score, was 19.5 [12 to 25] at rest and 55 [44 to 77] on movement with the transverse approach (n=28) vs. 22 [12 to 33.5] at rest and 59 [41.5 to 75] on movement with the parasagittal approach (n=27) (P = 0.57 at rest, P = 0.76 on movement). Median morphine consumption was 11.5 [5 to 21] and 11 [5 to 18] mg in the transverse and parasagittal approaches, respectively (P = 0.99). There were no clinically significant differences between approaches for continuous ultrasound-guided thoracic paravertebral block using a microconvex probe, and both approaches achieved a high rate of correct catheter placement. UMIN Clinical Trials Registry identifier: UMIN000015988.