Lateral ultrasound-guided paravertebral blockade: an anatomical-based description of a new technique.

BACKGROUND Paravertebral blockade (PVB) is a regional anaesthetic technique with a large number of indications. PVB is usually performed with landmark-based techniques or methods that rely on pressure differences between the extra- and intraparavertebral space. This consecutive case series was designed to describe the ultrasound appearance of the lateral thoracic paravertebral space (PVS) and develop an ultrasound-guided method for PVB. METHODS The PVS of 20 women undergoing breast cancer surgery was investigated with a high-frequency linear ultrasound transducer in the sitting position. After identification of the transverse process, internal intercostal membrane (IIM), and pleura at the T3 and T6 levels, the depths of the IIM and pleura, and the sagittal diameter of the PVS were determined. An out-of-plane needle guidance technique was used to perform the PVB with ropivacaine 0.75% (12 ml) at both levels. Successful blockade was determined by the ability to perform surgery under light general anaesthesia without opioids. RESULTS Appropriate ultrasound identification of the IIM, transverse processes, and pleura was possible in all cases. Correct placement of the tip of the needle in the PVS resulted in successful PVB. No correlations of morphometric data with ultrasound measurements of the PVS were detected. CONCLUSIONS After ultrasound identification of the boundaries of the lateral PVS, an out-of-plane needle guidance technique facilitated successful PVB. There were no clinically relevant correlations between morphometric data and ultrasound measurements.