Off side! A simple modification to the parasagittal in-plane approach for paravertebral block.

The use of thoracic paravertebral blocks (PVBs) for breast cancer surgery confers important analgesic benefits. Several ultrasound (US)-guided PVB approaches have been described, but still elusive is the ideal technique that (1) permits continuous visualization of the entire needle shaft and tip, (2) avoids aiming the needle tip and injectate directly toward the neuraxis, and (3) is easy to perform. Although the parasagittal view in-plane PVB approach satisfies the former 2 criteria, maneuvering the needle to reach the targeted paravertebral space can be difficult as its trajectory is often obstructed by the bony transverse processes. This brief technical report describes the "off-side" technique--a simple solution to the technical challenge posed by the double-fulcrum effect exerted first by the transducer and then by the adjacent inferior transverse process. Our "off-side" technique marks a departure from conventional US-guided regional anesthesia teaching that recommends positioning the target in the middle of the US field and may be useful in similar types of US-guided regional anesthesia procedures such as neuraxial blockade.