Paravertebral blocks

• A paravertebral block is essentially a unilateral block of the spinal nerve, including the dorsal and ventral rami, as well as the sympathetic chain ganglion. These blocks can be performed at any vertebral level. However, they are most commonly performed at the thoracic level because of anatomic considerations.
• They provide analgesia for ✔️Unilateral thoracic pain ✔️Rib fracture ✔️Refractory angina✔️Hyperhydrosis etc
• Usually a single level injection may cover less than four dermatomes
• Can be given under USG guidance or using a landmark technique 
• Point to be marked at a point 25 mm lateral to the spinous process of the level to be blocked
• After local anesthetic infiltration an 18 G epidural catheter is inserted to a depth, not greater than 35 mm till transverse process are hit (they are fairly superficial) and then the needle should be walked off the transverse process caudally, until it is 10mm deeper than the depth at which bone was initially contacted. (cranial walking of the needle increases the chance of pneumothorax)
• A loss of resistance to injection when the costotransverse ligament is passed is a clue to achieving of correct needle position,; but this is not as marked as the loss of resistance achieved during epidural insertion.
• If using a peripheral nerve stimulator, contraction of intercostal muscle or transverse abdominis may be elicited
• 3-5 mL of ropivacaine or levobupivacaine can be used per level. Addition of clonidine may prolong the blockade

reference: Deegan CA, Murray D, Doran P et al. Effect of anaesthetic technique on oestrogen receptor-negative breast cell cancer function in vitro. Br J Anaesth. 2009; 103(5): 685–690. Tighe SQM, Greene MD, Rajadurai N. Paravertebral block. Contin Educ Anaesth Crit Care Pain. 2010; 10(5): 133–137.