Distance between the skin and the thoracic paravertebral space.

A fundamental requirement for the safe and effective performance of paravertebral blockade is reliable estimates of the depth from skin to paravertebral space at different thoracic levels. This distance was assessed using a nerve stimulator guided paravertebral blockade technique in 527 separate blocks in 186 patients scheduled for various surgical procedures on the trunk. The median skin-paravertebral depth was 55.0 mm. The skin-paravertebral distance at upper (T1-3) and lower (T9-12) thoracic levels were significantly greater than mid-thoracic levels (T4-8) (p < 0.05). Body mass index significantly influences this depth at upper and lower thoracic levels (p < 0.001) but not in the mid-thoracic region.