Temporary paralysis of the lumbar sympathetic ganglions by means of a paravertebral injection of procaine hydrochloride is enjoying a well-earned measure of popularity both as a therapeutic test and as a means of treatment. Paravertebral blocks are commonly used to determine the degree of vasospasm in the legs and, thus, to discover how much relief can be expected from lumbar sympathectomy. Paravertebral block is almost a specific treatment for femoral thrombophlebitis (milk-leg).
It is important to note, however, that the indications for paravertebral sympathetic block often coincide with the indications for anticoagulant therapy. This is an important item to consider because, while the indications for use of paravertebral procaine injections may coincide with the indications for anticoagulant therapy, the simultaneous use of these procedures is fraught with great danger. In other words, paravertebral blocks should never be done in patients who are receiving anticoagulant therapy. This conflict in therapeutic agents
Cole F, Kleitsch WP. INCOMPATIBILITY OF LUMBAR BLOCK AND ANTICOAGULANT THERAPY. JAMA. 1951;147(13):1233–1234. doi:10.1001/jama.1951.73670300001012