Intercostal nerve block: a roentgenographic anatomic study of technique and absorption in humans.

Roentgenograms of iothalamate meglumine 60% (Conray) injected bilaterally into the intercostal grooves of the ninth or tenth ribs in 30 surgical patients showed extensive spread of the contrast central and peripherally from the site of injection within 30 seconds, with almost complete absorption within 10 minutes 30 seconds. The spread was visualized in two patients for diagnosis using CT (computed tomography) following injection of iothalamate. It was also confirmed by injecting liquid latex into two corpses prior to autopsy. These findings help to explain why the peak plasma level occurs more rapidly and is higher following intercostal nerve block than from other regional nerve blocks when comparable doses are injected. Also, the study revealed that the optimal site for blocking an intercostal nerve is at the angle of the rib and that the optimal needle is one with a short bevel.