Caudal epidurals: The whoosh test

Abstract

Caudal epidural injection is a simple procedure that carries a low risk of complications. The whoosh test (injection of air into the caudal epidural space with simultaneous auscultation over the thoracolumbar spine) has been recommended as an aid to correct needle placement. A 1-year prospective study, using fluoroscopic imaging to identify needle position, was conducted to compare the sensitivity and specificity of the whoosh test with that of clinical impression alone in assessing correct needle placement in the caudal space. Of 131 patients studied, correct needle placement was achieved in 121 on the first attempt (92%). Clinical impression alone had a sensitivity of 94% and a specificity of 20%. The whoosh test had a sensitivity of 80% and a specificity of 60%. The whoosh test is superior to clinical judgment in detecting incorrect caudal needle placement.