The 'swoosh' test--an evaluation of a modified 'whoosh' test in children

Caudal analgesia is widely used in paediatric anaesthetic practice. In adults, the 'whoosh' test has been recommended as a guide to successful needle insertion, but it has not been extensively studied in paediatric patients. We have investigated a modification of the 'whoosh' test, which we have christened the 'swoosh' test. It avoids the injection of air by performing auscultation during injection of the local anaesthetic solution. We have compared it with clinical judgement of correct placement.

We studied 113 children undergoing elective surgery. During insertion of the caudal block, a stethoscope was placed over the lower lumbar spine and the presence or absence of an audible 'swoosh' noted. The operator's clinical impression of successful insertion was also recorded.

The overall success rate of caudal anaesthesia was 95.6%. Of the 108 patients with a successful block, 98 had a positive 'swoosh' test. There were no false positive results. Calculations show the 'swoosh' test to have a sensitivity of 91%, a specificity of 100% and a positive predictive value of 100%.

The 'swoosh' test is a simple and accurate test to confirm successful caudal insertion in children, and is especially useful as a teaching aid for anaesthetists new to the technique.