"Whoosh" test as a teaching aid in caudal block

Fifty-three patients presenting for minor gynaecological procedures received caudal blocks performed by residents. These residents used the standard technique which relied on the "give" felt as a needle penetrates the sacrococcygeal membrane and the loss of resistance to air when the needle is correctly placed. The "whoosh" test was noted by the supervising anaesthetist who did not reveal his findings to the residents. A positive test consisted of a characteristic "whoosh" sound on auscultation of the thoracolumbar region when 2 to 3 ml of air was injected into the caudal extradural space. The predictive value of a positive test was found to be 78%, 80.7% and 97.7% (P < 0.01) for a positive "give", loss of resistance and "whoosh" test respectively. Negative tests had no predictive value for "give" and loss of resistance whilst the predictive value of an absent "whoosh" was 100% (P < 0.05). Thus we conclude that the "whoosh" test is an excellent aid in the teaching of caudal anaesthesia.