Wary of friendly rivalry

The recent article on the ‘whoosh’ test, an auscultation sign to confirm correct needle placement in the caudal epidural space by Drs Lewis et al. (Anaesthesia 1992; 47: 57-8) and subsequent correspondence items on this test by Dr Lee (Anaesthesia 1992; 47: 451-2) and Dr Thorogood (Anaesthesia 1992; 47: 452) are interesting. I, too, found the test very reliable in my day to day anaesthesia practice. However, the above paper and the letters raise further questions regarding the origin of this test. This test, as your readers recall, involves auscultation with a stethoscope over the thoracolumbar area for a characteristic transmitted sound (‘whoosh’, as Drs Lewis et al. describe) on injection of 2-3 ml of air in the caudal space. Dr Lee stated that he described this test in 1988 [I] after having been introduced to it in 1983. However, this test has been described, without reference, in a standard text book of neural blockade published in 1980. To quote the author of the chapter (Caudal blockade): ‘A useful test when substantial doubts about needle position cannot be resolved is slowly to inject 2 ml of air whilst listening with ear or stethoscope over the lumbar vertebrae for transmitted sound. Although I d o not use this test, many trainees find it exceptionally useful during their initiation into the problems of blockade in obese or anatomically difficult patients’ [2]. I therefore believe that this test has been known before the 1980s. although its origin remains unknown.