A dual technique for identification of the epidural space.

A method of identifying the epidural space is described in which the traditional loss of resistance to air technique is combined with amplification of the sound made by the epidural needle as it traverses the interspinous ligament and the ligamentum flavum and then enters the epidural space. The method retains all the advantages of the loss of resistance to air technique whilst, in addition, the auditory amplification gives a slightly earlier warning of entry into the epidural space. The apparatus necessary is readily available and the technique is easy to use. In addition to being useful in difficult epidurals, the technique would also be an excellent teaching aid.