A method of continuous epidural analgesia

Despite the manifest advantages of continuous epidural analgesia, especially in obstetrics 1 9 * , 3 and for the relief of post-operative pain41 5 there have been two main obstacles to its wider use. In the first place the repeated injection of analgesic solutions through a catheter involves a risk of introducing infection into the epidural space. Attempts have been made to reduce this risk by using a multidose container and two-way taps; and more recently by injecting the solution through a sterile chuck7. Both these require the administrator to perform a full surgical scrub-up prior to each injection and are not wholly reliable. Other devices have been described where the ‘topping-up’ syringe is kept in a flexible container or fitted into an autoclaved mechanical apparatus 8; but though these are possibly safer from the sterility angle and avoid repeated surgical ‘scrub-ups’, they are correspondingly more complicated and less practical. A flask and transfusion set have been used9 in order to administer a continuous epidural drip, but this method has been criticisedro and the use of a rigid vessel is also undesirable as air must enter to replace the solution run off. In the second place 1.5 per cent lignocaine has a relatively short action and this necessitates frequent administration to keep the patient pain free. Owing to the importance of a scrupulously aseptic technique in ‘topping-up’, this has been the anzesthetist’s responsibility, and he has therefore had to be virtually in constant attendance. This is impractical and a compromise has been effected whereby only a few cases are chosen, and the ‘topping-up’ by day is replaced by systemic analgesics at night which largely defeats the aim of the technique.