Respiratory arrest after sufentanil

I applaud Drs Phillips and Macdonald (Anaesthesia 1987; 42: 661-3) for their most valuable study of epidural catheter migration and agree most heartily with their final assertion that there is no room for complacency in the organisation of an epidural service. To misquote: the price of safety is eternal vigilance. I am interested to hear that, as a result of their experiences of inward migration of catheters, Drs Phillips and Macdonald suggest that a catheter with a single end hole may be safer than onc with three helical holes. There are many reports both in the literature and sub judice of failed aspiration tests for both subarachnoid and intravascular catheter placement, particularly from the US where single end hole catheters arc in widespread use. A moment’s reflection suggests that such false negatives are more likely to occur with a singlethan with a three-holed catheter. Moreover, the work of Hardy4 suggests that an epidural catheter cannot by itself penetrate the dura mater, though it may penetrate the arachnoid if the needle has first penetrated the dura. I can understand that in the cases cited by Drs Phillips and Macdonald, one catheter migrated into a previously penetrated blood vessel and another through the arachnoid following presumed needle penetration of the dura, but I would be surprised if the use of a single end hole catheter would necessarily have avoided both of these mishaps. There has been no case of intravascular catheter insertion that was not diagnosed at once on aspiration (as was the Leeds one) in 1 1 000 obstetric epidurals using three-holed catheters in this hospital, and only one in which a spinal headache followed an apparently uneventful epidural with four successful and harmless top-up doses. This headache started abruptly 48 hours post partum and required a blood patch to cure it. There is clearly a need for an extensive, randomised, controlled trial of the two catheter types before we all convert to the single end hole type of catheter. I would be interested to hear if any such has been instituted.