Confirming the position of the thoracic epidural catheter – a valuable sign

Thoracic epidural analgesia is widely used to provide effective post-thoracotomy analgesia [1]. It is increasingly recognised that thoracic epidural analgesia use reduces post-thoracotomy complications [2-4] and may reduce mortality [5-7]. The benefit of this technique is, however, reduced by the occurrence of unrecognised incorrect placement of thoracic epidural catheters, reported to occur in 10–15% of patients [8]. Concern about spinal cord injury has resulted in most, but not all, thoracic epidurals being sited in awake patients [9]. An additional reason for this change in practice is that it affords the ability to confirm correct catheter placement. A valuable observation, which in our experience can minimise the risk of unrecognised incorrect thoracic epidural catheter placement, relates to the sensation of having the catheter threaded. This sensation can often be localised. If the patient is asked to report this sensation and answers of ‘upwards’, ‘downwards’ or ‘not sure’ are suggested to the patient, it has been observed that the answer is upwards most of the time. Where doubt remains, the same question can be asked upon administering the test dose of local anaesthetic. In our experience, of many hundreds of thoracic epidurals, no patient reporting an upward sensation during thoracic epidural catheter insertion or test dose administration failed to develop a bilateral dermatomal block when epidural local anaesthetic was subsequently administered. Our observations provide further support for inserting thoracic epidurals in conscious patients.