Identifying the thoracic epidural space
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Drs Patrick and Miller  advocate the use of the hanging drop technique to identify the epidural space in the thoracic region. However, they do not specify whether the patient is awake or anaesthetised. The same issue of Anaesthesia contains two papers that both show that 15% of anaesthetists site epidurals in anaesthetised patients [2, 3].
I am fearful that some of the latter group will be tempted to try out a technique which relies upon negative pressure in the epidural space, and which does not work in patients undergoing intermittent positive pressure ventilation. Perhaps a note of caution should be published to prevent avoidable damage to patients through an increased risk of dural puncture?