Dural Puncture with a 26-Gauge Spinal Needle Affects Spread of Epidural Anesthesia

Abstract

To the Editor: We wish to comment on Suzuki et al.'s article [1], which suggests that dural puncture without intrathecal injection of local anesthetic in a combined spinal epidural technique increases the caudal spread of epidurally administered mepivacaine: 1. The study was not blinded, since the same anesthesiologist performed and assessed the block. 2. Increased caudal spread is not explained by Bernards et al.'s study [2], which actually showed that the flux of local anesthetic through a dural hole made by a 27-gauge Whitacre needle was not increased. However, flux did increase after dural puncture with larger needles (24-gauge Sprotte and 18-gauge Tuohy). 3. Since all patients were kept in the left lateral position throughout, intrathecal movement of mepivacaine, if in fact this did occur, presumably behaving as a hypobaric solution within the cerebrospinal fluid, would have affected the right upper side of the body more than the left lower side. Surprisingly, only the left side was tested. 4. The concept of puncturing the dura without injection in a combined spinal epidural technique is regarded as a useful clinical method to improve caudal analgesia by the authors without any mention of potential morbidity associated with the spinal component such as meningitis [3]. Simon Walker, MBBS Roshan Fernando, FRCA Department of Anaesthesia; Royal Free Hospital; London, United Kingdom