The need for epidural wings

Abstract

The recent correspondence by Yentis and Barnes [1] and Reynolds [2] has highlighted developments in the ‘Doughty’ technique. Looking at the illustrations it would appear that Yentis and Barnes favour the addition of wings to the epidural needle, although, as Reynolds points out, this was not part of Doughty's original technique. So why have epidural needle wings now become popular? In 1948, Macintosh first described the addition of wings to spinal needles [3]. This modification permitted lumbar puncture without the need to touch the needle point or shaft. Over the following decade, wings found their way onto epidural needles [4]. For advocates of the hanging drop technique, which is now rarely performed, wings provided greater control during needle advancement through the ligamentum flavum. A similar advantage could be suggested when using intermittent advancement with an air-filled syringe. These claims may have some validity when dealing with a more elderly population, such as that encountered in orthopaedic surgery, where ligaments are heavily calcified. However, this is not so in obstetrics and, as saline is the most widely used technique for locating the epidural space [5], the need for wings is questionable. Indeed, they may actually encourage needle advancement with both hands, rather than solely through the plunger of the syringe. Consequently, needle control is reduced and the risk of dural puncture increased. Some manufacturers include separate wings in their packs and these may be connected to the needle if required. Others, however, provide preattached wings, some of which cannot be removed. During a recent discussion with one leading manufacturer, I was disappointed to hear that they at least have no plans to produce a wingless epidural needle. Hopefully, this lack of flexibility will not be adopted by other companies. So should obstetric anaesthetists use wings simply because they are provided in the pack? Some may have no choice if their supplier does not produce a wingless needle. For those who do, we should consider whether wings confer any advantage to the user, which in the obstetric population is far from certain.