An unusual source of air during regional anaesthesia

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We would like to report an unusual incident that occurred during the placement of a brachial plexus block in a conscious patient before shoulder surgery. We were performing an interscalene block using an ultrasound-guided, in-plane technique. We had a good view of both the patient’s sonoanatomy and the needle’s tip throughout. The procedure was straightforward until, before our first injection, we aspirated a significant amount of air. As we had been using ultrasound and had been confident of our needle image throughout, we were sure that we had not breached the pleura or the trachea. We were using a 50-mm, 22-G Uniplex Nanoline regional block needle (Pajunk® UK Ltd, Newcastle-Upon-Tyne, UK) that has a facet tip, plastic Luer-lock hub, tubing and an electrical connection for a nerve stimulator. With the needle still in situ, we examined the apparatus for any obvious leaks or cracks and confirmed that all the connections were tight. We could still aspirate air. We then changed the tubing with the needle in situ with no improvement. We then removed the needle and performed the block again with a new needle, without any problems. We carefully examined and flushed the ‘rogue’ set with saline. No cracks or leaks were immediately evident. We ruled out any tubing fault by sealing the distal Luer-lock ends and injecting water through the proximal end under pressure. We then obstructed the distal part of the needle with a clamp and injected air through the needle, whilst holding the unit under water. A crack in the needle’s hub, alongside the manufacturing sealed lines and difficult to see with the naked eye, became evident. We then injected methylene blue dye through the needle whilst under water (Fig. 2) to demonstrate the fault. We examined a second needle set from the same lot and found a similar problem. We have made Pajunk aware of the faults. Needle fault demonstrated by methylene blue dye injection under water. We believe that clinicians should be aware of this potential equipment fault, and that this is yet another advantage to the many cited by Griffin and Nicholls regarding performance of nerve blocks under ultrasound-guidance [1]. Constant observation of our needle’s position allowed us to be certain from the outset that the aspirated air was due to a technical fault, rather than misplacement of our needle. No external funding and no competing interests declared. Previously posted at the Anaesthesia Correspondence website: http://www.anaesthesiacorrespondence.com.