We were intrigued by the case described by Montoro et al.1 concerning the appearance of a pneumothorax following an interscalene block. The authors describe the performance of an ultrasound-guided posterolateral approach to the brachial plexus with C5 nerve stimulation. A number of questions remain. If the nerve root was contacted, then the approach would need to be high in the neck and would be well above the dome of the pleura. With the described approach, the C5 and C6 roots are rarely more than 1 to 1.5 cm deep, the needle entering the neck and passing through skin into the scalenus medius muscle, and then directed to the roots in the interscalene groove. If needle imaging was imperfect, resulting in the needle mistakenly being passed too deep, it would pass into the scalenus anterior muscle. If the block was performed in the lower neck, the needle would be directed not at the C5 root but at the superior trunk, but even at this level, the muscular relationships remain and the dome of the pleura would be posterior to scalenus medius. The incidence of pneumothorax reported by Borgeat et al. following nerve stimulation-guided interscalene block does not describe the authors’ needle direction. Borgeat2,3 described the lateral modified approach with a cranial-caudal needle angle of 45 to 60° and needle entry point 0.5 cm below the cricoid cartilage. The reference by Bhatia et al.4 relates to supraclavicular brachial plexus block.
The authors’ comments on the loss of needle tip visualisation are well recognised. During the performance of in-plane ultrasound-guided blocks, the focus should remain on the shape of the needle tip. In this regard, the Tuohy needle has advantages as the Huber tip profile is easily identified. A problem highlighted by Gray and Schafhalter-Zoppoth5 is the flexibility of small gauge needles as used in this case, which may bend away from the ultrasound beam rendering them more difficult to image.
The report describes an association of a procedure with an outcome, but there is no certainty that the two are related. Did the patient have a short neck or anatomical abnormality? Is it possible that the pneumothorax was spontaneous, or due to surgery?
Acknowledgements relating to this article
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Conflicts of interest: none.
Comment from the editor: Dr Montoro and colleagues did not wish to respond to this letter.
1. Montoro E, Ferre F, Yonis H, et al. Pneumothorax as a complication of ultrasound guided interscalene block for shoulder surgery. Eur J Anaesthesiol
2. Borgeat A, Ekatodramis G. Anaesthesia for shoulder surgery. Best Prac Res Clin Anaesthesiol
3. Borgeat A, Dullenkopf A, Ekatodramis G, Nagy L. Evaluation of the lateral modified approach for continuous interscalene block after shoulder surgery. Anesthesiology
4. Bhatia A, Lai J, Chan VW, Brull R. Case report: pneumothorax as a complication of the ultrasound guided supraclavicular approach for brachial plexus block. Anesth Analg
5. Gray AT, Schafhalter-Zoppoth I. A concerning direction. Anesthesiology