Interscalene block is often used for shoulder and upper arm surgery. This form of regional anaesthesia decreases pain, nausea, vomiting associated with general anaesthesia, length of hospital stay and improves postoperative rehabilitation.1,2 The technique has undergone many changes from first use in 1970 to the start of the use of ultrasound. Several studies have observed a better success rate. However, there is no consensus on the contribution of ultrasound in reducing the incidence of complications.3,4 We obtained the consent of the patient to publish this report. A 77-year-old woman was scheduled for the insertion of a right shoulder reverse prosthesis. The patient was classed as ASA II for obesity (BMI 34), hiatal hernia and chronic myalgia. In the operation theatre, we performed an ultrasound-guided interscalene block. A linear ultrasound probe, 38 mm, 6 to 15 MHz (Sonosite) and a 22-gauge needle of 50 mm connected to a nerve stimulator (HNS 11, B Braun) delivering a current of 0.5 mA at 2 Hz were used throughout the procedure. Indeed, combining ultrasound and neurostimulation allows the identification of nerve roots visually. An experienced resident conducted the regional anaesthesia with a posterolateral approach (in the ultrasound's plane) supervised by a consultant anaesthesiologist. Vascular structures (carotid artery and internal jugular vein), muscular structures (anterior and middle scalene), nerve structures (nerve roots C5, C6 and C7) and bone structures (transverse process of C6 and C7) were visualised during the procedure. A musculocutaneous response (flexion of the forearm) obtained at 0.5 mA confirmed the identification of the C5 nerve root. After negative aspiration, slow and fractioned injection of 25 ml of ropivacaine 0.475% combined with 4 mg dexamethasone was performed. After induction of general anaesthesia, the patient was ventilated in a volume-controlled mode with a tidal volume of 8 ml kg−1 with an insufflation pressure of 21 cmH2O. Surgery and the postoperative recovery were uneventful. A right segmental pulmonary embolism was detected 3 days postoperatively. Surprisingly, a right anterior pneumothorax associated with ipsilateral pleural effusion was also highlighted (Fig. 1). Seven days postoperatively, a control chest CT scan showed a regression of the pneumothorax without thoracic drainage. The patient left the hospital 16 days after the surgical intervention. The incidence of pneumothorax after ultrasound-guided interscalene block is unknown and is probably rare. Borgeat et al.5 found an incidence of 0.2% for pneumothorax after interscalene block under neurostimulation alone. In this case, we used the easier ‘posterior, latero-medial approach’ which was criticised as a potential higher risk of pneumothorax.6 However, the ‘anterior, medio-lateral approach’ is also not free from the risk of pneumothorax, even with the use of ultrasound.7 During the procedure, the operator must position the probe in an oblique axial plane to obtain the best cross-section of the brachial plexus, and then maintain the target image in the centre of the screen while viewing the tip of the needle throughout the procedure. Even for experienced operators, the constant visualisation of the needle is often complex.8 However, a loss of needle visualisation is a limitation of the ultrasound-guided regional anaesthesia and needle progression must be stopped immediately if this occurs (Fig. 2a and b). We believe that a false estimate of the needle tip is probably responsible for pleural puncture, despite the use of the hydrolocalisation technique (visualisation of the tip via the injection of fluid) which can be helpful in positioning the tip of the needle.
Assistance with the letter: none declared.
Financial support and sponsorship: institutional and department sources.
Conflicts of interest: none declared.
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