Suprascapular nerve block and axillary nerve block have been introduced as alternatives to the interscalene brachial plexus block for the control of postoperative pain. Ultrasound-guided procedures are widely used in regional anaesthesia, and Rothe et al.demonstrated a method of ultrasound-guided block of the axillary nerve in which the block needle is inserted just cranial to the posterior circumflex humeral artery (PCHA). However, in clinical practice, two or more vessels can be observed when the user is searching for the PCHA under ultrasound guidance. In addition, variation in the origin of the PCHA is common and it sometimes follows an abnormal course. Patients with shoulder pain were allocated to one of two groups to receive ultrasound-guided axillary nerve block with either interfascial injection (IF Group) or perivascular injection with nerve stimulation (PV Group). The primary outcome was procedure duration, defined as the time interval from when the transducer contacted the skin to when the needle was removed from the skin. PCHA visibility, the number of visualised vessels, the appearance of conical structures, intravascular uptake of contrast material, and motor and sensory functions were evaluated as the secondary outcomes. We hypothesised that interfascial injection between the deltoid and teres minor muscle would reduce the time required to perform axillary nerve block and was as effective as perivascular injection.

Treatment

Patients were prepared in a sitting position, with the shoulder resting in a neutral position. The areas of injection were disinfected with povidone-iodine on a posterior aspect of the shoulder. Using a high-frequency linear transducer (13–5 MHz, EDGE ultrasound device, SonoSite Inc., Bothell, WA, USA), the neck and shaft of the humerus, the deltoid muscle, and the cross-section of the teres minor muscle and the posterior circumflex humeral artery were identified, parallel to the longitudinal axis of the shaft of the humerus. The block needle (UniPlex NanoLine cannula with facet tip 22 G 100 mm; Pajunk, Geisingen, Germany) was inserted from the cranial end of the transducer. Using the in-plane technique, the needle was advanced until its tip entered the interfascial space between the deltoid muscle and the teres minor muscle. Or, the needle tip was placed just cranial to the posterior circumflex humeral artery. Interfascial plane block was confirmed in the posteroanterior fluoroscopic view after injecting 3 mL contrast material (IOBRIX, 300 mgI/mL; Taejoon Pharm, Seoul, Korea). After the contrast material dispersed in the interfascial space between the deltoid muscle and the teres minor muscle without intravascular uptake, 8 mL 2% lidocaine was slowly injected with aspiration for every 2 mL injected. If vascular uptake was detected, the process was repeated after changing the needle position.

Arm Label

Target Number of Participant

Arm Type

Arm Description

Patients were prepared in a sitting position, with the shoulder resting in a neutral position. The areas of injection were disinfected with povidone-iodine on a posterior aspect of the shoulder. Using a high-frequency linear transducer (13–5 MHz, EDGE ultrasound device, SonoSite Inc., Bothell, WA, USA), the neck and shaft of the humerus, the deltoid muscle, and the cross-section of the teres minor muscle and the posterior circumflex humeral artery were identified, parallel to the longitudinal axis of the shaft of the humerus. The block needle (UniPlex NanoLine cannula with facet tip 22 G 100 mm; Pajunk, Geisingen, Germany) was inserted from the cranial end of the transducer. Using the in-plane technique, the needle was advanced until its tip entered the interfascial space between the deltoid muscle and the teres minor muscle. Interfascial plane block was confirmed in the posteroanterior fluoroscopic view after injecting 3 mL contrast material (IOBRIX, 300 mgI/mL; Taejoon Pharm, Seoul, Korea). After the contrast material dispersed in the interfascial space between the deltoid muscle and the teres minor muscle without intravascular uptake, 8 mL 2% lidocaine was slowly injected with aspiration for every 2 mL injected. If vascular uptake was detected, the process was repeated after changing the needle position.

Arm Label

Target Number of Participant

Arm Type

Arm Description

The patients were prepared in the manner described above. Axillary nerve block using the perivascular approach was performed using the method described by Rothe et al. Ultrasound images were obtained in the same manner as described for the IF Group. Next, the block needle (UniPlex NanoLine cannula with facet tip 22 G 100 mm; Pajunk, Geisingen, Germany) was inserted from the cranial end of the transducer and the needle tip was placed just cranial to the posterior circumflex humeral artery. When deltoid muscle contraction at a current of 0.5 mA (MultiStim VarioTM Peripheral Nerve Stimulator; Pajunk, Geisingen, Germany) was observed, 3 mL contrast material was administered. If the spread of contrast media was detected without intravascular uptake, 8 mL 2% lidocaine was slowly injected with aspiration for every 2 mL injected. If vascular uptake was detected, the needle was repositioned.

Gender

Age

Description

patients with shoulder pain

1. allergies or contraindications to local anaesthetics or contrast media
2. local infection
3. coagulopathy 
4. limited range of motion related to the deltoid muscle

procedure duration

during procedure

posterior circumflex humeral artery visibility

during procedure

the number of visualised vessels

during procedure

the appearance of conical structures

during procedure

intravascular uptake of contrast material

during procedure

Deltoid motor function

Before procedure, 15 min and 30 min after procedure

sensory function

Before procedure, 15 min and 30 min after procedure

The procedure time was significantly shorter in the IF Group than in the PV Group (mean [SD]: 64 [28.3] vs. 135 [50.3] s; P < 0.001). There were no differences in the visibility of the posterior circumflex humeral artery between the groups (96.4% vs. 100%; P = 1.000). The number of visualised vessels were similar between the groups. More than two blood vessels were observed in 17 patients (60.7%) in each group. There were no significant differences in the appearance of conical structures between the groups (85.7% vs. 82.1%; P = 1.000). There were only two (7.1%) cases of intravascular uptake in the PV Group, but there were no significant differences between the groups. There were no significant differences in complications between the groups (1 [3.6%] vs. 5 [17.9%]; P = 0.193). All complications, except for one instance of radial nerve weakness in the PV Group, were resolved within 30 min. There were no significant differences between groups in the success of axillary nerve block as assessed by loss of pinprick sensation as well as the presence of motor block of the deltoid muscle when assessed 30 min after blocks.