Ultrasound-guided single needle tip placement below axillary artery in the infraclavicular area: A cadaveric study

Abstract

Background and aims: The parasagittal ultrasound-guided infraclavicular block (ICB) aims to cover all the elements of brachial plexus for the surgeries at and below the elbow. Our aim was to demonstrate the spread of 20 ml latex in vicinity of brachial plexus cords after injecting posterior to the axillary artery in Thiel embalmed cadavers.

Material and methods: A blunt insulated needle was inserted posterior to the axillary artery in a traditional parasagittal infraclavicular in 2 Thiel embalmed cadavers, on both the sides (four specimens). A day later cadaver 1 was dissected and cadaver 2 was frozen at ‒20ºC for 2 weeks and sectioned. Both cadavers were photographed.

Results: In cadaver 1, dissection revealed a spread of red latex on the lateral cord extending onto the musculocutaneous nerve, the posterior cord engulfing the radial and axillary nerves distally. In cadaver 2, a cross-section revealed latex engulfed all three cords.

Conclusion: Single injection of 20 ml latex aimed posterior to the axillary artery in the parasagittal infraclavicular approach engulfed the posterior, medial and lateral cord in Thiel embalmed cadavers. This needs to be investigated in patients who receive ICB clinically and using contrast studies.

Keywords: Cadaver; infraclavicular; nerve block; regional anaesthesia; ultrasonography.

Figure 1

(a) Left parasagittal infraclavicular single needle-tip placement an injection of red latex. (b) Needle placement (white dashed line) posterior to the AA and spread of dye observed in real time (red-dotted area)

Figure 2

(a) Left infraclavicular area: The plane between the PMa and minor reflected medially depicting the thoraco-acromial artery and the pectoral nerves. Immediately below the PMi is the lateral cord. Contrast is seen lateral to lateral cord. (PMa, pectoralis major; PMi, pectoralis minor). (b) Left infraclavicular area: Retracting the and cutting the conjoint tendon reveals the red latex spread along the lateral, medial and superior aspect of the lateral and posterior cord. The posterior cord is posterior and medial to the lateral cord, and, lateral and posterior to the subclavian artery. (SuBM, subclavius; LC, lateral cord; PC, posterior cord; SCA, subclavian artery; SCV, subclavian vein; TAA, thoraco-acromial artery; TAAbr, branches of TAA; CT, conjoint tendon)

Figure 3

(a) Left infraclavicular area: Lateral retraction of deltoid demonstrates the neurovascular sheath. (b) Left infraclavicular area: The sheath is reflected medially and the latex gently peeled off from the cords demonstrating the formation of the medial nerve, the posterior cord terminating into the radial nerve and the musculocutaneous nerve disappearing into the coracobrachialis. (TAA, thoracoacromial artery; NVS, neurovasculae sheath; ICBN, intercostobrachial nerve; PECMi, pectoralis minor; MrM, medial root of median; LrM, lateral root of median; McN, musculocutaneous; RN, radial nerve; MN, median nerve; SCA, subclavian artery)

Figure 4

Left infraclavicular area: The specimen of brachial plexus cord below the level of clavicle depicting the latex engulfing the lateral cord, lateral root of median, medial root of median, median, radial, and musculocutaneous nerves. The axillary nerve from the posterior cord must be surrounded by the latex at its emergence. (SuBM, subclavius muscle; AxN, axillary nerve; MrM, medial root of median; LrM, lateral root of median; McN, musculocutaneous; CB, coracobrachialis; RN, radial nerve; MN, median nerve; SCA, subclavian artery)

Figure 5

(a) Proximal cross-section at the left infraclavicular area demonstrating the blue latex engulfing the all three brachial cords. The spread is far as the ventral aspect of the musculocutaneous nerve. (b) Distal cross-section depicting the periarterial blue latex involving the pf-MC and PC and consistently the LC. (c) Expanded figure demonstrating the blue latex engulfing the brachial cords. The dark brown shadows are the nerve fascicles and light brown interspersed are the connective tissue. (pf-LC, possible fascicles of lateral cord; pf-MC, possible fascicles of medial cord; pf-PC, possible fascicles of posterior cord; AA, axillary artery; AV, axillary vein; CB, coracobrachialis)