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A submandibular gland (hyperechoic echotexture, containing linear hyperechoic stripe)8 overlapped totally or partially the THM above the SLN space in 3% and 27% of the cases, respectively. In conclusion, the structures of the SLN space can be indentified using a 12 MHz probe. Whether this space could be a target for ultrasound-guided SLN block deserves further investigation.
Declaration of interest None declared.
1 Beny M, Bannister LH, Standring SM. Nervous system. In: Williams PL, ed. Gray’s Anatomy: The Anatomical Basis of Medicine and Surgery. New York: Churchill Livingstone, 1995: 901–1397 2 Stockwell M, Lozanoff S, Lang SA, Nyssen J. Superior laryngeal nerve block: an anatomical study. Clin Anat 1995; 8: 89– 95 3 Furlan JC. Anatomical study applied to anesthetic block technique of the superior laryngeal nerve. Acta Anaesthesiol Scand 2002; 46: 199–202 4 Gotta AW, Sullivan CA. Anaesthesia of the upper airway using topical anaesthetic and superior laryngeal nerve block. Br J Anaesth 1981; 53: 1055–8 5 Loveday EJ, Bleach NR, Van Hasselt CA, Metreweli C. Ultrasound imaging in laryngeal cancer: a preliminary study. Clin Radiol 1994; 49: 676–82 6 Manikandan S, Neema PK, Rathod RC. Ultrasound-guided bilateral superior laryngeal nerve block to aid awake endotracheal intubation in a patient with cervical spine disease for emergency surgery. Anaesth Intensive Care 2010; 38: 946–8 7 Brodsky JB, Mariano ER. Regional anaesthesia in the obese patient: lost landmarks and evolving ultrasound guidance. Best Pract Res Clin Anaesthesiol 2011; 25: 61 –72 8 Alyas F, Lewis K, Williams M, et al. Diseases of the submandibular gland as demonstrated using high resolution ultrasound. Br J Radiol 2005; 78: 362–9
doi:10.1093/bja/aes203
Possible explanation for failures during infraclavicular block: an anatomical observation on Thiel’s embalmed cadavers Editor—Ultrasound-guided infraclavicular block (US-ICB) yields a higher success rate and improved safety for analgesia of the upper limb compared with nerve-stimulationguided injection. However, even with adequate US-ICB
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Dorsal
LC
Right
PC
IM
SSM SAM 1
MC SA
1
DM
SV DAF
LHoB CbM
CPF SHoB
PmM
PMM
Fig 1 Axial view of the axillary region. The black arrow shows the thoracoscapular region between the subscapularis (SSM) and the serratus anterior (SAM) muscles, where the LAS was found in four cases of block failure. LC, lateral cord; PC, posterior cord; MC, medial cord; IM, infraspinatus muscle; DM, deltoid muscle; LHoB, long head of the biceps brachii muscle; CBM, coracobrachialis muscle; SHoB, short head of the biceps brachii muscle; PMM, pectoralis major muscle; CPF, clavipectoral fascia; SSM, subscapularis muscle; SAM, serratus anterior muscle; SA, subclavian artery; SV, subclavian vein; DAF, deep axillary fascia; PmM, pectoralis minor muscle; 1, normal space of LAS diffusion during infraclavicular block.
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G. Barberet Y. Henry L. Tatu F. Berthier G. Besch S. Pili-Floury E. Samain* Besancon, France * E-mail:
[email protected]
injection, block failure can occur, and no mechanism explaining such failures has yet been proposed. We investigated the possible causes of block failure after posterior (6 o’clock) injection relative to the axillary artery during bilateral US-ICB in 20 cadavers preserved according to Thiel’s embalming method. Before US-ICB was performed, the infraclavicular region was scanned with the probe. The probe was oriented with a 308–408 angle relative to the clavicle to obtain a transverse view of the axillary vessels. The needle was then inserted cranially relative to the probe, and advanced to reach the region immediately posterior to the axillary artery (6 o’clock point). Then, 0.5 ml kg21 of a local anaesthetic solution (LAS) composed of lidocaine 0.5% with methylene blue (MB) 0.02% (MB 1%, 2 ml per 100 ml of lidocaine) was injected into this site for each block with a 20 ml syringe, under ultrasound guidance, to achieve a U-shaped spread. A professional anatomist performed fine dissection of each brachial plexus injected and recorded which nerve structures of the brachial plexus were coloured by the MB solution. The primary endpoint was the failure of US-ICB. A procedure was considered successful if sufficient nerve structures were coloured by the MB solution to indicate that the target structures had actually been reached by the LAS. A total of 40 US-ICB were performed, and in 33, all nerves and cords of the brachial plexus were circumferentially coloured by MB, giving an ‘anatomical’ success rate of 82.5%.
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anatomical space, away from the structures targeted by the injection. We believe that this could provide an anatomical mechanism of action to explain unsuccessful US-ICB.
Declaration of interest Sonositew (Villebon sur Yvette, France) laboratory kindly provided the equipment used for the study. M. Benkhadra1* A. Faust 2 R. Fournier2 L.-S. Aho1 C. Girard1 G. Feigl 3 1 Dijon, France 2 Geneva, Switzerland 3 Graz, Austria * E-mail:
[email protected]
doi:10.1093/bja/aes204
Ultrasound-guided cannulation of the great saphenous vein at the ankle in infants Editor—We read with interest the paper by Triffterer and colleagues1 regarding ultrasound-guided cannulation of the great saphenous vein at the level of the medial malleolus in infants and congratulate them on the application of
Needle tip
Saphenous vein
Non compressed vein before cannulation
Needle compressing vein and tissue The tip is seen at the 12 o’clock position followed by a short rapid “stab”. Needle is then slowly withdrawn until flashback or aspiration confirms intravascular position.
Fig 1 Transfixion technique for cannulating the great saphenous vein in a 5 kg infant.
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In three cases, only one or two elements of the brachial plexus were coloured, and the combination was considered insufficient to have constituted a successful block. In four additional cases, there was no coloration, despite adequate spread of the LAS around the axillary artery. In these four cases, most of the staining solution was found in the thoracoscapular space, limited laterally by the subscapularis muscle and medially by the serratus anterior muscle (Fig. 1). In these four cases, block failure was likely due to the spread of the solution into this space. We propose that this could be an anatomical explanation for the failure of certain ICB, whether ultrasound-guided or not. The infraclavicular region is divided into a superficial and deep compartment (Fig. 1). The deep compartment contains the large subclavian vessels and the three cords of the brachial plexus, and has a proximal, a distal, and a dorsomedial extension. The distal extension is in the deep axillary space covered by the deep axillary fascia. In the deep axillary space, the cords split into the large nerves to innervate the upper limb. Cords and nerves can be separated from each other by variably developed dense connective tissue layers. The dorsomedial continuation of the deep infraclavicular compartment and of the deep axillary space is the thoracoscapular gliding space, which is filled with soft connective tissue to provide the movements of the scapula along the thorax. This space reaches its limit at the medial border of the scapula, with the insertion of the serratus anterior muscle. In four failed blocks observed in our study, the entire volume of injected LAS leaked into this little-known
