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Brown: Atlas of Regional Anesthesia, 3rd ed., Copyright © 2006 Saunders, An Imprint of Elsevier
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PLACEMENT

Anatomy.

Translaryngeal block is most useful for providing topical anesthesia to the laryngotracheal mucosa innervated by branches of the vagus nerve. The surfaces of the epiglottis and laryngeal structures to the level of the vocal cords receive innervation through the internal branch of the superior laryngeal nerve, a branch of the vagus. The distal airway mucosa also receives innervation through the vagus nerve but via the recurrent laryngeal nerve. Translaryngeal injection of local anesthetic is helpful for providing topical anesthesia for both of these vagal branches, as injection below the cords through the cricothyroid membrane results in the solution being spread onto the tracheal structures and coughed onto the more superior laryngeal structures ( Fig. 30-1 ).

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Figure 30-1  Translaryngeal block: anatomy and local anesthetic spread.


Position.

The patient is placed in a supine position, with the pillow removed and the neck slightly extended. As illustrated in Figure 30-2 , the anesthesiologist should be in position to place the index and third fingers in the space between the thyroid and the cricoid cartilages (cricothyroid membrane).

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Figure 30-2  Translaryngeal block: anatomy and technique.


Needle Puncture.

The cricothyroid membrane is localized, the midline identified, and the needle (22 gauge or smaller) inserted into the midline until air can be freely aspirated. When air is freely aspirated, 3 mL of local anesthetic is rapidly injected. The needle should be removed immediately because it is almost inevitable that the patient will cough at this point. Conversely, a needle-over-the-catheter assembly (intravenous catheter) can be used for the block. Once air has been aspirated, the inner needle is removed, and the injection is performed through the catheter.

Potential Problems.

The translaryngeal block can result in coughing, which should be considered in patients in whom coughing is clearly undesirable. The midline should be used for needle insertion, as the area is nearly devoid of major vascular structures. However, the needle does not need to be misplaced far off the midline to encounter significant arterial and venous vessels.

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