Translaryngeal Block

Published on 06/02/2015 by admin

Filed under Anesthesiology

Last modified 22/04/2025

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30 Translaryngeal Block

Perspective

This block, like all airway blocks, can be useful in sedated, spontaneously ventilating, “awake” patients requiring tracheal intubation.

Patient Selection

Any patient is a candidate in whom it is desirable to avoid the Valsalva-like straining that may follow awake tracheal intubation (in which the patient is sedated and spontaneously ventilating).

Pharmacologic Choice

The local anesthetic most often chosen for this block is 3 to 4 mL of 4% lidocaine. When multiple airway blocks are administered, the anesthesiologist should be aware of the total dose of local anesthetic used.

Placement

Anatomy

Translaryngeal block is most useful in providing topical anesthesia to the laryngotracheal mucosa innervated by branches of the vagus nerve. Both 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 through the recurrent laryngeal nerve. Translaryngeal injection of local anesthetic is helpful in providing topical anesthesia for both of these vagal branches because injection below the cords through the cricothyroid membrane results in solution’s being spread onto the tracheal structures and coughed onto the more superior laryngeal structures (Fig. 30-1).

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

Position

The patient should be 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).

Figure 30-2. Translaryngeal block: anatomy and technique.

Needle Puncture

The cricothyroid membrane should be localized, the midline identified, and the needle, 22-gauge or smaller, inserted into the midline until air can be freely aspirated. When air can be 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

This 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 because the area is nearly devoid of major vascular structures. The needle does not need to be misplaced far off the midline to encounter significant arterial and venous vessels.

Pearls

This block is most effective after the patient has been appropriately sedated. There has long been a belief that this block should be used cautiously, if at all, in patients at high risk for gastric aspiration. My belief is that the block is more frequently misused by not being applied in appropriate situations than by being applied when the patient is at risk for gastric aspiration.

Another hint is to perform the local anesthetic injection after asking the patient to forcefully exhale. This forces the patient to initially inspire before coughing, making distal airway anesthesia predictable.

Related

Atlas of Regional Anesthesia 4e