Local Anesthesia of the Airway Periprocedural Care

Elements of Informed Consent

Preparing a patient for awake airway instrumentation and manipulation requires proper planning. The patient is explained the procedure in adequate detail and should know what to expect. He should be aware of the reasons for performing the procedure awake. The patient is informed that he or she will be awake while the endotracheal tube or bronchoscope is inserted into his or her mouth or nose. He needs to be reassured that the discomfort can be largely mitigated by placing needles or inserting cotton into his nostril or any other local anesthetic technique that is suitable for performing the procedure on the airway. This is mostly a safe technique with not many complications. Temporary hoarseness or weakness of voice or coughing might occur in the postprocedure period.

See the list below:

• Antimicrobial solution for skin preparation (Betadine or chlorhexidine.)

• Short bevelled needles of 22-gauge to 25-gauge sizes

• 2 mL and 5 mL syringes

• Nebulizer or atomizer

• Tongue depressor

• Right-angled forceps

• Oxygen source and face mask

• Suction catheter and apparatus

• Monitors

• Routine monitoring devices like pulse oximeter, noninvasive blood pressure measurement, and ECG

Alleviation of anxiety

Sedation can be given after assessing the level of anxiety of the patient. Agents with a short duration of action that are titratable and reversible are preferred. They should also not depress the spontaneous respiration of the patient. Recommended titration is to the patient developing drowsiness or slurred speech. ^{[3, 4, 5]}

• Midazolam: 0.5-3 mg

• Fentanyl : 20-100 micrograms

• Alfentanil : 100-1000 micrograms

• Dexmedetomidine: 0.2-0.4 micrograms/kg/h

Oral secretions can interfere with visualization and performance of the airway procedure. Hence it should be decreased by administering antisialagogues intravenously or intramuscularly at least half an hour before the procedure, such as the following:

• Atropine: 0.5-1 mg

• Glycopyrrolate: 0.2-0.4mg

To reduce the risk of aspiration, keep the patient nil by mouth for at least 6 hours. Ranitidine and metoclopramide can be given 2 hours before the procedure.

If a procedure on the nose is planned, administering vasoconstrictor drops in the nostrils can help reduce the epistaxis due to trauma. Cocaine was used earlier as it is a good vasoconstrictor and local anesthetic. Currently, however, owing to concerns with substance abuse, it is not in use.

The following are administered half an hour before surgery and given after ruling out drug contraindications (ex, uncontrolled hypertension).

• 1% phenyl ephedrine spray

• Ephedrine drops

The patient is brought to the operating theater or any other place predetermined to perform the block with all facilities to provide the block safely and to manage any adverse events.

An intravenous cannula is started and all other monitors are connected to the patient.

Anesthesia

Various preparations of local anesthetics include the following:

• 1%, 2% , 4%,10% lidocaine (lignocaine) solutions

• 10% lidocaine (lignocaine) spray

• Lidocaine (lignocaine) 2-4% jelly

• Viscous lidocaine (lignocaine) 2% ^[6]

• Cetacaine spray (a pressurized solution containing a mixture of 14% benzocaine and 2% tetracaine

Complications

General

Because multiple nerve blocks have to be performed to abolish all airway reflexes, large volumes of local anesthetic might be needed. This could lead to the dose exceeding the toxic limits. Calculating the total dose that is allowed for the individual patient and drawing up only that amount and keeping it in a cup so that only contents of this cup will be put to use is a good practice.

The protective reflexes of the airway are lost. Therefore, chances of aspiration are high. This can be reduced by keeping the patient nil by mouth for a period of 6 hours and prescribing antiaspiration prophylaxis.

Mucosal trauma epistaxis is a complication involving the nasal cavity.

Glossopharyngeal nerve block

• Intraoral approach: Intravascular injection and hematoma formation due to close proximity to internal carotid artery.

• Peristyloid approach: Intravascular injection into the internal jugular vein and external carotid artery and hematoma formation.

Superior laryngeal nerve block

This block might rarely injure and cause intravascular injection into the superior laryngeal artery or vein as they lie in proximity to the nerve on the thyrohyoid membrane.

Loss of protective airway reflexes can cause complications like aspiration.

Transtracheal block

The patient might cough during injection of the drug. Trauma to the laryngeal mucosa can occur. Using the intravenous cannula and rapid injection of the drug once the airway is entered can minimize this risk.