Advanced Airway Support

Control of the airway is the single most important task for emergency resuscitation. If the patient has inadequate oxygenation or ventilation, inability to protect the airway due to altered sensorium from illness or drugs, or external forces compromising the airway .

INITIAL APPROACH

The initial approach to airway management is simultaneous assessment and management of the adequacy of airway patency (the A of ABCs) and oxygenation and ventilation (the B of ABCs).

1. The patient’s color and respiratory rate must be assessed; marked hypoventilation with or without cyanosis may be an indication for immediate intubation.
2. The airway should be opened with head tilt–chin lift maneuver (jaw thrust should be used if C-spine injury is suspected). If needed, the patient should be bagged with the bag-valve-mask device, including an O2 reservoir. For a good seal, the proper size mask should be ensured. This technique may require an oral or nasal airway or two rescuers to both seal the mask (two hands) and bag the patient.
3. The patient should be placed on a cardiac monitor, pulse oximetry, and possibly capnography (end-tidal CO2), while the remaining vitals, pulse, and blood pressure (temperature is important but can be delayed to assure the ABCs) can be collected.
4. The need for invasive airway management techniques must be determined as described later. It is essential to not wait for arterial blood gas analyses (ABG) if the initial assessment declares the need for invasive airway management. If the patient does not require immediate airway or ventilation control, he or she should be administered oxygen by face mask, as necessary, to assure an O2 saturation of 95%. Laboratory studies should be collected as needed. Do not remove a patient from oxygen to draw an ABG unless deemed safe from the initial assessment.

OROTRACHEAL INTUBATION

The most reliable means to ensure a patent airway, prevent aspiration, and provide oxygenation and ventilation is endotracheal (ET) intubation. Many conscious patients require intubation (see the section, “Rapid Sequence Induction” later). Selection of the blade should be considered in advance, if possible. The curved blade rests in the vallecula above the epiglottis and indirectly lifts it off the larynx because of traction on the frenulum. The straight blade is used to lift the epiglottis directly. The curved blade does a better job of clearing the tongue from view and may be less traumatic and reflex-stimulating. The straight blade is mechanically easier to insert in many patients.

Emergency Department Care and Disposition

• Adequate ventilation must be ensured while the equipment is prepared. The patient should be preoxygenated, with or without a bag-valve-mask device, depending on the clinical need. Vital signs must be monitored and pulse oximetry used throughout the procedure.
• The blade type and size (usually #3 or #4 curved blade, or #2 or #3 straight blade) should be selected; the blade light should be tested. The tube size (usually 7.5 to 8.0 in women, 8.0 to 8.5 in men) must be selected and the balloon cuff tested. The end of the tube should be lubricated with lidocaine jelly or similar lubricant. The use of a flexible stylet should be considered; the distal end should be bent upward if the patient’s anatomy requires it. The tube and tonsillar tip suction should be placed within easy reach. If there is an assistant, he or she should be asked to pass the items when needed.
• The patient should be positioned with the head extended and neck flexed, possibly with a rolled towel under the occiput. If C-spine injury is suspected, the head or neck should not be moved. Rapid sequence induction with in-line traction, nasotracheal intubation, or cricothyrotomy should be considered.
• The blade should be inserted on the right and slowly advanced in search of the epiglottis. The patient should be suctioned as necessary. If the curved blade is used, the tip should be slid into the vallecula and lifted (indirectly lifting the epiglottis); if a straight blade is used, the epiglottis should be lifted directly in the direction the handle points, that is, 90° to the blade. It is important to not rock back on the teeth.
• Once the vocal cords are visualized, it is important to not lose sight of them. The assistant should be asked to place the tube in the physician’s hand. Pass the tube between the cords, avoiding force. The stylet should be removed, the balloon cuff inflated. Ventilate the patient with a bag-valve device and check for bilateral breath sounds. Placement should be confirmed with an end-tidal CO2 detector (not reliable if the patient is in cardiac arrest) or capnography. Tube length should be checked; the usual distance (marked on the tube) from the corner of the mouth to 2 cm above the carina is 23 cm in men and 21 cm in woman.
• The tube should be taped in place and a bite block inserted. Correct intubation and tube placement can be verified with a portable chest x-ray.
• If unsuccessful, reoxygenation should be performed with bag-valve-mask device. The technique can be changed by possibly using a smaller tube, different blade type or size, or repositioning the patient and reattempting intubation.

Short-term complications from orotracheal intubation (trauma to surrounding structures) are unusual, as long as correct position is confirmed. Failure to confirm position immediately can result in hypoxia and neurologic injury. Endobronchial intubation is usually on the right side and is corrected by withdrawing the tube 2 cm and listening for equal breath sounds.

NASOTRACHEAL INTUBATION

Nasotracheal intubation is indicated in situations where laryngoscopy is difficult, neuromuscular blockade is hazardous, or crico-thyrotomy unnecessary. Severely dyspneic, awake patients with congestive heart failure, chronic obstructive pulmonary disease, or asthma often cannot remain supine for other airway maneuvers but do tolerate nasotracheal intubation in the sitting position. Relative contraindications for this technique include complex nasal and massive midface fractures and bleeding disorders.

Emergency Department Care and Disposition

1. Both nares should be sprayed with a topical vasoconstrictor and anesthetic. Between 4 to 10% cocaine solution is an appropriate single agent, but may cause unwanted systemic cardiovascular effects. Topical neosynephrine is an effective vasoconstrictor, and tetracaine is a safe effective topical anesthetic.
2. The tube size must be chosen, usually between 7.0 to 7.5 in women and 7.5 to 8.0 in men. The balloon cuff of the tube should be checked for leaks. The tube should be lubricated with lidocaine jelly or similar lubricant.
3. The largest nares should be used or the right side if the nares are equal. Some operators recommend dilating the nares with a lubricated nasal airway. The patient may be sitting up or supine.
4. An assistant can immobilize the patient’s neck. The physician should stand to the patient’s side, with one hand on the tube and with the thumb and index finger of the other hand straddling the larynx. The tube should be advanced slowly, with steady gentle pressure. The tube should be twisted to help move past obstructions in the nose and nasopharynx. The tube should be advanced until maximal airflow is heard through the tube; this means the larynx is now close by.
5. The physician should listen carefully to the rhythm of inspiration and expiration. The tube should then be gently but swiftly advanced during the beginning of inspiration. Entrance into the larynx may initiate a cough, and most expired air should exit the tube even though the cuff is uninflated. If the tube is foggy the cuff should be inflated.
6. If intubation is unsuccessful, the physician should carefully look for a bulge lateral to the larynx (usually the tip of the tube is in the pyriform fossa on the same side as the nares used). If found, the tube must be retracted until maximal breath sounds are heard and then intubation should be reattempted by manually displacing the larynx toward the bulge. If no bulge is seen, it is possible that the tube has gone posteriorly into the esophagus. In this case, the tube should be withdrawn until maximal breath sounds are heard. Intubation should again be reattempted after the patient’s head is extended and a Sellick’s maneuver performed. Another option is to use a directional control tip (Endotrol) or fiberoptic laryngoscope. The head should not be moved if C-spine injury is suspected.

Complications other than local bleeding are rare. Occasionally, marked bleeding will prompt the need for orotracheal intubation or cricothyrotomy.

CRICOTHYROTOMY

Indications for immediate cricothyrotomy include severe, ongoing tracheobronchial hemorrhage, massive midface trauma, and inability to control the airway with the usual less-invasive maneuvers. Cricothyrotomy is relatively contraindicated in patients with acute laryngeal disease due to trauma or infection or recent prolonged intubation and should not be used in children below the age of 12.

Emergency Department Care and Disposition

1. Sterile technique should be used. The cricothyroid membrane should be palpated with digital stabilizion of the larynx (see Fig. 1-1). With a #11 scalpel, a vertical 3 to 4 cm incision should be started at the superior border of the thyroid cartilage and incised caudally toward the suprasternal notch.
2. The membrane should be repalpated and a horizontal stab should be made through its inferior aspect. The blade should be kept temporarily in place.
3. The larynx should be stabilized by inserting the tracheal hook into the cricothyroid space and retracting upon the inferior edge of the thyroid cartilage (an assistant should hold after the hook is placed). Leaving the blade tip in the space, a slightly open hemostat should be inserted straddling the blade and spread open horizontally.
4. The scalpel should be removed and a dilator inserted (LaBorde or Trousseau). The tracheal hook can then be removed.
5. A #4 Shiley tracheostomy tube should be introduced (or the largest tube that will fit). Alternatively, a small cuffed endotrachial tube may be used (#6 or the largest tube that will fit). The balloon should be inflated and the tube secured in place.

The physician should check for bilateral breath sounds. Make sure subcutaneous air is not introduced. Placement can be checked with an end-tidal CO2 detector and chest x-ray.

RAPID SEQUENCE INDUCTION

Complex airway emergencies in select nonfasted patients may require rapid sequence induction. This technique couples sedation to induce unconsciousness (induction) with muscular paralysis. Intubation follows laryngoscopy while maintaining cricoid pressure to prevent aspiration. The principle contraindication is any condition preventing mask ventilation or intubation.

1. The cardiac monitor, oximetry, and capnography should be set up, if available. Equipment should be checked.
2. The patient should be preoxygenated with 100% oxygen.
3. Lidocaine (1.5 mg/kg intravenously) should be considered in a head trauma patient to prevent increased intracranial pressure. Atropine (0.4 mg/kg intravenously) should be considered to prevent reflex bradycardia, but is not essential.
4. Medication for sedation or analgesia should be considered, if such agents are not being used for induction.
5. A defasciculating dose of a nondepolarizing agent (i.e., vecuronium at 0.02 mg/kg) is used if succinylcholine is given for paralysis.
6. The patient should be induced with thiopental (3 to 5 mg/kg), methohexital (1 to 2 mg/kg), or midazolam (0.1 mg/kg with 5 mg maximum dose). Barbiturates should not be used in a patient with hypotension or reactive airway disease (caution in head injury). Benzodiazepines may be inadequate for induction, however, midazolam is an excellent amnestic agent. Etomidate, 0.3 mg/kg, is an excellent alternative in a hypotensive patient. Ketamine, 1 to 2 mg/kg, should be considered for the induction of a patient who has active bronchospasm for its bronchodilator properties.
7. In a patient needing analgesia in addition to sedation, opiates should be considered for induction. These agents are reversible with naloxone. Fentanyl, 2 to 10 µg/kg, is commonly used.
8. Cricoid pressure should be applied before paralysis and maintained until intubation is accomplished.
9. Succinylcholine (1.0 mg/kg) is chosen for paralysis in many cases because of its rapid onset and short duration of action; it should not be used in a patient with preexisting paralysis or > 2 h after severe burns, as hyperkalemia may occur. A nondepolarizing agent such as vecuronium (0.2 mg/kg) may be chosen for a patient with increased intracranial pressure, one in status asthmaticus, or at operator discretion.
10. The trachea should be intubated and cricoid pressure released.
11. The physician should be prepared to bag the patient if intubation proves unsuccessful. Invasive airway techniques should be considered as indicated.

Alternative drugs for rapid sequence induction are listed in Chap. 15 of Emergency Medicine, A Comprehensive Study Guide, 5th ed. Airway management alternatives to the methods described earlier include retrograde tracheal intubation, translaryngeal ventilation, digital intubation, transillumination, fiberoptic assistance, and formal tracheostomy. Translaryngeal ventilation may be used to temporarily provide ventilation until a more definitive procedure is possible. When oral intubation is indicated but has been unsuccessful, and the patient can be temporarily ventilated with a bag-valve-mask unit, the following assist methods are warranted. Retrograde tracheal intubation, digital intubation, transillumination, or fiberoptic assistance may be helpful. Formal tracheostomy is reserved for those experienced in the technique when less-invasive or more-rapid methods (cricothyrotomy) are unsuccessful..