Chapter 1. Advanced Airway Support

Control of the airway is the single most important task for emergency resuscitation.

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

1. Assess patient's color and respiratory rate; respiratory or cardiac arrest may be an indication for immediate intubation.

2. Open the airway with head tilt–chin lift maneuver (use jaw thrust if C-spine injury is suspected). If needed, bag the patient with the bag-valve-mask device that includes an O2 reservoir. A good seal depends on proper mask size. This technique may require an oral or nasal airway or two rescuers (one to seal the mask with 2 hands and the other to bag the patient).

3. Provide continuous monitoring of vital signs, oxygen saturation, and end-tidal CO2 (if possible).

4. Determine the need for invasive airway management techniques. Do not wait for arterial blood gas analyses if the initial assessment indicates the need for invasive airway management. If the patient does not require immediate airway or ventilation control, administer oxygen by facemask to ensure an O2 saturation of 95%. Do not remove oxygen to draw an arterial blood gas analysis unless deemed safe from the initial assessment.

5. Preoxygenate all patients prior to intubation regardless of saturation. Assess airway difficulty before initiation of advanced airway techniques.

The most common means used to ensure a patent airway, prevent aspiration, and provide oxygenation and ventilation is orotracheal intubation. Rapid sequence intubation (RSI) should be used unless the patient's condition makes it unnecessary (ie, cardiac arrest) or it is contraindicated because of an anticipated difficult airway.

Emergency Department Care and Disposition

1. Prepare equipment, personnel, and drugs before attempting intubation. Assess airway difficulty and anticipate required airway rescue. Assemble and place suction, bag-valve-mask and rescue devices within easy reach. Personnel should be present at the bedside to pass equipment or bag the patient, if required.

2. Ensure adequate ventilation and oxygenation and monitoring while preparing equipment. Preoxygenate with a non–rebreather oxygen mask at maximal oxygen flow rates or with a bag-valve-mask if the patient is not ventilating adequately.

3. Select blade type and size (usually a No. 3 or 4 curved blade or a No. 2 or 3 straight blade); test the blade light. Select the tube size (usually 7.5 to 8.0 mm in women, 8.0 to 8.5 mm in men) and test the balloon cuff. The use of a flexible stylet is recommended.

4. Position the patient with the head extended and neck flexed, possibly with a rolled towel under the occiput. If C-spine injury is suspected, maintain the head and neck in a neutral position with an assistant performing inline stabilization.

5. With the handle in the operator's left hand, insert the blade to push the tongue to the patient's left and slowly advance to the epiglottis. Suctioning may be required. It is not uncommon to go past the larynx into the esophagus. Gradually withdraw the blade to reveal the epiglottis. If the curved blade is used, slide the tip into the vallecula and lift (indirectly lifting the epiglottis); if a straight blade is used, lift the epiglottis directly. Lift along the axis of the laryngoscope handle. Avoid levering the blade on the teeth to prevent dental trauma.

6. Once the vocal cords are visualized, gently pass the tube between the cords. Remove the tube, check for tube placement by ventilating and listening for bilateral breath sounds and absence of epigastric sounds. Inflate the cuff.

7. If the cords are not visualized, manipulate the thyroid cartilage using backward, upward, and rightward pressure (the “burp” maneuver) to help bring the cords into view. If unsuccessful, reoxygenation may need to be performed with bag-valve-mask device. Consider changing the blade, the tube size, or the position of the patient before further attempts. Consider using an intubating stylet (bougie, see Fig. 1-1). Three unsuccessful attempts define a failed airway, and other rescue techniques must be considered.

8. Confirm placement objectively with an end-tidal CO2 detector, capnography, or in cardiac arrest, an esophageal detection device. Check tube length; the usual distance (marked on the tube) from corner of the mouth to 2 cm above the carina is 23 cm in men and 21 cm in women.

9. Secure the tube and verify placement with a portable radiograph.

Immediate complications include unrecognized esophageal intubation or mainstem bronchus intubation. Failure to confirm the 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.

RSI is the simultaneous administration of an induction and a neuromuscular blocking agent to facilitate orotracheal intubation. This technique couples sedation with muscular paralysis. Anticipated difficulty in mask ventilation or intubation is a relative contraindication to RSI.

The presence of 2 of the following 5 factors predict possible difficulty with bagging: facial hair, obesity, no teeth, advanced age, or snoring. Multiple external features, such as facial hair, obesity, short neck, short or long chin, and any airway deformity, suggest possible difficulty with intubation. A small oral opening, decreased neck mobility, a poor view of the posterior pharynx also suggest possible problems. If difficulty is anticipated, consider other methods of airway management such as videolaryngoscopy, awake intubation, cricothyrotomy, or an alternative airway device.

1. Prepare equipment, medication, and personnel before initiation of RSI. Check equipment function.

2. Preoxygenate the patient with 100% oxygen.

3. Consider pretreatment in patients with reactive airway disease or increased intracranial pressure. Evidence is mixed on whether pretreatment improves outcomes. Fentanyl, 3 micrograms/kilogram may be used in normotensive patients with possible raised intracranial pressure, cardiac ischemia, or aortic dissection. Lidocaine, 1 milligram/kilogram IV, could be used in patients with possible raised ICP or asthma.

4. An induction agent should be pushed intravenously. Etomidate, 0.3 milligrams/kilogram, is an excellent choice in most circumstances. Propofol, 0.5 to 1.5 milligram/kilogram or ketamine 1 to 2 milligram/kilogram may also be considered. Use caution in hypotensive patients; avoid propofol. Ketamine is a good choice for patients with active bronchospasm, and may be the best choice in hypotensive patients.

5. Push a paralytic agent intravenously immediately after the induction dose. Succinylcholine, 1.0 to 1.5 milligram/kilogram, is preferred in most cases because of its rapid onset and short duration of action; it should not be used in a patient with a neuromuscular disorder, a denervation injury older than 7 days, or severe burns older than 5 days because hyperkalemia may occur. Rocuronium, 1 milligram/kilogram IV, a non-depolarizing agent, is a reasonable alternative.

6. Cricoid pressure may be applied at the discretion of the provider, however, it can be associated with a worsening laryngoscopic view and ability to bag-ventilate.

7. Once muscle relaxation occurs, usually after 35 to 60 sec, intubate the trachea and confirm tube placement using the techniques described above.

8. Be prepared to use bag-mask ventilation if intubation fails and saturations are less than 90%. Three unsuccessful attempts define a failed airway, and other rescue techniques must be considered.

A number of rescue devices are available for management of the difficult airway. Intubating stylets (or gum elastic bougies) are semi-rigid stylets with a coude tip, which can be placed by feel, during laryngoscopy, into the trachea. The tracheal tube is then guided over the intubating stylet into the trachea. This device is useful for anterior cords that cannot be directly visualized.

The laryngeal mask airway (LMA) is an airway device that is placed blindly into the supraglottic space (Fig. 1-2). A distal ringed balloon is inflated which seals the glottis above the larynx and allows for ventilation. A disadvantage is that the airway is not protected from aspiration and leaks may occur at high ventilatory pressures. The Intubating-LMA allows for the placement of a cuffed endotracheal tube through the device.

Videolaryngoscopy is an excellent option for airway rescue or as a primary intubation technique. Most studies demonstrate improved laryngoscopic views compared to traditional laryngoscopy. These devices can be advantageous in patients with restricted oral opening or cervical spine mobility.

Cricothyrotomy

Cricothyrotomy is performed when intubation, ventilation, and airway rescue has failed. Cricothyrotomy is contraindicated in children younger than 10 to 12 years in whom trans tracheal jet ventilation is the preferred subglottic technique.

1. Use sterile technique. Palpate the cricothyroid membrane and stabilize the larynx (Fig. 1-3). With a No. 11 scalpel, make a vertical, 3 to 4 cm incision starting at the superior border of the thyroid cartilage. Incise caudally toward the suprasternal notch.

2. Repalpate the membrane and make a 1 to 2 cm horizontal incision through the cricothyroid membrane. Keep the blade in place temporarily.

3. Stabilize the trachea by inserting the tracheal hook into the cricothyroid space and retracting the inferior edge of the thyroid cartilage (an assistant should hold the hook after it is placed).

4. Remove the scalpel and insert a dilator to enlarge the opening (LaBorde or Trousseau).

5. Introduce a No. 4 cuffed tracheostomy tube (or the largest tube that will fit). Alternatively, use a small cuffed endotracheal tube (No. 6 or the largest tube that will fit). Inflate the cuff.

6. Check for bilateral breath sounds. After confirmation of tube placement, remove the hook. Secure the tube. The presence of subcutaneous air suggests placement outside the trachea. Placement should be confirmed with an end-tidal CO2 detector and radiograph.

Manufactured cricothyrotomy kits using a Seldinger technique are also available. Formal tracheostomy is not recommended as an emergency surgical airway technique due to increased technical difficulty and increased time required.

Noninvasive positive pressure ventilation (NPPV) provides positive pressure airway support using preset volume/pressure of inspiratory air through a face or nasal mask. NPPV has been used as an alternative to endotracheal intubation in patients with ventilatory failure due to COPD, and cardiogenic pulmonary edema. Patients need to be cooperative and without cardiac ischemia, hypotension or dysrhythmia.

Continuous positive airway pressure (CPAP) provides constant positive pressure throughout the respiratory cycle. CPAP pressures are usually between 5 and 15 cm H2O and are adjusted to the patients' response to therapy.

Bilevel positive airway pressure (BiPAP) uses different levels of pressure during inspiration and expiration. Initial settings of 8 to 10 cm H2O during inspiration and 3 to 4 cm H2O during expiration are reasonable and can be titrated up based on clinical response.

Alternative drugs for rapid sequence induction are listed in Chapter 30 of Emergency Medicine: A Comprehensive Study Guide, 7th ed. Airway management alternatives to the methods described earlier include blind nasotracheal intubation, digital intubation, transillumination, extraglottic devices, flexible and rigid fiberoptics, retrograde tracheal intubation, and translaryngeal ventilation. These techniques are described in Chapters 28, 30, and 31 of Emergency Medicine: A Comprehensive Study Guide, 7th ed.