Airway management

Airway management is the practice of evaluating, planning, and using a wide array of medical procedures and devices for the purpose of maintaining or restoring a safe, effective pathway for oxygenation and ventilation. These procedures are indicated in patients with airway obstruction, respiratory failure, or a need for airway protection (e.g., for general anesthesia or due to an aspiration risk).

Basic airway maneuvers are the most important first step and consist primarily of positioning, supplemental oxygen, and bag-mask ventilation with or without adjuncts. Patients with serious or persistent airway compromise typically require advanced airway devices, which consist of supraglottic devices, endotracheal tubes, and surgical airway devices.

In endotracheal intubation, a tube is inserted orally (or nasally) into the trachea to allow gas exchange, often via mechanical ventilation. The tube can be placed under direct visualization with the help of a laryngoscope or with video-assisted laryngoscopy. Correct placement is established based on multiple measurements, including exhaled CO₂ and evidence of bilateral breath sounds on auscultation. Common complications of endotracheal intubation include hypoxia, hypotension, airway trauma, accidental esophageal intubation, and aspiration.

Surgical airways may be performed in an emergency, particularly as part of a cannot intubate, cannot ventilate (CICV) scenario, or placed for long-term mechanical ventilation. Patients with surgical airways are vulnerable to a sudden loss of the airway due to displacement or blockage of the tubes with secretions.

Airway management is used for patients with signs of airway obstruction and for patients whose airway is considered at-risk due to a potential loss of protective airway reflexes.

Clinical features of partial airway obstruction ^[1]

• Noisy breathing
• Snoring
• Stridor
• Hoarse voice
• Gurgling from secretions
• Hypoxia or hypercarbia
• Signs of increased work of breathing

Clinical features of complete airway obstruction ^[1]

• Inability to speak or cough
• Inaudible breath sounds
• Paradoxical movement of the chest and abdomen
• Profound hypoxia

Features suggestive of an at-risk airway ^[2]

• Reduced GCS (traditionally ≤ 8) ^[3]
• Ability to comfortably tolerate an oral airway
• Inability to swallow secretions
• Features of a condition potentially requiring deep sedation or general anesthesia

Definition

Respiratory arrest is the complete cessation of breathing in patients with a pulse. ^[4]

Etiology

• Extrapulmonary
  • CNS depression: due to opioid intoxication, inhalant-related disorders, benzodiazepine intoxication, barbiturate intoxication, brain trauma and/or herniation, stroke
  • Respiratory muscle weakness: due to myasthenia gravis, Guillain-Barré syndrome, myopathies, ALS, high cervical spinal cord injury, poliomyelitis
  • External forces: due to drowning, trauma
  • Airway obstruction: due to aspiration, spasm and/or edema of the vocal cords, tumor, croup, epiglottitis, diphtheria, allergic reaction
• Pulmonary
  • Airway obstruction: due to severe bronchospasm in individuals with bronchial asthma or COPD
  • Impaired alveolar diffusion: due to pulmonary edema, severe pneumonia, pulmonary hemorrhage

Clinical features

• General
  • Cyanosis
  • Tachycardia
  • Diaphoresis
  • CNS impairment (e.g., altered mental status, agitation, coma)
• Additional in imminent respiratory arrest
  • Abnormal respiration (e.g., gasping, expiratory wheezing, inspiratory stridor)
  • Sternoclavicular and/or intercostal retractions

Diagnostics

• Clinical evaluation (for further information see “ABCDE approach”)
• Arterial blood gas analysis (ABG): decreased PaO₂ and increased PaCO₂
• Pulse oximetry

Management

• Intubation
• Mechanical ventilation
• In case of obstruction: airway opening maneuvers (for more information see sections below)
• Respiratory and cardiac monitoring
• Treatment of underlying conditions

Complications

• Hypoxic organ damage (e.g., hypoxic brain injury)
• Cardiac arrest

References:^[4][5][6]

• Basic airway maneuvers are used:
  • To relieve partial airway obstruction in obtunded but spontaneously breathing patients
  • As a temporary measure prior to placement of a definitive airway in apneic patients or those with profound respiratory failure
• All patients require monitoring with pulse oximetry.
• Most patients should receive supplemental oxygen (see “Oxygen therapy”).
• Patients requiring basic airway maneuvers are at high risk of further airway deterioration; prepare for an advanced airway for most patients.

These maneuvers may be used alone or combined with basic airway adjuncts and bag-mask ventilation.

All patients ^[7]

• Head-tilt/chin-lift maneuver
  • Description: a method of opening the airway that involves head and neck repositioning. It should be avoided if there is concern for C-spine injury.
  • Technique
    1. Tilt the head of the patient posteriorly to 15–30° of atlanto-occipital extension.
    2. Lift the chin with the fingers to pull the tongue and oropharyngeal soft tissue anteriorly.
    3. Use the thumb of the same hand to apply pressure below the lip, slightly opening the mouth.
    4. Maintain this “sniffing position” to align the oral, pharyngeal, and laryngeal axes.
• Jaw-thrust maneuver
  • Description
    • Maneuver in which the mandible is moved anteriorly to open the airway
    • May be used in conjunction with head-tilt/chin-lift or alone in patients with suspected C-spine injury
  • Technique
    1. With the patient supine, place fingers behind the angles of the lower jaw.
    2. Move the jaw anteriorly to pull the base of the tongue and soft tissues away from the airway.
    3. Use the thumbs to open the mouth slightly.

Spontaneously breathing patients only: the recovery position

• Description: positioning of the patient in a lateral decubitus position with slight neck extension
• Aim
  • Prevention of airway occlusion by the tongue and soft tissues
  • Reduction in the risk of aspiration if patients regurgitate
• Indications
  • Prehospital settings
  • Temporary airway compromise that can be managed by positioning alone (e.g., procedural sedation, alcohol intoxication)
• Contraindications
  • C-spine immobilization
  • Anticipated worsening of airway compromise
  • Transportation outside of a monitored environment

General overview ^[8][9]

• Definition: delivery of oxygen and provider-assisted breaths using a bag-valve-mask unit to patients with inadequate ventilation
• Indications
  • Bridge to intubation
    • Patients with acute respiratory failure
    • Preoxygenation prior to general anesthesia
  • Rescue ventilation: Use after failed intubation attempt (e.g., when safe apnea time has been exceeded) or accidental oversedation.
  • CPR

Procedure

Create a mask seal

• EC-clamp technique (one-person technique): commonly used in elective perioperative situations when the provider is alone
  1. With the patient supine, lift the jaw towards the mask using the 3^rd, 4^th, and 5^th fingers of one hand, forming an E-shape.
  2. Squeeze the mask onto the face with the thumb and index finger of the same hand, forming a C-shape.
  3. Deliver breaths with the second hand.
• Two-person bag-mask-ventilation technique: used in emergency settings in which the patient is deteriorating or ventilation is difficult, since it is more effective ^[10][11][12]
  • One provider makes a seal and opens the airway with both hands:
    • Squeeze the mask to the face using the thenar eminences of both hands, placed along the sides of the mask with the thumbs pointing inferiorly.
    • Perform a jaw-thrust maneuver using all 4 fingers of both hands.
    • A two-handed EC-clamp technique may also be used. ^[13]
  • The second provider delivers breaths.

Provide breaths

• Set minute ventilation
  • Aim: Deliver 500–600 mL (6–7 mL/kg) volume at 10–12 breaths/minute. ^[4]
  • Procedure: Squeeze the bag slowly and gently over approx. 1 second before allowing it to fully reinflate. Repeat every 5 seconds.
  • Adjust based on the clinical situation: E.g., follow compression-to-breath ratio in patients undergoing CPR without an advanced airway (e.g., 30:2).
• Confirm adequacy of BMV
  • Clinical
    • No leaks around mask
    • Bilateral chest rise
    • Air entry on auscultation of bilateral lung fields
  • Monitoring
    • Oxygen saturations in target range (may be above normal if preoxygenating)
    • Normal capnometry (waveform and EtCO₂ value)

Ensure oxygen is attached to the bag-mask apparatus!

Anticipation and management of BMV complications

Efficacy of BMV may be affected by provider technique or patient factors (such as obesity, reduced lung compliance, or craniofacial abnormalities).

Factors that contribute to difficult BMV can be remembered with the MOANS mnemonic: Mask seal, Obstruction/Obesity, Age > 55 years, No teeth, Stiff lungs/Sleep apnea.

These devices may be used alongside bag-mask ventilation or airway opening maneuvers to improve airway patency.

Oropharyngeal airway (OPA) ^[7]

• Description: a rigid curved device placed in the mouth to prevent the tongue from occluding the airway
• Indications
  • Unconscious patients with a large tongue, obstructed nasal passages, or copious nasal secretions
  • Typically used as a bridge to intubation
• Contraindications: conscious patient with intact gag reflex
• Sizing rule: from the incisors to the angle of the mandible, or corner of the mouth (oral commissure) to the earlobe
• Insertion technique
  • Adults: Insert concave up or concave lateral until past the tongue and then rotate until concave down.
  • Children: Using a tongue depressor to move the tongue down, insert carefully concave down.
  • Ensure OPA has bypassed the tongue and is not pushing it backwards.
• Further management: Toleration of an oropharyngeal airway indicates an at-risk airway; preparations should be made for intubation.

Nasopharyngeal airway (NPA) ^[7]

• Description: a long flexible tube inserted into the nostril and down into the nasopharynx to prevent the tongue from occluding the airway
• Indications: conscious or unconscious patients with current or potential oropharyngeal obstruction
• Contraindications: facial fractures, basilar skull fractures
• Sizing rule: nostril to the ipsilateral tragus
• Insertion technique
  1. Lubricate the tube.
  2. Select the wider nostril.
  3. Insert gently without forcing.
  4. Aim posteriorly, not superiorly.
  5. Twist the tube back and forth for ease of passage.
  6. If resistance is encountered, stop and attempt on the contralateral nostril.

General overview

• Definition: a collection of advanced airway devices that are inserted via the oropharynx to provide ventilation from above the glottis
• Indications
  • Cardiac arrest (pre-hospital and in-hospital), as they can be inserted by providers untrained in intubation
  • First-line for short durations of anesthesia
  • As an alternative advanced airway if intubation has failed (e.g., a CICV scenario)
• Contraindications: Avoid in conscious patients with an intact gag reflex.
• Caution: does not offer complete protection against aspiration, unlike an endotracheal tube

Options ^[9][14]

• Laryngeal mask airway (LMA): a supraglottic device consisting of an inflatable mask attached to the end of a tube
  • Second-generation LMAs feature safety adaptations such as bite blocks and a drainage tube.
  • Intubating LMAs (ILMA) feature additional adaptations to allow passage of an ET tube through the LMA.
• i-gel®: a type of supraglottic airway that is similar in structure to the LMA. However, the mask is anatomically-molded, noninflatable, and made of a soft gel-like material.
• Laryngeal tube airway (LTA)
  • An airway device consisting of a tube with 2 inflatable cuffs and ventilation holes between them.
  • Intubating LTAs feature additional adaptations to allow passage of an ET tube through the LTA.

Procedure ^[2][9]

1. Choose the appropriate size for the patient:
   • Small adult: size 3
   • Medium adult: size 4
   • Large adult: size 5
2. LMAs and LTAs: inflate cuffs fully to check for leaks before deflating.
3. Lubricate the tip of the device, being careful not to block ventilatory openings.
4. Place the patient in the sniffing position.
5. Open the patient's mouth wide.
6. Hold the device firmly (at the junction of the tube and mask for an LMA, at the bite block for an i-gel®, or at the connector for an LTA).
7. Insert the device.
   • LMA and i-gel®: Insert smoothly along the hard palate and downwards with the outlet facing caudally.
   • LTA: Insert the tube rotated at 45–90° from midline (towards concave lateral) until past the base of the tongue, where it should be rotated back to midline (towards concave up).
8. Stop when the device has passed the base of the tongue and resistance is felt (LMA or i-gel®) or the connector reaches the teeth (LTA).
9. LMAs and LTAs: Inflate the cuff.
10. Confirm supraglottic tube placement.

Pitfalls and troubleshooting of supraglottic airways

• Difficulty bagging or poor ventilation
  1. Reposition the patient's head and neck (see “Initial airway opening maneuvers”).
  2. Withdraw, advance or rotate the tube.
  3. Remove and reinsert the device or change size (a larger size may be required).
  4. Switch to a different adjunct.
• Air leak: Adjust cuff volume (if possible), then follow the troubleshooting steps above.

General principles ^[2][9]

• Defined as placement of a cuffed endotracheal (ET) tube below the vocal cords via direct laryngoscopy or videolaryngoscopy
• Mostly commonly placed orally (orotracheal intubation), although it may be placed nasally (nasotracheal intubation)
• Typically, sedation and paralysis are required to tolerate the procedure and subsequent mechanical ventilation. ^[15]
• Use modified rapid sequence intubation/induction (RSI) in an emergency (when patients have not fasted).
  • Goals: maximize first-pass success, reduce the risk of aspiration
  • Involves the rapid induction of anesthesia and paralysis, followed by intubation ^[16][17]
  • Differs from traditional intubation in two ways:
    • Weight-based bolus doses of short-acting agents are used without titration.
    • BMV is not performed (to avoid potential aspiration of stomach contents).

Indications for endotracheal intubation ^[2]

• Inability (or anticipated inability) to maintain the airway: e.g., general anesthesia, airway obstruction or reduced GCS (see “Clinical features of airway obstruction”)
• Failure (or pending failure) of ventilation or oxygenation: e.g., in severe acute asthma or COPD (see “Indications for invasive mechanical ventilation”)
• Conditions in which there is a high risk of deterioration: e.g., multisystem trauma, anaphylaxis, severe septic shock

Contraindications

• Do-not-intubate order
• Consider adjuncts to intubation or proceed to surgical airway management in:
  • Copious blood/secretions
  • Upper airway distortion
  • Mouth opening limited
  • Severe kyphosis

Preassessment ^[2][18]

• All patients should be assessed for conditions that can complicate intubation.
• See “Identification and management of difficult airways” for further information.

Preoxygenation

• Definition: administration of 100% oxygen prior to induction to denitrogenate air in the lungs ^[19]
• Rationale: lengthens safe apnea time to prevent desaturation, which can cause organ dysfunction (e.g., hypoxic brain injury, cardiac dysrhythmia) and death
• Target SpO₂: as close to 100% as possible
• Methods: ^[20]
  • First line: oxygen delivered by a nonrebreather device at high flow rate (10–12 L/min) for 3 minutes
  • Alternative (if 3 minutes of preoxygenation is not possible): 8 breaths (vital capacity inspirations)

Preoxygenation is vital for patients with risk factors for rapid desaturation during the apneic period (e.g., critical illness, obesity, preexisting lung disease).

Intubation medications ^[2][9]

Typically two classes of medication are given prior to intubation, a sedating (induction) agent and neuromuscular blocking agent to paralyze the patient.

Induction agents for intubation ^[2]

• Used to induce a state of sedation, which reduces airway reflexes and facilitates intubation
• Options include:
  • Propofol
  • Etomidate
  • Ketamine
• The choice of induction agent depends on patient characteristics and operator experience.
• The duration of bolus doses is typically short (∼ 10 minutes) and infusions are required for ongoing sedation (see “Adjunctive care of ventilated patients” for suggested medications and doses).

Paralytic agents for intubation (NMJ blockers) ^[2]

• Clinical applications
  • Improving airway visualization by relaxing the jaw muscles
  • Decreasing the risk of injuries, e.g., vocal cord damage
• Types
  • Depolarizing NMJ blockers: e.g., succinylcholine
    • Widely used due to rapid onset and offset time (spontaneous respirations normally return within 10 minutes)
    • It may precipitate hyperkalemia in at-risk patients; avoid in patients with contraindications to succinylcholine.
    • Rarely, prolonged paralysis occurs in patients with limited cholinesterase activity.
  • Nondepolarizing NMJ blockers: e.g., rocuronium
    • Used in patients with contraindications to succinylcholine
    • Avoid in patients with a suspected difficult airway because of the longer duration of action (risk of deterioration to a CICV scenario). ^[21]
• If ongoing paralysis is required, an infusion is necessary (see “Adjunctive care of ventilated patients” for suggested medications and doses).

Avoid succinylcholine in at-risk patients (including those with known renal impairment, burns, crush injuries, denervation, neuromuscular disease, or abdominal sepsis) because of the risk of hyperkalemia!

Intubation via direct laryngoscopy ^[9]

• Positioning: Place patient in sniffing position unless C-spine injury is suspected.
  • Head elevated to a height of 10 cm
  • The neck is mildly flexed at the lower cervical vertebrae and extended at the atlanto-occipital joint.
• Technique: The majority of patients should have received induction agents and been preoxygenated. Equipment should always be on hand to manage a failed intubation.
  1. Wear appropriate PPE.
  2. Choose the correct ET tube size. ^[22]
  3. Gently open the patient's mouth.
  4. Insert the laryngoscope blade, using the groove to sweep the tongue aside.
  5. Advance steadily until the tip is at the vallecula and the epiglottis is visible below it.
  6. Lift gently forward and upward to raise the epiglottis and reveal the arytenoid cartilages and vocal cords.
  7. Insert the ET tube with the stylet.
  8. Once the tip is at the glottis, remove the stylet and gently advance until the cuff is past the cords.
  9. Inflate the cuff to protect the airway from secretions and form a seal around the tube.
  10. Secure the tube once proper placement is confirmed.

Avoid rocking the laryngoscope on the teeth; it can cause dental injury and aspiration of tooth fragments.

Confirmation of tube placement ^[23]

• Auscultation of bilateral breath sounds over the lungs
• Consistent condensation visible in the tube upon exhalation
• Capnometry
  • Colorimetric capnometer: a qualitative CO₂ detector connected between the tube and the BMV equipment
    • A visual indicator changes color from purple to yellow upon contact with CO₂.
    • Consistent color changing with each breath > 3 times correlates with tracheal placement.
  • Capnography: measurement of end-tidal CO₂
• Direct visualization of endotracheal tube markers
  • Distal tube markers should be seen advancing past the vocal cords.
  • Proximal numbered tube markers should indicate approx. 21–23 cm at the patient's teeth.
• Imaging (e.g., CXR):
  • CXR: The distal tip of the endotracheal or tracheal tube should be 2–6 cm above the carina (reposition if necessary).
  • Trained practitioners only: Ultrasound may be used to confirm tube position.

Intubation is an aerosol-generating procedure that carries a high risk of transmission of respiratory pathogens to healthcare workers. Appropriate PPE for all participating providers is essential. ^[24]

Adjuncts may be used for anticipated difficult airways or by novice practitioners learning intubation.

Tracheal tube introducer/gum-elastic bougie (GEB) ^[9][25]

• Description
  • A long, semirigid, plastic introducer used to facilitate passage of the ET through the vocal cords using the Seldinger technique
  • The tip is slightly bent to allow passage through the epiglottis and to provide tactile feedback as it “clicks” over the tracheal rings.
• Indications: difficult intubation (e.g., C-spine immobilization) when the laryngeal inlet is partially visible, invisible, or narrower than expected (e.g., secondary to edema)

Videolaryngoscopy ^[9][26]

• Description
  • A type of laryngoscopy that relies on a rigid blade fitted with a fiberoptic camera
  • Facilitates real-time visualization of the airway on an adjacent screen during endotracheal intubation
• Indications
  • Preferred by some operators for routine intubation
  • Backup device after failed direct laryngoscopy
  • Suspected difficult airway
  • Teaching novice intubators

Flexible fiberoptic intubation ^[27]

• Description
  • A flexible fiberoptic laryngoscope is used to visualize the glottis and guide an endotracheal tube into place, under minimal sedation and with no paralysis (i.e., awake intubation).
  • Local anesthetic is used to minimize airway sensation/reflexes and medication is used to reduce secretions.
• Indications
  • Known or suspected difficult airway
  • Backup for failed intubation