• Clinical science

Airway management and ventilation


Airway management is the evaluation, planning, and use of medical procedures and devices for the purpose of maintaining or restoring ventilation in a patient. These procedures are indicated in patients undergoing general anesthesia and in patients with respiratory failure or acute airway obstruction.

In endotracheal intubation, a tube is inserted orally into the trachea to provide oxygen via mechanical ventilation during general anesthesia. The tube should be placed under direct visualization with the help of a laryngoscope. Correct placement is established based on measurement of exhaled CO2 and evidence of bilateral breath sounds on auscultation. Complications of endotracheal intubation include dental damage, esophageal misplacement of the tube, infections, and tracheal stenosis. If long-term intubation is expected, a tracheostomy is usually performed. This procedure involves the creation of a reversible or permanent stoma below the cricoid cartilage. Cricothyrotomy is an airway of last resort and performed in emergency situations, such as acute obstruction of the airway by blood, edema or a foreign body. An incision is made in the membrane between the thyroid and cricoid cartilage to obtain airway access.

Once access to an airway has been established by any of the above mentioned routes, mechanical ventilation is used to assist or replace spontaneous breathing. The breathing rate, amount of oxygen per breath, applied pressure, and other parameters can be adjusted to achieve best possible ventilation and oxygenation. Complications of mechanical ventilation include barotrauma (e.g., pneumothorax, pneumomediastinum) and ventilator-induced lung injury, which clinically resembles ARDS. Once patients show sufficient spontaneous breathing, they are weaned off ventilation support.


Endotracheal intubation

  • Definition: orotracheally or nasotracheally placement of a cuffed tube below the vocal cords
  • Indications
    • General anesthesia
    • Failure (or pending failure) of ventilation or oxygenation
    • Glasgow Coma Score ≤ 8
  • Procedure
    1. Preoxygenation: administration of 100% oxygen via face mask prior to intubation to ensure sufficient time to perform intubation.
    2. Sedation (e.g., propofol)
    3. Muscle relaxation (e.g., succinylcholine)
    4. Positioning of patient with mild cervical flexion (sniffing position)
    5. Placement of the endotracheal tube with the help of a laryngoscope: observe the tip of the tube passing into the larynx through the vocal cords (direct visualization).
    6. Signs of proper tube placement
      • Auscultation of bilateral breath sounds over lungs
      • Measurement of CO2 in the exhaled air (end-tidal CO2)
      • Distal tip should be 2–6 cm above carina (check with chest x-ray and reposition if necessary)
    7. Inflate the cuff to secure the tube if proper placement is ensured.
  • Rapid sequence intubation
    • A method of endotracheal tube intubation used for emergency airway management that involves rapid induction of unconsciousness followed by administration of a paralytic agent.
    • Differs from traditional intubation in that it uses weight-based doses of short-acting medications (rather than gradually titrating the dose) in order to forego bag-valve-mask ventilation and achieve more rapid intubation.

Complications of intubation



Surgical airway management




Mechanical ventilation


  • Definition: use of a respirator to assist or completely replace spontaneous breathing
  • Indications
    • General anesthesia
    • Breathing support
      • Respiratory distress or arrest
      • Hypoxemia (PaO2 < 70 mm Hg) or hypercapnia (PaCO2 > 50 mm Hg)
      • Metabolic acidosis
      • Respiratory muscle fatigue
      • Impaired consciousness and inability to protect airways
  • Technique: positive-pressure ventilation
  • Ventilation parameters
  • Capnometry/capnography: assessment of CO2 concentration in expired air to determine whether oxygenation is adequate
  • Ventilator weaning: Process of easing a patient off mechanical ventilatory support.
    • Spontaneous breathing trial
      • A test that is used to determine whether a mechanically ventilated patient is ready to breathe without a ventilator.
      • Performed once the patient has:
        • A stable/resolving lung disease
        • Normal PaO2 and O2 saturation on FiO2 < 0.4–0.5 and PEEP < 5–8 mm H2O,
        • A pH ≥ 7.35
        • Hemodynamic stability with little or no vasopressor therapy
        • An ability to spontaneously initiate an inspiratory effort (i.e., good neuromuscular function).

Ventilator settings

Mechanical ventilation with a very high PEEP may result in pneumothorax!

Special scenarios