Indications for Intubation
Endotracheal intubation is indicated for respiratory failure causing hypoxemia, hypercapnia, and acidosis; inability to maintain or protect the airway; diminished consciousness; and physical exhaustion. 1
Primary Respiratory Indications
Oxygenation Failure
- Severe hypoxemia with peripheral oxygen saturation <80% despite supplemental oxygen 2
- PaO₂/FiO₂ ratio <150 mmHg with acute respiratory distress 1
- Failure to improve after 2 hours of high-flow oxygen therapy or noninvasive ventilation 1
Ventilatory Failure
- Hypercapnic respiratory failure with rising PaCO₂ and acidosis 1
- pH <7.15 despite initial resuscitation and controlled oxygen therapy 1
- Respiratory rate >30 breaths per minute with acute respiratory distress 1
- Apneic episodes or imminent respiratory arrest 1
Airway Protection Indications
Neurological Impairment
- Glasgow Coma Score <8 indicating inability to protect the airway 1
- Decline in consciousness with inability to maintain a patent airway 1
- Depressed consciousness preventing adequate airway protection 1
Mechanical Airway Obstruction
- Upper airway obstruction with pooling secretions 1
- Severe facial or thermal burns with dyspnea, desaturation, or stridor 1
- Recent aspiration or high aspiration risk 1
Hemodynamic Indications
- Severe cardiovascular instability requiring airway control for resuscitation 2
- Cardiogenic shock where mechanical ventilation may improve outcomes 1
- Severe bradycardia or heart block causing hemodynamic compromise 1
Additional Clinical Scenarios
Neurological Emergencies
- Large territorial stroke with declining consciousness and inability to maintain airway patency 1
- Generalized tonic-clonic seizures requiring airway control 1
- Cervical spine injury with severe respiratory distress (use rapid sequence intubation with manual in-line stabilization) 1
Specific Thresholds for Decision-Making
For COPD exacerbations: Consider intubation when pH <7.25, with pH <7.15 being a strong indication after initial resuscitation 1. However, attempt noninvasive positive-pressure ventilation first unless contraindications exist (cardiovascular instability, severely impaired mental status, vomiting, possible pneumothorax) 1.
For ARDS: NIV may be attempted in mild ARDS (PaO₂/FiO₂ 200-300 mmHg) with intubation rates around 31%, and in moderate ARDS with PaO₂/FiO₂ >150 mmHg 3. However, 84% of severe ARDS patients require intubation, and NIV should not delay definitive airway management in this group 3.
Critical Pitfalls to Avoid
Do not rely on single threshold values alone. No single value for PaCO₂, pH, or PaO₂ constitutes an absolute indication for intubation across all patients 4. The decision must incorporate multiple factors including trajectory of deterioration, work of breathing, and underlying pathophysiology 4.
Do not delay intubation in severe ARDS. While NIV failure timing does not affect mortality in moderate ARDS, persisting with ineffective NIV adds to patient discomfort and risks cardiorespiratory arrest 1, 3.
Recognize that 45% of critically ill patients experience major adverse peri-intubation events, predominantly cardiovascular instability (42.6%), followed by severe hypoxemia (9.3%) and cardiac arrest (3.1%) 2. This high complication rate mandates meticulous preparation and monitoring.
Preparation Requirements
When intubation is indicated, ensure immediate availability of: laryngoscope (preferably videolaryngoscope), endotracheal tubes, bougie/stylet, suction, backup airway devices, and waveform capnography 5. Use neuromuscular blocking agents (rocuronium preferred over succinylcholine due to fewer side effects) to reduce complications 5, 6, 7. Preoxygenate with noninvasive ventilation when possible to prevent hypoxemia 8.