What are the indications for intubation in patients with severe respiratory or cardiac conditions, or those who are unable to protect their airway?

Indications for Intubation

Endotracheal intubation should be performed without delay in patients with airway obstruction, altered consciousness (Glasgow Coma Scale ≤8), haemorrhagic shock, hypoventilation, or hypoxaemia. 1

Absolute Indications Requiring Immediate Intubation

Airway Protection

• Glasgow Coma Scale ≤8 indicates inability to protect the airway and mandates intubation 1, 2, 3
• Diminished consciousness with inability to maintain airway patency requires immediate intubation 1, 2
• Upper airway obstruction with stridor, dyspnea, or desaturation from facial burns, anaphylaxis, or angioedema 1, 2, 3
• Inability to manage secretions with oropharyngeal accumulation and aspiration risk 2, 3

Respiratory Failure

• Apnea or respiratory arrest requires immediate intubation 2, 3
• Refractory hypoxemia (PaO₂/FiO₂ <150 mmHg or SpO₂ <80%) despite supplemental oxygen and non-invasive ventilation 2, 3
• Progressive hypercapnia with acidosis (pH <7.25, especially <7.15) after initial resuscitation 2, 3
• Respiratory rate >30 breaths per minute with acute respiratory distress that does not improve with high-flow oxygen therapy 2, 3
• Severe tachypnea (respiratory rate >40 breaths per minute), use of accessory muscles, or muscular respiratory failure 2

Cardiovascular Instability

• Haemorrhagic shock requiring airway control 1
• Cardiogenic shock with systolic blood pressure <90 mmHg despite treatment 4
• Cardiac arrest during cardiopulmonary resuscitation (interruptions limited to <10 seconds for intubation) 2

Specific Clinical Scenarios

Trauma Patients

• All trauma patients with GCS ≤8, haemorrhagic shock, hypoventilation, or hypoxaemia require intubation 1
• Rapid sequence induction is the preferred method 1
• Fluid administration should be concurrent, as positive intrathoracic pressure can induce severe hypotension in hypovolaemic patients 1

Acute Respiratory Distress Syndrome (ARDS)

• Severe ARDS (PaO₂/FiO₂ <100 mmHg) has an 84% intubation rate and non-invasive ventilation is not beneficial 5
• Moderate ARDS with PaO₂/FiO₂ <150 mmHg has a 74% intubation rate and should prompt early intubation 5
• Non-invasive ventilation may be attempted in mild ARDS or moderate ARDS with PaO₂/FiO₂ >150 mmHg (intubation rates 31-45%) 5

Cardiogenic Pulmonary Edema

• Intubation is indicated when inability to achieve adequate oxygenation despite 100% oxygen at 8-10 L/min by mask and non-invasive ventilation 4
• Evidence of respiratory exhaustion or excess respiratory work requires intubation 4
• Cardiovascular instability (systolic BP <90 mmHg despite treatment) mandates intubation with immediate cardiovascular support 4

COPD Exacerbations

• Non-invasive positive pressure ventilation should be the initial approach unless specific exclusion criteria are present 6, 7
• Exclusion criteria requiring immediate intubation include: cardiovascular instability, severely impaired mental status, inability to cooperate, vomiting, possible pneumothorax, and depressed consciousness 2, 6
• Failure of non-invasive ventilation after 2 hours of optimal treatment is an indication for intubation 3

High-Risk Populations Requiring Special Consideration

Obesity (BMI >30 kg/m²)

• Obesity doubles complication risk; BMI >40 kg/m² increases risk four-fold 1, 2
• Rapid refractory hypoxaemia is likely if intubation fails 1
• Do not recommend multiple intubation attempts, supraglottic airway rescue, or facemask ventilation—proceed promptly to front-of-neck access if initial attempts fail 1
• Head-up positioning, thorough preoxygenation with CPAP/NIV or high-flow nasal oxygen, and ramped position increase success rates 1

Cervical Spine Injury

• Rapid sequence intubation with manual in-line stabilization is recommended 1
• Remove anterior part of cervical collar to facilitate mouth opening 1
• Use bougie during direct laryngoscopy or videolaryngoscopy to increase success with minimal cervical movement 1

Traumatic Brain Injury

• Avoid extreme hyperoxia (PaO₂ >487 mmHg or >65 kPa) as it increases mortality 1
• Maintain normoventilation; hyperventilation only as life-saving measure with signs of cerebral herniation 1
• Hypoxaemia is particularly harmful and must be avoided 1

Critical Pitfalls to Avoid

Timing and Technique

• Limit laryngoscopy attempts to three maximum; have front-of-neck access equipment immediately available after one failed attempt 1
• Do not delay intubation while waiting for arterial blood gas or radiography if clear clinical signs of respiratory failure are present 3
• Intubation in critically ill patients carries 20-50% risk of life-threatening complications (collapse, severe hypoxemia, arrhythmia, cardiac arrest) 1, 4

Post-Intubation Management

• Mandatory use of waveform capnography to confirm intubation; absence of waveform indicates failed intubation unless proven otherwise 1
• Avoid hyperventilation post-intubation, which compromises venous return and cerebral blood flow; maintain 10 breaths/minute 2, 3
• Perform recruitment maneuver (inspiratory pressure 30-40 cm H₂O for 25-30 seconds) in hypoxic patients if haemodynamically stable 1

Non-Invasive Ventilation Contraindications

• Avoid non-invasive ventilation in patients with hypotension, vomiting, possible pneumothorax, and depressed consciousness 2
• Non-invasive ventilation should be avoided in sepsis-related ARDS as patients are more likely to fail this therapy 2