What are the established indications for intubation?

Established Indications for Intubation

Intubation should be immediately performed in patients with respiratory arrest, imminent respiratory arrest, or severe respiratory distress with failure of non-invasive ventilation, as these conditions pose immediate threats to life. 1

Primary Indications for Intubation

Respiratory Failure

• Acute hypoxemic respiratory failure:

  • PaO₂/FiO₂ ratio less than 150 mmHg 1
  • Severe hypoxemia (SpO₂ <80%) despite maximal oxygen therapy 2
  • No improvement after 2 hours of high-flow oxygen therapy or non-invasive ventilation 1

• Acute hypercapnic respiratory failure:

  • Persistent or worsening acidosis (pH <7.15) despite optimized NIV 1
  • Respiratory acidosis with altered mental status 1

Airway Protection

• Inability to maintain or protect the airway 1
• Depressed consciousness (Glasgow Coma Score <8) 1
• Loss of consciousness 1

Respiratory Mechanics

• Respiratory arrest or gasping respiration 1
• Severe respiratory distress with physical exhaustion 1
• Acute respiratory distress with respiratory rate >30 breaths/min and failing on standard oxygen 2

Cardiovascular Status

• Hemodynamic instability with signs of low cardiac output 1
• Cardiac arrest requiring CPR 3

Special Considerations by Patient Population

COPD Exacerbations

• Imminent respiratory arrest
• Failure of or contraindications to NIV
• Persisting pH <7.15 or deterioration in pH despite NIV
• Depressed consciousness (GCS <8) 1

Neuromuscular Disease or Chest Wall Disorders

• Consider intubation when vital capacity <1L and respiratory rate >20, even if normocapnic
• Do not delay intubation if NIV is failing 1

COVID-19 Patients

• Acute respiratory distress with respiratory rate >30/min
• PaO₂/FiO₂ <150 mmHg
• No improvement after 2 hours of high-flow oxygen therapy
• Loss of consciousness/inability to protect airway 1

Predictors of NIV Failure Requiring Intubation

• Under NIV: PaO₂/FiO₂ ratio ≤200 mmHg and tidal volume >9 mL/kg of predicted body weight after 1 hour 2
• Under standard oxygen: Respiratory rate ≥30 breaths/min 2

Technical Considerations for Intubation

• Proper pre-intubation preparation is essential to minimize complications:

  • Position patient in "sniffing position" (head extended on neck)
  • For obese patients, use "ramping" position (external auditory meatus level with sternal notch)
  • Verify all equipment is available (laryngoscope, endotracheal tube, stylet/bougie, suction, etc.)
  • Apply standard monitoring (pulse oximetry, waveform capnography, blood pressure, ECG) 4

• Preoxygenate with tight-fitting facemask using 10-15 L/min of 100% oxygen for 3 minutes 4

Complications and Pitfalls

• Major adverse peri-intubation events occur in approximately 45% of critically ill patients, with cardiovascular instability (42.6%) being most common, followed by severe hypoxemia (9.3%) and cardiac arrest (3.1%) 3

• Common pitfalls to avoid:

  • Delaying intubation when NIV is clearly failing
  • Persisting with ineffective NIV, which adds to patient discomfort and risks further deterioration
  • Waiting for specific threshold values of arterial blood gases before deciding to intubate 5
  • Inadequate preoxygenation leading to rapid desaturation during intubation attempts

Decision Algorithm for Intubation

1. Immediate intubation required:

   • Respiratory arrest
   • Imminent respiratory arrest
   • Severe respiratory distress with NIV failure
   • GCS <8 with inability to protect airway
   • pH <7.15 despite optimized NIV

2. Consider intubation based on clinical assessment:

   • Evaluate work of breathing (respiratory rate, accessory muscle use)
   • Assess mental status and ability to protect airway
   • Review oxygenation (PaO₂/FiO₂ ratio, SpO₂) and ventilation (pH, PaCO₂)
   • Consider response to and tolerance of non-invasive support
   • Evaluate hemodynamic stability

3. Prepare for intubation:

   • Optimize patient position
   • Preoxygenate thoroughly
   • Have all equipment ready
   • Select appropriate medications based on hemodynamic status
   • Ensure waveform capnography for confirmation of tube placement

Remember that there is no single value for arterial PaCO₂, pH, or PaO₂ that by itself constitutes an absolute indication for intubation in all patients 5. The decision must incorporate the overall clinical picture, trajectory of illness, and response to less invasive interventions.