What is the recommended technique for providing apneic oxygenation during rapid sequence intubation in an adult or pediatric patient without contraindications to nasal cannula placement?

Apneic Oxygenation During Rapid Sequence Intubation

Apply nasal cannula at 5 L/min during preoxygenation, then immediately increase to 15 L/min when the patient loses consciousness and maintain this flow throughout all intubation attempts. 1, 2

Technique and Equipment

Standard Nasal Cannula Method (Recommended for Most Patients)

• Place standard nasal cannula under the face mask during preoxygenation at 5 L/min 1
• Increase flow to 15 L/min immediately after induction of anesthesia and administration of neuromuscular blocking agents 1, 2
• Continue 15 L/min flow throughout all laryngoscopy attempts until the airway is secured 1, 2
• This simple technique achieves nearly 100% FiO₂ and significantly extends safe apnea time with universally available equipment 1

Airway Patency Requirements

• Maintain airway patency with jaw thrust or direct laryngoscopy during the apneic period 1
• Apneic oxygenation requires an open upper airway to allow mass movement of oxygen down the trachea into the alveoli 1

Evidence for Efficacy

Adult Patients

• Apneic oxygenation at 15 L/min via nasal cannula significantly prolongs safe apnea time and reduces desaturation events 3, 4
• In obese patients, oxygen insufflation at 15 L/min through nasal cannula increased median safe apneic duration by 103 seconds compared to controls 3
• Meta-analysis of emergency department and retrieval settings showed significant reduction in desaturation (RR=0.76, p=0.002) and critical desaturation (RR=0.51, p=0.01) with apneic oxygenation 4
• First-pass intubation success rate improved significantly (RR=1.09, p=0.004) when apneic oxygenation was used 4

Pediatric Patients

• Apneic oxygenation providing 100% FiO₂ significantly increases time until initial desaturation and reduces overall incidence of hypoxia during laryngoscopy in children 5
• Studies across 712 pediatric patients demonstrated that each apneic oxygenation method providing 100% FiO₂ resulted in significantly longer time until desaturation 5

High-Flow Nasal Oxygen (HFNO) as Alternative

When to Consider HFNO (30-70 L/min)

• Consider high-flow humidified nasal oxygen at 30-70 L/min for high-risk patients including those with obesity, respiratory failure, or anticipated difficult airway 1, 2
• HFNO provides superior CO₂ clearance compared to standard apneic oxygenation techniques, preventing the progressive respiratory acidosis seen with traditional methods 1
• In difficult airway scenarios, HFNO can extend safe apnea time to a median of 14 minutes without SpO₂ dropping below 90% 2

HFNO Advantages

• Delivers warmed, humidified oxygen which is better tolerated at high flow rates 1
• Cold dry oxygen at high flow rates causes mucosal drying, pain, and bleeding, limiting standard nasal cannula to 10-15 L/min in awake patients 1
• HFNO transforms difficult airway management from a hurried procedure to a smoother event within an extended safe apneic window 2

Critical Physiologic Considerations

Mechanism of Action

• During apnea, oxygen removal from alveoli creates a pressure gradient between the upper airway and alveoli, resulting in mass movement of oxygen down the trachea to replenish oxygen stores 1
• Significantly more CO₂ (90%) is buffered in bloodstream and tissues during apneic oxygenation, with only approximately 20 ml/min delivered to alveoli 1

Important Limitation

• Apneic oxygenation delays hypoxemia but does NOT prevent hypercarbia: CO₂ accumulates at approximately 3-4 mmHg per minute during apnea despite adequate oxygenation 2
• Safe apnea time is ultimately limited by significant increase in alveolar CO₂ concentration leading to progressive respiratory acidosis 1
• Following intubation, patients receiving apneic oxygenation had mean ETCO₂ levels 3.0 mmHg higher than controls 3

Common Pitfalls and Contraindications

Avoid These Errors

• Do not use apneic oxygenation in patients with suspected or confirmed base of skull fractures due to risk of pneumocephalus 2
• Do not assume apneic oxygenation eliminates the need for rapid intubation—it only extends the safe window 1, 2
• Do not rely on apneic oxygenation alone without proper preoxygenation; combine both techniques for optimal results 2

Infection Control Considerations

• During infectious disease outbreaks, keep oxygen flow to minimum required to maintain saturation, preferably below 5 L/min to reduce aerosolization risk 2
• Nasal cannula at 5 L/min can project exhaled air up to 1 meter caudally; higher flows create greater dispersion distances 2
• Consider placing a surgical facemask over oxygen delivery devices to limit droplet dispersion when infection control is a concern 2

Special Populations

Obese Patients

• Obese patients have reduced functional residual capacity and increased oxygen consumption, making them particularly high-risk for rapid desaturation 3, 6
• Apneic oxygenation is especially beneficial in this population, with demonstrated significant prolongation of safe apnea duration 3

Obstetric Patients

• Pregnant patients from the second trimester have decreased FRC and increased oxygen consumption, resulting in shorter time to desaturation 1
• During labor, time to SpO₂ < 90% averages only 98 seconds compared to 292 seconds in pregnant women not in labor 1

Pediatric Patients

• Children are at high risk of rapid desaturation and benefit significantly from apneic oxygenation techniques 5, 6
• The technique is effective across pediatric age groups when 100% FiO₂ is delivered 5

Algorithm Summary

1. During preoxygenation: Apply nasal cannula at 5 L/min under face mask 1, 2
2. After induction: Increase nasal cannula to 15 L/min immediately when consciousness is lost 1, 2
3. During laryngoscopy: Maintain 15 L/min flow and ensure airway patency with jaw thrust 1
4. For high-risk patients: Consider HFNO at 30-70 L/min instead of standard nasal cannula 1, 2
5. Continue until: Airway is secured with endotracheal tube 1, 2