Apneic oxygenation

Overview

• Technique to prolongs "safe apnea time" (time until desaturation to SaO2=88-90% after induction of apnea). This increases time for laryngoscopy/intubation.
• Used as an adjunct to preoxygenation: used to prolong oxygenation after optimal preoxygenation
• Low cost in terms of resources and set-up

Physiology

• Gas exchange during apnea creates subatmopsheric pressure in the alveoli
  • In healthy lungs, 200-250mL O2 per minute can be drawn into blood stream
  • In the absence of ventilation (i.e. during apnea), only 10-20mL CO2 enters alveoli from bloodstream per minute, due to increased CO2 tension
  • This causes a net decrease in gas in the alveoli
• This gradient can draw air into the lungs, even absent diaphragmatic movement
• Increases safe apnea time in healthy volunteers from 1 minute (room air) to 8-9 minutes

Indications

• Intubation

Contraindications

• Severe maxillofacial trauma
• Obstructed nares

Equipment Needed

• Nasal cannula
• Second oxygen source, e.g. mobile O2 tank

Procedure

1. Start pre-oxygenation while sitting upright, only lay back once RSI drugs pushed.
2. During preoxygenation, keep the nasal cannula on underneath your primary preoxygenation technique.
   • This can be achieved whether you use a mask, NPPV, or BVM; a good seal can still be obtained. Alternatively, you can use the high flow nasal cannula technique for preoxygenation.
   • Normal adjunctive airway techniques/equipment (jaw thrust, oropharyngeal airway) remain useful. In particular, nasal trumpet can maintain patencny of at least one nare.
3. Attach the nasal cannula to a separate oxygen source at 15L.
4. After preoxygenation, leave the nasal cannula on after removing mask/NPPV/BVM. It should not get in the way of laryngoscopy.
   • Consider taping cannula to face to prevent dislodgement.

Complications/Limitations

• Complications are limited and most can be quickly remedied by removing nasal cannula
  • If not well-positioned/attached, may complicate laryngoscopy
  • High flow oxygen from nasal cannula is cold and dry; may not be well-tolerated by patient
  • Extremely high flow oxygen (>70 L/M) may cause barotrauma
  • Increased apnea time increases respiratory acidosis
• Not shown to improve saturation in critically ill patients

See Also

Airway Pages

• Pre-intubation
  • Predicting the difficult airway
  • Bag valve mask ventilation
    • Oropharyngeal airway
    • Supraglottic airway
  • Apneic oxygenation
    • EBQ:ED Preoxygenation
• Induction
  • Critical care quick reference
  • Rapid sequence intubation
  • Delayed sequence intubation
• Intubation
  • Intubation (peds)
  • Direct laryngoscopy
  • Video Laryngoscopy
  • Bougie
  • The difficult airway
  • Advanced airway adjuncts
    • Supraglottic airway
  • Non-traditional intubation
    • Awake intubation
    • Nasal intubation
    • Blind digital intubation
• Surgical airways
  • Surgical cricothyrotomy
  • Needle cricothyrotomy
  • Pediatric jet ventilation
• Post-intubation
  • Mechanical ventilation (main)
  • Deterioration after intubation (DOPE)

External Links

• https://emcrit.org/pulmcrit/preoxygenation-apneic-oxygenation-using-a-nasal-cannula/