Apneic oxygenation: Difference between revisions
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==Overview== | ==Overview== | ||
*Technique to prolongs "safe apnea time" (time until desaturation to SaO2=88-90% after induction of apnea). This increases time for laryngoscopy/intubation. | |||
*an ''adjunct'' to preoxygenation: used to prolong oxygenation after optimal preoxygenation | *Used as an ''adjunct'' to preoxygenation: used to prolong oxygenation after optimal preoxygenation | ||
* | *Low cost in terms of resources and set-up | ||
==Physiology== | ==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== | ==Indications== | ||
* | *[[Intubation]] | ||
==Contraindications== | ==Contraindications== | ||
* | *Severe maxillofacial trauma | ||
* | *Obstructed nares | ||
==Equipment Needed== | ==Equipment Needed== | ||
* | *Nasal cannula | ||
* | *Second oxygen source, e.g. mobile O2 tank | ||
==Procedure== | ==Procedure== | ||
#Start pre-oxygenation while sitting upright, only lay back once [[RSI]] drugs pushed. | #Start pre-oxygenation while sitting upright, only lay back once [[RSI]] drugs pushed. | ||
Line 29: | Line 33: | ||
==Complications/Limitations== | ==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== | ==See Also== | ||
{{Related Difficult Airway Pages}} | {{Related Difficult Airway Pages}} | ||
==External Links== | ==External Links== | ||
https://emcrit.org/pulmcrit/preoxygenation-apneic-oxygenation-using-a-nasal-cannula/ | *https://emcrit.org/pulmcrit/preoxygenation-apneic-oxygenation-using-a-nasal-cannula/ | ||
==References== | ==References== | ||
<references/> | <references/> | ||
[[Category:Procedures]] | [[Category:Procedures]] | ||
[[Category:Critical Care]] |
Latest revision as of 13:34, 7 October 2019
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
Contraindications
- Severe maxillofacial trauma
- Obstructed nares
Equipment Needed
- Nasal cannula
- Second oxygen source, e.g. mobile O2 tank
Procedure
- Start pre-oxygenation while sitting upright, only lay back once RSI drugs pushed.
- 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.
- Attach the nasal cannula to a separate oxygen source at 15L.
- 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
- Induction
- Intubation
- Surgical airways
- Post-intubation