How is preoxygenation administered prior to rapid sequence intubation (RSI)?

Updated: Apr 07, 2020
  • Author: Keith A Lafferty, MD; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Preoxygenation with high-flow oxygen via a nonrebreather mask for 3-5 minutes leading up to intubation results in supersaturation of oxygen in the alveoli by way of displacement of nitrogen (nitrogen washout). This allows the patient to maintain blood oxygen saturation during the apneic period of paralysis and allows the physician more time to successfully intubate.

In healthy adult volunteers who have been preoxygenated for 3-5 minutes, the average time to desaturation (oxygen saturation < 90%) is approximately 8 minutes. This time is significantly shorter in patients who are critically ill and have a much higher metabolic demand for oxygen. [1]

Use the least assistance necessary to obtain good oxygen saturation and adequate preoxygenation (see Technique section below). High-flow oxygen via nonrebreather mask may be appropriate for a patient with good respiratory effort. High-flow oxygen via well-fitting bag-valve-mask (BVM) without additional positive pressure (ie, squeezing the bag) may be needed for those with more respiratory compromise. High-flow oxygen via BVM with positive pressure assistance (squeezing the bag) is used only when necessary.

Preoxygenation can also be accomplished with high-flow nasal cannula oxygen, which is very different from using a nonrebreather mask or increased nasal cannula oxygen. This is a modality of oxygen delivery that has had an increase in use, as both flow and oxygen levels can be adjusted. High flows translate to some positive airway pressures (much like CPAP), which can also help with airway patency.

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