What is the role of apneic oxygenation during rapid sequence intubation (RSI)?

Updated: Feb 28, 2019
  • Author: Keith A Lafferty, MD; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Answer

Because pulmonary blood flow is still occurring during the apneic period of ETT placement, oxygen is continually being diffused out of the alveoli epithelium at 250 mL/min and into the capillary endothelium and attaching itself to circulating hemoglobin. Despite no ventilations (RSI dictates this in assuming full stomachs unless oxygen saturations are low) after the patient is paralyzed, there is actual flow and movement of oxygen down these concentration gradients as the alveoli are somewhat subatmospheric and a mass flow of gas (oxygen) flows from the airways into the alveoli. By applying an NC at 15 L/min (noxious and otherwise not tolerable in the awake patient) proximal airways can come close to a FiO2 of 1.0 and serve to replace the alveoli oxygen. [15] Taha et al have shown that apneic oxygenation via an NC during RSI in comparison to those without this technique desaturated in 6 minutes compared with 3.65 minutes. [16]


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