What is the role of preoxygenation in 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

The step of preoxygenation maximizes hemoglobin and plasma oxygen saturation and creates an oxygen reservoir in the lungs by replacing nitrogen at the alveolar level and supersaturating the blood with oxygen (nitrogen washout). This oxygen reservoir in the lungs can eliminate the need for BVM ventilation for most patients undergoing RSI during the iatrogenically created period of apnea. Preoxygenation is accomplished by delivering 100% oxygen at high flow given to a spontaneously breathing patient through a nonrebreather mask for 3 minutes without "bagging" the patient.

Studies such as the one by Barker and colleagues have shown that 8 vital capacity breaths over 60 seconds results in the same degree of preoxygenation as the standard 3 minutes of tidal volume breathing of 100% oxygen by mask. This technique may be used as an alternate to the traditional 3-minute tidal volume technique. Comorbidities such as the presence of a hypermetabolic state, obesity, or a primary respiratory problem (eg, congestive heart failure, acute respiratory distress syndrome, pneumonia) cause patients to desaturate rapidly despite attempts at adequate preoxygenation.

A patient who is hypoxemic during attempts at intubation should undergo positive pressure ventilation with a BVM to raise PaO2 levels. Consider applying cricoid pressure.


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