September 16, 2019

Background: Rapid sequence intubation (RSI) involves the use of an induction agent followed by a neuromuscular blocking (NMB) agent to obtain optimal intubating conditions.  Administration of a NMB results in apnea which, in turn, can lead to oxygen desaturation.  Oxygen desaturation during rapid sequence intubation may lead to serious adverse events including dysrhythmias, hypotension, and cardiac arrest.  Preoxygenation helps extend the duration of safe apnea and has 2 major goals:
  1. Attempt to achieve an O2 saturation of 100%
  2. Maximize oxygen storage in the lungs by denitrogenation of the residual capacity of the lungs (Approximately 95% of oxygen reservoir)
Preoxygenation is assessed in the ED but usually through pulse oximetry which is inadequate.  In the operating room, anesthesiolgists use gas analyzers to quantify and optimize preoxygenation with ETO2.  In critically ill patients, preoxygenation should be performed to achieve an ETO2 ≥85% based on the response to the 4th National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society [2].
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