II. Definitions

  1. End-Tidal O2
    1. Measured concentration of oxygen in expired breath
    2. Measured by Face Mask or nasal detector that attaches to a monitor module (measures EtCO2 and EtO2)

III. History

  1. Has historically been limited to operating room measurement, but is becoming available in Emergency Department in 2019

IV. Indications

  1. Endotracheal Intubation Preoxygenation
    1. Adjunct to Oxygen Saturation in identifying adequate preoxygenation (prevents desaturation during apnea)
    2. Ideal Oxygen Saturation prior to intubation: Approaching 100%
    3. Ideal End-Tidal Oxygen: >=85%
      1. Suggests adequate nitrogen wash-out in Functional Residual Capacity
      2. Ideal EtO2 is difficult to achieve without high oxgen flow rates or Positive Pressure Ventilation
        1. Caputo (2019) Ann Emerg Med 74(3):410-5 +PMID:30879700 [PubMed]

V. References

  1. Swaminathan and Caputo in Herbert (2019) EM:Rap 19(12): 14-5

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