Rate of Decline in Oxygen Saturation at Various Pulse Oximetry Values with Prehospital Rapid Sequence Intubation

Abstract

Background. A high incidence of desaturations has been observed during prehospital rapid sequence intubation (RSI). The rate of decline in oxygen saturation (SpO2) at various pulse oximetry values has not been defined with emergency RSI. Objective. To define the rate of SpO2 decline at various pulse oximetry values andidentify a threshold below which active BVM should be performed during prehospital RSI. Methods. Traumatic brain injury (TBI) patients undergoing RSI by prehospital providers were included in this analysis. The time period from the highest to the lowest preintubation SpO2 value was selected for review. The mean rate of SpO2 decline was calculated for each SpO2 value andthen used to define a theoretical SpO2 desaturation curve. The rate of desaturation to hypoxemia (SpO2 ≤ 90%) was defined for intubation attempts initiated at each SpO2 value. Results. A total of 684 SpO2 values from 87 patients were included. Lower SpO2 values were associated with a faster rate of SpO2 decline, with an inflection point occurring at 93%. The rate of desaturation to hypoxemia with intubation attempts initiated with SpO2 ≤ 93% was much higher than with SpO2 above 93% (100% vs. 6%, p < 0.01). In patients undergoing multiple attempts, SpO2 values with BVM between attempts was consistently higher than the preintubation SpO2 value. Conclusions. The rate of SpO2 decline increases as SpO2 decreases, with an inflection point occurring around 93%. Intubation attempts below this value are almost always associated with subsequent desaturation, suggesting that BVM should be used prior to laryngoscopy in these patients.

Keywords:

• rapid sequence intubation
• desaturation
• hypoxemia
• pulse oximetry