(1165) High FIO2 and Low Tidal Volume in Normoxemic Patients Intubated in the Emergency Department

Introduction: The use of lung protective strategies in ALI reduces mortality but may be harmful in patients with normal lung physiology. Boarding of intubated patients in the Emergency Department (ED) is increasing, and often initial ventilator settings remain once set. Ventilator dyssynchrony may develop, and deep sedation is frequently required for patient tolerance. Research indicates that ED exposure to hyperoxia is associated with greater mortality in invasively ventilated patients. Thus, we sought to study the incidence and risk factors for initial high FIO2 or low VT in patients intubated in the ED with normoxemia.

Methods: Multicenter, retrospective study of all patients intubated in the ED with a P/F ratio ≥ 300. Data were entered into REDCap, including demographic and clinical information. High FIO2 was defined as ≥ .60; low VT was defined as ≤ 6.5 mL/kg/IBW. Data were uploaded to SAS and compared using Chi-square for ordinal data, or Student's t-test for continuous variables, following normality testing and log-transformation. Uni- and multivariate logistic analyses were used to examine the dependent variables.

Results: Of the 1693 subjects intubated in the ED during the 2019 study period, 515 were normoxemic (P/F 411±97). Sixty-two percent of subjects were initially placed on a FIO2 ≥ .60 post intubation, with 53% placed on a FIO2 of 1.0 (median 1.0 [IQR .50-1.0]); 75% left the ED with an FIO2 ≥ .60; 32% percent were placed on low VT, with a mean VT of 7.2±1.2 ml/kg/IBW. Significant univariate variables for low VT included race, sex, weight, height, and set PEEP. In multivariate analysis, only weight and race were independently associated with the use of low VT (AUC .84). Significant univariate variables for high FIO2 included differential diagnosis, reason for intubation, post-intubation hypotension, vasopressor use, OHCA, initial RR and initial O2 device. Initial RR, post-intubation hypotension and respiratory distress or cardiac failure as intubation reason were independently associated with use of a high FIO2 (AUC .65).

Conclusions: Among intubated, normoxemic patients in the ED, approximately one third are placed on low tidal volume ventilation and half are placed on a FiO2 of 1.0, with disparate associations for their use. Additional study to determine potential harm is warranted.