Respir Care. 2021 Aug 17:respcare.09053. doi: 10.4187/respcare.09053. Online ahead of print.
ABSTRACT
BACKGROUND: Several markers of oxygenation are used as prognostic markers in acute hypoxemic respiratory failure. Real-world use is limited by the need for invasive measurements and unreliable availability in the electronic health record. A pragmatic, reliable, and accurate marker of acute hypoxemic respiratory failure is needed to facilitate epidemiologic studies, clinical trials, and shared decision-making with patients. FIO2 is easily obtained at the bedside and from the electronic health record. The FIO2 trajectory may be a valuable marker of recovery in patients with acute hypoxemic respiratory failure.
METHODS: This was a historical cohort study of adult subjects admitted to an ICU with acute hypoxemic respiratory failure secondary to community-acquired pneumonia and/or ARDS.
RESULTS: Our study included 2,670 subjects. FIO2 and SpO2 were consistently more available than was PaO2 in the electronic health record: (FIO2 vs SpO2 vs PaO2 : 100 vs 100 vs 72.8% on day 1, and 100 vs 99 vs 21% on day 5). A worsening FIO2 trajectory was associated with reduced ventilator-free days. From days 2 to 5, every increase in FIO2 by 10% from the previous day was associated with fewer ventilator-free days (on day 2: adjusted mean -1.25 [95% CI -1.45 to -1.05] d, P < .001). The SpO2 /FIO2 trajectory also provided prognostic information. On days 3 – 5, an increase in SpO2 /FIO2 from the previous day was associated with increased ventilator-free days (on day 3: adjusted mean 2.09 (95% CI 1.44-2.74) d; P < .001). SpO2 /FIO2 models did not add predictive information compared with models with FIO2 alone (on day 2: adjusted FIO2 vs SpO2 /FIO2 R2 0.122 vs 0.119; and on day 3: 0.153 vs 0.163).
CONCLUSIONS: FIO2 and SpO2 /FIO2 are pragmatic and readily available intermediate prognostic markers in acute hypoxic respiratory failure. The FIO2 trajectory in the first 5 d of ICU admission provided important prognostic information (ventilator-free days). Although the SpO2 /FIO2 trajectory was also associated with ventilator-free days, it did not provide more information than the FIO2 trajectory alone.
PMID:34404689 | DOI:10.4187/respcare.09053
