Abstract
Background High Flow Nasal Cannula (HFNC) has gained widespread use for acute hypoxemic respiratory failure on the basis of recent publications demonstrating fewer intubations and perhaps lower mortality in certain situations. However, a subset of patients initiated on HFNC for respiratory failure ultimately do require intubation. Our goal is to identify patient level features predictive of this outcome.
Materials and methods: This is a retrospective cohort study of patients with hypoxemic respiratory failure treated with HFNC. Individuals were described as having “succeeded” (if weaned from HFNC) or “failed” (if they required intubation). A variety of easily measurable variables were evaluated for their ability to predict intubation risk, analyzed via a multivariate logistic regression model.
Results: Of a total of 74 subjects, 42 “succeeded” and 32 “failed.” Net fluid balance in the first 24 hours after HFNC initiation was significantly lower in the success group (-33 ± 80 vs. +72 ± 117 mL / h, p <0.01). An adjusted model finds only fluid balance and the previously described Respiratory Rate - Oxygenation (ROX) index (a ratio of the oxygen saturation (SpO2) divided by the fraction of inspired oxygen (FiO2) to the respiratory rate (RR), [SpO2/FiO2]/RR) at 12 hours as significant predictors of successful weaning (negative fluid balance adjusted OR 0.77 [0.62 - 0.96] for -10 mL/Hr increments, p = 0.02; ROX adjusted OR 1.72 p <0.01).
Conclusions: Negative fluid balance while on HFNC discriminates well between those who will require intubation versus those who will be successfully weaned.
Footnotes
- Rajiv Sonti (rajiv.sonti{at}gunet.georgetown.edu)
- Received September 5, 2020.
- Accepted September 9, 2020.
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