What We Already Know About the Topic
Per the FLORALI study, patients managed with HFNC appear to have better mortality outcomes than those managed with combination of HFNC and non-invasive ventilation (NIV). Furthermore, the LUNG SAFE study showed that hypoxemic patients failing NIV had higher mortality rate than those invasively ventilated. This introduces the topic of the optimal pre-intubation (i.e. noninvasive ventilation) strategy in ICU patients.
Why This Study is Important
Helps to guide the airway management for hypoxemic respiratory failure patients. Further, the increased work on patient self-induced lung injury (P-SILI) has shown that large swings in transpulmonary pressure may help characterize patients who do not do well in acute respiratory failure.
Purpose (PICO format)
In a post hoc analysis of a randomized controlled trial, ICU patients with acute respiratory failure were randomized to receive standard oxygen, HFNC, or NIV with measured outcomes of early and late predictors of intubation as well as 90 day mortality.
23 centers in France and Belgium
This analysis a post hoc look at a randomized controlled trial of ICU patients. Acute respiratory failure was defined as RR > 25 bpm, PaO2/FiO2 < 300 mm Hg and a PaCO < 45 mm Hg. Data collection was at baseline and at 1 hour post-randomization to specific oxygen strategy. Intubation criteria were predetermined and were 1) worsening respiratory failure via > 2 of criteria: RR > 40, no improvement in signs of respiratory muscle workload, copious secretions, pH < 7.35, or SpO2 < 90% for 5 min; 2) HD instability; or 3) Deterioration of mental status.
Identify early factors associated with intubation–at baseline and 1 hour after initiation of each treatment. Secondary outcome was to identify factors associated with mortality at 90 days.
ICU patients with acute respiratory failure
Severe neutropenia, acute-on-chronic respiratory failure, cardiogenic pulmonary edema, shock, or altered consciousness
Of the 310 patients included, most of them had moderate hypoxemia (i.e. PaO2/FiO2 ratio between 101 and 200 mm Hg). 94 patients received standard oxygen (mean gas flow ~13LPM). 106 patients received HFNC (mean gas flow 48 LPM). 110 patients were treated with NIV (mean expired tidal volume 8.7 mL/kg). 45% of the population needed intubation. For each group, independent factors predictive of intubation were as follows: standard oxygen patients – RR > 30 bpm, HFNC patients – increased HR at one hour after intiation, NIV patients – both PaO2/FiO2 ratio at one hour < 200 mm Hg and expired TV at one hour > 9 mL/kg.
In terms of 90 day mortality, factors significantly associated were the following: standard oxygen or HFNC – SAPS II score, NIV – TV > 9 mL/kg of PBW one hour post oxygen strategy implementation.
Tempting to extrapolate these data findings to emergency department patients; though, would have caution as these are different substrates.
Conclusions of the Authors of the Study
Finding the significant factors predictive of intubation and mortality can help physicians decide airway management strategies early in the acute respiratory failure process.
Take Home Points for Us
Pay attention to certain variables like RR, HR, and expired tidal volumes when managing tenuous acute respiratory failure patients in the ICU. Realize that these variables may represent crucial pathophysiological changes portending worsened prognosis (i.e. large expired TV may represent swings in transpulmonary pressure and the resultant baro-/atelectatrauma of ARDS).