Intubation-extubation paradox: Failure of rigid extubation criteria
Imagine what would happen if guidelines requiring FiO2 ?40% before extubation were followed for a patient with a baseline oxygen saturation 85-90% on six liters nasal cannula (which generates an inhaled oxygen concentration of ~44% FiO2). If this patient were intubated for any reason (e.g. seizures, elective surgery), it would be impossible to ever reach extubation criteria! Of course, in reality, if nothing changed with the patient's respiratory system, it should be possible to extubate the patient back to their chronic home oxygen prescription. This illustrates that extubation criteria should not be applied rigidly, but instead may require adaptation to the clinical scenario.
HFNC provides administration of higher levels of FiO2 than previously practical following extubation
Hypoxemia alone is usually not the cause of post-extubation respiratory failure
Symmetric nature of intubation and extubation
As shown below, a patient with more severe disease may require intubation even with HFNC support. However, HFNC might still facilitate early extubation to a greater level of noninvasive respiratory support:
Evidence regarding the use of HFNC following extubation
Since then, Stephan 2015 explored the use of HFNC in patients extubated following cardiothoracic surgery. BiPAP has been shown to reduce reintubation in this setting, so this trial was designed involving 830 patients randomized to BiPAP vs. HFNC. The two groups had nearly identical rates of reintubation. It is unclear exactly how this extrapolates to non-surgical patients, but overall the study supports post-extubation HFNC.