UMEM Educational Pearls

When patients fail simple respiratory support therapies like nasal cannula or non-rebreather, it is often a point of debate whether to move next to High Flow Nasal Cannula (HFNC) or Noninvasive Positive Pressure Ventilation (NIPPV).  This study randomized patients in acute respiratory failure (ARF) to CPAP, a form of NIPPV, vs HFNC.  They looked at all comers in ARF, and primary outcome was need for intubation.  Importantly, they excluded asthma/COPD exacerbation, for which BiPAP is typically considered the first line therapy due to improved CO2 clearance.

They found a significantly lower number of patients required intubation in the CPAP (28.9%) group than the HFNC (42.6%) group (p=0.006).  They hypothesized that the enhanced PEEP improved oxygenation (hypoxia being a common trigger for moving to intubation), but as opposed to BiPAP,  the lack of additional driving pressure limited tidal volumes and Patient Self-Inflicted Lung Injury (P-SILI), which is a known mechanism of ARDS and mortality.  They use this argument to explain why trials like FLORALI, pitting HFNC vs BiPAP, tend to not find an advantage for the NIPPV arm.  While this rationale makes sense, it should be noted that the study does not directly investigate if this was the reason for the difference, and for what its worth the inverse argument that using driving pressure to reduce respiratory rate, hypercarbia, and work of breathing (other very common indications for intubation) would also theoretically reduce intubations.  Furthermore, it's not clear why reducing P-SILI, which tends to cause mortality on a much longer duration, would improve the short-term outcome of need for intubation.

 

Bottom Line: This study demonstrated a benefit to CPAP over HFNC in terms of decreasing need for intubation amongst non-asthma/non-COPD patients with acute respiratory failure, and offered a physiologic rationale but one that requires further verification and discussion.  While it may be reasonable to choose CPAP instead of HFNC in marginal patients at risk of intubation (but stable enough to trial noninvasive support first), in my opinion more studies are likely needed before a wholesale change in practice.  The study also does not take into consideration the enhanced comfort and compliance we tend to see with HFNC over NIPPV, which should be considered as well.  

References

Nagata K, Yokoyama T, Tsugitomi R, Nakashima H, Kuraishi H, Ohshimo S, Mori Y, Sakuraya M, Kagami R, Tanigawa M, Tobino K, Kamo T, Kadowaki T, Koga Y, Ogata Y, Nishimura N, Kondoh Y, Taniuchi S, Shintani A, Tomii K; JaNP-Hi Study Investigators. Continuous positive airway pressure versus high-flow nasal cannula oxygen therapy for acute hypoxemic respiratory failure: A randomized controlled trial. Respirology. 2023 Aug 30. doi: 10.1111/resp.14588. Epub ahead of print. PMID: 37648252.