To: Efficacy and safety of high-flow nasal cannula oxygen therapy in moderate acute hypercapnic respiratory failure

To the Editor,

We read with great interest the article “Efficacy and safety of high-flow nasal cannula oxygen therapy in moderate acute hypercapnic respiratory failure” by Yuste et al., where the use of high-flow nasal cannula (HFNC) is evaluated in patients with moderate hypercapnic respiratory failure (HRF).⁽¹⁾ We complement the authors for their exciting work; however, we consider that the conclusions of this study and its results can be commented on from a clinical perspective that in our opinion should be taken into account.

The protocol implemented for HFNC applications needs attention. Although the authors indicate that they used an established protocol, it is essential to know the method of HFNC use in context, specifically, a) if the authors maintained their application during the nighttime^(2,3) and b) if the use of the HFNC step with other devices was regulated by some criteria, such as the flow or previous pressures.⁽⁴⁾ We think that these considerations can raise the importance of their results and their clinical extrapolation.

Furthermore, although the authors use hypercapnia as a criterion, the patients in their study may have a different etiology of hypercapnia (hypoventilation, increased airway resistance or cardiac insufficiency). This perspective on the use of HFNC can condition the results and the clinical extrapolation of them.^(5,6)

Lastly, we do not reject the authors’ claim about the efficacy and safety of HFNCs in such patients, but we feel that other aspects of interest, such as time to control of hypercapnia, clinical improvement and successful management of patients with noninvasive mechanical ventilation after HFNC failure, also need to be described and considered. The authors have defined the indication for the use of the HFNC, but selecting one method over another was kept at the physicians’ discretion, which poses an inherent bias. Therefore, even though they had acceptable nonresponders to HFNC therapy, future studies will be required for better acceptance of their results and conclusions.

REFERÊNCIAS

• ¹
  Yuste ME, Moreno O, Narbona S, Acosta F, Peñas L, Colmenero M. Efficacy and safety of high-flow nasal cannula oxygen therapy in moderate acute hypercapnic respiratory failure. Rev Bras Ter Intensiva. 2019;31(2):156-63.
• ²
  Biselli P, Fricke K, Grote L, Braun AT, Kirkness J, Smith P, et al. Reductions in dead space ventilation with nasal high flow depend on physiological dead space volume: metabolic hood measurements during sleep in patients with COPD and controls. Eur Respir J. 2018;51(5). pii: 1702251.
• ³
  Biselli PJ, Kirkness JP, Grote L, Fricke K, Schwartz AR, Smith P, et al. Nasal high-flow therapy reduces work of breathing compared with oxygen during sleep in COPD and smoking controls: a prospective observational study. J Appl Physiol (1985). 2017;122(1):82-8.
• ⁴
  Papazian L, Corley A, Hess D, Fraser JF, Frat JP, Guitton C, et al. Use of high-flow nasal cannula oxygenation in ICU adults: a narrative review. Intensive Care Med. 2016;42(9):1336-49.
• ⁵
  Bräunlich J, Wirtz H. Nasal high-flow in acute hypercapnic exacerbation of COPD. Int J Chron Obstruct Pulmon Dis. 2018;13:3895-7.
• ⁶
  Hill NS, Spoletini G, Schumaker G, Garpestad E. Noninvasive ventilatory support for acute hypercapnic respiratory failure. Respir Care. 2019;64(6):647-57.

Publication Dates

• Publication in this collection
  08 May 2020
• Date of issue
  Jan-Mar 2020

History

• Received
  10 June 2019
• Accepted
  05 Aug 2019