Increased use of high-flow nasal oxygen during bronchoscopy

To the Editor:

High-flow nasal cannula (HFNC) oxygen therapy is increasingly applied in adult patients with acute respiratory failure (ARF) [1–4]. It delivers heated and humidified air providing higher and more expected gas flow rates and fraction inspired oxygen (F_iO2) than traditional oxygen therapy [2].

We read carefully the article by La Combe et al. [1] and congratulate the authors on their study. There are, however, some limitations to the study that need considering.

First, during bronchoscopy, arterial oxygen tension (P_aO2) can decrease approximately 20 mmHg and the most critical reduction usually occurs, when bronchoalveolar lavage (BAL) is performed [3, 4].

Second, in the procedure failure group, median baseline P_aO2 was 68 mmHg but, according to the American Thoracic Society recommendations, bronchoscopy and BAL should not be carried out in patients with hypoxaemia that cannot be corrected to a P_aO2 of at least 75 mmHg or to an arterial oxygen saturation of 90% with supplemental oxygen [3, 5].

Third, to better identify patients at higher risk of procedure failure and therefore with a poorer prognosis, it would be interesting to know the diagnosis at the time of admission in the intensive care unit.

Fourth, in the procedure failure group, all the baseline arterial blood gas values were lower than in the other group, except for the median arterial carbon dioxide tension, suggesting that maybe parameters were not sufficiently adjusted, such as the oxygen flow.

In conclusion, HFNC is easy to perform and is well tolerated [1, 3], which may lead to increasing its use in the future.