An introspection into the management of subglottic stenosis in pregnant women using advanced apnoeic ventilatory techniques by Damrose et al

Dear Editors,

Apnoeic ventilation during tracheal surgical procedures is challenging. Recently, we read an article published in your journal related to subglottic stenosis management.¹ It described a novel application of non-invasive devices that allows oxygenation to be maintained during the procedure. We want to highlight this study; however, there are some aspects that we consider of interest for adequate extrapolation of the results.

In the case of nasal high-flow oxygen application with the mouth open, we do not know if it allows adequate stability of the pressures reached during high nasal flow.² A study has shown a significant reduction in the expiratory positive airway pressure.³ We consider this aspect of interest in patients with low pulmonary compliance and reserve as it occurs in pregnant patients, because of the patient's position during the procedure, the elevation of the diaphragm and physiological changes in pregnancy. The use of sedation can also interfere with the tonicity of the upper muscles. Therefore, more information related to ventilation during this procedure – for example, data on hypoventilation, capnography and oxygenation – will be interesting to know.

A high-flow nasal cannula has been used in airway management to delay desaturation, but it has limitations too.⁴ We congratulate the authors for their excellent work, but it is felt that further information related to the above will be contributory to the evidence and interpretation of results.