Introduction High-flow nasal cannula (HFNC) provides benefits to patients undergoing flexible bronchoscopy (FOB). We compared the effects of HFNC versus standard therapy (ST) on gas exchange, lung volume and diaphragm function in patients undergoing FOB for bronchoalveolar lavage (BAL).
Methods 36 outpatients were randomised to ST or HFNC. Arterial blood gases, episodes of severe desaturation, changes of end-expiratory lung impedance (ΔEELI), diaphragm ultrasound were recorded. Measurements were done at baseline (T0), after bronchoscope insertion (T1), at the end of the procedure (T2) and 10 min afterwards (T3).
Results Arterial partial oxygen pressure (PaO2) was not different between T0 (10.8 (95% CI 8.7 to 12.0) kPa and T2 (11.1 (95% CI 10.4 to 12.0) kPa) with HFNC, while decreased from 11.1 (95% CI 10.5 to 12.1) to 9.1 (95% CI 8.4 to 9.8) kPa with ST. At T2, PaO2 was significantly higher with HFNC than with ST (p<0.001). Also, with HFNC, compared with ST, fewer desaturations occurred (11% vs 56%; p<0.01). ΔEELI was no different at the different time points with HFNC, while with ST there was a significant decrease at T1 (−170 (95% CI −382 to −32) mL, p=0.003), T2 (−211 (95% CI −425 to −148) mL, p<0.001) and T3 (−213 (95% CI −398 to −81) mL, p<0.001), as opposed to T0. EELI was lower with ST than HFNC at T1 (p=0.006), T2 (p=0.001) and T3 (p=0.002). Diaphragm displacement was no different between groups (p=0.748), while the thickening fraction significantly increased at T1 and T2 with ST only (p<0.01).
Conclusions During FOB for BAL, HFNC improves gas exchange, avoiding loss of end-expiratory lung volume and preventing increase of diaphragm activation.
Trial registration number NCT04016480.
- imaging/CT MRI
- respiratory measurement
- respiratory muscles
Data availability statement
All individual, de-identified datasets generated during and/or analysed during the study are available from the corresponding author on reasonable request.
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FL and CP contributed equally.
Contributors FL, CP, EG, AB, GPel and PN participated in the conception and study design. All authors were responsible for acquisition, analysis and/or interpretation of the data. All authors participated in the manuscript draft and revised it for important intellectual content. They also approved the final manuscript version and accounted for all aspects of the work, ensuring that questions related to accuracy and integrity of any part of the study were appropriately investigated and resolved.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests PN’s research laboratory has received equipment and grants from Draeger and Intersurgical. He also received honoraria/speaking fees from Philips, Resmed, MSD and Novartis. PN contributed to the development of the helmet Next, whose licence for patent belongs to Intersurgical and receives royalties for that invention. FL and PN contributed to the development of a new device (not discussed in the present study), whose patent is in progress (European Patent application number EP20170199831).
Provenance and peer review Not commissioned; externally peer reviewed.