Effect of high-flow nasal cannula at different flow rates on diaphragmatic function in subjects recovering from an acute exacerbation of COPD: a physiological prospective pilot study

• Published in: Journal of Anesthesia, Analgesia and Critical Care (Online) Vol. 4; no. 1; pp. 37 - 9
• Main Authors: Colaianni-Alfonso, Nicolás, Castro, Iván, Cáceres, Vanesa, Montiel, Guillermo, Maggiore, Salvatore Maurizio, Vetrugno, Luigi
• Format: Journal Article
• Language: English
• Published: England Springer Nature B.V 24.06.2024; BMC
• Subjects: Body mass index; Chronic obstructive pulmonary disease; Data collection; Diaphragm ultrasound; Dyspnea; Gases; Hemodynamics; High-flow nasal cannula; Noninvasive ventilation; Oxygen therapy; Patients; Physiology; Pilot projects; Respiratory failure; Spirometry; Ultrasonic imaging; Variance analysis; Ventilators; New Zealand; United States > US; Chronic obstructive pulmonary disease; Noninvasive ventilation; Respiratory failure; Diaphragm ultrasound; High-flow nasal cannula
• ISSN: 2731-3786; 2731-3786
• DOI: 10.1186/s44158-024-00173-3

Noninvasive ventilation (NIV) is widely employed as the initial treatment for patients with chronic acute exacerbation of obstructive pulmonary disease (AECOPD). Nevertheless, high-flow nasal cannula (HFNC) has been increasingly utilized and investigated to mitigate the issues associated with NIV. Flow rate may play a significant role in diaphragmatic function among subjects recovering from AECOPD. Based on these observations, we conducted a physiological study to assess the impact of HFNC therapy on diaphragmatic function, as measured by US, respiratory rate (RR), gas exchange, and patient comfort at various flow rates. A prospective physiological pilot study enrolled subjects with a diagnosis of AECOPD who required NIV for more than 24 h. After stabilization, these subjects underwent a 30-min trial using NIV and HFNC at different sequential flow rates (30-60 L/min). At the end of each trial, diaphragmatic displacement (DD, cm) and diaphragmatic thickness fraction (DTF, %) were measured using ultrasound. Additionally, other physiological variables, such as RR, gas exchange, and patient comfort, were recorded. A total of 20 patients were included in the study. DD was no different among trials (p = 0.753). DTF (%) was significantly lower with HFNC-30 L/min compared to HFNC-50 and 60 L/min (p < 0.001 for all comparisons). No significant differences were found in arterial pH and P CO at discontinuation of NIV and at the end of HFNC trials (p > 0.050). During HFNC trials, RR remained unchanged without statistically significant differences (p = 0.611). However, we observed that HFNC improved comfort compared to NIV (p < 0.001 for all comparisons). Interestingly, HFNC at 30 and 40 L/min showed greater comfort during trials. In subjects recovering from AECOPD and receiving HFNC, flows above 40 L/min may not offer additional benefits in terms of comfort and decreased respiratory effort. HFNC could be a suitable alternative to COT during breaks off NIV.