High-flow nasal cannula therapy for acute hypercapnic respiratory failure: A randomised controlled trial

<bold>Introduction:</bold> Non-Invasive ventilation (NIV) is the gold standard for managing acute hypercapnic respiratory failure (AHRF). High-flow nasal cannula therapy (HFNT) could reduce the need for NIV in the management of AHRF. <bold>Aims and objectives:</bold> This study aimed to investigate the effectiveness of HFNT in reducing hypercapnia and NIV need. <bold>Methods:</bold> A randomised unblinded controlled trial comparing HFNT with low-flow oxygen (LFO) recruited adult AHRF patients (pH <7.35 and PaCO2 >6 KPa) in the emergency departments of two hospitals in Belfast, UK from June 21 - Jan 23. Randomisation was performed immediately after AHRF detection. NIV escalation was by clinical team after 1hr of HFNT or LFO therapy based on BTS AHRF guidelines. A sample size of 39 per arm was planned. <bold>Results:</bold> 28 patients were recruited (15 HFNT vs 13 LFO) with no baseline difference except for bronchiectasis which was higher in HFNT arm. HFNT compared to LFO resulted in a significantly lower proportion escalating to NIV at 6hrs (Table), a reduction in PaCO2 at 6hrs (p=0.08) and within HFNT group, pH was significantly higher at 1hr (Table). HFNT significantly reduced dyspnoea compared to LFO at 1hr (p=0.004). No significant differences were found in the mortality rate or hospital length of stay. <bold>Conclusion:</bold> This study demonstrated the potential use of HFNT in reducing the need for NIV when compared to LFO at 6hrs after randomisation but limited by failure to recruit the planned sample size. Further larger clinical trials powered for meaningful clinical outcomes are required. <table-wrap><object-id>erj;64/suppl_68/PA1694/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td> Outcome </td><td> HFNT</td><td> LFO</td><td> p value</td></tr><tr><td> NIV at 6hrs n/N (%) </td><td> 2/15 (13.3%)</td><td> 8/13 (61.5%)</td><td> 0.01</td></tr><tr><td>Within group analysis pH at 1hr Mean(SD)</td><td>7.31 (0.05)</td><td> -</td><td> 0.04</td></tr></tbody></table></table-wrap>