Effect of high-flow nasal therapy on dyspnea, comfort, and respiratory rate

Systematic reviews comparing the effect of high-flow nasal treatment (HFNT) to conventional oxygen therapy (COT) or noninvasive ventilation (NIV) have focused on major clinical outcomes (i.e., endotracheal intubation, mortality) [1–3]. None have explored weaker outcomes that may nonetheless be important from the patient’s perspective, yet physiopathological mechanisms suggest that the HFNT may provide some advantage in this regard [4, 5]. We therefore systematically reviewed all randomized (RCTs) and crossover trials enrolling patients either post-extubation or during acute respiratory failure (ARF), comparing HFNT to COT or NIV and reporting data about dyspnea, comfort, and respiratory rate (RR) (PROSPERO CRD42019119536). Full search strategy, detailed study methods, reference lists, and risk of bias assessments are reported in Additional file 1. Twenty-four relevant studies were identified and included: for patients post-extubation, ten RCTs and one crossover trial and, for patients in ARF, eight RCTs and five crossover trials. The summary of our findings is presented in the Table 1. More studies compared the effects of HNFT vs COT rather than vs NIV. Overall, there seems to be a trend showing that HFNT is probably not inferior to COT in most studies and perhaps better than NIV in terms of dyspnea, comfort, and decreasing of RR in some studies. Heterogeneity in case-mix, the tools used for outcome assessment and measurement time-points precluded performance of meta-analysis. Neither patients nor treating clinicians were blinded to the intervention in any of the trials, introducing a high risk of detection bias. Differences in HFNT settings (i.e., flow and temperature) and a lack of full description for weaning criteria or protocol may have also contributed to the diversity in findings with regard to comfort and dyspnea. In this analysis of the literature, the use of HFNT during ARF or post-extubation seems to be not clearly associated with improvements in comfort, dyspnea, and RR since findings from the most recent available evidence were inconsistent. However, in this regard, HFNT does not seem inferior to either COT or NIV. Future research should be focused in assessing patient-reported outcomes using appropriate standardized and validated measures in order to investigate the comparative effectiveness of the different respiratory support strategies.