High-flow nasal cannula oxygen therapy versus conventional oxygen therapy in patients after planned extubation

Abstract

We read with great interest the recent systematic review and meta-analysis of high-flow nasal cannula (HFNC) oxygen therapy versus conventional oxygen therapy (COT) in patients after planned extubation [1]. We greatly appreciate Zhu Y and colleagues' efforts, but some important issues may better be discussed.First, randomized controlled trials (RCTs) and non-RCTs may be inappropriately combined together in the meta-analysis, which goes against the principle of pooling studies with the similar design [2, 3]. Thus, results from RCTs and non-RCTs may better be separately pooled ( Fig. 1a, b). Our Fig. 1 a and b show that the pooled results of RCTs and non-RCTs were not entirely consistent and subgroup analyses significantly decreased the heterogeneity, which suggested that the heterogeneity may originate from pooling studies with the different design. While we found that the pooled results of RCTs were even more biased in favor of HFNC than non-RCTs.Second, using the standardized mean difference as the summary statistic for the meta-analyses of PaO 2 and respiratory rates may be improper. The standardized mean difference is utilized as the summary statistic in the meta-analysis when the trials all assess the same outcome, but measure it in various ways [3]. Moreover, the standardized mean difference is unitless, which only shows the difference in a relatively measurement scale rather than a real difference in variability [3]. Therefore, the mean difference may better be used as the summary statistic to pool data (Fig. 1a, b).Third, trial sequential analysis for comparison of postextubation respiratory failure between two groups may better be drawn based on the accurate relative risk reduction (RRR) of 37.17% ( 118 534 − 74 533 118 534). Then, Fig. 1c is drawn to show that the line of cumulative Z-curve neither crossed the line of the trial sequential monitoring boundary for benefit nor the required information size boundary, which established inconclusive evidence [4]. But in the authors' Figure S7, the line of cumulative Z-curve obviously crossed the line of the trial sequential monitoring boundary for benefit, which may mislead the interpretation because of the inaccurate trial sequential analysis. Therefore, the figure of trial sequential analysis may better be not drawn based on a rough estimated RRR. Thank you very much for giving us the opportunity to respond to the valuable comments pointed out by Meng-Si Luo and colleagues with regard to our study [1].First, randomized controlled trials (RCTs) and crossover studies were not pooled together for primary outcome and main secondary outcomes in our article, only pooled together for secondary outcomes of respiratory rate, PaO 2 , and comfort score. According to the guidelines described in the Cochrane Handbook for Systematic Reviews of Interventions, quasi-RCTs and cross-over studies can be included for analysis, particularly when few RCTs addressing the topic of the review are identified [3]. Furthermore, for resolving the potential bias

Early prediction of high flow nasal cannula therapy outcomes using a modified ROX index incorporating heart rate

“…It is an attractive alternative to non-invasive ventilation (NIV) or conventional oxygen therapy because of its reported advantages in patient comfort, improved oxygenation, and decreased work of breathing in respiratory failure [3][4][5]. HFNC may also be used to reduce the rate of respiratory failure following a planned extubation [6][7][8][9]. Along with the growing use of HFNC, there is a need to improve early prediction of HFNC failure as delayed intubation is associated with increased mortality [10][11][12].…”