Daily Respiratory Research Analysis
Analyzed 83 papers and selected 3 impactful papers.
Summary
A large multicenter RCT found that high-flow nasal cannula oxygen did not reduce 28-day mortality in acute hypoxemic respiratory failure, though it modestly lowered intubation rates. Empiric azithromycin in hospitalized COVID-19 patients rapidly reshaped the upper respiratory microbiome and increased macrolide resistance gene expression without anti-inflammatory benefit. A network meta-analysis suggests pulmonary rehabilitation started within two weeks post-discharge best reduces readmissions and dyspnea, while initiation after 48 hours of admission most improves exercise capacity.
Research Themes
- Oxygen therapy strategies in acute hypoxemic respiratory failure
- Antibiotic stewardship and respiratory microbiome/resistome dynamics
- Optimal timing of pulmonary rehabilitation after COPD exacerbations
Selected Articles
1. High-Flow or Standard Oxygen in Acute Hypoxemic Respiratory Failure.
In a multicenter randomized trial of 1110 patients with acute hypoxemic respiratory failure, high-flow nasal oxygen did not reduce 28-day mortality compared with standard oxygen. High-flow oxygen modestly reduced intubation by day 28 but had a slightly higher rate of serious adverse events during spontaneous breathing.
Impact: This high-quality RCT delivers definitive evidence on a widely used therapy, clarifying that high-flow oxygen should not be expected to reduce short-term mortality in acute hypoxemic respiratory failure.
Clinical Implications: Use high-flow nasal oxygen to potentially lower intubation risk but not as a mortality-reducing strategy; protocols should balance benefits in avoiding intubation with adverse event risks and resource utilization.
Key Findings
- 28-day mortality was identical in both groups: 14.6% (81/556) with high-flow vs 14.6% (81/554) with standard oxygen (P=0.98).
- Intubation by day 28 was lower with high-flow oxygen: 42.4% vs 48.4% (difference −5.93 percentage points; 95% CI, −11.78 to −0.08).
- Serious adverse events during spontaneous breathing occurred in 2.3% with high-flow vs 1.1% with standard oxygen.
Methodological Strengths
- Large multicenter randomized design with predefined primary endpoint (28-day mortality)
- Intention-to-treat analysis with adequate sample size and clinically relevant outcomes
Limitations
- Open-label design may introduce performance bias
- Slightly higher serious adverse events in the high-flow group; generalizability may vary by setting and patient selection
Future Directions: Identify patient subgroups most likely to benefit from high-flow oxygen (e.g., based on severity, etiology), optimize escalation/weaning protocols, and evaluate combined strategies (e.g., awake prone positioning) and cost-effectiveness.
BACKGROUND: Data are needed on the effect of oxygen delivered through a high-flow nasal cannula, as compared with standard oxygen therapy, on intubation and mortality in patients with acute hypoxemic respiratory failure. METHODS: In this multicenter, open-label trial, we randomly assigned patients who had acute hypoxemic respiratory failure to receive high-flow-oxygen or standard-oxygen therapy. All the patients had a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen of 200 or less, a respiratory rate of more than 25 breaths per minute, and pulmonary infiltrate on chest imaging. The primary outcome was death by day 28. RESULTS: A total of 1116 patients underwent randomization. Of these patients, 1110 (556 in the high-flow-oxygen group and 554 in the standard-oxygen group) were included in the analysis. Mortality at day 28 was 14.6% (in 81 of 556 patients) in the high-flow-oxygen group and 14.6% (in 81 of 554 patients) in the standard-oxygen group (difference, -0.05 percentage points; 95% confidence interval [CI], -4.21 to 4.10; P = 0.98). The incidence of intubation by day 28 was 42.4% (in 236 of 556 patients) in the high-flow-oxygen group and 48.4% (in 268 of 554 patients) in the standard-oxygen group (difference, -5.93 percentage points; 95% CI, -11.78 to -0.08). Serious adverse events (cardiac arrest or pneumothorax) occurred during spontaneous breathing in 13 patients (2.3%) in the high-flow-oxygen group and in 6 patients (1.1%) in the standard-oxygen group. CONCLUSIONS: Among patients with acute hypoxemic respiratory failure, the use of oxygen delivered through a high-flow nasal cannula did not significantly reduce mortality at day 28. (Funded by the French Ministry of Health and Fisher and Paykel Healthcare; SOHO ClinicalTrials.gov number, NCT04468126.).
2. Empiric azithromycin alters the upper respiratory microbiome and resistome without anti-inflammatory benefit in COVID-19.
In hospitalized COVID-19 patients, empiric azithromycin rapidly shifted upper respiratory microbiome composition and increased MLS resistance gene expression within one day, persisting for over a week, without detectable anti-inflammatory benefit. Findings were observed relative to no-antibiotic and other-antibiotic controls using longitudinal metatranscriptomics.
Impact: This large, multi-centre, omics-driven study provides real-world evidence that empiric azithromycin can promote macrolide resistance in the respiratory tract without anti-inflammatory gain, directly informing antimicrobial stewardship.
Clinical Implications: Avoid empiric azithromycin for viral respiratory infections such as COVID-19 unless clear bacterial indications exist; prioritize diagnostic stewardship and narrow-spectrum, targeted therapy to limit resistance emergence.
Key Findings
- Azithromycin altered upper respiratory microbiome composition compared with no-antibiotic and other-antibiotic groups.
- Expression and relative abundance of MLS resistance genes increased after 1 day of azithromycin and persisted for over a week.
- No differences in host inflammatory gene expression in blood or airways were detected despite microbiome/resistome shifts.
Methodological Strengths
- Prospective multicentre cohort with longitudinal metatranscriptomics
- Comparison across azithromycin, no-antibiotic, and other-antibiotic groups to control for indication effects
Limitations
- Observational design with potential residual confounding by indication and disease severity
- Focused on hospitalized COVID-19 and upper airway samples; generalizability to outpatients and lower airway may be limited
Future Directions: Validate findings in other viral respiratory infections, quantify clinical outcome impacts of microbiome/resistome shifts, and test stewardship interventions that minimize resistance while preserving outcomes.
Azithromycin is a widely used antibiotic and was frequently used to treat hospitalized patients during the COVID-19 pandemic. The impact of empiric azithromycin use on the respiratory microbiome in patients with viral respiratory infections is unclear. Here we used longitudinal metatranscriptomics on nasal swabs from a prospective multicentre cohort of 1,164 patients hospitalized for COVID-19. We compared the upper respiratory microbiome, resistome and systemic immune response in patients treated with azithromycin (n = 366) with those who received no antibiotics (n = 474) or other antibiotics (n = 324). We found that azithromycin altered microbiome composition and increased the expression and relative proportion of macrolide/lincosamide/streptogramin (MLS) resistance genes. These changes occurred after 1 day of exposure and persisted for over a week. MLS resistance gene expression was associated with commensals and potential pathogens, while there were no differences in host inflammatory gene expression in blood and airways. This demonstrates that empiric azithromycin treatment impacts the upper respiratory microbiome and resistome without apparent anti-inflammatory benefit.
3. The timing of the commencement of pulmonary rehabilitation in hospitalized patients with acute exacerbation of COPD: a systematic review and network meta-analysis.
Across 26 RCTs (n=1,800), initiating pulmonary rehabilitation within two weeks post-discharge best reduced readmissions, dyspnea (mMRC), and improved quality of life (SGRQ), while starting after 48 hours of admission most improved 6-minute walk distance. No timing strategy altered mortality, FEV1%, or dyspnea on the Borg scale.
Impact: This network meta-analysis synthesizes randomized evidence to resolve a key implementation question in COPD care, offering actionable timing recommendations that can shape clinical pathways and guidelines.
Clinical Implications: Adopt a pragmatic pathway: initiate in-hospital pulmonary rehabilitation after 48 hours to boost exercise capacity, and ensure a structured program begins within two weeks post-discharge to reduce readmissions and dyspnea and improve quality of life.
Key Findings
- PR initiated within two weeks post-discharge ranked best for reducing readmissions, improving SGRQ, and lowering mMRC versus usual care.
- PR initiated after 48 hours of hospital admission ranked best for improving 6-minute walk distance.
- No significant differences across initiation timings for mortality, predicted FEV1%, or dyspnea on the Borg scale.
Methodological Strengths
- Prospectively registered (PROSPERO) systematic review with network meta-analysis of RCTs
- Standardized quality/risk-of-bias assessment (TESTEX and Cochrane ROB 2)
Limitations
- Heterogeneity in PR content, intensity, and adherence across trials
- Timing categories may overlap and patient selection criteria varied, potentially affecting comparability
Future Directions: Conduct head-to-head, adequately powered RCTs testing integrated in-hospital plus post-discharge PR pathways, with standardized protocols and longer-term outcomes including exacerbations and healthcare utilization.
BACKGROUND: Pulmonary rehabilitation (PR) is an effective intervention for patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) following hospitalization. However, the optimal timing for initiating PR after admission remains controversial. This study conducted a systematic review and network meta-analysis to evaluate the therapeutic effects of initiating PR at different time points, with the aim of providing evidence-based recommendations to inform clinical decision-making and guideline development. METHODS: Randomized controlled trials (RCTs) on PR following AECOPD were systematically searched in the PubMed, Embase, Web of Science, and Cochrane Library databases. The primary outcome was hospital readmissions. Prespecified secondary outcomes were: exercise capacity (six-minute walk test, 6MWT), lung function (forced expiratory volume in one second, percent predicted, FEV₁%), health-related quality of life (St. George's Respiratory Questionnaire, SGRQ), Dyspnoea (modified Medical Research Council scale, mMRC; modified Borg scale, mBorg), mortality, and adverse events. Data analysis was conducted using R software and Stata. Study quality and risk of bias were assessed using the TESTEX tool and the Cochrane ROB 2 tool. This study was prospectively registered in the PROSPERO database (CRD42024550770). RESULTS: A total of 26 studies involving 1,800 patients evaluated four PR initiation time points. Network meta-analysis showed that PR initiated within 2 weeks after discharge was statistically effective in reducing hospital readmissions, alleviating mMRC, and improving SGRQ compared with usual care, and it ranked highest for these outcomes. In contrast, initiating PR after 48 h of hospital admission was statistically effective in improving 6MWT and ranked highest for this outcome. No statistically significant differences were observed across initiation timings for mortality, predicted FEV₁%, or dyspnoea mBorg scale. CONCLUSIONS: Initiating PR within two weeks post-discharge is most effective for reducing readmissions, alleviating dyspnoea, and enhancing quality of life, whereas initiating after 48 h of admission provides greater benefits for improving exercise capacity. These findings support a pragmatic rehabilitation pathway combining early in-hospital and structured post-discharge PR. Further high-quality RCTs are needed to confirm optimal timing strategies.