Daily Respiratory Research Analysis
Today’s top respiratory research spans perioperative risk reduction in children, contemporary burden of pneumococcal community-acquired pneumonia in U.S. adults relevant to the new 21-valent PCV (V116), and a mechanistic-prognostic link between circulating MMP-9 and COPD progression supported by Mendelian randomization. Together, these studies inform immediate practice, vaccination policy, and biomarker-driven risk stratification.
Summary
Today’s top respiratory research spans perioperative risk reduction in children, contemporary burden of pneumococcal community-acquired pneumonia in U.S. adults relevant to the new 21-valent PCV (V116), and a mechanistic-prognostic link between circulating MMP-9 and COPD progression supported by Mendelian randomization. Together, these studies inform immediate practice, vaccination policy, and biomarker-driven risk stratification.
Research Themes
- Perioperative respiratory safety in pediatric airway surgery
- Pneumococcal CAP burden and vaccine-targetable serotypes (V116)
- Biomarkers and causal pathways in COPD progression (MMP-9)
Selected Articles
1. Effect of Intravenous, Inhalational, or Combined Anesthesia Maintenance on Postoperative Respiratory Adverse Events in Children Undergoing Adenotonsillectomy (AmPRAEC): A Multicenter Randomized Clinical Trial.
In a 12-center randomized trial of 760 children undergoing adenotonsillectomy, propofol-based intravenous maintenance reduced postoperative respiratory adverse events compared with inhalational anesthesia, with combined IV–inhalational intermediate. Number needed to treat was as low as 3 versus inhalational-only. Findings support IV propofol maintenance to mitigate PRAEs.
Impact: This large multicenter RCT provides high-level evidence to change anesthesia maintenance strategies to reduce common respiratory complications in pediatric airway surgery.
Clinical Implications: For pediatric adenotonsillectomy, consider intravenous propofol maintenance (with or without inhalational agents) to lower PACU respiratory adverse events and improve perioperative safety.
Key Findings
- IV propofol maintenance had the lowest PRAE incidence (18.8%) versus IVIH (28.5%) and IH (43.4%).
- Adjusted odds of PRAE were 56% lower for IV versus IH (aOR 0.25) and 43% lower for IVIH versus IH (aOR 0.44).
- Number needed to treat to prevent one PRAE was 3 (IV vs IH) and 7 (IVIH vs IH).
Methodological Strengths
- Multicenter randomized design with large pediatric sample
- Modified intention-to-treat analysis and adjusted odds ratios
Limitations
- Likely open-label design may introduce performance bias
- Outcomes focused on PACU period; longer-term respiratory outcomes were not reported
Future Directions: Evaluate applicability to other pediatric surgeries, refine dosing strategies, and assess sustained benefits (e.g., unplanned admissions, oxygen therapy) post-discharge.
BACKGROUND: General anesthetic drugs may affect the risk of postoperative respiratory adverse events (PRAEs) in children, but the effect of anesthesia maintenance strategies on these events has not yet been widely validated. This study tested the hypothesis that anesthesia maintenance with propofol infusion in addition to inhalation anesthesia or alone would lead to a progressive reduction in the incidence of PRAEs. METHODS: This multicenter randomized clinical trial (AmPRAEC study) enrolled 760 children aged 0 to 12 yr who underwent adenotonsillectomy at 12 hospitals in China. Patients were randomly assigned to the intravenous anesthesia maintenance (IV group), the combined intravenous-inhalation anesthesia maintenance (IVIH group), or the inhalation anesthesia maintenance (IH group). Tracheal tubes were used for airway management, with all children undergoing awake extubation. The primary outcome was PRAE incidence in the postanesthesia care unit. RESULTS: A total of 760 children (median [interquartile range] age, 6 [4 to 7] years; 460 boys [60.5%]) were randomized, and 729 total samples were available for modified intention-to-treat analysis. The IV group had the lowest incidence of PRAEs (45 of 239 [18.8%]), followed by the IVIH group (70 of 246 [28.5%]) and the IH group (106 of 244 [43.4%]). Compared to the IH group, the IVIH group had a significantly lower risk of PRAEs (adjusted odds ratio [aOR], 0.44; 95% confidence interval [CI], 0.29 to 0.65; number needed to treat, 7). The IV group had significantly lower risk compared to both the IVIH group (aOR, 0.57; 95% CI, 0.36 to 0.90; number needed to treat, 6) and the IH group (aOR, 0.25; 95% CI, 0.16 to 0.39; number needed to treat, 3). CONCLUSIONS: Anesthesia maintenance with propofol infusion in addition to inhalation anesthesia or alone resulted in a progressive reduction in the incidence of PRAEs. Propofol intravenous anesthesia maintenance should be considered for children undergoing adenotonsillectomy.
2. All-Cause and Pneumococcal Community-Acquired Pneumonia Hospitalizations Among Adults in Tennessee and Georgia.
Prospective active surveillance at 3 US hospitals found 13.8% of adult CAP hospitalizations were pneumococcal, and 9.8% were due to serotypes included in the adult-targeted PCV21 (V116). Estimated incidence per 100,000 adults was 340 for all-cause CAP, 43 for pneumococcal CAP, and 30 for V116 serotypes, with highest burden in adults ≥65 years.
Impact: Provides contemporary, serotype-resolved burden estimates linking adult CAP to V116-covered serotypes, informing adult pneumococcal vaccination strategies and policy.
Clinical Implications: Supports prioritizing adult pneumococcal vaccination—particularly in adults ≥65 years—using formulations with broad serotype coverage (e.g., V116) to reduce CAP hospitalizations.
Key Findings
- 13.8% of CAP hospitalizations had evidence of pneumococcal pneumonia; 9.8% matched V116 serotypes.
- Incidence estimates (per 100,000 adults): all-cause CAP 340; pneumococcal CAP 43; V116 serotypes 30.
- Burden was consistently highest in adults aged ≥65 years.
Methodological Strengths
- Prospective active surveillance with serotype-agnostic and serotype-specific urinary antigen assays
- Incidence estimation accounting for enrollment probability and hospital market share
Limitations
- Conducted at three hospitals within two states; generalizability may be limited
- Cross-sectional surveillance design; patient-level longitudinal outcomes were not assessed
Future Directions: Broaden surveillance to diverse regions, evaluate vaccine effectiveness against hospitalization, and monitor serotype replacement under adult PCV programs.
IMPORTANCE: Although the use of pneumococcal conjugate vaccines (PCV) has reduced the overall burden of pneumococcal disease, recent measurements of pneumococcal pneumonia incidence are lacking. OBJECTIVE: To prospectively quantify the burden of pneumococcal pneumonia and to assess the potential impact of the recently approved adult-specific 21-valent pneumococcal conjugate vaccine (V116). DESIGN, SETTINGS, AND PARTICIPANTS: This cross-sectional study for prospective active surveillance included adults residing in defined catchment areas in Tennessee and Georgia hospitalized with clinical and radiographical evidence of community-acquired pneumonia (CAP) at 3 hospitals between 2018 and 2022. Data were analyzed from July 2024 to January 2025. MAIN OUTCOMES AND MEASURES: Pneumococcal etiology was determined using an on-market serotype-agnostic urinary antigen test, serotype-specific urinary antigen detection assays covering 30 serotypes, and routine clinical tests. Overall and age-stratified incidence rates for pneumonia hospitalizations were estimated accounting for the probability of enrollment and hospital market share of enrolling hospitals within the catchment area. RESULTS: Among 2016 patients hospitalized for CAP, the median (IQR) age was 60.1 (47.0-70.2) years; 726 patients (36.0%) were Black, 81 (4.0%) were Hispanic, and 1209 (60.0%) were White; 1863 patients (92.4%) lived in a community dwelling. A total of 279 patients (13.8%) hospitalized for CAP had evidence of pneumococcal pneumonia, and 198 (9.8%) had detection of serotypes included in V116. The overall estimated annual incidence of hospitalizations for all-cause CAP was 340 per 100 000 adults. The incidence of hospitalizations for pneumococcal CAP and pneumococcal CAP due to serotypes included in V116 was 43 and 30 per 100 000 adults, respectively. The burden of all-cause and pneumococcal CAP was consistently highest among adults age 65 years or older. CONCLUSIONS AND RELEVANCE: This prospective surveillance study demonstrated a large burden of hospitalizations for CAP among US adults, with the highest burden of disease among adults age 65 years or older. A sizable fraction of CAP was caused by Streptococcus pneumoniae, especially by serotypes included in V116.
3. Elevated MMP-9 Is Associated With Accelerated Lung Function Decline and COPD Development: A Prospective Cohort Study and Mendelian Randomisation Analysis.
In a 2-year prospective cohort (n=1328 baseline; 1034 followed), higher baseline plasma MMP-9 associated with chronic respiratory symptoms, severe emphysema/air-trapping, faster FEV1 decline, and spirometry-defined COPD development. Two-sample Mendelian randomization supported a causal link between MMP-9 expression and impaired lung function.
Impact: Combines prospective phenotyping with MR to implicate MMP-9 as both a prognostic biomarker and potential causal driver of COPD progression, informing therapeutic targeting.
Clinical Implications: Plasma MMP-9 may help identify adults at risk for accelerated lung function decline and COPD development; interventional studies targeting MMP-9 pathways could be prioritized.
Key Findings
- Higher baseline MMP-9 associated with chronic respiratory symptoms, severe emphysema, and air trapping on CT.
- Each SD increase in plasma MMP-9 predicted faster pre-bronchodilator FEV1 decline over 2 years.
- Two-sample Mendelian randomization indicated genetically predicted MMP-9 adversely affects lung function.
Methodological Strengths
- Prospective cohort with spirometry, CT phenotyping, and biomarker measurement
- Causal inference strengthened by two-sample Mendelian randomization
Limitations
- Two-year follow-up may undercapture long-term COPD trajectories
- Single-cohort biomarker thresholds and residual confounding remain possible
Future Directions: Validate MMP-9 thresholds for risk stratification, test MMP-9 modulation in randomized trials, and integrate with multi-omic predictors to refine COPD prognostic models.
BACKGROUND AND OBJECTIVE: The imbalance in proteases/antiproteases caused by inflammation contributes to COPD, and matrix metalloproteinase-9 (MMP-9) may play an important role. Therefore, we aimed to investigate the associations of MMP-9 with respiratory health outcomes. METHODS: This study was conducted in two parts. Firstly, we performed a prospective cohort study to investigate the association of circulating MMP-9 and respiratory health outcomes. Participants completed a questionnaire, spirometry, and chest CT, and provided blood samples at baseline. Follow-up visits were conducted annually. Study outcomes were the development of spirometry-defined COPD, lung function decline, and exacerbations. Secondly, we performed a two-sample Mendelian randomisation (MR) study to evaluate the causal effect between genetically predicted MMP-9 expression and lung function. RESULTS: Overall, 1328 participants were included in the baseline analysis, and 1034 (78%) completed the 2-year follow-up. Higher plasma MMP-9 at baseline was associated with chronic respiratory symptoms, severe emphysema, and air trapping. During the 2-year follow-up, each SD increase in plasma MMP-9 was associated with accelerated decline in pre-bronchodilator FEV