Utility of bronchoscopy in immunocompromised paediatric patients: Systematic review

Diagnostic yield of bronchoscopy in children with leukemia or post hematopoietic stem cell transplant

BACKGROUND

The utility of bronchoscopy with bronchoalveolar lavage (BAL) in immunocompromised children is not well understood. We aim to describe the bronchoscopy diagnostic yield and complications and to investigate factors associated with diagnostic yield.

METHODS

This is a single-center, retrospective cohort study of 60 children with leukemia or post-hematopoietic stem cell transplant who had a bronchoscopy with BAL between 2017 and 2021. Comparisons were done with regression analysis.

RESULTS

Of the 60 bronchoscopies performed, 46 (77%) revealed diagnostic information: 39 (65%) identified a pathogen, 14 (23.3%) found secretions/mucus plugging, and 6 (10%) found pulmonary hemorrhage. BAL results changed antimicrobial therapy in 27 (45%) cases. Bronchoscopies were performed in the intensive care unit (27/60) or operating room (33/60), with the former having a higher diagnostic yield (96% vs. 60%, p = 0.001). Half (50%) of bronchoscopies found a new infectious diagnosis. Respiratory symptoms (n = 58, 97%), supplemental oxygen use (n = 39, 65%), and antibiotic use (n = 56, 93%) before bronchoscopy were all common. The median volume of fluid instilled during bronchoscopy was 1.3 mL/kg (interquatile range [IQR]: 0.7, 2.6). None of these factors were associated with the diagnostic yield. Complications were rare and minor with only one child having self-resolved bleeding and four children, previously in room air requiring a nasal cannula. For the 27 (45%) children on mechanical ventilation when the bronchoscopy was performed, there was no difference in ventilator settings pre- and post-bronchoscopy.

CONCLUSION

Bronchoscopies with BAL are useful, safe, and important in the diagnostic management of pulmonary complications in this cohort of children.

Cellular analysis and metagenomic next-generation sequencing of bronchoalveolar lavage fluid in the distinction between pulmonary non-infectious and infectious disease

Background

The aim of the current study was to investigate the clinical value of cellular analysis and metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF) in differentiating pulmonary non-infectious and infectious diseases in immunocompetent patients.

Methods

The present retrospective study was conducted from December 2017 to March 2020, and included immunocompetent patients with suspected pulmonary infection. High-resolution computed tomography, total cell counts and classification of BALF, conventional microbiological tests (CMTs), laboratory tests and mNGS of BALF were performed. Patients were assigned to pulmonary non-infectious disease (PNID) and pulmonary infectious disease (PID) groups based on final diagnoses. PNID-predictive values were analyzed via areas under receiver operating characteristic curves (AUCs). Optimal cutoffs were determined by maximizing the sum of sensitivity and specificity.

Results

A total of 102 patients suspected of pulmonary infection were enrolled in the study, 23 (22.5%) with PNID and 79 (77.5%) with PID. The diagnostic efficiency of BALF mNGS for differentiating PID from PNID was better than that of CMTs. Neutrophil percentage (N%) and the ratio of neutrophils to lymphocytes (N/L) in BALF were significantly lower in the PNID group than in the PID group. The AUCs for distinguishing PNID and PID were 0.739 (95% confidence interval [CI] 0.636-0.825) for BALF N%, 0.727 (95% CI 0.624-0.815) for BALF N/L, and 0.799 (95% CI 0.702-0.876) for BALF mNGS, with respective cutoff values of 6.7%, 0.255, and negative. Joint models of BALF mNGS combined with BALF N/L or BALF N% increased the respective AUCs to 0.872 (95% CI 0.786-0.933) and 0.871 (95% CI 0.784-0.932), which were significantly higher than those for BALF mNGS, BALF N%, and BALF N/L alone.

Conclusions

BALF N% ≤ 6.7% or BALF N/L ≤ 0.255 combined with a negative BALF mNGS result can effectively distinguish PNID from PID in immunocompetent patients with suspected pulmonary infection. BALF mNGS outperforms CMTs for identifying pathogens in immunocompetent patients, and the combination of mNGS and CMTs may be a better diagnostic strategy.