Non-Invasive Assessment of Bronchiectasis Severity Using Exhaled H2O2 Levels

Pranav Nair^*
*Correspondence: Pranav Nair, Department of Chemical Sciences and Biosensors, Indian Institute of Science Education and Research (IISER), Pune, India, Email:

Introduction

Bronchiectasis, a chronic lung condition characterized by irreversible airway dilatation, recurrent infections and persistent inflammation, poses significant challenges for clinical management due to its progressive nature and variable severity. Traditional diagnostic and monitoring methods, such as High-Resolution Computed Tomography (HRCT) and spirometry, provide valuable insights but are often invasive, costly, or limited in capturing dynamic inflammatory processes. The need for non-invasive, cost-effective tools to assess disease severity and guide treatment has driven research into biomarkers of airway inflammation and oxidative stress. Hydrogen Peroxide (H2O2) in Exhaled Breath Condensate (EBC) has emerged as a promising biomarker, reflecting oxidative stress in the airways caused by inflammatory cells like neutrophils. Elevated H2O2 levels in EBC have been associated with bronchiectasis and other respiratory diseases, offering a simple, non-invasive method to monitor disease activity. Studies have shown that H2O2 concentrations correlate with lung function impairment and inflammation, making it a potential tool for assessing bronchiectasis severity and evaluating treatment response, thus enhancing personalized patient care [1].

Description

The measurement of H2O2 in EBC involves collecting breath samples from patients using a cooled condenser system, which captures volatile and non-volatile compounds exhaled from the lungs. This non-invasive technique is straightforward, requiring patients to breathe tidally into a mouthpiece for 10-15 minutes, with the condensate analyzed using sensitive assays like colorimetric or fluorometric methods to quantify H2O2 concentrations. In bronchiectasis, elevated H2O2 levels result from increased reactive oxygen species (ROS) production by activated neutrophils and macrophages in inflamed airways. Research has demonstrated that patients with bronchiectasis exhibit significantly higher EBC H2O2 levels compared to healthy controls, with concentrations often exceeding 0.5 µM in diseased states versus less than 0.2 µM in healthy individuals. These elevated levels correlate with disease severity, as assessed by lung function parameters like Forced Expiratory Volume In One Second (FEV1) and Forced Vital Capacity (FVC). For instance, patients with severe bronchiectasis, characterized by extensive airway damage and frequent exacerbations, show higher H2O2 levels than those with milder disease. The methodâ??s reproducibility and sensitivity make it suitable for longitudinal monitoring, allowing clinicians to track changes in inflammation over time or in response to therapies like antibiotics or anti-inflammatory agents. Notably, H2O2 levels have been observed to decrease following successful treatment, suggesting its utility as a marker of therapeutic efficacy.

The clinical implications of EBC H2O2 measurement extend beyond severity assessment to understanding the pathophysiology of bronchiectasis. Oxidative stress, driven by excessive ROS, contributes to airway tissue damage, mucus hypersecretion and chronic infection, perpetuating a vicious cycle of inflammation. H2O2, as a stable ROS byproduct, serves as a direct indicator of this process. Studies have also explored factors influencing H2O2 levels, such as the use of inhaled corticosteroids, which showed no significant impact on H2O2 concentrations in bronchiectasis patients, indicating that oxidative stress may persist despite steroid therapy. This finding underscores the need for targeted antioxidant or anti-inflammatory treatments to address underlying oxidative damage. Compared to other biomarkers, like sputum neutrophil counts or serum C-reactive protein, EBC H2O2 offers advantages in ease of collection and specificity to airway processes. However, challenges remain, including standardization of EBC collection protocols and accounting for environmental factors like smoking or air pollution, which can elevate H2O2 levels. Advances in portable EBC devices and real-time H2O2 sensors could further enhance its clinical applicability, enabling point-of-care testing in outpatient settings. By integrating EBC H2O2 measurement with existing tools like HRCT and spirometry, clinicians can achieve a more comprehensive assessment of bronchiectasis, tailoring interventions to individual patient needs and improving outcomes [2].

Conclusion

The non-invasive assessment of bronchiectasis severity using H2O2 levels in exhaled breath condensate represents a significant advancement in respiratory medicine. This simple, reproducible method captures airway oxidative stress, offering insights into disease severity, progression and treatment response through elevated H2O2 concentrations that correlate with lung function impairment. Its ease of use, specificity to airway inflammation and potential for longitudinal monitoring make it a valuable complement to traditional diagnostics like HRCT and spirometry. While challenges like protocol standardization and environmental confounders require further research, the development of portable EBC devices could transform H2O2 measurement into a routine clinical tool. By providing a window into the oxidative processes driving bronchiectasis, EBC H2O2 measurement paves the way for personalized management strategies, ultimately improving patient care and quality of life in this debilitating condition.

Acknowledgement

None.

Conflict of Interest

None.

References

1. Nagaraja, C., B. L. Shashibhushan, Mohamed Asif and P. H. Manjunath. "Hydrogen peroxide in exhaled breath condensate: A clinical study." Lung India29 (2012): 123-127.

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2. Loukides, Stelios, Ildiko Horvath, Theresa Wodehouse and Peter J. Cole, et al. "Elevated levels of expired breath hydrogen peroxide in bronchiectasis." Am J Respir 158 (1998): 991-994.

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