How to interpret an Exhaled Breath Condensate (EBC) test?

From the Guidelines

To read an EBC test, it is essential to understand that it measures inflammatory markers in exhaled breath condensate, which helps diagnose and monitor respiratory conditions, and the most recent guidelines recommend defining exhaled volume, collection temperature, and condenser material, as well as preventing salivary and environmental contamination 1. When interpreting EBC test results, consider the following key points:

• Look for the presence and quantity of inflammatory markers such as 8-isoprostane, hydrogen peroxide, leukotrienes, and airway pH, which indicate oxidative stress and airway inflammation 1.
• Normal results typically show minimal or no inflammation, while positive results indicate increased airway inflammation.
• The test is reported either as positive/negative or with specific numerical values depending on the laboratory.
• Higher levels of inflammatory markers suggest active airway inflammation, which occurs in conditions like asthma or chronic obstructive pulmonary disease (COPD). Some important factors to consider when reading EBC test results include:
• Collection methods: tidal breathing with a noseclip and saliva trap, defined cooling temperature and collection time, and use of inert material for condenser 1.
• Potential sources of error: salivary contamination, environmental contamination, and variations in condenser systems 1.
• Clinical context: consider EBC test results alongside clinical symptoms, medical history, and other laboratory findings, as EBC tests are most valuable as part of a comprehensive diagnostic approach. It is crucial to consult with a pulmonologist or a healthcare professional who can properly interpret the findings in the context of specific symptoms and medical history, especially if the results are abnormal or inconclusive 1.

From the Research

Understanding EBC Test Results

To read an EBC (Exhaled Breath Condensate) test, it's essential to consider the various factors that can influence the results. The EBC test is a non-invasive method used to sample airway fluid from the lower respiratory tract, providing insights into airway inflammation and pH levels.

Factors Affecting EBC Test Results

• The pH level of the EBC can be affected by oral contamination with ammonia (NH3) 2
• The presence of gastric droplets in the EBC can also influence the pH level 2
• Smoking status can impact EBC pH, with smokers tend to have more acidic condensates than non-smokers 3, 4
• The use of nose pegs during sample collection can introduce variability in EBC pH measurements 5

Interpreting EBC pH Levels

• A decrease in EBC pH has been observed in patients with asthma exacerbations 3
• In contrast, EBC pH remains relatively unchanged in patients with chronic obstructive pulmonary disease (COPD) during exacerbations 3
• However, smokers with COPD tend to have more acidic EBC than non-smokers with COPD 3, 4

Limitations and Considerations

• The extreme and variable dilution of ELF (epithelial lining fluid) droplets with condensed water vapor can compromise the usefulness of EBC measurements 2
• The sources of EBC droplets and the estimation of dilution are crucial for accurate interpretation of EBC results 2
• Advanced techniques, such as metabolomic and proteomic profiling, may provide a more comprehensive understanding of inflammation pathways and mechanisms related to asthma, COPD, and asthma-COPD overlap 6