Computerized single-breath nitrogen washout in children: variability and reproducibility

Area of Science:

• Pediatric Pulmonology
• Respiratory Physiology
• Medical Device Technology

Background:

• The single-breath N2 test is a valuable tool for assessing lung function.
• Computerized systems offer potential for standardized and efficient lung function analysis.
• Understanding the reliability of these tests in children is crucial for epidemiological research.

Purpose of the Study:

• To evaluate the short-term and long-term reproducibility of lung function variables derived from a computerized single-breath N2 test.
• To assess the variability of these measurements in healthy children aged 10-16 years.
• To determine the suitability of computerized single-breath N2 testing for pediatric epidemiological studies.

Main Methods:

• A computerized system was used to perform single-breath N2 tests on 56 healthy children (aged 10-16 years).
• Variability and reproducibility were assessed over 1-hour and 2-week intervals.
• Key lung function variables including vital capacity, total lung capacity, residual volume, phase III N2 slope, and closing volume were analyzed.

Main Results:

• Vital capacity and total lung capacity showed low variability (CV < 3%) and good reproducibility.
• Residual volume and phase III N2 slope demonstrated moderate variability (9-13%) with satisfactory reproducibility.
• Closing volume exhibited very high variability (>50%), with the computer algorithm failing to identify it in 18.3% of trials. Reproducibility of closing volume was poor, potentially due to methodological factors.

Conclusions:

• Computerized single-breath N2 testing yields reliable static lung volumes and phase III N2 slope in children.
• Closing volume measurements are not reliable or reproducible in this pediatric population using the evaluated system.
• The system is suitable for epidemiological studies focusing on static lung volumes and phase III N2 slope in children, but not for closing volume.