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Computerized single-breath nitrogen washout: predicted values in a rural French community
D B Teculescu1, M C Damel, E Costantino
1Unité 420 de l'INSERM, Faculté de Médecine, Vandoeuvre-lès-Nancy, France.
Lung
|January 1, 1996
Summary
Computerized lung function tests show differences in measurements. The single-breath nitrogen washout test has a high failure rate in field surveys, limiting its use for epidemiologic studies.
Area of Science:
- Pulmonary Physiology
- Respiratory Medicine
- Epidemiology
Background:
- Manual and computerized methods for measuring lung function parameters like alveolar nitrogen slope and closing volumes show systematic differences.
- Standardized conditions are crucial for computerized systems used in field surveys to obtain reliable predicted values.
Purpose of the Study:
- To establish prediction equations for alveolar nitrogen slope (PIII), closing volume to vital capacity ratio (CV:VC), and closing capacity to total lung capacity ratio (CC:TLC) in a healthy population.
- To assess the feasibility and failure rate of the single-breath nitrogen washout (SBN2) test in a field survey setting.
Main Methods:
- 158 healthy subjects (ages 21-64) from a rural, non-polluted area underwent single-breath N2 washout maneuvers.
- Alveolar nitrogen slope (PIII), CV:VC ratio, and CC:TLC ratio were measured and regressed against age, height, weight, and BMI.
- Prediction equations with 95% confidence intervals were computed.
Main Results:
- PIII increased with age in both sexes and tended to decrease with height in males.
- CV:VC and CC:TLC ratios were dependent on age and, in males, increased with BMI.
- A high failure rate (53.7%) was observed for the SBN2 test, even with a 15% tolerance for vital capacity variation.
Conclusions:
- Age and BMI are significant factors influencing lung function parameters measured by SBN2.
- The high failure rate of the SBN2 test in field surveys poses a significant limitation for its use in epidemiologic studies, particularly with older, naive populations.
