[Normal values of functional residual capacity (author's transl)]

Area of Science:

• Pulmonary Physiology
• Respiratory Medicine
• Biomedical Engineering

Context:

• Accurate measurement of lung volumes is crucial for diagnosing respiratory diseases.
• Existing methods for measuring functional residual capacity (FRC) may have limitations.
• Establishing reliable reference values for FRC is essential for clinical interpretation.

Purpose:

• To compare different methods for measuring functional residual capacity (FRC).
• To investigate the relationship between FRC and anthropometric factors (age, height, weight) in a large cohort.
• To develop allometric equations for predicting FRC reference values.

Summary:

• Functional residual capacity (FRC) was measured in healthy subjects using helium dilution (closed and open systems) and constant pressure plethysmography, yielding comparable results.
• In 177 men and 100 women (aged 18-77 years), FRC was found to be dependent on age and height, increasing with both.
• For a given height and age, FRC decreased with increasing weight, leading to the development of allometric relationships to calculate FRC reference values.

Impact:

• Provides validated reference values for FRC, aiding in the clinical assessment of lung function.
• Demonstrates the reliability of helium dilution and plethysmography for FRC measurement.
• Establishes a basis for deriving reference values for other pulmonary function tests, such as TLCO and lung compliance.