European reference equations for CO and NO lung transfer

Area of Science:

• Pulmonary Physiology
• Respiratory Medicine
• Gas Exchange

Background:

• Accurate reference equations are crucial for interpreting lung function tests.
• Previous studies show variability in gas transfer measurements, but reasons are unclear.

Purpose of the Study:

• To establish reference equations for lung transfer of carbon monoxide (T(L,CO)) and nitric oxide (T(L,NO)).
• To investigate factors influencing these transfer measurements, including age, height, sex, and geographic location.
• To derive capillary lung volume (V(c)) and membrane diffusing capacity (D(m)) for both gases.

Main Methods:

• Single-breath technique used to measure T(L,NO) and T(L,CO) in 303 individuals (18-94 years).
• Measurements conducted in two distinct cities to assess localization effects.
• Derived parameters included V(c), D(m,CO), and D(m,NO) using the Roughton-Forster equation.

Main Results:

• Lung transfer of both gases depended on age, height, sex, and location.
• Transfer decline accelerated after age 59.
• Normalized transfers (T(L,NO)/V(A) and T(L,CO)/V(A)) were solely age-dependent.
• Mean T(L,NO)/T(L,CO) was 4.75 and D(m)/V(c) was 6.17 min(-1)kPa(-1), independent of covariates.
• Recommended coefficients for the Roughton-Forster equation were provided.

Conclusions:

• Lung gas transfer reference values are influenced by population characteristics, not solely measurement methods.
• Age, height, sex, and location are significant factors in T(L,CO) and T(L,NO).
• The study provides recommended coefficients for deriving D(m) and V(c) for both gases.