The total-breath method yields higher values of DLCO and TLC than the conventional method

Area of Science:

• Pulmonary Function Testing
• Respiratory Medicine
• Cardiopulmonary Diagnostics

Background:

• The 2017 ATS/ERS guidelines recommend the rapid-gas-analyzer (RGA) or total-breath (TB) method for determining total lung capacity (TLC).
• Comparison of DLCO and TLC measurements between TB and conventional methods is crucial for clinical application.
• Evaluating the accuracy of TB-derived TLC against body plethysmography is essential.

Purpose of the Study:

• To compare single-breath diffusing capacity (DLCO) and total lung capacity (TLC) values obtained using the TB method versus the conventional method.
• To assess how TLC estimated by TB and conventional methods compares to TLC measured by body plethysmography.
• To determine the accuracy of estimating plethysmographic TLC using TB TLC and FEV1 Z-Score.

Main Methods:

• 95 individuals with COPD (GOLD grades 1-4) and 23 healthy subjects participated.
• Pulmonary function was assessed using the EasyOne Pro (for TB) and Master Screen Body (for plethysmography).
• DLCO and TLC were measured using both the TB and conventional methods.

Main Results:

• The TB method yielded significantly higher DLCO and TLC values compared to the conventional method (p<0.001).
• In healthy subjects, the ratio of TB to conventional DLCO was approximately one.
• TLC estimated by both methods was lower than plethysmography; TB method showed a smaller difference.

Conclusions:

• The TB method provides higher DLCO and TLC measurements than the conventional method, especially in COPD patients.
• TB-derived TLC can estimate plethysmographic TLC with greater accuracy than the conventional method.
• The TB method offers a potentially more accurate approach for TLC assessment in clinical practice.