Lung diffusing capacity for nitric oxide and carbon monoxide: dependence on breath-hold time

Area of Science:

• Pulmonary Physiology
• Respiratory Medicine
• Diagnostic Tools

Background:

• Diffusing capacity of the lung for nitric oxide (Dlno) and carbon monoxide (Dlco) are noninvasive lung function tests.
• Methodological factors, such as breath-hold time, can affect Dlno and Dlco measurements and their reproducibility.
• Quantifying the impact of breath-hold duration is crucial for accurate interpretation of these tests.

Purpose of the Study:

• To investigate the influence of varying breath-hold times on Dlno and Dlco measurements.
• To compare these effects in healthy subjects and patients with cystic fibrosis (CF).
• To determine optimal breath-hold durations for reliable Dlno and Dlco assessments.

Main Methods:

• Simultaneous single-breath measurements of Dlco and Dlno were conducted.
• Participants included 10 healthy subjects and 10 CF patients.
• Breath-hold times of 4, 6, 8, and 10 seconds were tested using a Masterscreen PFT device.

Main Results:

• In healthy subjects, Dlno and Dlco varied significantly with breath-hold times, particularly at 4 and 10 seconds.
• Dlno, Dlco, and alveolar volume (VA) remained consistent at 6 and 8-second breath-hold times in both groups.
• Measurement variability was not dependent on breath-hold duration, with acceptable ranges observed at 6 and 8 seconds.

Conclusions:

• Breath-hold times of 6 and 8 seconds yield comparable Dlno and Dlco results in subjects with and without airway obstruction.
• Reproducibility of Dlno and Dlco measurements is acceptable within this 6-8 second range.
• Standardizing breath-hold time is essential for consistent clinical and research applications of Dlno measurements.