Performing body plethysmography with low breathing frequency (< 0.5 Hz) vs. breathing frequency 0.5-1.0 Hz.

<bold>Introduction:</bold> The 2023 ERS/ATS guideline for lung volume measurements states that a body plethysmography measurement with a breathing frequency lower than 0.5 Hz (30/min) against a closed valve should be discarded. However, in our experience it is not possible for every patient, especially those with airflow obstruction, to generate a breathing frequency of 0.5-1.0 Hz. We conducted a pilot study to measure the effect of breathing frequency when determining lung volume in the body box. <bold>Methods:</bold> In 10 healthy subjects and 10 obstructive patients, the body plethysmography measurements (Masterscreen Body, Vyaire) were performed in two ways during one visit: once with low (<0.5 Hz) and once with a breathing frequency between 0.5-1.0 Hz. With the exception of breathing frequency, all measurements were performed in line with the ERS/ATS guidelines. <bold>Results:</bold> The mean difference for the Total Lung Capacity (TLC) in healthy subjects and obstructive patients (FEV1 26±8 %pred, FEV1/FVC %29±7) was -0.07±0.12 L (p 0.10) and 0.00±0.08 L (p 0.95), respectively (see Figure 1, BA-plots). <bold>Conclusion:</bold> In our pilot study, there was no clinically relevant or statistically significant difference in TLC measured with body plethysmography at low breathing frequency (< 0.5 HZ) vs breathing frequency 0.5-1.0 Hz, both in healthy subjects and obstructive patients.