Abstract
Introduction
The 2017 ERS/ATS standards for Diffusion Capacity (DLCO) recommends performing each week or whenever problems are suspected, a DLCO simulation using a 3L syringe.
According to this standard, the measured DLCO value should be <0.166 mmol/min/kPa and the measured alveolair volume (VA) should be 3±0.3L.
Aim
To analyze VA and DLCO data from simulated DLCO measurements and determine the Quality Control (QC) limits of our rapidly responding gas analyser (RGA) system (Diffustik, Accuramed, Belgium)
Results
Mean values and standard deviations (SD) of 52 simulated DLCO measurements are shown in Table1 and Figure1
Two data points in the VA figure are outside 3SD, resp 3.37L and 3.46L, indicating an error. All DLCO measurements were within 3SD. After replacement of the flow sensor VA was resp. 3.01L and 3.07L.
| mean(m) | SD | m-2SD | m+2SD | m-3SD | m+3SD | |
| DLCO (mmol/min/kPa) | -0.013 | 0.078 | -0.168 | 0.142 | -0.25 | 0.220 |
| VA(L) | 3.117 | 0.036 | 3.045 | 3.189 | 3.01 | 3.224 |
Conclusion
Our study shows that for an acceptable simulated VA for our devices smaller QC limits (3.01-3.224L) are possible than the limits (2.7-3.3L) recommended by the ERS/ATS standard.
To properly identify DLCO system errors, each laboratory should establish their own QC limits for simulated DLCO and VA.