Pulmonary airway resistance variability in normal biologic quality control subjects among pulmonary function testing systems across British Columbia

Introduction: The College of Physicians and Surgeons of British Columbia’s Diagnostic Accreditation Program (DAP) is responsible for accrediting pulmonary function laboratories (PFL) throughout the province. Currently there are no recommendations by professional societies on the target coefficient of variability (CV) for airway resistance (Raw) and/or specific conductance (sGaw) in biological quality control subjects (BioQC). There are two techniques currently being used in the clinical measurement of Raw and sGaw: panting {P) and tidal breathing (TB). Our aim is to characterize the variability in BioQC normals using these two techniques. Methodology: We analyzed the BioQC data submitted to DAP over a six-month period (168 test sessions) from the laboratories performing and reporting Raw/sGaw values. Results: Eighteen PFL reported Raw/sGaw data using 28 body plethysmographic (BP) testing systems. Eighteen PF systems used the P technique, whereas 10 reported using the TB technique. Summary: The ATS-ERS Lung Volume standard recommends at least monthly BioQC testing, but gives no guidance on Raw/sGaw testing methodology and/or target CVs. It appears from these data a CV < 10% would be an acceptable Raw/sGaw target in BioQC subjects. It also appears the P technique has overall less variability and CV than the TB method. This data might be helpful for laboratories implementing a BioQC quality assurance program.