PT  - JOURNAL ARTICLE
AU  - Hegewald, Matthew J
AU  - Markewitz, Boaz A
AU  - Wilson, Emily L
AU  - Gallo, Heather M
AU  - Jensen, Robert L
TI  - Single-Breath Diffusing Capacity for Carbon Monoxide Instrument Accuracy Across 3 Health Systems
AID  - 10.4187/respcare.03512
DP  - 2015 Mar 01
TA  - Respiratory Care
PG  - 430--436
VI  - 60
IP  - 3
4099  - http://rc.rcjournal.com/content/60/3/430.short
4100  - http://rc.rcjournal.com/content/60/3/430.full
AB  - BACKGROUND: Measuring diffusing capacity of the lung for carbon monoxide (DLCO) is complex and associated with wide intra- and inter-laboratory variability. Increased DLCO variability may have important clinical consequences. The objective of the study was to assess instrument performance across hospital pulmonary function testing laboratories using a DLCO simulator that produces precise and repeatable DLCO values. METHODS: DLCO instruments were tested with CO gas concentrations representing medium and high range DLCO values. The absolute difference between observed and target DLCO value was used to determine measurement accuracy; accuracy was defined as an average deviation from the target value of < 2.0 mL/min/mm Hg. Accuracy of inspired volume measurement and gas sensors were also determined. RESULTS: Twenty-three instruments were tested across 3 healthcare systems. The mean absolute deviation from the target value was 1.80 mL/min/mm Hg (range 0.24–4.23) with 10 of 23 instruments (43%) being inaccurate. High volume laboratories performed better than low volume laboratories, although the difference was not significant. There was no significant difference among the instruments by manufacturers. Inspired volume was not accurate in 48% of devices; mean absolute deviation from target value was 3.7%. Instrument gas analyzers performed adequately in all instruments. CONCLUSIONS: DLCO instrument accuracy was unacceptable in 43% of devices. Instrument inaccuracy can be primarily attributed to errors in inspired volume measurement and not gas analyzer performance. DLCO instrument performance may be improved by regular testing with a simulator. Caution should be used when comparing DLCO results reported from different laboratories.