TY - JOUR T1 - Noninvasive Measurement of Carboxyhemoglobin Levels for Adjustment of Diffusion Capacity Measured During Pulmonary Function Testing JF - Respiratory Care SP - 1741 LP - 1743 VL - 52 IS - 12 AU - Anne M Mahoney AU - Claudia L Stimpson AU - Karen L Scott AU - Neil B Hampson Y1 - 2007/12/01 UR - http://rc.rcjournal.com/content/52/12/1741.abstract N2 - BACKGROUND: The diffusing capacity of the lungs for carbon monoxide (DLCO) is commonly measured during pulmonary function testing (PFT). Although adjustment of the measured DLCO for an elevated baseline carboxyhemoglobin level is recommended, carboxyhemoglobin is not routinely measured, which may reduce the accuracy of DLCO measurements. We sought to assess the utility of routine carboxyhemoglobin measurement and subsequent DLCO correction in patients referred for PFT. METHODS: We retrospectively reviewed 100 consecutive PFT results, including DLCO assessment. We used a pulse CO-oximeter (recently approved by the Food and Drug Administration) to noninvasively measure baseline carboxyhemoglobin (SpCO). We used simple descriptive statistics to compare the SpCO values. In subjects with elevated SpCO (> 2%) we adjusted the percent-of-predicted DLCO. Interpretation of DLCO was categorized according to the American Thoracic Society classification scheme for respiratory impairment. RESULTS: The self-reported smokers had higher average SpCO than did self-reported nonsmokers (1.6% vs 3.5%, p < 0.001), although 14% of nonsmokers had an elevated SpCO and 26% of smokers had normal SpCO. When the DLCO was corrected for elevated SpCO, 2 patients moved from a category of moderate impairment to mild impairment. Both were smokers. CONCLUSIONS: The noninvasive measurement of carboxyhemoglobin is easy to perform during PFT. When precise measurement of DLCO is important, noninvasive measurement of carboxyhemoglobin may be of value. If routine SpCO measurement is considered, the highest yield is among current smokers. ER -