SESSION TITLE: Pulmonary Physiology Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM
PURPOSE: Body mass index (BMI) affects both resting and exercise-related respiratory physiology. Diffusion capacity adjusted for alveolar volume (DLCOalv) has been reported to correlate better with gas exchange parameters on cardiopulmonary exercise testing (CPExT) than diffusion capacity (DLCO), in obese individuals. How DLCO and DLCOalv correlate with gas exchange parameters during exercise such as ventilatory equivalent for carbon dioxide (Ve/VCO2) or oxygen (VE/VO2) at anaerobic threshold and dead space-tidal volume ratio (Vd/Vt) during exercisein non-obese subjects is not known. The objective of this study was to determine the correlation between DLCO and DLCOalv with respectively, VE/VO2, VE/VCO2, and Vd/Vt at rest and exercise during CPExT, in non-obese patients.
METHODS: Records of patients with BMI < 30 who underwent CPExT for evaluation of dyspnea in our exercise test laboratory were reviewed. Parameters obtained from records included: age, gender, BMI; DLCO (%Predicted) and DLCOalv (%Predicted) from PFTs; VE/VO2, VE/VCO2; Vd/Vt at rest and exercise on CPExT. Correlation between DLCO and DLCOalv respectively with VE/VO2, VE/VCO2, Vd/Vt at rest and Vd/Vt with exercise was determined by using Pearson’s test for linear correlation. p < 0.05 was deemed statistically significant.
RESULTS: Of 57 patients with BMI <30, who underwent CPExT, 67% were females; mean age was 51+ 18 years. Mean BMI was: 24+ 3 kg/sqm. Mean DLCO was 87 + 24; mean DLCOalv was 102 + 23. The correlation coefficient (r) between studied parameters and their statistical significance are shown below: DLCO (%predicted) vs.Vd/Vt Rest ⇒ r = 0.042; p=0.7 DLCO (%predicted) vs. Vd/Vt Exercise⇒ r = -0.453; p = <0.001 DLCO (%predicted) vs.VE/VO2 ⇒r = -0.29; p = 0.0.03 DLCO (%predicted) vs.VE/VCO2 ⇒ r = -0.33; p = 0.01 DLCOalv (%predicted) vs.Vd/Vt Rest ⇒ r = -0.004; p=0.9 DLCOalv (%predicted) vs.Vd/Vt Exercise ⇒ r = -0.437; p<0.001 DLCOalv (%predicted) vs.VE/VO2 ⇒r = -0.211; p = 0.0.14 DLCOalv (%predicted) vs.VE/VCO2 ⇒ r = -0.261; p = 0.07.
CONCLUSIONS: In non-obese patients with exertional dyspnea, DLCO had a significant correlation with Vd/Vt at exercise, VE/VO2 and VE/VCO2. DLCOalv correlated only with Vd/Vt at exercise.
CLINICAL IMPLICATIONS: In non-obese subjects, DLCO is a better indicator of gas exchange than DLCOalv.
DISCLOSURE: The following authors have nothing to disclose: Antranik Mangardich, Aaron Glucksman, Debapriya Datta
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