SESSION TITLE: Physiology/PFTs/Rehabilitation Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 29, 2014 at 01:30 PM - 02:30 PM
PURPOSE: The 6-minute walk test (6MWT) is not intended to document oxygen (O2) desaturation during exertion but is often used for this purpose. Because of this, it only has modest reproducibility in determining the need for ambulatory O2 therapy in patients with cardiopulmonary disease. The diagnostic and prognostic value of detecting exertional O2 desaturation is still unknown. Our aims were to determine the prevalence of exertional O2 desaturation and whether pulmonary function tests (PFT) can predict the occurrence of O2 desaturation during a 6MWT.
METHODS: This retrospective cohort study reviewed the results of 6MWT and PFT of patients who were being evaluated for dyspnea and suspected cardiopulmonary disease at an academic medical center. The patients were categorized into 3 groups based on the change in SpO2 from start to end of the 6MWT: (1) decreased SpO2 (D £ -4%); (2) no change in SpO2 (-4% < D < +4%); and increased SpO2 (D ³+4%). Demographic, anthropometric, and lung function measurements were analyzed to determine which factors predicted O2 desaturation during 6MWT.
RESULTS: Of the 329 patients who underwent PFT and 6MWT from November 2005 until December 2010 (mean age= 54±0.78 years, 63% women, BMI = 29.55±8.10 kg/m2, FEV1=1.95±0.05 L), only 60 (18%) exhibited decreased SpO2 while 146 (44%) had no change and 113 (34%) had increased SpO2. Our bivariate analysis found age, 6MWT distance, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and diffusion capacity (DLCO) differed significantly among the 3 groups (p<.05). Multivariate logistic regression analysis revealed that only DLCO was a significant predictor of O2 desaturation in patients undergoing 6MWT. Receiver operating curve analysis revealed that an optimal DLCO cut-off of 45.5% of predicted is 80% sensitive and 70% specific in identifying O2 desaturators.
CONCLUSIONS: DLCO is the only significant independent predictor of O2 desaturation in patients with dyspnea and suspected cardiopulmonary disease.
CLINICAL IMPLICATIONS: A DLCO cut-off of 45% may be useful in identifying patients at risk for exertional hypoxemia.
DISCLOSURE: The following authors have nothing to disclose: Raghav Gupta, Gregg Ruppel, Joseph Espiritu
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