A Comparison Between Pulmonary Function Tests and Disease Impact With Exertional Oxygen Desaturation in Patients With COPD

Abstract

SESSION TITLE: Airways 1 SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, October 26, 2016 at 01:30 PM - 02:30 PM PURPOSE: Exertional desaturation (ED) is associated with increased mortality and deleterious cardiopulmonary effects in patients with COPD. While O2 therapy during exercise has not shown a mortality benefit, it has shown to significantly boost health-related quality of life measures. The current study aims to compare the incidence of ED, its correlation with pulmonary function tests (PFTs), and its association with patient-rated disease impact as per the St. George’s Respiratory Questionnaire (SGRQ) in patients with COPD. METHODS: A retrospective chart review of 233 patients was performed in the pulmonary rehabilitation center of a major urban medical center. 105 patients were identified with primary diagnosis of COPD, not on home oxygen. PFTs were performed within 6 months of enrollment; SGRQs were completed during intake, and all patients underwent standard 6 Minute Walk Tests (6MWTs) with SaO2 recorded by pulse oximeter. A drop in SaO2 of ≥4% or SaO2 <90% was defined as ED. Analysis groups were divided into GOLD Stage I-II and III-IV, and DLCO >50% and <50%. RESULTS: In Stage I-II, 65.22% and 74.58% in Stage III-IV experienced ED (p=0.149), compared to 65.79% and 87.80% in the >50% and <50% DLCO groups (p=<0.01). DLCO had a significant inverse correlation with ED (r=-0.28; p=<0.01), while FEV1 (r=-0.04; p=0.32), and FEV1/FVC (r=-0.1; p=0.15) did not. Degree of heart rate elevation during 6MWTs showed a significant correlation with degree of ED (r=+0.23; p=<0.01). Resting SaO2 did not show a significant correlation with ED (r=+0.15; p=0.69). Stage III-IV patients endorsed significantly more symptoms (p=<0.01), more social impairment (p=0.01) and higher overall disease impact (p=<0.01) compared to Stage I-II on SGRQ, but not higher limitations in activity (p=0.18). <50% DLCO patients endorsed significantly more symptoms (p=<0.01), higher limitations in activity (p=0.04), more social impairment (p=0.02) and higher overall disease impact (p=<0.01) compared to >50% DLCO patients on SGRQ. CONCLUSIONS: Decreased DLCO may predict risk of ED in patients with COPD better than FEV1 or resting SaO2. Degree of elevation from baseline heart rate during exertion may signify risk for ED. While Stage III-IV patients endorsed more overall disease impact than Stage I-II, stratification by >50% or <50% DLCO performed better in highlighting limitations in activity. CLINICAL IMPLICATIONS: DLCO should be included in all PFTs performed in patients with COPD, and a diffusion capacity of <50% should prompt an evaluation for ED. DISCLOSURE: The following authors have nothing to disclose: Marjan Islam, Matthew Frank, Ted Marks, Corinne Rey, Jonathan Raskin No Product/Research Disclosure Information