219 - Mild to Moderate Hypoxemia among Stable Heart Failure Patients with Reduced Ejection Fraction: 24-hour Oxygen Monitoring

Abstract

Introduction: Chronic heart failure (HF) patients with reduced ejection fraction experience dyspnea from fluid overload that may result in hypoxemia. Undetected hypoxemia may lead to fatigue, and reduced physical and cognitive performance reported by HF patients. Thus, understanding hypoxemia is critical to guide HF management, which may improve health outcomes. Aims: The primary aim was to compare 24-hour oxygen saturation (SpO2) between HF patients with optimal medical therapy and age-matched healthy participants. The secondary aim was to evaluate perceived physical function capacity and quality of life as correlates of SpO2 in the HF patients. The exploratory aim was to examine differences in 24-hour SpO2 between HF patients with NYHA classes I/II and III/IV. Methods: In this comparative study, 20 HF patients and 20 healthy adults completed 24-hour SpO2 monitoring using Nonin pulse oximetry. Inclusion criteria for HF patients were having systolic HF, LVEF <40%, and medically stable status confirmed by their HF cardiologist within past 2 weeks. Exclusion criteria included receiving oxygen therapy, having anemia, COPD, or sleep apnea. Duke Activity Status Index and Minnesota Living with Heart Failure were respectively used to measure perceived functional capacity and quality of life. Results: Mean ages were similar in HF patients and healthy adults (61 ± 16 vs. 55 ± 12 yrs, P = .256). Compared with age-matched healthy adults, HF patients had significantly higher frequency and longer duration of desaturation events, and lower average SpO2 (Fig. 1). Among the HF patients, 42% had SpO2 <95%. Oxygen saturation did not correlate with perceived functional capacity or quality of life in HF patients. Frequencies of NYHA classes were: I = 3, II=11, III=5, and IV = 1. Desaturation events did not significantly differ between NYHA classes I/II and III/IV. Post hoc analysis showed that the largest (312 ± 193) and the longest (197 ± 127 minutes) desaturation events were observed in NYHA class II. Conclusions: Despite receiving optimized medical care, HF patients still experienced mild to moderate hypoxemia. Hypoxemia may influence cognitive function by failing to supply necessary oxygen to the brain and thereby reduce the ability to perform HF self-care. Future studies need to be replicated in a larger sample with equal number of patients in each NYHA class.