Raw data of paper entitled: "Peripheral oxygenation in heart failure patients with periodic breathing: insights from NIRS"

Background. Periodic breathing (PB) is characterized by cyclic fluctuations in ventilation and expired gases. PB is observed at rest or during exercise and is a marker of poor prognosis. In this study we investigated whether PB affects oxygen availability in peripheral muscles. Materials and Methods. This pilot, prospective, single-center study enrolled severe reduced ejection fraction heart failure (HF) patients exhibiting PB. Oxygenated (O2Hb) and deoxygenated hemoglobin (HHb) in the quadriceps femoralis were measured using near-infrared spectroscopy (NIRS), along with ventilation and expired gases. NIRS and ventilation data were collected at rest and analyzed for cyclic patterns. Clinical evaluations, including cardiopulmonary exercise test (CPET) and echocardiography, were performed. The Metabolic Exercise Combined with Cardiac Kidney Indexes (MECKI) score was used for prognosis evaluation. Results. Twenty HF patients with PB were evaluated. NIRS revealed two distinct periodic behaviors: in 7 patients, O2Hb and HHb fluctuated in-phase; in 13, they were out-of-phase. In-phase patients had higher left ventricular ejection fraction, lower LV volumes, and lower BNP and soluble interleukin 1 receptor-family member ST2 concentrations. Out-of-phase patients had more severe HF, with longer, less variable cycles and a higher MECKI score. Six of 13 out-of-phase patients died within 6 months, compared to 2 of 7 in-phase patients. Conclusion. PB is associated with distinct peripheral oxygenation patterns, potentially representing disease progression stages. In-phase O2Hb and HHb suggest blood flow cycling, while out-of-phase behavior suggests periodicity in ventilation/perfusion mismatching. These findings provide novel insights into the dynamic effects of PB on peripheral oxygenation.