Effective nocturnal oxygen therapy increases circulating level of tumor necrosis factor-α in heart failure

OBJECTIVES: Tumor necrosis factor (TNF)-alpha is elevated in chronic heart failure (CHF). The cause of this increase is not well known. Several hypotheses have been investigated. Previous experimental and clinical studies detected changes in TNF circulating levels related to arterial oxygen (O2) saturation. The aim of the present study was to evaluate whether standard O2 hospital therapy affects plasma concentration of TNF-alpha in stable CHF patients. METHODS: A total of 18 patients (New York Heart Association class II and III) were enrolled and randomly assigned to two different orders of treatment: nine patients underwent a first night of O2 applied by nasal prongs and a second night of air delivered by nasal prongs, whereas the other nine patients were assigned to the contrary order of treatments (i.e. first night with air and second night with O2) in a crossover design. RESULTS: Ten patients out of 18 had O2 saturation above 95% for at least 360 min. In these ten patients, the TNF-alpha plasma level increased after O2 compared to the basal condition (delta 5.47 +/- 1.72 pg/ml; P < 0.05) whereas, in the same patients, the TNF-alpha plasma level did not change after the night with air (delta -0.05 +/- 3.03 pg/ml). A linear positive correlation (r = 0.62, P < 0.01) between minutes of O2 saturation above 95% and TNF-alpha circulating differences from basal to post-O2 therapy was found. CONCLUSIONS: Effective nocturnal hospital O2 therapy affects TNF-alpha plasma levels and the increase of TNF-alpha appears to be linearly related to the time of blood O2 saturation above 95%.