Oxygen flow rate affects the apnea index and nocturnal sympathetic nerve activity in heart failure patients with Cheyne-Stokes respiration

Abstract

Purpose: The significance of oxygen flow rate was evaluated in nocturnal oxygen therapy to heart failure patients with Cheyne-Stokes respiration (CSR-CSA). Methods: Nine of heart failure patients with CSR-CSA (BMI 22.7 ± 3.8, EF 31.3 ± 7.6%) diagnosed by Morpheus C set TM were re-monitored under oxygen therapy with 2l/min. and 3l/min. at flow rate. Three cases were excluded due to atrial fibrillation in the analysis of sympathetic nerve activity. Results: The mean of Respiratory Disturbance Index (RDI) improved significantly by oxygen therapy from 37.9 ± 13.7 to 11.7 ± 8.2 under 2l/min. (p < 0.0001) and to 7.5 ± 9.2 under 3l/min. (p < 0.0001). Central apnea index improved significantly from 18.1 ± 14.8 to 5.6 ± 6.9 under 2l/min. (p < 0.05) to 2.5 ± 4.4 under 3l/min (p < 0.0001), while obstructive apnea index unchanged.There was also a significant difference between percent changes of apnea index (AI) (AI room air - AI oxygen/AI room air×100(%)) in both oxygen flow rate(−66.3 ± 40.3% vs −81.4 ± 28.6%, p < 0.05). The mean of LF/HF in 6 cases due to heart rate variability analysis also improved significantly even with 2l/min oxygen therapy (2.54 ± 2.38 vs 1.35 ± 0.96, p < 0.05). Conclusion: These data suggested that AI improved with oxygen therapy in flow dependent manner in heart failure patients with CSR-CSA, however sympathetic nerve activity itself might be improved even by low flow rate of oxygen therapy.