Adaptive servo ventilation reduces central sleep apnea in chronic heart failure patients: beneficial effects on autonomic modulation of heart rate.
Adaptive servo ventilation (ASV) is a method of ventilator support aimed to treat central sleep apnea (CSA). We investigated the effects of an acute use of ASV in chronic heart failure (CHF) patients with CSA and the potential influence on sympathetic nerve activity. Patients were studied with ambulatory cardio-respiratory 24 Holter (Somtè) recording of air flow, ECG and oxygen saturation. Comparison before and after ASV treatment was made for apnea index (AI), apnea-hypopnea index (AHI), pulse oxygen saturation, desaturation related to apnea, heart rate (HR) and heart rate variability (HRV). Seventeen patients were enrolled. At baseline, apnea index and apnea-hypopnea index were, respectively, 16.92 ± 7.8 and 41.37 ± 17.5. During ASV, they significantly decreased to 0.06 ± 0.0 (P < 0.001) and 2.84 ± 1.1 (P < 0.001). The mean and minimal oxygen saturation (%) increased from 94 ± 1 and 86.5 ± 4 to 95 ± 2 (P = 0.04) and 91 ± 2 (P = 0.008). Mean HR decreased from 68 ± 10 to 62 ± 7 beats/min (P < 0.003). In 11 out of 17 patients, HRV was calculated, documenting a significant improvement of the standard deviation of the average of NN - normal sinus to normal sinus (SDANN), standard deviation of NN intervals (SDNN) and SDNN index (respectively, 71.5 ± 31.1 vs. 80.4 ± 36.1, P = 0.008; 99.7 ± 31.3 vs. 112.7 ± 37.5, P = 0.003; 57.8 ± 20.7 vs. 69.3 ± 30.8, P = 0.03). The acute use of ASV is effective on CSA by increasing oxygen saturation and reducing HR. Moreover, the significant improvement of HRV highlights ASV's benefit in moderating the sympathetic adrenergic tone.