Abstract 2477: Repetitive Apneic Events Augment Arterial Blood Pressure Fluctuation in Patients with Central and Obstructive Sleep Apnea Syndrome

Background: Sleep apnea-hypopneas induce transient increases in arterial blood pressure (BP). We test the hypothesis that periodic nocturnal apneic events augment those hemodynamic responses in patients both with central and obstructive sleep apnea syndrome (SAS). Methods: Eleven patients with central SAS (CSAS: mean age 70 ± 10 years), 11 patients with obstructive SAS (OSAS: mean age 64 ± 12 years), and 8 normal controls (Control) were studied. Polysomnography was performed and BP was measured on a beat-by-beat basis by finger plethysmography all through the sleep. Severity of SAS was assessed by apnea-hypopnea index (AHI). The degree of BP fluctuation associated with periodic nocturnal apnea-hypopnea was assessed by spectral analysis of mean BP variability. Spectral plots of mean BP were calculated in 2-min segments using a maximum entropy method. Power spectrum of mean BP variability was quantified by measuring the area in the very-low-frequency band which coincides with frequency of apnea-hypopneas (sleep apnea band: 0.01– 0.03 Hz), and was normalized by dividing by the total power in the spectrum up to 0.4 Hz. Results: AHI was similar in CSAS and OSAS (38.3 ± 9.5* and 39.8 ± 11.3*, *p<0.05 vs. Control: 2.5±1.6*). Repetitive fluctuations in BP coincided with periodic apnea-hypopneas were clearly observed in patients with SAS, and were more prominent in CSAS (Normalized spectral power of mean BP in sleep apnea band: 0.72 ± 0.10*† in CSAS, 0.62 ±0.13* in OSAS, and 0.46±0.07 in Control, * p<0.05 vs. Control, and †p<0.05 vs. OSAS). Conclusion: Periodic nocturnal apneic events augment blood pressure fluctuation in patients both with central and obstructive SAS.smoking.