Ambulatory blood pressure monitoring (ABPM) and heart rate variability measurement are frequently used by general practitioners for diagnostic of various cardiovascular diseases. Coincidence of hypertension, heart failure and sleep related breathing disorders are very common. Therefore we proposed to use ambulatory blood pressure monitoring device (ABPM), as a tool, for selection of proper patients for polysomnographic examination in sleep laboratory.
Methods: Power spectral analysis of heart rate (HR) monitored together with blood pressure (BP), was performed using a ABPM device (Cardiotens 01, Meditech Budapest) in 24 adults patients. Low frequency/high frequency ratio (LF/HF), which reflects the sympatho-vagal balance, was calculated for the period of sleep versus wakefulness (S/W). Our aim was to detect changes in sympatho-vagal tone during sleep in the following groups of patients: obstructive sleep apnea syndrome (OSAS, respiratory disturbance index RDI = 43.8, arousal index ArI = 17.1), upper airway resistance syndrome (UARS-RDI = 7.4, ArI = 18.3), CPAP treated group (RDI = 6.4, ArI = 8.1) and controls.
Results: S/W ratio reflecting sympathetic activation, was lower in controls (0.59), than in patients with OSAS (0.9; p < 0.025) or UARS (2.16, p < 0.01). S/W ratio in patients treated with CPAP (0.68) was similar to controls (p = 0.38). S/W ratio correlated moderately with arousal index (r = 0.94 in group of patients with OSAS).
Conclusion: S/W ratio reflecting sympathetic activation upon arousal can be used for screening of patient with sleep related breathing disorders, as well as for assessment of CPAP treatment. ABPM with measurement of heart rate variability can detect also effectiveness of antihypertensive treatment with drugs influencing the autonomous nervous system.