A NEW METHOD TO CAPTURE SLEEP APNEA-INDUCED BLOOD PRESSURE SURGE CORRECTLY AND EFFICIENTLY: PP.32.285

Abstract

Objective: It is well known that obstructive sleep apnea (OSA) causes steep blood pressure (BP) surge while apnea episode takes place. It could be clinically meaningful to measure the BP surge as it can develop cardiovascular risks through huge and repetitive transmural pressure load. However, the OSA-induced BP surge cannot be caught correctly by ambulatory BP monitoring which measures unsynchronizedly with OSA episodes. The purpose of our study was to develop a BP monitoring system capable of precisely capturing OSA-induced BP surge. Design and Method: Block diagram of our experimental system is shown in the figure. SpO2 was continuously monitored by a pulse-oximeter. BP measurement (BPM) with an oscillometric BP monitor, HEM-770 (Omron Healthcare, Co., Ltd., Kyoto) was triggered by the PC program. We compared the performance of two PC programs; Program-1 to trigger BPM when SpO2 dropped down to a fixed threshold which was set as baseline value minus 10% and Program-2 with a variable threshold set depending on time from the last deep desaturation (drop of SpO2). Thirteen OSA patients (52±12.6 years of age, 1 female) underwent polysomnography (PSG) for two nights simultaneously with BP monitoring with the Program-1 and -2 one night each. The performance of the programs was evaluated based on the correlation between the indices related to the BP surge and AHI (severity of OSA) determined by the PSG, and the number of BPMs. Results: The correlation coefficient between the BP surge and AHI was 0.693 (p = 0.009) with the Program-1, and 0.745 (p = 0.003) with the Program-2. The correlation between the timerate (velocity of the BP surge) and AHI was not significant (r = 0.444, p = 0.13) with the Program-1 whereas that with the Program-2 significant (r = 0.585, p = 0.036). Mean number of BPMs was 60±55.0 and 36±22.7 times for the Program-1 and -2, respectively (p = 0.040). Conclusion: OSA-induced BP surge was measured more correctly and efficiently with BP measurement triggered by time-dependent threshold in SpO2 comparing to that with fixed threshold.