Background: The oscillometric blood pressure (BP) measurement technique estimates BPs from analyzing the envelop of oscillometric cuff pressure waveform. The oscillometric waveform envelope shape is associated with physiological changes and influences BP measurement accuracy. The aim of this study was to comprehensively quantify BP- and age-related changes of oscillometric waveform envelope characteristics.
Method: Manual systolic and diastolic BPs were measured from 472 patients (219 female, 253 male), and the cuff pressure were digitally recorded during linear cuff deflation that was used to derive oscillometric waveform envelopes. All patients were divided into different categories according to their BP level and age. The envelope width in high-pressure region (above mean arterial pressure, MAP) and low-pressure region (below MAP) were compared between different BP and age categories to qualify their changes with increased BP and aging.
Results: The envelop widths increased significantly with increased BPs (P < 0.001 between optimal, normotensive and hypertensive groups) and aging (P < 0.001 for >50 years old group in comparison with younger groups). The envelope widths in high-pressure region were significantly larger than in low-pressure region in normal and hypertensive categories (all P < 0.05) and elderly patients aged over 60 years (all P < 0.001), and the envelope width ratios between them increased with increased BP and aging.
Conclusion: This study has concluded an asymmetrical oscillometric waveform envelope in normotensive and hypertensive categories, as well as in elderly group (aged over 60 years), and their asymmetrical features were significantly more obvious with increased BP and aging.
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