The accuracy of systolic and diastolic blood pressure levels from oscillometric devices is difficult to assess for patients with atrial fibrillation and arterial stiffness; in such cases, changes in these levels from heartbeat to heartbeat can only be known if the actual total waveform during a test can be observed. Variation in these levels affects the accuracy of the algorithms in oscillometric devices where precision is of paramount importance according to the American College of Cardiology and the American Heart Association. Recently issued guidelines lowered the definition of high blood pressure; approximately three-quarters of men over 65 years of age meet the criterion and are diagnosed as hypertensive. A review in 2019 reported that atrial fibrillation affects approximately 3% of the general population in the U.S. and is twice as common in hypertensive patients. The actual shape and details of the arterial blood pressure waveform not only reveal variations in rhythm and in systolic and diastolic levels but has also proven to be valuable in the diagnosis of arterial stiffness and atrial fibrillation which are vital to determining the physiological status of a patient’s cardiovascular system. This research pertains to the identification of a patient’s total arterial blood pressure waveform using only the measured pulsations in the cuff of an oscillometric device.
Empirically formulated hypothetical arterial blood pressure waveforms were simulated and assumed to be unknown. Oscillometric pulsations corresponding to these simulated unknown waveforms were used as input to a new model-based extended Kalman filter algorithm for identifying the levels, shape and features of the unknown waveforms.
Simulations with hypothetical waveforms with varying systolic and diastolic levels and with variations in heartbeat rhythm associated arterial fibrillation and stiff arteries, demonstrate potential arterial pressure estimate accuracies of 1.5 mmHg with standard deviations on the order of 0.1 mmHg; in addition, variations in heartbeat rhythm were observed and degrees of arterial stiffness identified and quantified.
Computational analysis of the oscillometric cuff pulsations with the extended Kalman filter can be used to detect variations in heartbeat rhythm and blood pressure levels associated atrial fibrillation, quantify arterial stiffness, and provide noninvasive continuous blood pressure monitoring without the need for electrocardiogram or photoplethysmography sensors.
Copyright © 2020. Published by Elsevier B.V.