There are no easily identifiable SBP and DBP points on the waveform envelope. 3Įxamination of oscillometric waveforms in Figures 1 and 2 reveals the challenge that designers of oscillometric BP devices face in attempting to determine SBP and DBP algorithmically. Disagreements over the use of phase 4 and phase 5 Korotkoff sounds have existed, but the latest guidelines from the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends phase 5 (the point before sound disappearance) for detection of DBP. The diastolic blood pressure (DBP) is the cuff pressure at which the phase 4 (muffling) or phase 5 (disappearance) of Korotkoff sounds occurs. The SBP is determined as the point at which the phase 1 Korotkoff sound is first heard. With the stethoscope placed over the brachial artery, the cuff is deflated at a rate of 3 to 5 mm Hg per second. The cuff is usually wrapped around an upper arm and inflated to about 30 mm Hg above the expected systolic blood pressure (SBP). The manual auscultatory method uses a sphygmomanometer (inflatable cuff and a manometer) and a stethoscope. This method has been used by health care professionals without substantive changes to the present time. The Korotkoff 2 method for determining systolic and diastolic pressure in 1905 marked the beginning of the auscultatory method of blood pressure (BP) determination. The era of noninvasive blood pressure (NIBP) measurement started with the introduction of the modern sphygmomanometer by Riva-Rocci 1 in 1896. The concept and significance of an oscillometric blood pressure waveform database is introduced and its applications are discussed. A finger photoplethysmograph (PPG) was used to demonstrate a potential improvement of SBP determination. Some representative oscillometric waveforms are introduced here to demonstrate the oscillometric method and its shortcomings. The authors developed a compact system for acquisition of NIBP waveforms. The issue of accuracy is becoming very important as health care professionals increasingly rely on electronic NIBP devices. Instruments for bench testing of NIBP devices are useful for some device functions, but they cannot perform dynamic accuracy tests. Several validation protocols have been developed but they are expensive and time consuming to conduct and they have their own limitations. Accuracy of oscillometric devices has been questioned and validation studies have revealed problems. While there is a general agreement about MAP determination, controversy exists about the determination of SBP and DBP. Published studies of oscillometric methodology introduced varied algorithmic approaches for determination of systolic (SBP), diastolic (DBP), and mean arterial (MAP) blood pressures. Most noninvasive blood pressure (NIBP) devices use the oscillometric method.
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