![]() ![]() ![]() In serious cases, though, hypotension can result in a decreased supply of oxygen and nutrients to your brain and other essential organs, which can eventually lead to life-threatening shock. Some adults regularly have blood pressure in the hypotensive range but have no symptoms and do not require treatment. Generally, if the blood pressure reading is under 90/60 mm Hg, it is abnormally low and is referred to as hypotension. If your blood pressure is 120/80 millimeters of mercury (mm Hg) or lower, it’s considered normal. Diastolic pressure is the bottom number, showing the pressure in your arteries while your heart is filling with blood. Systolic pressure is the top, or first, number in your blood pressure reading it indicates the pressure within your arteries when your heart pumps out blood. Understanding HypotensionĪ blood pressure reading contains two numbers: systolic pressure and diastolic pressure. At times, continually low blood pressure or a sudden drop in blood pressure can lead to worrisome symptoms and even serious health problems. Ultimately, exploiting the joint time and frequency characteristics of the sounds may improve blood pressure measurement and help to assess the stiffness of the peripheral arteries.Low blood pressure, or hypotension, may be a sign of good health and of a decreased risk of heart disease. This study has demonstrated that joint time-frequency analysis of Korotkoff sounds was able to identify characteristic differences associated with the different phases classified by the expert cardiologist. Overall, the statistically significant transitions between phases were: phase I to II with increases in high frequency (224 to 275 Hz) (p < 0.01) and sound duration (49 to 98 ms) (p < 0.0001), II to III with a significant decrease in sound duration (to 37 ms) (p < 0.0001), III to IV with decreases in maximum amplitude (0.95 to 0.25), highest frequency (262 to 95 Hz), and relative high frequency energy of the sounds (0.61 to 0.10) (all p < 0.0001), and IV to V with decreases in the maximum amplitude (0.25 to 0.13) (p < 0.0002) and high frequency energy (0.10 to 0.03) (p < 0.005). In contrast, phases IV and V had the lowest amplitude and frequency components. Phase II had the greatest high frequency component and longest murmur, and was visibly the most complex phase in terms of time and frequency content. It was found that on average, phase III had the largest overall amplitude and high frequency energy. The digitized sounds were processed using a MATLAB-based short-time Fourier transform JTFA technique and differences in time, frequency and amplitude characteristics between the phases compared. We have shown that using this system the phase classification by the cardiologist is repeatable, with no significant differences found in the number of sounds allocated to phases on two separate recording assessments. A single operator recorded Korotkoff sounds from 25 healthy subjects using a measurement system comprising cardiology stethoscope, microphone, amplifier and recording system for computer sound digitization, and a MiniDisc system for playback to the cardiologist for Korotkoff phase classification. The aim of this study was to compare features associated with the different phases of the Korotkoff sounds obtained during blood pressure measurement using a joint time-frequency analysis (JTFA) technique. However, such analysis may be missing potentially useful clinical information. The frequency ranges of the sounds have already been described simply using the overall peak frequencies within each phase by Fourier methods. The sounds associated with the five classical Korotkoff phases are clinically important for measuring systolic and diastolic blood pressures. ![]()
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