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Monitoring Blood Pressure

Monitoring Blood Pressure

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Monitoring Blood Pressure

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  1. Monitoring Blood Pressure Biomedical Signal Processing

  2. Outline • Short history • Definition of Blood Pressure • What is hypertension? • Various methods used for measurements of blood pressure • How often should we measure blood pressure? • Sampling and Aliasing • New resources – An Oxford University Project Blood Pressure - Biomedical Signal Processing

  3. The first to measure BP • 1733 - Reverend Stephen Hales first to measure BP • Measured the height of a column of blood after cannulating the carotid artery in a horse with a brass pipe. I’m that good!!! Blood Pressure - Biomedical Signal Processing

  4. The first measurement of BP • The brass pipe was attached to a 12 inch glass tube • Tube was connected to the pipe via a trachea of a goose Blood Pressure - Biomedical Signal Processing

  5. A second try… • 100 years later: a mercury manometer connected to the artery was used to measure the BP • However: • Both of these methods are invasive … And maybe… a bit uncomfortable for the patient! Blood Pressure - Biomedical Signal Processing

  6. Eureka! • In late 1890s, an Italian physician – Scipione Riva Rocci invented the Sphygmomanometer Shygmo (from the Greek) => pulse Manometer => pressure meter - Consisted of a mercury column Manometer, a rubber sleeve which is filled with air, and a squeeze bag to inflate the rubber sleeve I had an idea! Blood Pressure - Biomedical Signal Processing

  7. Nowadays BP monitors Blood Pressure - Biomedical Signal Processing

  8. What is Blood Pressure? • Blood Pressure is a measurement of the force against the walls of the arteries as the heart pumps blood throughout the body • Blood pressure is measured in mmHg (millimeters of mercury) Blood Pressure - Biomedical Signal Processing

  9. What is Blood Pressure? • Blood Pressure is a measurement of the force against the walls of the arteries as the heart pumps blood throughout the body • Blood pressure is measured in mmHg (millimeters of mercury) • 1,000 Pa is about 7 mmHg! Blood Pressure - Biomedical Signal Processing

  10. What is Blood Pressure? • The blood pressure reading is taken in 2 numbers: systolic and diastolic. Measure of pressure as the heart is beating Systolic Diastolic Measure of pressure while the heart is at rest between beating Blood Pressure - Biomedical Signal Processing

  11. Hypertension • Blood pressure changes all the time: • It decreaseswhen we sleep, or when we are at rest • It increases when we are active, excited, practicing sports, stressed and nervous • Changing blood pressure is a vital part of a healthy cardiovascular system • Hypertension, or high blood pressure, happens when the blood pressure stays too high over an extended period of time: • Can cause the heart to have to work too hard and the force of the blood flow can damage your arteries, heart, kidneys, brain and eyes. Blood Pressure - Biomedical Signal Processing

  12. Hypertension Know your numbers: Blood Pressure - Biomedical Signal Processing

  13. Hypertension Hypertension depends on several factors: Gene/Environment Interactions Blood Pressure - Biomedical Signal Processing

  14. How to measure? Invasive blood pressure (IBP): • It measures the BP internally by using a sensitive IV catheter inserted into an superficial artery. This is the procedure taken where continuous BP monitoring is required. Non-invasive blood pressure (NIBP): • Auscultation • Oscillometry • Doppler (determines the flow distal to the artery) • Arterial tonometry, Arterial volume clamp are other types of NIBP measure Blood Pressure - Biomedical Signal Processing

  15. How to measure? • Non-invasive blood pressure • Auscultation • Oscillometry Mercury sphygmomanometer + stethoscope Mechanical manometer + stethoscope Blood Pressure - Biomedical Signal Processing

  16. How to measure? Blood Pressure - Biomedical Signal Processing

  17. The auscultation method Blood Pressure - Biomedical Signal Processing

  18. The auscultation method Blood Pressure - Biomedical Signal Processing

  19. The auscultation method Systolic BP Diastolic BP Blood Pressure - Biomedical Signal Processing

  20. The oscillometric method Blood Pressure - Biomedical Signal Processing

  21. The oscillometric method • It is based on the change of the magnitude of oscillation • MAP – Mean Arterial Pressure Blood Pressure - Biomedical Signal Processing

  22. The oscillometric method • It is based on the change of the magnitude of oscillation • MAP – Mean Arterial Pressure Blood Pressure - Biomedical Signal Processing

  23. How often should we measure? Lets first consider an example… MATLAB Demo Blood Pressure - Biomedical Signal Processing

  24. How often should we measure? Why is this important for blood pressure monitoring? How much does your blood pressure vary in one day? Blood Pressure - Biomedical Signal Processing

  25. How often should we measure? Why is this important for blood pressure monitoring? How much does your blood pressure vary in one day? Kotsis et al. Hypertension, 2005 Blood Pressure - Biomedical Signal Processing

  26. How often should we measure? BP Treat Treatment threshold Do not treat 24hr mean SBP DBP time 2pm 4am 8am 4am 10pm Blood Pressure - Biomedical Signal Processing

  27. How often should we measure? BP Under-sampling Treat Treatment threshold + + Do not treat 24hr mean + time 2pm 4am 8am 4am 10pm Blood Pressure - Biomedical Signal Processing

  28. How often should we measure? BP Aliasing effect Treat Treatment threshold + + Do not treat + time 2pm 4am 8am 4am 10pm Blood Pressure - Biomedical Signal Processing

  29. Under-sampling and aliasing Blood Pressure - Biomedical Signal Processing

  30. Sampling and Aliasing • Under-sampling looses (important) wave details! • It also may change the wave form/shape due to Aliasing • Sampling is a discrete observation or measurement, while Aliasing is an illusion, appearance of something that is not, due to shortcomings of sampling Blood Pressure - Biomedical Signal Processing

  31. New resources http://www.worldlifeexpectancy.com/cause-of-death/hypertension/by-country Blood Pressure - Biomedical Signal Processing

  32. Low-cost BP monitor http://code.google.com/p/ewh-bp-project/ Blood Pressure - Biomedical Signal Processing

  33. Low-cost BP monitor http://code.google.com/p/ewh-bp-project/ Blood Pressure - Biomedical Signal Processing

  34. Awards Blood Pressure - Biomedical Signal Processing

  35. Break! Blood Pressure - Biomedical Signal Processing