Date: 12thOctober 2018
Time: 4:00 p.m.
Venue:ESB 244, Dept. ofElectrical Engineering
Speaker:Nabeel P M (EE13D213)
Guide:Dr. Mohanasankar Sivaprakasam
Dr. Jayaraj Joseph (Co Guide)
Non-invasive assessment of blood pressure (BP) at the brachial artery by sphygmomanometry is the conventional method for prediction of various pathologies of clinical importance. Despite the wide use of brachial diastolic and systolic BP values in clinical diagnostic practice, these BP estimates are poor surrogates for central BP (aortic or carotid) that most target organs experience.Direct measurement of central BP parameters using cuff-type manometers is impractical due to methodological issues and occlusiveness.Recent advancement in technology has enabled the evolution of cuffless techniques for arterial BP measurement in a continuous and non-invasive manner. However, the accuracy and reliability of the existing cuffless techniques are not feasible for central aortic BP measurement due to several methodological issues and innate error sources. These limitations were discussed during the Seminar talk I.
This work proposesa calibration-free method and system for cuffless blood pressure (BP) measurement from superficial arteries.A novel physiological phenomenon – variation in local pulse wave velocity (PWV) over the cardiac cycle was explored to realize the calibration-free approach. Mathematical models relating BP parameters of an arterial segment to its dimensions and local PWV are introduced. A prototype device was designed and developed to estimate carotid BP – an indicator of central aortic pressure. This device utilizesa bi-modal probe employing ultrasound and photoplethysmograph sensors. It non-invasively measures the arterial dimensions and local PWV (from multiple fiducial points) at the same location on the carotid artery.Carotid systolic and diastolic BP was estimated using the measured physiological parameters without any subject- or population-specific calibration procedures. The proposed cuffless BP estimation method and system were tested for accuracy, usability and for potential utility in hypertension screening, on a total of 83 subjects.The study results clearly indicate the potential of the developed bi-modal probe and measurement system in measuring BP and local arterial stiffness indices at the carotid artery in a cuffless manner, and its potential for hypertension screening and management.