Blood Pressure Estimation using On-body CW Radar

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Monitoring vital signs, including blood pressure (BP), heart rate (HR) and respiratory rate (RR) continuously for ambulatory situations is constantly essential to evaluate people's physical and mental health. The BP is defined as two higher systolic BP (SBP) and lower diastolic BP (DBP) and shows the maximum contraction of the heart and the resting pressure of the heart, respectively. 

My study was developing a non-cuff-based method of determining BP based on time parameters using a combination of a continuous-wave radar (CWR) sensor on the sternum, bio-impedance (BImp) sensors across the shoulders, and a photoplethysmograph (PPG) sensor on the left earlobe.

First, two "time delay" parameters (Pre-ejection period (PEP) and pulse transit time (PAT)) were acquired. The aortic arch motions were detected by placing the CWR antennae on the sternum, which matched the PEP. The BImp sensors across the shoulders indicated the central arteries PATs, while the PPG sensors measured the peripheral arteries PATs. Then pulse transit time (PTT) were calculated by deducting the PEP from the PAT.

The technique was examined under three conditions as various postures to monitor the BP at rest situations, exercise tasks for increasing BP and spraying inconstant doses of the Glyceryl trinitrate (GTN) medication to decrease BP. Data were obtained from 41 subjects in posture tasks. Among them, 24 volunteers participated in exercise tasks, and 17 subjects undertook the GTN ones. Continuous beat-to-beat BPs using Finapres and cuff-based BPs using a Sphygmomanometer were collected during data collection as the references. Later, various regression methods were employed to estimate the BPs based on PTTs using the beat-to-beat and cuff-based BP values.

Eliminating the PEPs from the PATs (Result in PTT measurements) improves BP calculations by around 9%. A comparison is further made between the calculated BPs from the BImp-based (central arteries) PTTs and the one from PPG (peripheral) signals. The results prove that the PTTs derived from central arteries achieve higher than 3% accuracy in BP extraction than the peripheral ones.



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  • Date: 20 May 2021
  • Time: 04:00 PM to 05:00 PM
  • All times are (UTC+10:00) Canberra
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The event will be held virtually. The Zoom link will be sent out one day before the event.

  • Melbourne, Victoria
  • Australia

  • Starts 09 May 2021 12:00 AM
  • Ends 19 May 2021 12:00 AM
  • All times are (UTC+10:00) Canberra
  • No Admission Charge


  Speakers

Melika P. Ebrahim Melika P. Ebrahim

Biography:

Melika P. Ebrahim received the B.S. degree in Telecommunication/Electrical Engineering from the Ferdowsi University of Mashhad, Iran in 2009 and the M.S. degree in Biomedical Engineering from the Amirkabir University of Technology - Tehran Polytechnic in 2012. 

She is pursuing a PhD degree in Electrical Engineering at the Department of Electrical and Computer Systems Engineering, Monash University, Australia. 

Her current research interests include designing and implementing Radar device to monitor vital signs, including blood pressure, pulse rate, respiratory rate, biomedical signal processing, and health care systems.