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School of Biomedical Engineering, Science & Health Systems BIOMEDICAL SIGNALS & SYSTEMS RESEARCH Impedance Cardiography for Non-invasive Monitoring of Hemodynamics Impedance cardiography (ICG) is a safe, affordable, non-intrusive, and non-invasive technology that has special significance in its application to monitoring of the heart. As a cardiac diagnostic tool, this technology measures continuously any electrical impedance changes that occur throughout the thorax in response to changes in blood flow resulting from each and every heartbeat. P R O G R A M O V E R V I E W Gastroscope Non-invasive Monitoring of Gastric Contractility The Gastroscope is proposed as the only non-invasive system for measuring and monitoring the myoelectrical activity of the stomach. This will be achieved by placing electrodes on the abdominal surface and recording the signals preceding gastric activity. The Gastroscope is designed specific to this task and will incorporate electronic components for extracting and manipulating pre-determined frequency components of importance. The system will be programmed for signal processing techniques and mathematical computations for revealing specific information visually to a medical professional operating the device. 3.3 cpm 12 dB fEGG= 27 dB POWER MENU E Faculty: Dr. Hun H. Sun, Ph.D., Drexel University; Dr. Han C. Ryoo, Ph.D., Drexel University. Collaborating Researchers: Dr. Ata Akin, Ph.D., Drexel University. WWW.BIOMED.DREXEL.EDU/ResearchPortfolio/ V 2.0 SD [020204] School of Biomedical Engineering, Science & Health Systems IMPEDANCE CARDIOGRAPHY FOR NON-INVASIVE MONITORING OF HEMODYNAMICS Impedance cardiography (ICG) is a safe, affordable, non-intrusive, and non-invasive technology that has special significance in its application to monitoring of the heart. As a cardiac diagnostic tool, this technology measures continuously any electrical impedance changes that occur throughout the thorax in response to changes in blood flow resulting from each and every heartbeat. Figure 1 shows two pairs of disposable impedance electrodes positioned on a patient’s neck and thorax , as well as to an ECG lead array. The other end of the electrodes are connected to a monitor, which displays the heartbeat-induced impedance signals, as seen in Figure 2. Continuous measurement of these impedance signals makes it possible to measure, calculate, and monitor the complete cardiac cycle, including stroke volume, cardiac output, contractility parameters, and total thoracic fluid status. Figure 1 - Electrode configuration Clinical Applications Out Patient Chronic Heart Failure Hypertension Pacemaker Dialysis In Patient Critical Care Surgery / Anesthesia Emergency Care P R O J E C T O N E P A G E R Figure 2 - Monitor-displayed impedance signals An ICG measures the heart’s mechanical activity in a way similar to how an ECG measures the heart’s electrical activity. Measurement of the heart’s mechanical activity is indicated by a change in impedance over time that results from the heartbeat-induced changes in blood flow. The change in impedance over time is indicated as dZ/dt in Figure 3. Cardiac events are marked as points A, B, C, X, and O on the impedance signals in Figure 3. By using advanced signal processing techniques, these points are localized and integrated into system models (such as Kubicek or Sramek) to obtain hemodynamic information that can be used to show cardiac performance. Figure 3 - ECG phonocardiograph and impedance signals showing cardiac events The phonocardiograph signal in Figure 3 indicates the opening and closing of the heart valve, but is not used in the signal processing. Faculty/Contact: Dr. Hun H. Sun, Ph.D., Drexel University; Dr. Han C. Ryoo, Ph.D., Drexel University. E-mail: [email protected]; [email protected] Collaborating Researchers: Dr. Ata Akin, Ph.D., Drexel University. Funding: Wantagh, Inc. Laboratorie: Biomedical Information Technology Laboratory (BITLab). WWW.BIOMED.DREXEL.EDU/ResearchPortfolio/ V 2.0 SD [020204] School of Biomedical Engineering, Science & Health Systems GASTROSCOPE NON-INVASIVE MONITORING OF GASTRIC CONTRACTILITY The Gastroscope is proposed as the only non-invasive system for measuring and monitoring the myoelectrical activity of the stomach. This will be achieved by placing electrodes on the abdominal surface and recording the signals preceding gastric activity. The Gastroscope is designed specific to this task and will incorporate electronic components for extracting and Problem Statement: manipulating pre-determined A need for non-invasive monitoring of stomach activity frequency components of Ambulatory recording is required importance. The system will be Cost of diagnosing gastric motility disorders is high programmed for signal processing Follow-up tests are uncomfortable to patients techniques and mathematical computations for revealing specific information visually to a medical professional operating the device. Solution = Gastroscope Components of Gastroscope: High gain low noise amplifier Low pass filter Analog Digital Converter Digital Signal Processor Memory Display Ports for data transfer Biomedical Sensors Amplifier Fiter Memory DSP Data Transfer (PC) A D C Signal Processing of fEGG: The acquisition of myoelectrical signals of the stomach are called the Electrogastrogram (EGG). EGG signals have a dynamic range of 0.01 Hz to 2 Hz (1-120 cycles per minute, cpm). The frequency component within 2-5 cpm is called the primary/dominant signal while the high frequency components at the 50-80 cpm are called the fast EGG (fEGG) fEGG signals are correlated with the peristaltic contractions; hence the motility. fEGG signals can be extracted by using a bandpass filter with appropriate bandwidth Design of a portable handheld NIR Breast Cancer Imager Touchscreen LCD 3.3 cpm 12 dB fEGG= 27 dB POWER MENU EGG Signal Primary Signal 3 cpm Fast Fourier Transform E Secondary Signal 50 - 80 cpm Data Windowing (1 minute) Peak Detection and Corresponding Frequency Butterworth Filter Power Average Power Display and Memory Faculty/Contact: Dr. Ata Akin, Ph.D., Drexel University. E-mail: [email protected] Funding: Drexel University, Sanhill, Inc. Laboratorie: Biomedical Information Technology Laboratory (BITLab). WWW.BIOMED.DREXEL.EDU/ResearchPortfolio/ V 2.0 SD [020204] P R O J E C T O N E P A G E R