Biomedical Engineering. Diagnostic application of biosignals. Biosignal: a description of a physiological phenomenon

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1 Biomedical Engineering Biosignal: a description of a physiological phenomenon Basic procedures for biosignal assessment from (a) visual appraisal of patient by a physician to (b) application of a biomedical sensor on the patient Model of biosignal generation, propagation, coupling, and registration. (a) Permanent biosignal. (b) Induced biosignal The biomedical sensor on the chest for the registration of body sounds. The generation phenomena of the acoustic biosignals are depicted, along biosignal s propagation, coupling, and registration Diagnostic application of biosignals The therapeutic application of biosignals could be demonstrated by functional muscle stimulation (e.g., on the leg) or functional nerve stimulation (e.g., on the ear auricle). While the stimulation (i.e., therapy) is performed by the use of electric impulses in both cases, the respective feedback is given, for instance, by electromyography or force/torque measurement to assess the muscle response in the former case and by heart rate variability to assess the response of the autonomic nervous system in the latter case.

2 Major milestones in (some) biomedical engineering Hippocrates described direct auscultation in de Morbis as If you listen by applying the ear to the chest... Galen of Pergamum (around ) described the pulsation as The feeling of the artery striking against the fingers and characterized it in many details as the worm-like pulse, feeble and beating quickly; the ant-like pulse that has sunk to extreme limits of feebleness. 1761: Dr. Leopold Auenbrugger ( ), Austrian physician, introduced the percussion technique as a diagnostic tool in medicine in Vienna, Austria. 1806: The first endoscope was developed by Philipp Bozzini in Mainz with his introduction of a "Lichtleiter" (light conductor) "for the examinations of the canals and cavities of the human body" 1808: Dr. Jean-Nicolas Corvisart ( ), French physician and primary physician of Napoleon Bonaparte, widely disseminated the technique by translating Auenbrugger s book into French. 1816: French physician Dr. Rene Theophile Hyacinthe Laennec ( ), a student of Dr. Corvisart, improved the auscultation technique by making observation with a wooden cylinder, which was primarily sought to avoid embarrassment from placing his ear next to a young woman s bare chest, so he rolled up a newspaper and listened through it, triggering the idea for his invention that led to today s ubiquitous stethoscope. 1894: A. Bianchi introduced a rigid diaphragm over the part of the (wooden) cylinder. 1895: X-ray discovered by C. Roentgen (Germany) using gas discharged tubes. 1896: Discovery of X-ray emission from uranium ore by H. Becquerel (France) 1901: Nobel Prize awarded to Roentgen for discovery of X-rays. 1903: W. Eindhoven invented the electrocardiogram (ECG). 1921: First formal training in biomedical engineering was started at Oswalt Institute for Physics in Medicine, Frankfurt, Germany. 1927: Invention of the Drinker respirator. 1929: H. Berger invents the electroencephalogram (EEG). Historical Biosignal Acquisition for Diagnoses Inspection Palpation: feeling the surface of the body with the hands to determine the size, shape, stiffness, or location of the organs beneath the skin Percussion: The sounds produced display a resonant or dull character, indicating the presence of a solid mass or hollow, air-containing structures, respectively, and may help determine the size and position of internal organs, in localizing fluid or air in the chest and abdomen, and diagnose certain lung disorders. Auscultation: The body sounds may be comprised of heart sounds due to closure of the heart valves or lung sounds due to air turbulences in the branching airways. Major milestones in (some) biomedical engineering 1930: X-rays were being used to visualize most organ systems using radio-opaque materials, refrigeration, permitted blood banks. 1931: E. Ruska and M. Knoll (Germany) constructed the prototype electron microscope s early 1940's: Antibiotics, sulfanilamide and pencillin reduced cross-infection in hospitals. 1940: Cardiac catheterization 1944: Gamma camera invented by Sir S. Curran (U.K.) 1946: Successful treatment of a patient with thyroid cancer metastases using nuclear medicine (radioiodine I-131) reported in the JAMA by S. Seidlin 1950 s early 1960 s: Nuclear medicine. 1950s Concept of emission and transmission tomography introduced by D. E. Kuhl, L. Chapman and R. Edwards 1953: Cardiopulmonary bypass (heart lung machine). 1957: B. Hirschowitz and L. Curtiss invented the first fiber optic endoscope. 1967: The first commercially viable CT scanner was conceived by Sir G. Hounsfield (U.K.) at EMI Central Research Laboratories using X-rays. 1969: Case Western Reserve created the first MD/PhD program 1971: Magnetic resonance imaging (MRI) invented by P. C. Lauterbur. 1980: Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) commercialized 1982: First artificial heart successfully implanted in a human (Jarvik-7) designed by a team inocluding W. J. Kolff and R. Jarvik. 1997: First Indigenous endovascular coronary stent (Kalam-Raju stent) developed by the Care Foundation. 2003: P. C. Lauterbur and P. Mansfield shared the Nobel Prize for MRI Hippocrates is pictured palpating a young patient

3 Surgical instruments found in Pompeii The House of the Surgeon, or Casa del Chirurgo, is situated on the east side of the Via Consolare about 50 meters inside the Herculaneum Gate. Roman surgical instruments included forceps, scalpels, catheters and even arrow extractors. The fresco shows the Iapyx removing an arrow head from the thigh of Aeneas (from the House of Siricus). Direct auscultation of body sounds, ca. early 20 th century Sketch of a figure, taken from Feer's Textbook of Pediatrics (1922), showing the direct method of auscultation being used on an infant. Title page of Corvisart translation about percussion as a diagnostic tool Drawings of the original Rene Laennec s stethoscope (France, 1816) The original Marsh binaural stethoscope, circa 1851: in its original wood box (top) and the assembled stethoscope (bottom).

4 Indirect auscultation of body sounds with Laennec s stethoscope Laennec, inventor of the stethoscope, applies his ear to the chest of a patient Problems faced by the traditional biosignal acquisition methods Proof of biosignals reproducibility Analysis of biosignals - restricted to an instantaneous and subjective impression by the physician Comparison of biosignals - restricted to a single physician and recent impressions Circulation of biosignals - lack of archives Approaches to objectify and characterize the attained biosignals Verbal descriptions Musical notes Technical tools

5 Coding of heart pulses with musical notes (Marquet 1769). (a) Natural regulated pulse. (b) Three different abnormal pulses including, from top to bottom, discontinuous pulse, irregular intermittent pulse, and irregular pulse arising in between normal pulses Biomedical Engineering: a little bit of history Dr. Willem Einthoven invented the first practical electrocardiogram in 1903 and received the Nobel Prize in Medicine in 1924.

6 The AbioCor artificial heart, an example of a biomedical engineering application of mechanical engineering with biocompatible materials for Cardiothoracic Surgery using an artificial organ. Breast implants, an example of a biomedical engineering application of biocompatible materials to cosmetic surgery. Biomedical Engineering A pump for continuous subcutaneous insulin infusion, an example of a biomedical engineering application of electrical engineering to medical equipment. An image of a whole-body scan, obtained using a radiopharmaceutical labelled with technetium-99m which collects in the bones. ges.html On the left is the first x-ray, taken in On the right is a modern equivalent. A volume rendered CT image of the pelvis and a mammogram (x-ray image of the breast).

7 A whole-body PET scan superimposed on an X-ray CT image (grey/blue on slide). In this way, doctors get the benefit of high contrast from the PET scan and good spatial resolution from the CT image. Ultrasound image of human fetus Surface rendered ultrasound images. These ultrasound images have been processed by computer to show the surface of the baby in 3D. A photograph and an x-ray image of an endoscope

8 Traditional means of biosignal acquisition in Korea?.! (2008) Images taken using an endoscope, showing a worm (left) and a polyp (right) Classification of Biosignals Biosignals classified into the existence Permanent biosignals: electrocardiogram, phonocardiogram Induced biosignals: electric plethysmography, optical oximetry Biosignals classified into the dynamic nature (Quasi) Static biosignals: e.g. core body temperature dynamic biosignals: e.g. instantaneous beat-to-beat changes of the heart rate

9 Biosignals classified into the origins Electric biosignals: electrocardiogram, electroencephalogram, electromyogram Magnetic biosignals: magnetocardiogram Mechanic biosignals: mechanorespirogram Optic biosignals: optoplethysmogram Acoustic biosignals: phonocardiogram Chemical biosignals Thermal biosignals Other biosignals The possible classifications of biosignals according to their (a) existence, (b) dynamic, and (c) origin, with indicated heart rate f C, respiratory rate f R, and additional information Trends of Biosignals Monitoring Multi-parametric + Portable/Pervasive Monitoring

10 Trends of Biosignals Monitoring B: Arterial blood pressure recording in which decreasing cuff pressure on the upper arm is recorded in parallel to sounds recorded by a microphone over the brachial artery A: Respiratory rate assessed by a respiratory belt around the thorax Future vision of physiologic monitoring including standard and novel techniques. Qualitative relationship is given between the significance and comfort of the different monitoring systems, i.e., number of physiological parameters attained versus number of sensors needed, including novel multi-parametric sensors. Trends of Biosignals Monitoring D: An acoustic body sound sensor on the chest offers for monitoring cardiac activity, respiratory activity, and breathing obstruction from a single spot Future vision of physiologic monitoring including standard and novel techniques. Qualitative relationship is given between the significance and comfort of the different monitoring systems, i.e., number of physiological parameters attained versus number of sensors needed, including novel multi-parametric sensors. Trends of Biosignals Monitoring C: sleep monitoring of a large number of brain, cardiac, and respiratory parameters with the use of the corresponding single parameter sensors for a comprehensive sleep assessment, e.g., for sleep staging. Future vision of physiologic monitoring including standard and novel techniques. Qualitative relationship is given between the significance and comfort of the different monitoring systems, i.e., number of physiological parameters attained versus number of sensors needed, including novel multi-parametric sensors. Trends of Biosignals Monitoring Single-sensor realization of the multi-parametric monitoring Novel sensor concepts, e.g., based on advances in technology as miniaturization Optimized sensor location, e.g., proximal instead of distal to increase physiological content of biosignal Type of recorded signals, e.g., optic instead of electric to get a higher spatial resolution Mutual interrelations and clinical correlations of physiologic parameters to derive, e.g., use of cardiorespiratory interrelations Advanced signal processing methods, e.g., decomposition of signals into its components based on their independence

11 Principle of multi-parametric physiologic monitoring Application point of view Beginning with a basic inspection without any (or with simple) instruments. Established clinical applications: highest reliability but requiring a large effort in all three: applied devices, attending physicians, and laboratory premises. Furthermore, the laboratory window of observation is limited in time, i.e., infrequent (usually vital) physiologic events are easy to miss. Portable applications emerge in response to economic imperatives and need of improved access to diagnosis and a realistic appraisal of 24-h pathology and more complete information about the physiologic state of the patient. Unattended studies conducted in a home environment allow for improved comfort and familiarity. However, portable recording usually suffers from several problems, e.g., difficult hook-up of patients, poor assessment of signal quality and data loss, as well as insufficient experience required for proper interpretation of portable data records. Lastly, pervasive applications govern the research trends in biomedical engineering. The goal of pervasive health care is to provide continuous personalized health monitoring of patients and healthy individuals at any time without constraints of space, time, and physician availability. Paradigm changes from history, which brought basic monitoring functions, to present times, which emphasize advanced functionality in both clinical settings and portable home applications, to the future, which may yield integrated biomedical monitoring not perceivable by patient but easily usable by the physician. The portable LifeShirt system shown is taken from RAE Systems. Pervasive monitoring system Hardware-related requirements - minimal obtrusiveness and compactness, nonhazardous and inexpensive design for a minimum number of spatially distributed sensors and avoiding tethering patients in a tangle of cables - inconspicuous and nonstigmatizing design needed for long-term monitoring - unnoticeable monitoring, e.g., with capacitive, magnetic, and optical technologies because of their noncontact physical nature - the recorded biosignal should be robust, i.e., its resistance to prevalent environmental impacts such as body motions, temperature changes, or external interference (noise) while wirelessly communicating - preprocessing of the biosignal, its storage and transmission under (very) low power consumption would comprise the most important design characteristics - safety and security risks to be accounted for and acceptable in relation to an expected monitoring benefit and health regulations

12 Pervasive monitoring system System-related requirements - real time, robust, reliable, and sensitive data interpretation (besides fixed thresholds) to minimize false alarms - bidirectional data transfer is necessary for sensing and (adaptive) therapy, e.g., diagnosis of cardiac state and urgent therapy by defibrillation if necessary - context-aware health representation may be needed; the collected data is presented in different ways to the physician (e.g., more details included) and the user (e.g., less details but personalized with a visual representation of health lifestyle tendencies) - readily accessible to physicians, patients, and even to healthy individuals Who may benefit from pervasive monitoring system? High-risk patients (e.g., with apneas given by a temporal cessation of breathing during sleep) and chronic patients (e.g., chronic heart failure) profit from pervasive monitoring, as well as athletes (interested in cardiorespiratory feedback during rest or training), the elderly (with restricted mobility), or even specialized occupations (e.g., professional drivers) forced to undergo preventive medical checkup to receive more timely treatment. Pervasive systems may be more relevant to healthy individuals than to ill clinical patients. Pervasive assistance using smart tools alleviate the limitation on the physician s workload associated with diagnostic examinations of the demographically evolving population.

13 Optical sensing for smart healthcare Smartphone based SPR sensor Smartphone based Ag coated SPR sensor Bremer et al., "Fibre optic surface plasmon resonance sensor system designed for smartphones." Opt. Express 23, (2015) Liu et al., "Surface plasmon resonance biosensor based on smart phone platforms." Scientific reports 5 (2015). Smartphone based fluorimeter Yu et al., "Smartphone fluorescence spectroscopy. Anal. Chem. 86, 8805 (2014). Label-free photonic crystal biosensor Gallegos et al., "Label-free biodetection using a smartphone." Lab on a Chip 13, 2124 (2013). Optical imaging for smart healthcare Portable spectrometer Hossain et al., Portable smartphone optical fibre spectrometer," OFS24, Chip microscope Portable fluorescence microscopy Wei et al., "Fluorescent imaging of single nanoparticles and viruses on a smart phone." ACS Nano 7, 9147 (2013) Lee et al., "A smartphone-based chip-scale microscope using ambient illumination." Lab on a Chip 14, 3056 (2014) Smart window Llordés et al., "Tunable near-infrared and visible-light transmittance in nanocrystal-in-glass composites." Nature 500, 323 (2013)

14 Smart healthcare Smart healthcare Peek Vision Qloudlab Eyenaemia (Australia) ANU 3D / (MWC 2015) D - EYE : portable ophthalmoscope Smart healthcare Telemedicine ( ) SVOne:

15 Mobile hospital Telemedicine Prospects of pervasive health monitoring systems Pervasive applications can be expected to reduce total medical costs, increase continuity and improve availability of health care and facilitate the work of physicians. Increasingly, physicians, patients, and healthy subjects appear to accept information technology to assist in their decision making, to turn the physician s attention to the person if necessary, and to be an objective guide through the positive way of life.