Principles of Biomedical Systems & Devices. At the Clinic. Objectives WEEK 1: INTRODUCTIO N. Principles of Biomedical Systems and Devices (3)

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1 1 Principles of Biomedical Systems & Devices / WEEK 1: INTRODUCTIO N Edna Jones, 67, retired Female Difficulty with vision near accident incident 173cm (5 8 ), 90 kg (198 lb) BP: 118/76, HR: 63 bpm Core body temp: 37ºC (98.6 ºF) Other Water consumption Eye exam Skin temp Sensation Blood glucose ECG Blood test Urine test At the Clinic Objectives Principles of Biomedical Systems and Devices (3) / Fall 2004 Class Homepage: Instructors: Robi Polikar, Maria Tahamont (Guest lectures on A&P) Office& Phone: Polikar Rowan, Tahamont 256 Science, Office Hours: T: 11-12, F: Open door policy polikar@rowan.edu tahamont@rowan.edu Class Meeting: 1615 in Rowan 239 Texts: Introduction to Biomedical Engineering, Enderle, Academic Press, 2000 A basic medical dictionary, available at any bookseller. The main objective of this course is to introduce you to basic biomedical engineering technology, so that you can understand, design and evaluate systems and devices that can measure, test and/or acquire biological information from the human body. In order to achieve this goal, we will emphasize: Essential background on anatomy and physiology, in particular fundamental characteristics of signals acquired from the human body Electrical safety issues that must strictly be adhered to in designing medical equipment Practical issues in designing and testing electronic medical equipment. Specific algorithms and techniques in analysis and processing of biological signals Ethical issues regarding biomedical and biotechnology research.

2 Definition of Biomedical Engineering: (from Whitaker) Biomedical Engineering Biomedical engineering is a discipline that advances knowledge in engineering, biology and medicine, and improves human health through crossdisciplinary activities that integrate the engineering sciences with the biomedical sciences and clinical practice. It includes: 1. The acquisition of new knowledge and understanding of living systems through the innovative and substantive application of experimental and analytical techniques based on the engineering sciences. 2. The development of new devices, algorithms, processes and systems that advance biology and medicine and improve medical practice and health care delivery. As used by the foundation, the term biomedical engineering research is thus defined in a broad sense: It includes not only the relevant applications of engineering to medicine but also to the basic life sciences. Bioinstrumentation Biomaterials Biomechanics Biosignals Biosystems Biotransport Cellular engineering Clinical engineering Tissue engineering Rehabilitation engineering Also related: Biostatistics Bioinstrumentation Biomaterials Apply fundamentals of measurement science to biomedical instrumentation for measuring physiological variables that may originate from molecular, cellular or systemic process. May be described by mechanical, electrical, chemical, optical or other events Uses sensors and/or transducers Sensors must be designed to / so that Minimize disturbance to the measured variable and the environment Comply with the requirements of the living system Maximize SNR Achieve accuracy and repeatability Measured signal is usually fed into a signal processing algorithm for further conditioning and analysis. Application of engineering materials to the production of medical / biological / diagnostic products Design and development of new biological materials, often to replace failing biological organs / limbs Designing new materials that the body will not reject one of BME s most challenging problem. Material must be nontoxic, noncarcinogenic, chemically inert, stable, and mechanically strong enough to withstand the repeated forces of a lifetime 2

3 Biomechanics Biosignals / Biopotentials Study of composition, properties and interaction of biological tissues (such as muscle, bone, etc.) and fluids (such as blood, inter/intracellular fluid, etc.) Study of motion, material deformation, flow within the body and in devices, and transport of chemical constituents across biological and synthetic media. Development of the artificial heart, replacement heart valves, the artificial kidney, the artificial hip, patient assistance devices, and ergonomic design all fall within the realm of biomechanics. Biomechanics include both fluid mechanics and solid mechanics at molecular, cellular, macroscopic or system level. Analysis of biological data to uncover the nature of underlying physiological phenomena Signal processing Time series analysis Origins of signal variability Transform and statistical techniques Analysis of chaotic behavior of signals / fractal analysis Clinical Engineering Cellular Engineering Application of technology in health care Clinical engineers typically work in hospitals to assist doctors / nurses with their medical technology needs Managing diagnostic and laboratory equipment in hospitals, interface of different equipment with each other and/or with computers Determine equipment needs Search for and specify optimal equipment Train healthcare workers on equipment Perform maintenance and safety inspections Design of quantitative biochemical and biophysical techniques and procedures for the study and manipulation of cell function, such as Cell metabolism Inter and intra cellular signaling and regulation Biomolecular uptake and secretion Cellular proliferation, migration, adhesion Closely related to biochemistry, biophysics, and molecular biology 3

4 Rehabilitation Engineering Biostatistics A new and growing area of BME Expand capabilities and improve the quality of life for individuals with physical impairments Design or modify new/old equipment for an individual or a group of individuals with a specific disability A specialized branch of applied statistics that deals with the statistical evaluation of experimental research or clinical trial results. Can also be applied to statistical evaluation of biomedical measurements, statistical evaluation of biomedical equipment, etc. Relevant topics: Calculation of mean, standard deviation Gaussian and Poisson distributions Statistical estimation Hypothesis testing Calculation of prevalence, sensitivity, specificity, positive predictive value, and negative predictive value Agriculture - Soil monitoring Botany - Measurements of metabolism Genetics - Human genome project Medicine Microbiology - Tissue analysis Pharmacology - Chemical reaction monitoring Veterinary science - Neutering of animals Zoology - Organ modeling Disciplines in which bioengineers work Anatomy, anesthesiology, biomolecular chemistry, biostatistiscs, medical informatics, microbiology and immunology, medical physics, neurology, neurophysiology, obstetricsgynecology, oncology, opthalmology, pathology, pediatrics, physiology, psychiatry, radiology, rehabilitation medicine, surgery. Where Do Biomedical Engineers Work? In industry Design of new biomedical equipment, devices and system where an in-depth understanding of living systems and of technology is essential. Performance testing of new or proposed products. In government positions Product testing and safety, Establishing safety standards for biomedical devices and systems. In hospitals, Provide advice on the selection and use of medical equipment, Supervise medical device performance testing and maintenance. Customize devices for special health care or research needs. In research institutions Supervise laboratories and equipment, participate in or direct research activities with other researchers with such backgrounds as engineering, medicine, physiology, and nursing. In academia Training next generation biomedical and/or other engineers Academic research 4

5 5 Are There Jobs Out There? U.S. Dept. of Labor estimates that the job market for BMEs will increase by 31.4%, faster than the average of all occupations, through This is double the overall job growth rate of 15.2% and more than three times the overall growth rate of 9.4% for all engineering jobs. Median annual earnings of biomedical engineers were $60,410 in The middle 50 percent earned between $58,320 and $88,830. The lowest 10 percent earned less than $48,450, and the highest 10 percent earned more than $107, Biological Measurements General Instrumentation Systems Measurand: The physical quantity to be measured Control and feedback Measurand Primary sensing element Sensor Variable conversion element Transducer Power source Signal processing Output display Perceptible output Calibration Signal Data storage Data transmission Radiation, electric current, or other applied energy The sensor converts energy or information from the measurand to another form (usually electric). This signal is the processed and displayed so that humans can perceive the information. Elements and connections shown by dashed lines are optional for some applications.

6 6 Common Medical Measurands (invasive & Noninvasive) Sensor Specifications & Constraints Measurement Range Frequency, Hz Method Blood flow Blood pressure Cardiac output Electrocardiography Electroencephalography 1 to 300 ml/s 0 to 400 mmhg 4 to 25 L/min 0.5 to 4 mv 5 to 300 µ V 0 to 20 0 to 50 0 to to to 150 Electromagnetic or ultrasonic Catheter, Cuff or strain gage Fick, dye dilution Skin electrodes Scalp electrodes Specification Pressure range Overpressure without damage Maximum unbalance Value 30 to +300 mmhg 400 to mmhg ±75 mmhg Electromyography 0.1 to 5 mv 0 to Needle electrodes Linearity and hysteresis ± 2% of reading or ± 1 mmhg Electroretinography 0 to 900 µ V 0 to 50 Contact lens electrodes Risk current at 120 V 10 µa ph pco 2 3 to 13 ph units 40 to 100 mmhg 0 to 1 0 to 2 ph electrode pco 2 electrode Defibrillator withstand 360 J into 50 Ω po 2 Pneumotachography Respiratory rate 30 to 100 mmhg 0 to 600 L/min 2 to 50 breaths/min 0 to 2 0 to to 10 po 2 electrode Pneumotachometer Impedance Sensor specifications (for a blood pressure sensor) are determined by a committee composed of individuals from academia, industry, hospitals, and government. Temperature 32 to 40 C 0 to 0.1 Thermistor System Specifications Physiological Effects of Electricity Medical Safety Specification Input signal dynamic range Dc offset voltage Slew rate Frequency response Input impedance at 10 Hz Dc lead current Return time after lead switch Overload voltage without damage Risk current at 120 V Value ±5 mv ±300 mv 320 mv/s 0.05 to 150 Hz 2.5 MΩ 0.1 µα 1 s 5000 V 10 µα Specification values for an electrocardiograph are agreed upon by a committee. Threshold or estimated mean values are given for each effect in a 70 kg human for a 1 to 3 s exposure to 60 Hz current applied via copper wires grasped by the hands.

7 7 Panel / Series Measurements Laboratory test Hemoglobin Hematocrit Erythrocyte count Leukocyte count Typical value (male) 13.5 to 18 g/dl 40 to 54% 4.6 to / µl 4500 to 11000/ µl Differential count Neutrophil 35 to 71% Band 0 to 6% Lymphocyte 1 to 10% Monocyte 1 to 10% Eosinophil 0 to 4% Basophil 0 to 2% Levels of Organization Closely related measurements are often grouped together, and called series / panel measurements, e.g., blood count. How do we measure these? Anatomical Directions Anatomical Definitions

8 What s In This Course? The BME challenge: Food for thought Week of August 30 September October November December 6 13 Material to be uncovered Introduction and motivation: Why do we study biomedical engineering, basic measurement and physiological concepts. Introduction to bioinstrumentation The origin of biopotentials, electrical activity of excitable cells, action potentials, membrane models The origin of biopotentials, continued: ECG, EMG, EEG, MEG, etc. Biopotential electrodes and amplifiers Measurement of blood flow and pressure Cardiovascular system, hemodynamics - Midterm exam Respiratory system, measurements of the respiratory system Measurement of blood pressure Processing of biological signals - Part I Processing of biological signals - Part II Contemporary topics - Clinical laboratory systems Contemporary topics - Biomedical imaging systems Electrical safety Contemporary topics - Other Contemporary topics - Other FINALS WEEK The Cardiovascular System The Heart As a Pump No ordinary pump 100,000 km (60000 miles) of blood vessels During sleeping pumps 30 x of its weights, 5 L of blood / minute 14,000 liters (3,600 gallons) blood per day after day after day 10,000,000 liters (2,600,000 gallons) blood per year Multiply by 70 years (average life expectancy)!!! and that is only if you sleep all day! Homework Read Chapter 1 and 2 of the text. Find the meaning and definitions of prevalence, sensitivity, specificity, positive predictive value, and negative predictive value 8