Medical Instrument Lecture Notes PDF

Medical instrument Second stage Lecture NO.1 Introduction to medical instrument BY: Ass. Lec. Shelan khudhur saleh Introduction Biomedical instrumentation is the application of knowledge and technologies to solve problems related to living biological systems. It involv...

Medical instrument Second stage Lecture NO.1 Introduction to medical instrument BY: Ass. Lec. Shelan khudhur saleh Introduction Biomedical instrumentation is the application of knowledge and technologies to solve problems related to living biological systems. It involves the diagnosis, treatment and prevention of disease in humans. Generalized Medical instrumentation System Every instrumentation system has at least some of the functional components shown in Figure below. The primary flow of information is from left to right. Elements and relationships depicted by dashed lines are not essential. The major difference between this system of medical instrumentation and conventional instrumentation systems is that the source of the signals is living tissue or energy applied to living tissue. Fig(1): Generalized Medical instrumentation System Components of Biomedical Instrumentation System Each Medical instrument consist of the following function parts: 1. Measured: is the physical quantity, and the instrumentation systems measure it. Human body acts as the source for measuring, and it generates bio-signals. Example: body surface or blood pressure in the heart. 2. Sensor / Transducer: The transducer converts one form of energy to another form usually electrical energy. For example, the piezoelectric which converts mechanical vibrations into the electrical signal. (The sensor is used to sense the signal from the source. It is used to interface the signal with the human.) 3. Signal Conditioner: Signal conditioning circuits are used to convert the output from the transducer into an electrical value. The instrument system sends this quantity to the display or recording system. Generally, signal conditioning process includes amplification, filtering, analogue to digital and Digital to analogue conversions. Signal conditioning improves the sensitivity of instruments. 4. Display: It is used to provide a representation of the measured parameter or quantity. Like:  Visual sense  Numerical or graphical  Discrete or continuous  Auditory sense  Tactile sense 5. Auxiliary elements  Calibration  Control and feedback  Storage and transmission Types of Biomedical Instrumentation Systems Direct / Indirect Invasive / Noninvasive Contact / Remote Sense / Actuate Dynamic / Static 1. Direct/Indirect: The sensing system measure a physiologic parameter directly, such as the average volume blood flow in an artery, or measures a parameter related to the physiologic parameter of interest (e.g., ECG recording at the body surface is related to propagation of the action potential in the heart but is not a measurement of the propagation waveform). 2. Invasive/Noninvasive: Direct electrical recording of the action potential in nerve fibers using an implantable electrode system is an example of an invasive sensor. An imaging system measuring blood flow dynamics in an artery (e.g., ultrasound color flow imaging of the carotid artery) is an example of anon-invasive sensor. 3. Contact/Remote: (Contact) A strain gauge sensor attached to a muscle fiber can record deformations and forces in the muscle. (Remote) An MRI or ultrasound imaging system can measure internal deformations and forces without contacting the tissue. 4. Sense/Actuate: (A sensor) detects biochemical, bioelectrical, or biophysical parameters. (An actuator) delivers external agents via direct or indirect contact and/or controls biochemical, bioelectrical, or biophysical parameters. An automated insulin delivery pump is an example of a direct, contact actuator. Noninvasive surgery with high intensity, focused ultrasound (HIFU) is an example of a remote, noninvasive actuator. 5. Dynamic/Static: (Static instruments) measure temporal averages of physiologic parameters. (Real-time instruments) have a time response faster than or equal to the physiologic time constants of the sensed parameter. For example a real-time, ultrasound Doppler system can measure changes in arterial blood velocity over a cardiac cycle.  Types of biomedical instrument : 1. Diagnostic equipment: includes medical imaging machines, used to aid in diagnosis. Examples are ultrasound and MRI machines, and CT scanners, and x-ray machines. 2. Therapeutic equipment includes infusion pumps, medical lasers. 3. Life support equipment is used to maintain a patient body function. This include medical ventilator, anesthetic machines, heart-lung machines and dialysis machines. 4. Medical monitors allow medical staff to measure a patient's medical state. Monitors may measure patient vital signs and other parameters including ECG, EEG, blood pressure, and dissolved gases in the blood. 5. Medical laboratory equipment automates or helps analyze blood, urine and genes.