III/IV B.Tech Regular Degree Examination. Scheme of Evaluation

Transcription

1 III/IV B.Tech Regular Degree Examination Scheme of Evaluation Subject : Bio-Medical Electronics Code -14EC606C April Max Marks : a. Advantages of needle electrodes ease of use, low impedance, stability, small size No electrolyte gel is required to maintain the interface between the patient and electrode It reduces the interface impedance and movement artifacts b. Types of Muscles: Voluntary muscles (Ex: Muscles in arm) Involuntary muscles (Ex: Cardiac Muscles) Various types of muscles skeletal, cardiac, and smooth c. Diathermy is a medical and surgical technique involving the production of heat in a part of the Body by high-frequency electric currents, to stimulate the circulation, relieve pain, destroy Unhealthy tissue or cause bleeding vessels to clot. It is the treatment process by which cutting, Co-agulation..etc of tissues are obtained d. Half cell potential is A half-cell is a structure that contains a Conductive electrode and a surrounding Conductive electrolyte which depends on the metal, concentration of ions in solution and Temperature e. Direct methods of BP measurement prcutaneous insertion, catheterization and Implantation of a transducer in a vessel or the heart f. The disadvantages of AC defibrillators are. Repeated attempts are required. Causes Violent contraction n of thoracic muscles and burning of skin under the electrodes. g. x rays to see whether bones are broken, diagnoses of common oral problems, such as cavities, even in CT scan h. phonocardiography is the recording of all the sounds made by the heart during a cardiac cycle.. I.Limitations of MRI. An MRI is a very expensive and time consuming investigation compared to other Methods such as X-ray and CT. An MRI may not always be able to tell the difference between some Disease processes. Patients who have heart pacemakers, metal implants, or metal chips or clips in or around the eyeballs cannot be scanned with an MRI because of the risk that the magnet may Move the metal in these...

2 j. A ph of 7 is neutral. The lower the ph, the more acidic the blood. A variety of factors affect blood ph including what is ingested, vomiting, diarrhea, lung function, endocrine function, kidney function, and urinary tract infection. The normal blood ph is tightly regulated between 7.35 and k. ultrasound is used to see internal body structures such as tendons, muscles, joints, blood vessels, and internal organs. Therapeutic purpose or Diagnostic purpose To detect the brain tumors To know the presence of twins To know the movements of walls and valves of the heart etc l. Bioelectric potentials are generated by a variety of biological processes and generally range in Strength from one to a few hundred millivolts in living systems. It is also used in clinical medicine for Diagnostic purposes (electrocardiography, electroencephalography, electromyography, and so on). UNIT-I 2. a. problems encountered in Bio-medical measurements: 6M I/O relationships are not deterministic Accessibility problem Patient safety Pain and discomfort Variability of the Data Artifacts Energy Limitations Inaccessibility of variables for measurement Effect of transducer on measurement Interaction among various physiological systems Lack of knowledge about inter relationships Safety considerations

3 2. B.Transmission of impulse from nerve to muscle cells 6M Neuron is a highly specialized cell. It carries impulses or messages It consists of long transmitting fiber called axon. The motor nerves carry the impulses from the brain or spinal cord to the muscles The dendrites carry impulses to the cyton. The axon carries to the impulses away from the Cyton The following figure shows the steps involved in the transsimission process: 14

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5 3.a. 6M The electrical potential of a neuron or other excitable cell relative to its surroundings when not stimulated or involved in passage of an impulse. When a section of the cell membrane is excited by the flow of ionic current or by some form of externally applied energy, the permeability of the membrane changes so that Na + are allowed to enter inside the cell This movement of sodium ions into the cell constitutes an ionic current which further reduces the barrier of the membrane to sodium ions. The net result is an avalanche effect. Such that sodium ions rush into the cell and try to balance with the ions outside.

6 Mean while K + ions are leaving the cell but are unable to move as rapidly as the sodium ions. Therefore the cell has a slightly positive potential on the inside due to imbalance of K + This positive potential of the cell membrane during excitation is called action potential and is about 20mV As long as the action potential exists, the cell is said to be depolarized When the passage of sodium ions is stopped, the ionic currents that lowered the barrier to sodium ions are no longer present and the membrane reverts back to the polarized condition. The following figures shows Depolarization of cell and depolarized cell airing action potential

7 3.b. It is the Pneumatic system. 6M A system that work with air pressure. An air pump (diaphragm) which alternatively create negative and positive pressures in a sealed chamber (Thoracic cavity). Thoracic cavity sucked air in to and forced out to two elastic bags (Lungs). The lungs are connected to the external environment through a pass way (nasal cavities, pharynx, larynx, trachea, bronchi and bronchioles) At one point, this passage is common with the tube that carries liquid and solids to stomach. A special valving arrangement interrupts the respiratory system whenever solid or liquid passes through the common region. The passage divides to carry air in to each bag. In each bag, it is sub divided many times to carry air in to and out of each of many tiny air spaces (pulmonary alveoli). In case of nasal blockage, air input can be taken from mouth. Oxygen is taken from the air and transferred in to blood. Cabondioxide is transferred from blood to air. The system has a number of fixed volumes and capacities.

8 UNIT-II 4.a) Explain the working of ECG machine With a neat block diagram 8M The following figure shows the block diagram of the ECG recorder The potentials picked up by the patient electrodes are taken to the lead selector switch. In the lead selector, the electrodes are selected two by two according to the lead program By means of capacitive coupling, the signal is connected to the long pair differential pre amplifier. The pre amplifier is usually a 3 or 4 stage differential amplifiers having a sufficiently large negative feedback from the end stage to the first stage, which gives a stabilizing effect. The amplified output signal is picked up single-ended and is given to the power amplifier. The power amplifier is generally of the push-pull differential type. The base of one input transistor of this amplifier is driven by the pre-amplified unsymmetrical signal where as the base of the other is driven by the feedback signal resulting from the pen position and connected via frequency selective network. The output of the power amplifier is single-ended and is fed to the pen motor which deflects the writing arm on the paper. The auxiliary circuits provide 1mv calibration signal and automatic blocking of the amplifier during a change in the position of the lead switch It may include speed control circuit for the chart drive motor Frequency selective network is an RC network which provides necessary damping of the pen motor and is

9 4(b) Write short note on EEG in diagnostics 4M These potentials are vary with respect to position of electrode on the surface of skull. Therefore during recording, the electrodes are placed around the frontal, temporal, parietal, occipital lobes of the brain. Electro encephalogram is the record of Brain waves made by an Electro encephalograph. As we known the brain waves are the summation of neuronal depolarization in the Brain due to Stimuli from the five senses as well as from the thought process. The intensities of the brain waves on the surface of the scalp range from μvolts and frequency Range from one in every few seconds to 50 or more per second. Much of the time, the brain waves are irregular and no general pattern can be discerned in the EEG. EEG helps physicians to Diagnose: A. The level of consciousness B. Sleep disorders C. Brain death D.Brain tumors E. Epilepsy 5.a With a neat diagram, explain the working principle of EMG. 6M EMG is usually recorded by using surface electrodes or often needle electrodes inserted directly in to the muscle.

10 These electrodes pick-up the potentials produced by the contracting muscle fibers. Then the signal can be amplified and displayed on the screen of a CRT The signal is also applied to an audio-amplifier connected to a loud speaker. The waveform can also photo graphed from the CRT screen by using synchronized camera. 5.b. Equivalent circuit for bio-potential electrode interface 6M Microelectrodes : Used to measure bio-potential signals at the cellular level Due to small dimensions (mm), impedance levels are high So amplifier needs very high input impedance

11 6.a.OPERATION OF ULTRASONIC BLOOD FLOW METER 6M (Any one method is sufficient) A beam of ultrasonic energy is used to measure the velocity of flowing blood

12 Transit-Time Ultrasonic Flow Meters Ultrasonic Transducer BME 312-BMI II-L3-ALİ IŞIN 2015 Ultrasonic Transducer Transit-Time Ultrasonic Flow Meters Where t D c u - transit time - Distance between the transducers - Sound velocity - blood flow velocity BME 312-BMI II-L3-ALİ IŞIN 2015 (OR)

13 Doppler Type Ultrasonic Flow Meters BME 312-BMI II-L3-ALİ IŞIN 2015 Doppler Frequency equation Where fd = Doppler frequency shift f0 = source frequency u = target velocity c = velocity of sound BME 312-BMI II-L3-ALİ IŞIN b. Sphygmomanometer is Indirect Measurement Technique for Blood Pressure Measurement 6M The cuff is wrapped and secured with hooks around patient s upper arm at a point midway Between the elbow and the shoulder The stethoscope is placed over the bronchial artery at the elbow level where it is close to the skin surface The cuff is normally inflated manually with a rubber bulb so that the pressure inside the inflated bladder is more than the arterial pressure.

14 This pressure compresses the artery against the underlying bone and causes a complete stoppage of blood flow in the blood vessel The pressure in the cuff is gradually reduced by operating the needle type pressure release valve so that there is a gradual fall of mercury in the manometer, of the order of 3mm/sec When the systolic pressure in the pulsatile blood pressure pulse first just exceeds the cuff pressure, the branchial artery takes the shape of a venture meter with extremely small throat area. Turbulence is generated as the blood flow experiences a sudden expansion downstream of the tiny throat opening of the venturi. The sounds generated by the turbulence are known as kortokoff sounds. The sounds can be heard through the stethoscope placed over the branchial artery downstream of the cuff. The pressure of the cuff that is indicated on the manometer when the first kortokoff sound is heard is known as systolic blood pressure. As the cuff pressure continues to drop, the throat area of the venturi formed in artery also starts increasing and thus the severity of sudden expansion downstream of the throat continues to decrease. Consequently the kortokoff sounds start becoming less sound and muffled Ultimately, these sounds disappear when the cuff pressure drops just below the diastolic pressure.

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16 7.a. Mesurement of Heart sounds by phonocardiography 6M The graphic record of the heart sounds is called phonogram. Because the sound is from the heart, it is called phonocardiogram. The instrument used to measure the heart sounds is called Phonocardiograph. Phonocardiograph consists a photo catheter, a device similar to a conventional catheter, with a microphone at the tip. The basic aim of Phonocardiograph is to pick-up the different heart sounds, filter out the heart sounds and to display them or record the Heart sounds 1. First heart sound: Origin: It is produced by a sudden closure of the mitral and tricuspid valves associated with myocardial contraction. Timing: The low frequency vibrations occur approximately 0.05sec after the onset of the QRS complex of the ECG. Duration: The first heart sound lasts for 0.1 to 0.12 sec Frequency: The first heart sound ranges from 30-50Hz Ausculatory area: The first heart sound is best heard at the apex of the mid pericardium 2. Second heart sound: Origin: Due to the vibration setup by the closure of semilunar valves i.e. the closure of aortic and pulmonary valves. Timing: The second heart sound starts approximately sec after the end of T wave of the ECG.

17 Duration: This lasts for sec. Frequency: The frequency is up to 250Hz. Asculatory area: The second sound is best heard in the aortic and pulmonary areas. 3. Third heart sound: Origin: The third heart sound arises as the ventricles relax and internal pressure drops well below the pressure in atrium. Timing: This starts at sec after the onset of the 2 nd heart sound. Frequency: Hz Ausculatory area: Best heard at the apex and left lateral position after lifting the legs. 4. Fourth Heart sound: Origin : Due to atrial contraction. Timing : The fourth heart sound starts approximately sec after the onset of the P-wave. Duration: The sound lasts for sec. Frequency: 10 to 50Hz Ausculatory area: Because of its extremely low frequency it is inaudible. 7.b.Thermal dilution technique to measure Cardiac output : 6M Cardiac output is the Volume of blood ejected from left ventricle in one minute It is the determinant of global oxygen transport from the heart to the body It reflects the efficiency of cardiovascular system There no absolute value for cardiac output measurement Based on how fast the flowing blood can dilute the substances introduced into the circulation Stewart-Hamilton Equation: CO = I x 60 / cm x t x 1/k Area under the curve is inversely proportion to the rate of blood flow. This flow is equivalent to cardiac output in the absence of shunt

18 Thermodilution Curve UNIT-IV 8.a. Operation of Short wave Diathermy (Microwave Diathermy) 6M 1. Treatment process by which cutting, Coagulation etc.. of tissues are obtained 2.High frequency currents are used in operating rooms for surgical purposes Involving cutting and coagulation. 3.The frequency used is 2450 MHz corresponding to a wavelength of 12.25micro meter 4.Heating of the tissue is produced due to absorption of the micro wave energy 5.Here the microwaves are transmitted in to the portion of the body to be treated directly from the director of the unit 6. Normally magnetron is used to produce microwaves. In this method the output of the RF oscillator is applied to the pair of patient electrodes. The RF energy heats the tissue and promotes the heating of injured tissue and inflammations healing. The power delivered by the unit is 500W. The electrodes or pads are not directly contact with the skin. Usually layers of the towel are interposed between the metal and surface of the body. The pads are placed so that the portion of the body to be treated is sandwiched between them. The pads are forming capacitor plates and the body tissues between the pads acts as a dielectric.

19 When the RF current is applied to the pads the dielectric loss of the capacitor produces heat in the intervening tissues.this technique is called condenser or capacitor technique. Further there is also inductor method in which a flexible cable is coiled around the arm or knee or any other portion of the patients body. Short wave Diathermy unit Power RF Oscillator Monitor&Control Isolation To Patient Bio-Medical electronics K Sambasiva Rao 33 8.b. A Complete Blood Gas Analyzer 6M Complete blood gas analyzer is useful to obtain the various blood gas parameters such as P H, partial pressures of various gases (O 2, CO 2, CO-etc) from a small sample of blood Within a minute

20 9.a. Dialysis process : 6M A process by which the waste products in the blood are removed and restoration of normal P H value of the blood is by an artificial kidney machine Processes involved in dialysis: 1.Diffusion 2.osmosis 3.Ultra filtration Dialysis Procedures: A. Extra corporeal Dialysis (OR) Hemo-Dialysis: Blood is purified by an artificial kidney machine called Hemo dialyser In this method blood is taken out from the body and waste products diffuse through a semi Permeable membrane which continuously rinsed by dialyzing solution or dialysate. It is More effective approach, Technically complex and risk and requires 3-6 hours For Dialysis B. Intra corporeal dialysis (OR) Peritoneal Dialysis: The peritoneal cavity in our body is used as a semi permeable membrane and by passing dialysate into it, waste products are removed from the blood by diffusion This method is Less effective, simple and free and requires 9-12 hours for dialysis Hemo Dialysis Machine (OR) Artificial Kidney Machine

21 Hemo Dialysis Machine (OR) Artificial Kidney Machine Water Dialysate Concentrate Metering Pump Metering Pump Mixing Chamber Waste Pump Exchange Chamber-Dialysate Membr ane Venous Blood Blood Pump Arterial Blood Bio-Medical electronics K Sambasiva Rao 24 9.b. Pacing Modes 6M Pacemaker is an Electric Pulse generator for starting and/or maintaining the normal Heart beat External Pacemakers: The pacemaker is placed outside the body In the form of wrist watch No need of open chest surgery Easy replacement of Battery Doctor supervision is not necessary Safety is less Used for temporary irregularities Internal Pacemakers: Small in size Surgically implanted Requires open chest surgery Doctors supervision is necessary Good safety to the system Suitable for permanent damages

22 Different Pacing modes : Fixed Rate Pacemaker Demand Type Pacemaker Rate Responsive Pacemaker

23 Scheme & Solutions of 14EC 606C (April-2018) Prepared By: Head of the Department K SAMBASIVA RAO Dept of ECE Associate Professor Deartment of ECE Bapatla Engineering College Bapatla Phone number: External Examiner: