iv_unit.pptx physical medicine and biotelemetry 4th year biomedical engineering

biomedical

1. UNIT-IV PHYSICAL MEDICINE AND BIOTELEMETRY

2. The term diathermy means through heating or producing deep heating directly in the tissues of the body. The subject of the body becomes a part of the electrical circuit and heat is produced within the body and not transferred through the skin. Diathermies

3. The treatment can be controlled precisely. Placement of the electrodes in right part of the body permit the heat to the localized in that region to be treated . Amount of heat adjusted by a circuit parameters . Advantages of diathermy

4. The heating of the tissues is carried out by high frequency alternating current which generally has a frequency of 27.12MHz and wavelength of 11m. SHORT WAVE DIATHERMY

5. SHORT WAVE DIATHERMY

6. Current of such high frequency do not stimulate motor or sensor nerve sensor do they produce any molecule contraction when such a current is passed through the body to discomfort is caused to the subject. SHORT WAVE DIATHERMY

7. The RF energy heats the tissues and promotes healing of injured tissues and inflammations OSCILLATING CIRCUIT   Which produces a high frequency current   patient circuit   which is connected to the oscillating circuit and through which the electrical energy is transferred to the patient   CIRCUIT DIAGRAM OF SHORT WAVE DIATHERMY UNIT

8.   Single-ended or push pull oscillators filtered power supplies transformer T , the primary of which can be energized from the mains supply is a step up transformer for providing EHT for the anode of the triode valve a seconding winding can be provide heating current for the cathode of the triode valve. The tank circuit is formed by the coil AB in parallel with the condenser C1 the positive feedback is generated by the coil CD another coil EF and variable condencer C2 which form the patient resonator circuit due to its coupling with the oscillator coil AB. Circuit description

9. The variable condenser C2 is adjusted to achieve a maximum reading on the meter the needle swinging back on the either side of the tuned position. The maximum power delivered by these machieves is 500w regulating the intensity current by adjusting the grid bias by putting a variables resistance as the grid leak resistance method to applying electrode in shortwave diathermy treatment . Circuit description

10. Controlling the anode voltage Controlling the filament heating current Adjusting the grid bias by change of grid leak resistance Adjusting the position of the resonator coil with respect to the oscillator coil Adjusting the grid bias by putting a variable resistance as the grid leak resistance. Ways of regulating intensity current

11. The output of the short wave diathermy machine is connected to metal electrodes which are positioned on the body over the region to be treated. These pads are electrodes do not directly come into contact with the skin The arrangement is called the condenser method where in the metal pads acts as two plates while the body tissuses between the pads as dielectric of the capacitor When the radio frequency output is applied to the pads the dielectric losses of the capacitor manitest themselves as heat in the intervening tissues. CAPACITIVE METHOD

12. CAPACITIVE METHOD

13. Dielectric losses occurs due to Vibration of ions and rotation of dipoles in the tissue fluids Molecular distortion in tissue which are virtually insulating like fats CAPACITIVE METHOD

14. The output of thee diathermy machine be connected to a flexible cable instead of pads. INDUCTIVE METHOD (INDUCTO THERMY)

15. When RF current is passed through such an electrostatic field is set up between its end and a magnetic field around its center Deep heating in the tissues result from electro-static action where as the heating of the superficide tissue is obtained by eddy current setup by a magnetic effect this technique is know as inducto thermy   Advantage Output power control Diapulse therapy The increase in energy output while avoiding the dangers of heat has been achieved in a machine is called diapulse . INDUCTIVE METHOD (INDUCTO THERMY)

16. The effects of ultrasonic on the tissues is thus a high speed vibration of micro massage Massage as a modality in physical medicine has been used in the treatment of soft tissue lesion for centuries. ULTRASONIC DIATHERMY

17. Used for curing the diseases of peripheral nervous system Skeletal muscle system Skin ulcers Achieve the localisation of heat to the affected part. ULTRASONIC DIATHERMY

18. ULTRASONIC DIATHERMY OSCILLATOR POWER AMPLIFIER

19. LC tuned colpitt oscillator-four pair transistor placed in a bridge configuration.

20. Time oscillator provides the electrical oscillator of the required frequency   The oscillator output is given to a power amplifier which derives the piezo electric crystal to generate ultrasonic waves   The output of the oscillator can be controlled by either of following two methods Using a transformer with a primary winding having multitapped windings and switching the same as per requirements Controlling the firing angle of a triac placed in the primary circuit of the transformer and there by varying the output of the transformer ULTRASONIC DIATHERMY

21. The machine can be operated in Continuous –full wave rectifiers used Pulsed mode –half wave rectifier is used The metal face plate in the crystal is made to vibrates due to the oscillating of the crystal and ultrasonic waves are emitted from the plate  The frequency range of 800KHZ-1MHZ is suitable for the ultrasonic method of treatment. The timer is an electrically operated contact which can be set into 15mints and gets switched off after the preset time   The transducer probe is in direct contact with the patient and it can be move up and down circularly around the treatment area for uniform distribution of ultrasonic energy. ULTRASONIC DIATHERMY

22. The thermal effect of ultrasound is depend on the amount of energy absorbed, the length of the time of the ultrasound application, frequency of the ultrasound generator. Power required<3W/cm 2 . ULTRASONIC DIATHERMY

23. Microwave diathermy consists in irradiating the tissues of the patient`s body with very short wireless waves having frequency in the microwave region Microwave are a form of electromagnetic radiation within a frequency range of 300-30,000MHz. Wavelength varying from 10mm to 1m. Microwave diathermy

24. 2450MHz wavelength of 12.25 cm. Microwave diathermy

25. No usage of pad electrodes and flexible cable. Microwave is transmitted into body and treat directly from the direction of unit. Usually microwaves are produced with the help of magnetron. 3-4 minutes required to heating of magnetron. Lamp light arrangement is provided to indicate that the magnetron is ready to deliver its output. Proper cooling arrangements are made for the purpose of cooling the magnetron. Microwave diathermy

26. Excessive dosage causes skin burns and the skin should be dry as the waves are rapidly absorbed by water. Microwave diathermy-precautions

27. Patients with implanted pacemaker should not undergo this treatment. There are possibilities of over heating. Care should be taken while the treatment is made near the eyes. Microwave diathermy-disadvantages

28. Microwave diathermy

29. The mains supply voltage is applied to an interference suppression filter . This filter helps to bypass the high frequency pick-up generated by the magnetron. A fan motor is directly connected to the mains supply. The fan is used to cool the magnetron. Microwave diathermy

30. A part from the thermal and threapeutical application the high frequency currents are also used for surgical purpose like cutting and coagulation . The frequency of current used here is 1-3MHZ. SURGICAL DIATHERMY

31. CUTTING COAGULATION FULGURATION DESICCATION

32. When a high frequency current flows through sharp edge of a wire or the point of a needle into the tissue there is a high concentration of cur-rent at this point   The tissues get heated and as a result the cells immediately under the electrode are turn a part by the boiling of cell fluid SURGICAL DIATHERMY

33. SURGICAL DIATHERMY

34. The other electode called indifferent electrode has large area of constant with the patient and the rf current passed through it induces only a very little heat at the electrode this type of tissue separation is called as electro surgical cutting.   Coagulation   The coagulation process is achieved by the high frequency current flowing through the tissues and results in heating and coagulation   The process of coagulation is accompanied by a greyish white discolouration of the tissues at the edge of electrode   Better coagulation is achieved by high frequency currents as this does not cause buring . SURGICAL DIATHERMY

35. Concurrent use of continuous radio frequency current for cutting and a burst wave radio frequency for coagulation is called haemostasis mode.

36. High and Low Frequency Waveform

37. The continuous radio frequency current is used for cutting and burst wave radio frequency is used for coagulation. The electrode melts through the tissues and seals capillaries and other vessels even if the high frequency surgery is not used the method for electro coagulation can be used. Advantage   It provides simple and effortless surgery. This method presents the contamination of bacteria. Bleeding can be arrested immediately by touching the spot with the coagulation electrode. SURGICAL DIATHERMY

38. Automated communications process by which measurements are made and other data collected at remote or inaccessible points and transmitted to receiving equipment for monitoring. Telemeter   The Device used to remotely measure any quantity consists of a sensor, a transmission path, and a display, recording, or control device, or hard-wired, analog or digital.   Telemetry

39. Meteorology Oil and gas industry Space science Motor racing Agriculture Water management Swimming Pools Defense, space and resource exploration Energy monitoring Medicine/Healthcare Communications Applications

40. The radio frequency biotelemetry uses either the VHF or UHF band set aside by the Federal Communications Commission (FCC) exclusively for the medical telemetry or the unused television channels. Analog modulation techniques - biotelemetry.   Amplitude Modulation (AM) and Frequency Modulation (FM) Pulse Amplitude Digital modulation techniques - biotelemetry Frequency selection

41. Modulation (PAM), Pulse Width Modulation (PWM) and Pulse Code Modulation (PCM) Frequency Multiplexing (FM) is preferable. Each channel of data is either frequency – or amplitude modulated using separate sub-carrier and these sub-carriers are either frequency or amplitude-modulated using a RF carrier. For example, if sub-carriers frequency modulate individual data channels and RF carrier amplitude modulates these subcarriers, then such system is termed as FM/AM. FM/FM denotes that sub-carriers frequency modulate individual data channels and RF carrier frequency modulates these sub-carriers. Frequency selection

42. Measurement of biological parameters over a distance is known as biotelemetry. Applications:   Monitoring physiological conditions of astronauts in space, workers in deep mines.   subjects during exercise or in a normal working environment.   patients in an ambulance or in a location away from the hospital.   Remote medical data collection from home or office.   Monitoring animals for research in their natural habitat. Biotelemetry:

43. Biotelemetry Transmitter and   Receiver

44. pressure-sensing endoradiosonde is a “radio pill”less than 1 cm3 in volume , it can be swallowed by the patient. As it travels through the gastrointestinal tract, it measures the various pressures it encounters.   Radio pill

45. Electrical current can be flow through the Human body either accidently or intentionally. ELECTRICAL CURRENTS ARE ADMINISTERED INTENTIONALLY IN THE FOLLOWING CASES   For the measurements of respiration rate by impedance method-a small current at high fre-quency is made to flow between the electrodes applied on the surface of the body   High frequency currents are also passed through the body for therapeutic and surgical purposes   When recording signals like ECG and EEG the amplifiers used in the preamplifiers stage may deliver small current themselves to the patient electrical safety

46. Gross shock is experienced by the subject by an accidental contact with the electrical wiring at any point on the surface of the body Current must enter the body at one point and leave at some other point   Electrical stimulation of the excitable tissues- herves and muscles   Resistance heating of tissues   Electrode-chemical burns and tissue damage for direct current and very high voltages GROSS SHOCK(MACRO SHOCK)

47. THRESHOLD OF PERCEPTION   The threshold varies considerably among indi-viduals and with the measurements conditions The lowest threshold could be 0.5MA when the skin is moistented at 50HZ   Threshold for DC current are 2 to 10 ma   LET-GO CURRENT   The maximum current at which the subject is still capable of releasing a conductor by using muscles directly stimulated by that current is called “let-go” current   Let-go current range for male and female vaies from 9 and 6mA   Male-16Ma   Femle-10.5mA   EFFECTS OF ELECTRIC CURRENT ON THE HUMAN BODY

48.   PHYSICAL INJURY AND PAIN At current levels higher than the let-go current the subject loses the ability to control his own muscle action and the is unable to release his grip on the electrical conductor such currents are very painful and hard to bear this type of accident is called the type hold-on –type acci -dent and is caused by currents in the range of 20-100mA EFFECTS OF ELECTRIC CURRENT ON THE HUMAN BODY

49. VENTRICULAR FIBRILLATION   Ventricular fibrillation is a serious cardiac emer-gency because once it starts it practically never stop spontaneously even when the current that triggered it is removed

50. It proves fatal unless corrected with in minutes, since the brain begins to die 2 to 4minutes affer it is robbed of its supply of oxygenated blood   SUSTAINED NYOCARDICAL CONTRACTION At currents in the range of 1-6 the entire heart muscle contrats although the heart stops beat- ing while the current is applied it may revert to a normal rhythm if the current is discontinued in fine just as in defibrillation   BURNS AND PHYSICAL INJURY   At very high currents of the order of 6 amperes and above there is a dangers of temporary respiratory paralysis and also of serious burns   Gross shock hazards are usually caused by electrical wiring failures  

51. MICRO CURRENT SHOCK   In which the current passes directly through the heart wall this is the case when cardiac cathe-ters may present in the heart chambers even very small amounts of currents can produce fatal result   FACTORS FOR MICRO SHOCK   Leakage current: the leakage current is due to   Ungrounded equipment   Broken ground wire Unequal around potentials   Leakage current is an extraneous current flow- ing along a path other than those intended it could be due to resistive inductive or capacitive coaplings with the mains or some electric equipment  

52. STATIC ELECTRICITY   Static electricity may be dangerous to people and sensitive equipment having integrated cir- cuit sparks from static electricity could ignite flammable gases causing an explosion   Shocks from static electricity could cause car- diac arrest if applied to a pacing patient   Floor cspecting is common source for static electricity charge build up

53. INTERRUPTION OF POWER   Interruption of electrical power to the life sup-port equipment can be dangerous   If a delay occurs before emergency power is brought into operation te failure of a respirator monitor defibrillator pacemakers or other life support equipment can be fatal   The possibility of a power failure must be con- sidered in the planning of a power distribution system  

54. use three wire chords to ensure the earth connection to the equipment .   all equipment used for a patient should have power supply with in 5mm distance and from a single bank of power points .   do not use other electrical systems in the neighborhood of the patient.   use earth fault trip relays   keep all non-electrical but conductive metal devices at ground potential by connecting it to the ground .   often check the chords for any damage.   use monitoring devices with isolated inputs .   the potential difference between the grounded metal case of the equipment and ground connection should be within 5mv.   check the ground connection for all equipment periodically.   PRECAUTIONS TO MINIMIZE ELECTRIC SHOCK HAZARDS

55. Grounding Double insulation Protection by low voltage Earth fault circuit interrupter Isolation of patient and instrument METHODS OF ACCIDENT PREVENTIONS