PowerPoint Presentation

BIOMEDICAL TELEMETRYAND TELEMEDICINE

BiotelemetryBiotelemetry is wireless transmission of automatically measured physiological data from the point of sensing to a remote location.In practice the term also refers to bidirectional wireless data transfer and remote powering.It is a modification of existing methods of measuring physiological variables to a method of transmission of resulting data.2

The transmission of data from one point of generation to the point of reception can be done in various ways.Example: stethoscopeSimplest device which uses the principle of biotelemetry.It amplifies acoustically the heartbeats and transmit their sound to the ears of the doctor through a hollow tube suction.

Certain applications of biotelemetry use telephone lines for transmission.However biotelemetry mainly uses radio transmission by suitably modifying the biological data. 3

Earlier times, the telemetry could be applied to measure:Temperature by rectal or oral thermistorECG by surface electrodes.Indirect blood pressure by contact microphone and cuffRespiration by impedance pneumograph

However it is possible now to apply biotelemetry to almost all measurements such asBioelectrical variables such as ECG, EEG,EMGPhysiological variables that require transducers eg. Blood pressure, blood flow, temperature.The signal is obtained directly in electrical form in bioelectrical measurements.

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Applications Multi-electrode recordingVital sign monitoring in critical and ambulatory careVital sign monitoring of pilots and astronautsMeasurements like- temperature, pressure, EMG, EEG, ECG.5

MODULATION SYSTEMSThe sub-modulator can be a FM or PM system, whereas the final modulator is practically always an FM system. Frequency modulation:In frequency modulation, information is transmitted by varying the instantaneous frequency in accordance with the signal to be modulated, keeping the amplitude of the carrier wave constant.Usually an FM signal is produced by controlling the frequency of an oscillator by the amplitude of the modulating voltage.Pulse width modulation: this has an advantage of being less perceptive to distortion and noise.

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Single channel telemetry systemIn majority of situations requiring monitoring of patients by wireless telemetry, most commonly studied parameter is ECG.

ECG telemetry systemConsists of a transmitter and a receiver.

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BD of single channel telemetry system

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For distortion-free transmission of ECG, the following requirements must be met

The subject should be able to carry on his normal activities whilst carrying the instruments without any discomfort.Motion artifacts and muscle potential interference should be kept minimum.The battery life should be long enough so that complete experimental procedure may be carried out.9

B.D of ECG telemetry transmitter

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B.D of ECG telemetry receiver

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Temperature telemetry systemSystems for transmission of alternating potentials representing parameters as ECG, EEG and EMG are relatively easy to construct.Telemetry systems which are sufficiently stable to telemeter direct current outputs from temperature, pressure for long periods present greater design problems.A temperature telemetry system based on this principle is shown in fig. 12

Temperature telemetry system

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Multi-channel wireless telemetry systemMedical measuring problems often involve the simultaneous transmission of several parameters.For this purpose, a multi-channel telemetry system is employed.Multi-channel telemetry is particularly useful in athletic training programs as it offers the possibility of simultaneously surveying several physiological parameters of the person being monitored.With appropriate pre-amplifiers, the multi-channel systems permit the transmission of ECG and heart rate, respiration rate, temperature, intravascular and intra-cardiac blood pressure.

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Multi-channel wireless telemetry systemIn multi-channel telemetry, the number of sub-carriers used are the same as the same as the number of signals to be transmitted.Each channel therefore has its own modulator.The RF unit-the same for all channels- converts the mixed frequencies into the transmission band.And demodulator contains the RF unit and one demodulator for each channel.

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Multi-channel wireless telemetry systemPulse width modulation is better suited for multi-channel biotelemetry systems.Such systems are insensitive to carrier frequency shifts and have high noise immunity.FM-FM systems for similar use may have low power consumption and high baseline stability, but they are more complicated and turn out to be more expensive.They can be troubled by interference between different channels.Pulse position amplitude modulation easily gets into synchronization difficulties caused by noise and thus result in loss of information transmitted.

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Telemetry of ECG and repiration

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Obstetrical telemetry systemThis provides greater freedom of movements to patients during labour while the patient is continuously monitored through a wireless link.In delivery room, telemetry reduces the number of instrumentation cables at the bedside.When an emergency occurs, there is no loss of monitoring in the vital minutes needed for patient transfer.The patient carries a small pocket-sized transmitter which is designed to pick up signals for foetal heart rate and uterine activity 18

Obstetrical telemetry systemThe foetal heart rate is derived from foetal ECG which is obtained via scalp electrode attached to the foetus after the mothers membrane are ruptured.Uterine activity is measured via an intra-uterine pressure transducer.The receiver located away from the patient, is connected to a conventional cardiotocograph.19

Telemetry in operating roomsThe use of telemetry in operating rooms offers a means of achieving a high degree of patient safety from electric shock as well as elimination of the hanging inter-connecting patient leads which are necessary in direct-wired equipment.The most common parameters of interest while monitoring surgical patients are ECG, blood pressure, peripheral pulse and EEG. 20

Sports physiology studies through telemetryMonitoring of pulmonary ventilation, heart rate and respiration rate is necessary for a study of energy expenditure during physical work, particularly for sports such as squash, handball, tennis etc.For this purpose, the transmitter uses pulse duration modulation, i.e. each channel is sampled sequentially and a pulse is generated, the width of which is proportional to the amplitude of the corresponding signal.The transmitter is designed to work in a range of 100m, which can be extended by using a whip antenna.

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Sports physiology studies through telemetryFor recording ECG, the electrodes are placed at the sternum.The pulmonary ventilation and respiration rates are derived from a mass flow transducer.At the receiving end the system contains an FM tuner and circuitry to convert the pulse width coded signals back to analog signals and a multi-channel pen recorder to display the physiological signals.22

Multi-patient telemetryThis provides a sort of intermediate stage of care that smoothens the patients transition back to a normal life.Avoids the need of confining the patient to bed.Transmitters of very small size and weighing less than 115g, including battery are available.Data from different patients is received at the nurses central station.The station may have the facility of non-fade display of received waveforms, an ECG recorder which gets activated when the patient goes into alarm, loose lead/loss of signal alarm.The heart rate of each patient is derived and displayed simultaneously with a digital display.

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Implantable telemetry systemsIt allows the measurement of multiple physiological variables over long periods of time without any attachment of wires, anesthesia to monitored subject.24

Implantable telemetry system for blood pressure and blood flow

Used in case where information about the blood flow over a period of several months is required.Electromagnetic flowmeters are not suitable for implant purposes, as they consume a lot of power.Ultrasonic Doppler shift principle is the most widely used technique for implantable blood flowmeter.

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B.D of implantable blood flowmeter

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Transmission of analog physiological signals over telephoneThis method has an advantage that individual patients can be managed in remote areas.By sending ECG and other signals over the telephone lines, a patient can communicate with the doctor or specialist from his home while lying on bed.Another necessity for such transmission is to use telephone lines for the collection of data for a central computer, from anaesthetized patients undergoing surgery in operating theatres and from conscious patients in recovery rooms, for maintenance of records for future reference.27

Transmission of analog signals over telephone lines

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Multi-channel patient monitoring telephone telemetry systemThis is employed due to increasing need for multi-channel parameter monitoring, especially the simultaneous transmission of ECG, blood pressure, respiration and also temperature.A frequency modulation system using 750Hz, 1750Hz, 2750Hz is employed.29

B.D of 3 channel telephone trasmitter

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B.D of 3 channel telephone receiver

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TELEMEDICINETelemedicine, as the name suggests, is the application of computer technology and telecommunication to provide health care from one place to another.

Telemedicine uses information technology to provide timely treatments to those in need by telecommunication of the necessary expertise, diagnosis and information among distant located parties.

Physicians, labs and patients can be distant located parties. Telecommunication enables all parties to interact as they are at one place, resulting in an improved patient care and management, cost effectiveness and better utilization of expertise.

Telemedicine includes hardware, software, medical equipment and communication link.32

Telemedicine supports a range of applications

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Telemedicine ApplicationsTelepathology is used to obtain an expert opinion in biopsy reports and microscopic photos of pathology slides.

Teleradiology is used for telecommunication of radiology images like radiographs, CT scan, MRI and nuclear medicine from one place to another for expert interpretation and consultation. The problem faced in radiology is the vast data associated wit each image and lack of standardization of data for transmission.

Telecardiology relates to telecommunication of ECG, echo cardiography and color dopler of patients to experts for advice.

Teleconsultation is used by a hospital or a patient to consult specialist doctors.

Tele-education can be used for providing medical education to junior doctors working at smaller towns who are professionally isolated from teaching hospitals.34

Telemedicine concepts can be:Store and forward:In this, information is compiled and stored.The stored information can be in the form of video images and clips or laboratory reports.The information in digital form is stored and forwarded to experts for interpretation and advice.The experts can access the same whenever possible and they can transmit back their advice.

Real time:In this, real time exchange of information takes place between two medical professionals or two centers.The real time information may be in the form of video conference or it may take place simultaneously with the examination and imaging of the patient35

Telemedicine system

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TELEMEDICINE TECHNOLOGYTransmission of medical images:Includes transmission of X-rays, CT, MRI etc.These images are first converted into digital form.

Types of diagnostic images used in telemedicine include:Image stored on traditional film or print media and converted into digital format by direct imaging or scanning. CCD(charged coupled devices) and laser based scanners are used for digitization of images.Computer generated images (e.g. ultrasound, CT) which are already in digital format does not require any further digitization.

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Transmission of video imagesTelemedicine applications usually require video and individual still-frame images for interactive visual communication and medical diagnosis.38

Transmission of digital audioAudio channels are usually provided for diagnostic instruments such as an electronic stethoscope or Doppler ultrasound.To produce heart and lung sounds accurately, an electronic stethoscope must have a uniform frequency response from 20Hz to 2kHz, while Doppler ultrasound requires a uniform frequency response from 100Hz to 10kHz.Audio use for conversation and medical diagnosis in a telemedicine system must be digitized and compressed before it can be combined with digital video and other information. 39

Video conferencingOne of the essential components in a telemedicine system is the video conferencing facility, which permits real time transmission of both audio and video information.40

Digital communication systemsTelemedicine primarily demands a continuous and reliable communication link for the exchange of information.There are various digital communication services available today for this purpose.They are POTS (Plain Old Telephone Service), DDS (Digital data system), ISDN (Integrated services digital network), ATM (Asynchronous transfer mode).

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Telemedicine using mobile communication

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Use of internet resource for telemedicineThe world wide web (WWW) is an internet resource through which information producing sites offer hyper-linked multi-media information to the general public or in some cases restricted access to a certain group of people.

Graphical browser programs are specially designed to access WWW resources and view their contents in text, graphics images and video. 43

THANK YOU44