Bio-telemetry is the electrical technique for conveying biological information from a living organism and its environment to a location where this information can be observed or recorded. A mobile medical device that can be used to monitor the human temperature and blood pressure (BP) using single chip microcontroller. A software algorithm acquires temperature and blood pressure, process, transmits, displays and stores it in the built microcontroller. Once the desired programmed trigger level of any of the signal is reached, the microcontroller downloads the current value of the temperature and BP of the GSM modem. Then, GSM automatically sends a message to the stored mobile number.
This method is used to track the patient’s condition during required situation. This project is a combination of techniques used in embedded systems and bio telemetry. The main tools used are the microcontrollers, analogue to digital convertor, amplifiers, transformers, LCD and sensors for the measurement of body temperature and blood pressure of the human body. Bio telemetry is one of the highly applied methods and widely used in research and development in the field of biomedical. This subject is widely sort out in the field of research since it provides practical application in the medical sciences. It is used in keeping a regular watch on the patients who might have survived a serious operation or undergoing medical supervision for critical conditions like heart attacks, blocks or chokes in the arteries. They are also used in cases where the person needs to be continuously monitored and the patient might not be in the proximity of the doctors.
Many other branches of this bio telemetry are now coming up and the one developing rapidly is telemedicine. This method is similar to our project where patient’s information is conveyed to the medical supervisor using mobile systems like GSM, GPRS etc... Earlier the messages were sent through radios but with the advent in communication technologies several other methods have been used which has given better results which are accurate and less time consuming than the older methods. This method is much more reliable.
Mobile Patient Monitoring System
The mobile patient monitoring system being designed in our project consists of two sensors which are RTD (resistance temperature detector) which is used in measuring the body temperature and the other sensor is the sphygmomanometer used for measuring the blood pressure of the body. Here we hae taken into consideration such parameters which do not need invasive methods of measurement. Both the sensors will be used on the patient for regular readings. The information acquired from the patient using these sensors will be amplified and converted and sent to the microcontroller which will check the readings to see if they lie in the normal range, if not then a message will be sent using GSM modem to the medical supervisor for instant action to be taken. In cases of normalcy being shown by the patient the LCD display will continuously show the readings Thus in this way we will be monitoring the patient in remote areas and the message will be conveyed to the medical supervisors in distant places. Patient monitoring systems is the term for all the various devices that are used to supervise patients. One category of such devices is devices that alerts if the patient gets into a critical state.
The need for patient monitoring is apparent in situations where the patient is:
• In unstable physiological regulatory systems, for example in the case of a drug overdose or anesthesia
• In a life threatening condition, for example where there are indications of a heart attack.
• In risk of developing a life threatening condition.
• In a critical physiological state. Patient monitoring is not a new in health care.
The first primitive patient monitoring started with the work done by Santorio in 1625 that was measuring of body temperature and blood pressure. The development of new technology after World War 2 and up to today has developed a vast amount of different types of monitoring that can be done. A schematic diagram is shown below for the better understanding on the working of the device and all the parts used in the construction of the mobile patient monitoring system
Objective
The main objective of this project is to apply the combined methods of biomedical and embedded system to produce a device capable of monitoring patients in remote conditions and in case of emergency to convey the message using GSM (global system for mobile communication).
� To monitor the temperature and blood pressure of the patient using single chip micro controller.
Materials and Methods
The materials used for the construction of the mobile patient monitoring system are as follows
�Sensor1-resistance temperature detector (RTD)
�Sensor2-spygmomanometer
�Amplifier(LM358)
�ADC(AD0809)
� Microcontroller(AT89C51)
�Max232
� GSM
� LCD Display
Resistance Temperature Detector
Resistance Temperature Detectors or RTDs for short, are wire wound and thin film devices that measure temperature because of the physical principle of the positive temperature coefficient of electrical resistance of metals. The hotter they become, the larger or higher the value of their electrical resistance. They, in the case of Platinum known variously as PRTs and PRT100s, are the most popular RTD type, nearly linear over a wide range of temperatures and some small enough to have response times of a fraction of a second. They are among the most precise temperature sensors available with resolution and measurement uncertainties or ±0.1 °C or better possible in special designs. The advantages of RTDs include stable output for long period of time, ease of recalibration and accurate readings over relatively narrow temperature spans
Working
The sensors resistance temperature detector works on the simple principle that resistance is directly proportional to temperature. Thus when there is a change in temperature a change in resistance is experienced. Measuring the change in resistance the corresponding temperature can be obtained. This RTD is placed on the patient’s hand which reads the temperature of the patient since it is highly sensitive it can even measure a small change of plus or minus one degree Celsius which would be expressed in term of resistance. The figure given below shows how the patient interacts with the RTD sensors.
Conclusion
The patient is continuously monitored and his blood pressure and temperature is recorded and displayed on the LCD screen. In case of emergency that is when the values of body temperature and blood pressure vary below or above the normal range then the microcontroller sends the message to the medical supervisor through the GSM modem. The number of messages to the pre-stored mobile numbers can be decided accordingly; similarly the number of recipients can also be decided according to the name. The figure below shows a mobile which has received an emergency message..
The microcontroller has already been programmed to check if the incoming signals lie within the normal range of the respected parameters. In cases where the input signal are not in the range then a message is sent through the GSM modem to the medical supervisor. This helps in taking immediate action the patient. The basic idea behind the whole device is that the patient should be monitored continuously and in case of emergency the respected medical attendant should be altered regarding the patient’s condition and they take proper action.
A further enhancement is done in the project by increasing the number of message recipients that is; first the GSM modem sends a message to the first pre stored mobile number according to the priority hierarchy. If the first person does not respond then within a stipulated time then another message is sent to the second mobile number. This acts as a safety measurement. If the final recipient has not attended the message then the second person will also be reported and action can be expected from his said. The other advantage is that the message is sent successfully to the mobile number till a response is received from the patient..