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After discussing the problems involved in in vivo pH measurements, pH telemetry is presented as a new method. Long-term in vivo measurements of the pH are intended to be performed by means of a miniature transmitter implanted into the subcutaneous tissue of guinea pigs.
An ultrasonic blood flowmeter telemetry system, using only two integrated circuits and one transistor, has been designed for chronic unanesthetized animal studies. Standard components and construction techniques are utilized. The CW Doppler system employs LZT piezoelectric 10 MHZ transmitting and receiving crystals held in a lightweight polystyrene arterial transducer. The audio frequency, FM Doppler signal modulates an FM oscillator-transmitter to produce an FM/FM radio frequency carrier which is transmitted to an FM receiver at a remote location. The transmitted Doppler audio flow signal is demodulated at the receiver by a zero crossing detector. Power consumption is 48 mw. The 12.4 cc package volume can be further reduced for animal implantation.
A six channels telemetry system for recording masticatory force of complete denture wearers has been developed. This system is consisted of three blocks, the transmission block, the receiver block and the data storage and correction block. The transmission block is embedded in a lower complete denture. System has six load sensors and a standard resistor to correct sensor data. Data from six load sensors and standard resistor as well as standard zero are multiplexed using a division multiplex communication method. The sampling frequency is 666 Hz. And the signal is transmitted by FM modulation. The carrier wave frequency is 64 MHz. Receive data are decoded using start-stop system. The wave form noise is reduced using a signal averaging technique at an integrator. The data are input into the computer with an A/D converter. In this system, the sensor data is corrected at the computer with the standard resistor data. This method could reduce the influence of battery power changes and thermal drift significantly. For the load of 10 kg or less, the total linearity of the system remained at +/- 4% of the calibrated value. The noise level is 300 g.
By the method of ECG telemetry was investigated the cardiac, activity in 245 cows, from which 125--in the lactation period, 48--pregnant and 112--new-calved. It was established that the cardiac frequency in pregnant cows is 83.3 min-1, in new-calved--83.7 min-1 and in milch-cows--86.3 min-1. The elements of ECG are similar in value for the separated groups of cows, and are in the limits for the peak P by amplitude--from 0.22 to 0.24 mV and duration--from 0.080 to 0.083 s, for the peak R the amplitude is from 1.17 to 1.20 mV and the duration--from 0.063 to 0.065 s. The values of interval and segment P--Q, of segment S-T, interval Q--T and segment T--P are shown. Proved are changes in the shape and duration of the T wave, which occurs as diphasic in the pregnant and new-calved cows--up to 45% and in the milch-cows--9.6%.
Comparative ECG telemetry studies were carried out on the proper fixation of electrodes with a view to leading biopotentials from the heart with a total of 185 cows and calves. Conductions were made following the pattern of a standard ECG and the known points for telemetric investigations as suggested by various authors. As optimal sites for fixing the electrodes were shown to be the Ist precordial lead after Gabrashanski, the IInd one after Spörri, the IIIrd one (sagittal) after Roshtevskii, Horma and coll., and the sites suggested by us--apex cordis and the front angle of the left scapula. It was found that best information about the work done by the heart could be obtained by placing the electrodes along the axis line of the heart dipole polarity, and this corresponded to the negative electrode (a red one) of apex cordis--Vth and VIst interrib space at the height behind the elbow processus, and to the positive electrode (a yellow one) of the front angle of the right and the left spadebone. At such lead the basic ECG vector--QRS--was positive, and the peak P and the wave T were negative. The negative charge of the heart dipole was fed to the negative input of the amplifier for biopotentials, and the positive charge of the dipole is fed to the positive input.
A multichannel personal type telemetry system is described that utilizes PCM encoding for the most effective range with minimum RF bandwidth and noise interference. Recent IC developments (COS MOS) make it possible to implement a sophisticated encoding system (PCM) within the low power and size constraints necessary for a personal biotelemetry system. This system includes low level, high impedance preamplifiers to make the system suitable for EEG recording.
Simultaneous telemetry of salivary fluoride and of interproximal plaqua pH at the entrance to an interproximal space was used to investigate the effects of sucrose-containing fluoride tablets dissolving in the vicinity of the fluoride and pH sensors. The dissolving of 1.0 mg fluoride-42 mg sucrose tablets caused only slight pH depressions ranging between 6.7 and 6.0 with concurrent increases in salivary F to as high as 190 ppm. Acid formation in interproximal plaque by fluoride-free, sucrose-containing placebo tablets decreased pH to 4.2.
The clinical application of prolonged monitoring by the combined EEG and videotape recording of patients was evaluted. This test was found to be useful in diagnosing epileptic seizures in patients in whom both the history and diurnal EEG studies were unhelpful, and it assisted with the accurate classification of seizure types. It enabled seizure focus lateralisation in medically intractable epileptic who were being evaluated for surgery, and it also provided an objective estimate of minor seizure frequency. Prolonged EEG telemetry and videotape recording was especially useful in assessing additional seizures that develop in known epileptics. In some patients with syncope and drop attacks this technique helped to exclude atonic epileptic seizures and intermittent cardiac tachy-brady-arrhythmia as the underlying cause. As a method for identifying sleep disorders it has greater merits than conventional methods of polygraphic recordings.
Long-term in vivo measurements of the corrosion potentials of various implantable metal materials are performed using an implantable multichannel telemetry system. The data acquisition system has been designed to achieve maximum ease of operation for routine tests in animal applications. A novel signal encoding technique offers advantageous properties in connection with a commercial audio cassette tape recorder for signal storage. The flexibility of the design extends the scope of application to include not only biomaterial testing but all low frequency data transmissions in biological research.
A pulse width tracking system is described which converts a pulse width modulated telemetry signal into an analog signal. The converter, which is based on an integrated circuit chip design, contains a feedback feature that makes it ideal for high stability servo applications. The converter was designed as an integral part of a long-range radiotelemetry system used in occupational health field research.
An implantable radio telemetry system for transmitting deep body temperatures from dogs subjected to hyperbaric conditions was designed and tested. The design was adapted from a transmitter described by J. L. Riley, and was successfully tested both in vitro and in vivo to a simulated depth of 1000 FSW. Circuit schematic, printed circuit layout, and component layout are given.
We compared flying performance with the results of laboratory and airborne visual tests. Pilots flew high-performance, telemetry-tracked A4 and F-14 aircraft. In the low-level task, the index of performance was bombing accuracy; in air-to-air combat, performance was assessed by the number of missile hits scored per hit received (win/loss ratio). The chief laboratory tests comprised discrimination between two speeds of a radially-expanding flow pattern, and manual tracking of a visual target. Airborne tests comprised visual acquisition distance of an A4 aircraft, and visual sensitivity to a change in the course of an approaching A4 aircraft. We found that the flow pattern and movement-in-depth tracking test results correlated with bombing accuracy, confirming previously reported simulator findings. The results of airborne visual tests correlated with the win/loss ratio in combat, and tracking test results correlated with the number of missiles fired per combat engagement. Subsidiary tests of motion, grating contrast, and visual acuity thresholds were carried out for comparability with other studies, but these measures did not predict flying performance.
An eight channel telemetry system is presented which has low dimensions, low weight and is easy to use. The transmission is in the 430 MHz band on the basis of pulse-width modulation in a time-multiplex mode. A standard 9 volt battery offers a minimum of 15 hours operation with an accuracy of 1%. The upper limit frequency is currently at about 100 Hz. A 9th channel serves to monitor the function of the system.
Data of 170 consecutive patients admitted to a coronary care unit (CCU) with acute myocardial infarction (AMI) are reviewed and nature, incidence and time of occurrence of complications are studied. 94 of 170 patients had complications during the day of admission, while 7 of the remaining 76 experienced problems on the second day. On the third day only 3 patients had complications. Patients with complications on the day of admission are at high risk for severe complications and have a hospital mortality of 42%. Patients without complications during first 24 hours rarely have complications later and have a hospital mortality of 4%. It is concluded that patients with uncomplicated AMI can be transferred to a general ward after a 24 hour period of monitoring in CCU. These patients need supervision of myocardial function and rhythm over the next days. Checking of myocardial function has to be done clinically, while rhythm monitoring continuous telemetry of the ECG signal is suitable.
Design of a small and simple sensor for direct measurement of swimming speed of fish and its incorporation into ultrasonic telemetry transmitters is described. The sensor used measures the speed of rotation of a free-wheeling propeller which is exposed to water flow. Two transmitters incorporating this sensor are described. The first is a very simple one providing swimming speed while the second incorporates two temperature sensors as well.
Results in the development of intracranial pressure(ICP) telemetry systems are reported. Included are a single-channel ICP system and a two-channel ICP and temperature system. The unit used hybrid-integrated circuits housed in a Kovar flatpack and packaged with polyurethane or Hysol epoxy. Battery and radio frequency (RF) induction power supplies were tested. The two-channel systems used RF power at 3.5 MHz and transmitted signals around 120 MHz. The package measures 3 x 2 x 0.8 cm and weighs 9 g. The pressure range is -20 to +100 mm Hg with accuracy to 1.0 mm Hg. The implant measures absolute pressure and has a baseline stability of better than +/- 2 mm Hg/month. 17 dogs and 4 goats were used for in vivo evaluation. A summary of results is presented. Detailed evaluation is given in section II of this paper.
An implant telemetry system for the simultaneous monitoring of temperature, activity, and EKG from small animals, such as rats, has recently been designed with the novel feature that instead of a battery the system is energized by an inductive field. A 250 kHz resonant coil surrounds the cage (30 X 30 X 20 cm) and provides the approximately 100 muW of power required to operate the implant transmitter while allowing the animal unrestrained movement in the cage. The implant can also be battery operated if desired RF transmission is in the 8-10 MHz band, which allows the use of a simple, essentially single IC chip, receiver.
A low-cost FM/FM radio telemetry system is detailed, designed for motion analysis of the knee joint during walking in total knee replacement patients.