Telemetric monitoring device to detect thrombosis in the external arteriovenous shunt.
A telemetric monitoring system of the external arteriovenous shunt for long term hemodialysis was deviced. Analysis of the arteriovenous shunt bruit showed that frequency distribution of the bruit ranged between 25 and 500 Hz. An air transmission type microphone with an optimum frequency at 200 Hz was designed. The monitoring system, including the microphone, a small FM transmitter and an FM receiver with an alarm system by the transmitter. The signals received by the FM receiver were amplified and selected by a bandpass filter. After being all-wave rectified, and averaged for one min by the averaging circuit, the signals were finally balanced by the standard signal and the precision comparator. When the arteiovenous shunt bruit ceased for more than one min, the alarm system went off. The system frequently detected obstruction of blood flow due to flection of the forearm during sleep and by other causes, thereby preventing clotting of the arteriovenous shunt flow. Thrombosis in the arteriovenous shunt was detected 5 times by the telemetric device while the patients were alseep at home, and declotting was successful in all the cases. The system has proven to be available for early detection of shunt obstruction and of clot formation inside the arteriovenous shunt.
D000818:Animals; D001166:Arteriovenous Shunt, Surgical; D004285:Dogs; D004582:Electronics, Medical; D005542:Forearm / Q000098:blood supply; D006801:Humans; D012039:Regional Blood Flow; D006435:Renal Dialysis; D012212:Rheology; D013686:Telemetry / Q000295:instrumentation*; D013927:Thrombosis / Q000175:diagnosis*