An Ultrafiltration Monitor for Hemodialysis Research

The ultrafitration rate of hemodialysis membranes should be carefully controlled for maximum patient benefit. A special purpose instrument is described that takes in analog pressure information and the analog output of an appropriate weighing system and produces both digital displays and analog outputs (for a strip-chart recorder) of ultrafiltration rate and ultrafiltration index as well as the averaged mean transmembrane hydrostatic pressure drop and volume of ultrafiltrate. The instrument normally uses an averaging time of about 2 min.