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Measurement of Urea in Blood by Differential Heat of Hydrolysis

IP.com Disclosure Number: IPCOM000089992D
Original Publication Date: 1969-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Neff, GW: AUTHOR [+3]

Abstract

The system directly determines the concentration of urea in whole biological fluids such as blood. The sample of biological fluid is introduced into sample chamber 1 via fluid input 2. Since the measuring technique is nondestructive to the fluid sample, the latter, outputted via fluid output 3, can be reused. Thus, the arrangement can be used on-line with a patient.

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Measurement of Urea in Blood by Differential Heat of Hydrolysis

The system directly determines the concentration of urea in whole biological fluids such as blood. The sample of biological fluid is introduced into sample chamber 1 via fluid input 2. Since the measuring technique is nondestructive to the fluid sample, the latter, outputted via fluid output 3, can be reused. Thus, the arrangement can be used on-line with a patient.

The urea from the fluid sample, in sample chamber 1, is diffused across membrane 4 and is distributed around the lower ends of thermistors 5 and 6. Thermistor 5 is surrounded, at its lower end, with a layer of electrolyte 7 containing the enzyme urease. Thermistor 6 is surrounded, at its lower end, with a layer of electrolyte 8 containing no urease. Washer 9 acts to separate the thermistors and seal the chamber.

The urease in layer 7 reacts with the diffused urea to effect a hydrolytic reaction around the surface of thermistor 5. Since layer 8 contains no urease, no such reaction occurs around the surface of thermistor 6. Thermistor 5 senses the heat of reaction to unbalance the resistive bridge 10.

The difference in temperature, as sensed by the pair of thermistors, is proportional to the concentration of urea in the sample. Galvanometer 11 provides a continuous real-time indication of the magnitude of this concentration.

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