PRURITOMETER-1 - A PORTABLE MEASURING SYS TEM FOR THE QUANTIFICATION OF SCRATCHING AS AN OBJECTIVE CRITERION OF CHOLESTATIC PRURITUS

Objective assessment of subjective symptoms such as pruritus always pr esents problems, which can often be resolved only indirectly. The obje ctification of pruritis was necessitated by a study on the efficacy of a serotonin antagonist used as treatment of cholestatic pruritus. In the present paper, a portable measuring system for the indirect object ive assessment of pruritus via the quantification of scratching is des cribed. A piezoelectric scratch-vibration sensor for attachment to the middle finger of the patient's dominant hand was developed. A sensor interface detects the scratching signals and generates pulses that are then summed in an adapted sports watch. The entire system - Pruritome ter 1 - is worn by the patient like a wrist watch, and is characterize d by ease of handling. Acceptance by the patient is reported to be goo d. A statistically good correlation between measured (Pruritometer) an d visually counted scratches was demonstrated. Pruritometer 2, which w ill enable scratch frequency and intensity distribution over time to b e determined, is presently being developed.