Oscillometric blood pressure monitor modeling

Oscillometric blood pressure monitors are fairly reliable medical equipments, inexpensive and widely used both in domicile and clinical measurements of blood pressure, however they have not yet been subject of deep investigation. The research reported in this paper presents the development of an analytical model of an oscillometric blood pressure monitor, a task which has not been dealt with and is useful in order to improve these devices´ accuracy limitations. The approach taken was to divide the transducer in two distinct components, the electromechanical and the pneumatic, considering compression and decompression phases. Differential equations were derived, using electric and mechanical principles, to explain the equipment´s behavior during the air-pump compression, and the pressure evolution during decompression was identified by exponential approximation. This comprehensive study obtained several non-ideal and nonlinear dynamics, and describes some of the possible simplifications to the models used.