補正ノルム比によるタッピングアーチファクトに埋もれた脈波の分離

抄録

This paper proposes a compensated-norm-ratio Φ_N⁺ algorithm to improve the separation of a submerged pulse wave in a heavy tapping artifact that is measured by two wave lengths (denoted by IR, R ) of SpO₂. This algorithm employs a 2×2 inverse matrix to separate the pulse wave. Parameters Φ_S and Φ_N are unknown for the inverse matrix. Φ_S and Φ_N are respectively the R/IR norm ratio of the pulse wave and the artifact wave for the observed signals. It is able to determineΦ Φ_S from the stable pulse wave segment. By contrast,careful estimation is necessary for Φ_N. This is because, _N is shifted from Φ_N^true due to the pulse wave superimposed on the artifact segment. This shift induces poor pulse wave separation. A compensation algorithm is necessary to make Φ_N closer to Φ_N^true. The proposed compensated-norm-ratio Φ_N⁺ results in better separation of the pulse wave than that obtained using Φ_N. This algorithm is also effective for case with other body movement artifact. This algorithm can not only be not be applied to two-wave pulse photometry but can be also extended to multi-wave pulse photometry.