A new method for pulse oximetry possessing inherent insensitivity to artifact

A new method for pulse oximetry is presented that possesses an inherent ins ensitivity to corruption by motion artifact, a primary limitation in the pr actical accuracy and clinical applicability of current technology, Artifact corruption of the underlying photoplethysmographic signals is reduced in r eal time, using an electronic processing methodology that is based upon inv ersion of a physical artifact model. This fundamental approach has the pote ntial to provide uninterrupted output and superior accuracy under condition s of sustained subject motion, therefore, widening the clinical scope of th is useful measurement. A new calibration technique for oxygen saturation is developed for use with these processed signals, which is shown to be a gen eralization of the classical interpretation. The. detailed theoretical and practical issues of implementation are then explored, highlighting importan t engineering simplifications implicit in this new approach. A quantitative investigation of the degree of insensitivity to artifact is also undertake n, with the aid of a custom electronic system and commercial pulse oximeter probes, which is compared and contrasted with the performance of a convent ional implementation, It is demonstrated that this new methodology results in a reduced sensitivity to common classes of motion artifact, while retain ing the generality to be combined with conventional signal processing techn iques.