Algorithm for reduction of mechanical noise in arterial pulse recording with tonometry

The quality of arterial pulse recording is diminished by mechanical noise, mainly in the form of movement by the subject, which is unavoidable in environments such as treadmill stress testing aid in aerospace settings. A method is presented for minimizing motion artifacts in such recordings. The pulse shape is obtained, through the principle of tonometry, by means of two piezoelectric (crystal) sensors positioned at the pulse site. One motion sensor output is subtracted from the other (pulse sensor=pulse+mostly common-mode motion) output. Observations show that the mechanical gain at each sensor´s interface differs. Subject movements can shift the transducer slightly and makes the gain time-varying. An algorithm is developed that estimates the best fit of pulse signal vs. noise signal in real time, using the method of least squares. An equation is presented to correct the pulse