ECG Enhancement by Adaptive Cancellation of Electrosurgical Interference

A technique utilizing a combination of adaptive noise canceling and conventional signal processing is developed to enhance electrocardiographic monitoring in the operating room by reducing the noise interference that is created by an electrosurgical instrument. Significant amounts of interference are eliminated by radio frequency shielding, passive and active low-pass filtering, and optical isolation. A digital adaptive canceler using the least mean-square algorithm of Widrow and Hoff is used to reduce the remainder of the interference, yielding an improvement in signal-to-noise ratio of approximately 110 dB. Clear electrocardiograms have been obtained with electrocautery equipment in operation.