An improved data display system for fetal heart rate monitoring

Fetal heart rate (FHR) monitor records, particularly those derived from external sensors, may contain artifactual information closely resembling true FHR patterns. Additional machine-determined information may be used to help discriminate these data. Present commercial systems for indicating potentially artifactual FHR modify the FHR display, and this tends to cause the physician to ignore the absence of data or annoy him by obliterating some useful as well as potentialy useless information. Therefore, we chose to put the information that the data may be artifactual on another channel and allow the physician, rather than the instrument, to modify the interpretation of the FHR as necessary. A computer study was made of the characteristics of FHR beat-to-beat changes during poor signal to determine the most appropriate criteria for indicating when the FHR record is highly likely to be artifactual. Unphysiologic, erratic FHR changes are easily flagged by the presence of 3 serial beat-to-beat changes greater than 25 beats/min. Clinical testing demonstrated that this system allows the physician to better discriminate between valid and invalid data and increases the amount of usable data, particularly in active patients.