Fetal heart rate monitoring

• Main Authors: DEANS; ANNE CATHERINE, STEER; PHILIP JAMES, GENEVIER; ERIC SERGE GILLES
• Format: Patent
• Language: English
• Published: 16.09.1997
• Edition: 6
• Subjects: DIAGNOSIS; HUMAN NECESSITIES; HYGIENE; IDENTIFICATION; MEDICAL OR VETERINARY SCIENCE; SURGERY

A method and apparatus for deriving a pulse sequence corresponding to a fetal heart rate (FHR) from a composite ECG signal which includes a signal from a second source, such as from the mother or a twin. A peak detection technique is used to identify apparent QRS complex signal components in the composite ECG signal, which are then compared against a template by calculating a statistical correlation coefficient. If the correlation result exceeds a predetermined threshold, the complex is flagged as a match. The template is an adaptive one, and is initialized by taking the complexes associated with the first n peaks encountered in the composite ECG signal. It is then continuously updated with each QRS complex which provides an exceptional match. After event sorting and output validation, a sequence of pulses is produced which represents the fetal heartbeat and which can be passed to a conventional heart rate monitor for display. The maternal heart rate can be derived and monitored in the same way, a maternal template being created from identified complexes which fail the correlation against the fetal template. The apparatus and method are particularly applicable to a composite ECG signal monitored by way of an intrauterine probe which is non invasive to the fetus.