Apparatus for monitoring fetal health during labor detects the occurrence of a fetal ECG in digital signals derived from electrodes on a fetus using a matched filter routine to detect a QRS complex. The peaks of successive R waves are then found and used to determine fetal heart rate. After time coherent filtering of digital samples representing the fetal ECG the P-R interval and the elevation of the S-T interval are found and a correlation coefficient between the fetal heart rate and the P-R interval is derived. The elevation and the coefficient are displayed. If the correlation coefficient becomes positive for about half an hour and a significant fall in the elevation of the S-T interval also occurs it is an indication of acidosis of the fetus.
A method and apparatus are provided for measuring selected patient heartbeat parameters such as heartrates and amplitude variations, for processing the measured parameters to place them in more usable form and for analyzing measured and processed heartbeat parameters to obtain certain useful information concerning the condition of the patient's cardiac function. Measurement preferably involves detection and storage of at least two of the P, R and T pulses for each heartbeat and the conversion of such information into time series for selective heartrates. Indicators .delta..sub.j are computed for selected ones of the time series for selected values of j and the computed .delta..sub.j 's are then compared against stored .delta..sub.j values to obtain a measure of the state of cardiac function. The time series are preferably notched, detrended and normalized prior to being analyzed.
A system used by a technician for evaluating a Holter ECG tape having a signal representing a series of waveforms thereon and for generating a report reflecting the evaluation. A tape reader generates from the ECG tape an analog signal representative of the ECG waveforms recorded on the tape. An A/D converter converts the analog signal into a digital signal. A computer including a data bus, a memory, a processor controls the operation of the system. A display displays waveforms representing the ECG. A storage device is connected to the data bus. A direct memory access device moves the digital signals from the converter to the memory for storing the digital signal in the storage device. The converter provides at least a 12 bit a digital signal corresponding to the analog signal and includes means for converting the 12 bit digital signal to an 8 bit digital signal.
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.
A method (10) for suppressing the maternal electrocardiograph (MECG) signal from a composite abdominal ECG including an MECG signal, an fetal ECG (FECG) signal and noise to obtain a substantially MECG-free FECG trace. The method (10) of the present invention includes the placement of a plurality of electrodes (26) about the periphery of the mother to detect a substantially pure MECG (12) and a composite MECG+FECG signal (14). A scalp electrode (32A), which is invasive to the fetus (72), and an intrauterine catheter electrode (32B), which is non-invasive to the fetus (72), may be alternately used to detect the signal (14), both electrodes (32A,32B) being invasive to the mother. A preprocessor (34) converts the signals (12,14) obtained by the individual electrodes (26,32A,32B) attached to, or invasive to, the mother (70) into appropriate electrical or digital signals for MECG suppression, and selectively performs a filtering operation to remove noise and other distortions. The MECG suppression is achieved by using a substantially pure MECG trace ( 12) as a trigger signal to calculate an MECG complex template (18) which is subtracted from the composite signal (14) using the MECG trace (12) to align the MECG complex template (18) with each MECG complex (16) in the composite signal (14).
A fetal monitor is provided for gathering characteristic data such as fetal electrocardiogram, temperature and intra-uterine pressure so that fetal health may be determined during intra-operative and postoperative periods. The fetal monitor comprises a remote sensing unit, the remote sensing unit containing sensors which continually sample fetal temperature and electrocardiogram. A transceiver is housed in the remote sensing unit and outputs the sampled fetal temperature and electrocardiogram signals to an external antenna. A monitoring station is provided for monitoring the fetal temperature and electrocardiogram signals from the antenna. Additionally, a pressure transducer may be housed in the remote sensing unit for continually sampling intra-uterine pressure. This intra-uterine pressure signal in combination with the above signals are utilized to determine fetal health or the onset and progress of parturition.
