Fetal brain monitor

• US 6,556,861 B1
• Filed: 11/20/2000
• Issued: 04/29/2003
• Est. Priority Date: 11/20/2000
• Status: Expired due to Term

• Current Assignee: New York University
• Original Assignee: New York University
• Inventors: Prichep, Leslie S
• Primary Examiner(s): DOERRLER, WILLIAM CHARLES
• Application Number:
  US09/716,517
• Time in Patent Office: 890 Days
• Field of Search: 600/544-545, 600/300, 600/559, 607/45, 607/48, 607/62, 128/510
• US Class Current: 600/544
• CPC Class Codes: A61B 2503/02 Foetus
• CPC Class Codes: A61B 5/38 Acoustic or auditory stimuli
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

A Fetal Brain Monitor (FBM) utilizes a transducer which is placed on the abdomen of a mother and which is pulsed to generate auditory sounds, i.e., clicks, to provide auditory brainstem evoked responses (BAER) of a fetus within the mother'"'"'s uterus. The fetus'"'"' brain waves are detected by a biosensor, amplified, converted to digital data, and analyzed, in one embodiment, using a digital comb filter to improve the signal/noise ratio. The computer system uses QEEG (Quantitative EEG) to compare the data from the fetus to normative data or to prior states of the fetus'"'"' own data (self-norm)

Claims

1. A method of monitoring a brain wave response of a fetus in utero, comprising the steps of:

(a) removably connecting an auditory transducer to an abdomen of a mother of the fetus;

(b) removably connecting at least one biosensor electrode to the mother'"'"'s abdomen to detect brain wave activity in the fetus;

(c) pulsing the transducer to emit pulsed audible sounds at predetermined times;

(d) detecting, for each pulsed audible sound, a series of voltage oscillations corresponding to brain stem auditory evoked responses (BAER) of the fetus which are time-locked to the corresponding audible sound; and

(e) converting the BAER analog output to BAER digital data.

2. The method of monitoring as in claim 1, further comprising the step of improving a signal to noise ratio of the BAER digital data using a computer-based QEEG (Quantitative EEG) system.

3. The method of monitoring as in claim 2, further comprising the step of displaying results of the QEEG analysis as an indication of the status of brain function of the fetus.

4. The method of monitoring as in claim 1, wherein, in step (b), the at least one biosensor electrode comprises an array of biosensor electrodes connected to the mother'"'"'s abdomen.

5. The method of monitoring as in claim 1, wherein, in step (c), the pulsing of the transducer generates the audible sounds from the transducer at a predetermined rate selected to optimize recording of data.

6. The method of monitoring as in claim 2, further comprising the step of passing the BAER digital data through a a digital comb filter having a plurality of band pass frequency ranges within an overall frequency range of 50-2000 Hz.

7. The method of monitoring as in claim 6, further comprising the steps of:

passing the data from the digital comb filter through a Fast Fourier Transform (FFT) arrangement to transform the data to a frequency domain;

elminating non-significant portions of the data from the digital comb filter using the FFT arrangement; and

transforming significant coefficients of the data from the FFT arrangement back into a time domain using an Inverse Fast Fourier Transform (IFFT) arrangement.

8. The method of monitoring as in claim 2, further comprising the step of comparing the BAER digital data to reference BAER data from a control group to determine one of an abnormality and normality of the BAER of the fetus being monitored.

9. The method of monitoring as in claim 2, further comprising the step of comparing successive recordings of the BAER digital data from the fetus being monitored using an initial recording from the fetus being monitored as a “

self-norm”

to determine a degree of change from an initial state.

17. The method of monitoring as in claim 6, further comprising the step of setting the band pass frequencies of the digital comb filter by comparing a SIGNAL sample of data corresponding to a time period during which pulsed audible sounds were generated by the transducer and a NOISE sample of data corresponding to a time period during which no pulsed audible sounds were generated by the transducer.

18. The method of monitoring as in claim 7, wherein after the significant coefficients of the data from the FFT arrangement have been transformed back into a time domain using the IFFT arrangement, mean amplitudes and variances of amplitudes are computed at each of a plurality of sampling points corresponding to times during which brain responses to the pulsed audible signals are generated to produce a wave corresponding to the BAER.

19. The method of monitoring as in claim 18, further comprising the step of smoothing successive peaks of the wave.

20. The method according to claim 18, wherein significant coefficients of the data from the FFT arrangement are identified by analyzing phase variations of the data from time periods during which pulsed audible signals are generated as compared to time periods during which pulsed audible signals are not generated.

10. A Fetal Brain Monitor for monitoring a brain wave response of a fetus in utero, comprising:

(a) an auditory transducer producing pulsed audible sounds and adapted to be placed on an abdomen of a mother of the fetus;

(b) at least one biosensor electrode adapted to be placed on the mother'"'"'s abdomen for detecting electrical activity of a brain of the fetus;

(c) a pulsing arrangement pulsing the transducer so that it emits pulsed audible sounds at predetermined times;

(d) an amplifier connected to the at least one biosensor electrode to amplify brain stem auditory responses (BAER) of the fetus detected by the at least one biosensor electrode which are time-locked to the sounds;

(e) an analog/digital converter converting the analog BAER data to BAER digital data;

(f) a computer-based QEEG (Quantitative EEG) system improving a signal to noise ratio of the BAER digital data and analyzing the BAER digital data; and

(g) a display displaying results of the QEEG analysis as an indication of a status of the BAER.

11. The Fetal Brain Monitor as in claim 10, wherein the at least one biosensor electrode includes 3 electrodes.

12. The Fetal Brain Monitor as in claim 10, wherein the pulsing arrangement generates audible sounds from the transducer at a predetermined optimal rate per second.

13. The Fetal Brain Monitor as in claim 10, wherein the computer system includes a digital comb filter having a plurality of band pass frequency ranges in an overall frequency range of 50-2000 Hz.

14. The Fetal Brain Monitor as in claim 13, further comprising:

a Fast Fourier Transform (FFT) arrangement transforming the digital data which passes through the digital comb filter into a frequency domain and eliminating non-significant coefficients from the data; and

an Inverse Fast Fourier Transform (IFFT) arrangement transforming significant coefficients from the data transformed by the FFT arrangement back into a time domain.

15. The Fetal Brain Monitor as in claim 10, further comprising:

an arrangement comparing the BAER digital data to comparative BAER data from a normal group of fetuses to determine one of an abnormality and normality of the BAER.

16. The Fetal Brain Monitor as in claim 10, further comprising:

an arrangement comparing to one another successive recordings of BAER digital data from the fetus being monitored using an initial recording as a “

self-norm”

to determine a degree of change from an initial state.