FETAL HEART MONITOR WITH PARTICULAR SIGNAL CONDITIONING MEANS

• US 3,703,168 A
• Filed: 03/30/1970
• Issued: 11/21/1972
• Est. Priority Date: 03/30/1970
• Status: Expired due to Term

• Current Assignee: Richard D. Frink
• Original Assignee: Richard D. Frink
• Inventors: Frink, Richard D.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/023,737
• Time in Patent Office: 967 Days
• Field of Search: 128/2.6B,2.6F,2.6G,2.6R,2S 333/7G 330/69 307/233
• US Class Current: 600/511
• CPC Class Codes: A61B 5/344 Foetal cardiography
• CPC Class Codes: A61B 5/4356 Assessing uterine contractions A61B5/033 takes precedence
• CPC Class Codes: A61B 5/4362 Assessing foetal parameters

Abstract

A fetal heart monitor capable of detecting fetal heart activity in a non-invasive manner and in the presence of noise and substantially stronger maternal heart signals. The system is also operative to simultaneously monitor labor contractions in a noninvasive substantially noise free manner, and additionally provides means for selectively displaying the rhythm ECG.

Claims

1. A non-invasive fetal heart monitor comprising:

an amplifier having low input impedance and adapted for connection to a plurality of surface electrodes attached to a mother'"'"''"'"'s skin;

filter means coupled to said amplifier and operative to substantially eliminate 60-cycle signal components;

high-Q critically damped active filter means responsive to the fetal complex and operative to provide an enhanced fetal R-wave and to substantially reject spurious signals;

said active filter means including first switching means operative to alter the bandwidth of said active filter means to provide relatively wideband operation for detection of rhythm ECG;

baseline correction circuitry coupled to said active filter means and operative to maintain the output signal of said active filter means at a stable reference level; and

second switching means for bypassing said baseline correction circuitry when said first switching means is operative;

said output signal being adapted for application to utilization means.

2. A non-invasive fetal heart monitor according to claim 1 including active bandpass filter means coupled to said amplifier and having a passband of approximately 0.1 to 1.0 Hz for providing a signal representative of labor contractions simultaneously with the output signal of said high-Q active filter means.

3. A non-invasive fetal heart monitor comprising:

an amplifier having low input impedance and adapted for connection to a plurality of surface electrodes attached to a mother'"'"''"'"'s skin;

filter means coupled to the output of said amplifier and operative to substantially eliminate power line noise frequencies;

multistage variable bandwidth active filter means each stage being a high-Q critically damped active filter operative to provide maximum response to the fetal complex and to discriminate against other waveforms;

said active filter means being operative in a narrowband mode to provide a first output signal representing an enhanced fetal R-wave and to substantially reject spurious signals, and operative in a relatively wideband mode to provide a second output signal representing a rhythm ECG;

first switching means coupled to said active filter means and operative to select said narrow band or wideband mode;

baseline correction circuitry coupLed to the output of said active filter means and operative to maintain the output signals of said active filter means at a stable reference level; and

second switching means cooperative with said first switching means for bypassing said baseline correction circuitry when said wideband mode is selected by said first switching means.