Method and apparatus for using multiple leads for QRS detection

• US 5,697,378 A
• Filed: 12/16/1996
• Issued: 12/16/1997
• Est. Priority Date: 12/16/1996
• Status: Expired due to Term

• Current Assignee: Draeger Medical Systems Incorporated (Dragerwerk AG)
• Original Assignee: Siemens Medical Systems, Inc. (Siemens AG)
• Inventors: Elghazzawi, Ziad Fawaz
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US08/768,093
• Time in Patent Office: 365 Days
• Field of Search: 128/696, 128/901, 128/702, 128/703-705, 128/708, 128/920
• US Class Current: 600/508
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: Y10S 128/901 Suppression of noise in electric signal

Abstract

A method and apparatus for reducing noise in an output signal produced from a plurality of input signals indicative of a repetitious phenomena exhibited by a signal source. The apparatus comprises: (a) signal receiving means adapted for being coupled to a plurality of sensors positioned with respect to a signal source such that each of the sensors is subjected to a unique representation of a repetitious phenomena exhibited by the signal source, for obtaining from the sensors a plurality of received signals in which noise may be present; (b) signal detecting means for detecting the occurrence of the phenomena in each of the plurality of received signals; (c) signal strength determining means responsive to the plurality of received signals for determining the signal strength of the phenomena in each of the plurality of received signals; and (d) proportional adding means for additively combining the plurality of received signals together for developing a combined signal, with each received signal having a weight in the combined signal which is in direct proportion to the signal strength of the phenomena in that signal as determined by the signal strength determining means, the output signal indicative of the phenomena being developed from the combined signal. In a preferred embodiment the signal detecting means is responsive to the output signal of the proportional adding means.

Claims

1. A method for reducing noise in an output signal produced from a plurality of input signals indicative of a repetitious phenomena exhibited by a signal source, said method comprising the steps of:

obtaining from a plurality of sensors positioned with respect to the signal source so as to be subjected to a unique representation of a repetitious phenomena exhibited by the signal source, a corresponding plurality of received signals in which noise may he present;

detecting the occurrence of said phenomena in each of said plurality of received signals;

determining the signal strength of said phenomena in each of said plurality of received signals; and

additively combining said plurality of received signals together for developing a combined signal, with each received signal having a weight in the combined signal which is in direct proportion to the signal strength of the phenomena in that signal as determined by the prior step, the output signal indicative of said phenomena and having reduced noise being developed from said combined signal.

2. The method of claim 1, wherein said detecting step is responsive to said output signal developed by said combining step for determining timing information needed for detecting the occurrence of said phenomena in each of said plurality of received signals.

3. The method of claim 1 further including a filtering step which precedes said additive combining step for filtering each of said plurality of received signals in a frequency range which is exclusive of a given frequency range of said repetitious phenomena.

4. The method of claim 3, wherein said filtering step comprises filtering each of said received signals with a low pass filter, followed by a high pass filter.

5. The method of claim 4, wherein said low pass filter passes signals below said given frequency range and said high pass filter passes signals above said given frequency range.

6. The method according to claim 1, wherein said repetitious phenomena has a given frequency range and each of said received signals is checked for signal activity that exceeds a given threshold level in a frequency range in at least one of above and below said given frequency range, and received signal having signal activity that exceeds the given threshold level in at least one of said given frequency ranges, is not used in said additively combining step.

7. The method according to claim 1, further including the step of squaring said combined signal for developing a squared signal as said output signal, so as to enhance the amplitude of said repetitious phenomena in said output signal.

8. The method according to claim 7, wherein said detecting step comprises an amplitude detecting step, responsive to said squared signal, for detecting the occurrence of said repetitious phenomena upon detection of a signal level in said squared signal that exceeds a given amplitude threshold level.

9. The method according to claim 8, further including a step for low pass filtering of said squared signal before applying it to said amplitude detector.

10. The method according to claim 1, wherein said detecting step comprises an amplitude detecting step, responsive to said output signal, for detecting the occurrence of said repetitious phenomena upon detection of a signal level in said output signal that exceeds a given amplitude threshold level.

11. The method of claim 1, wherein said repetitious phenomena comprises a QRS complex and said signal source comprises a medical patient.

12. Apparatus for reducing noise in an output signal produced from a plurality of input signals indicative of a repetitious phenomena exhibited by a signal source, said apparatus comprising:

signal receiving means adapted for being coupled to a plurality of sensors positioned with respect to a signal source such that each of said sensors is subjected to a unique representation of a repetitious phenomena exhibited by the signal source, for obtaining from the sensors a plurality of received signals in which noise may be present;

signal detecting means for detecting the occurrence of said phenomena in each of said plurality of received signals;

signal strength determining means responsive to said plurality of received signals for determining the signal strength of said phenomena in each of said plurality of received signals; and

proportional adding means responsive to said plurality of received signals and said signal strength determining means for additively combining said plurality of received signals together for developing a combined signal, with each received signal having a weight in the combined signal which is in direct proportion to the signal strength of the phenomena in that signal as determined by said signal strength determining means, the output signal indicative of said phenomena being developed from said combined signal.

13. Apparatus in accordance with claim 12, wherein said signal detecting means is responsive to said output signal developed by said proportional adding means for determining the timing for detecting the occurrence of said phenomena in each of said plurality of received signals.