Timing biological imaging, measuring, and therapeutic timing systems

• US 3,871,360 A
• Filed: 07/30/1973
• Issued: 03/18/1975
• Est. Priority Date: 07/30/1973
• Status: Expired due to Term

• Current Assignee: American Electronics, Inc. (Ducommun Incorporated)
• Original Assignee: Joseph M Van Horn, Patrick G. Phillipps, Paul Epstein
• Inventors: Van Horn, Joseph M., Epstein, Paul, Phillipps, Patrick G.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/383,707
• Time in Patent Office: 596 Days
• Field of Search: 128/1D,2.6A,2.6B,2.6F,2.6G,2.6R,2.5R,2.08,2.1R,2.1Z,DIG.13,145. 340/279
• US Class Current: 600/484
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: G01T 1/1648 Ancillary equipment for scintillation cameras, e.g. reference markers, devices for removing motion artifacts, calibration devices adapted for flow studies G01T1/1647

Abstract

System for timing biological imaging, measuring, or therapeutic apparatus in accordance with selected physiological states of a subject, featuring in various aspects generation of respiratory windows on the basis of processed electrical signals derived from prior respiration history, digital offset correction circuitry for the respiratory signals, and generation of cardiac timing signals on the basis of prior cardiac cycle history.

Claims

1. A system for timing biological imaging, measuring, or therapeutic apparatus in accordance with selected respiratory events in a subject, comprising respiratory input circuitry means for providing electrical signals representative of the respiratory cycles of said subject, respiratory timing circuitry means effectively connected to said input circuitry means for processing said electrical signals and for generating a succession of windows surrounding predicted respiratory events of successive respiratory cycles, including means for basing the generation of each said window in a given cycle upon the results of said processing of electrical signals derived from respiration prior to said given cycle, and means for effectively connecting said system to said apparatus to be controlled.

2. The system of claim 1 further comprising cardiac input circuitry means for providing electrical signals representative of the cardiac cycles of said subject, cardiac timing circuitry means effectively connected to said cardiac input circuitry means for producing a successsion of timing signals corresponding to selected points in successive cardiac cycles, and output circuitry means effectively connected to said respiratory and cardiac timing circuitry means, and including logic circuitry means, for producing a succession of output signals corresponding to successive said timing signals occurring within said windows.

3. The system of claim 2 wherein said respiratory timing circuitry includes means for causing the majority of said windows to be of duration longer than the combined duration of a plurality of successive said timing signals occurring within the respective said window, and the interval between said successive signals.

4. The system of claim 2 further comprising recorder means effectively connected to said cardiac input circuitry means aNd to said logic circuitry means, for recording a synchronous display of said cardiac cycle and the timing of said output signals.

5. The system of claim 4 wherein said recorder means includes means for including in said synchronous display a record of said respiratory windows.

6. The system of claim 2 wherein said cardiac timing circuitry means includes cardiac interval circuitry means effectively connected to said cardiac input circuitry means for generating a succession of interval values corresponding to the lengths of successive cardiac cycles, and timing signal circuitry means effectively connected to said interval circuitry means for generating each said timing signal at a time dependent upon a fraction of the interval value for the next previous cardiac cycle.

7. The system of claim 6 wherein said timing signal circuitry means includes means for generating each said timing signal at a time dependent upon a constant value plus a fraction of the interval value for the next previous cardiac cycle.

8. The system of claim 6 wherein said interval circuitry means includes means for generating a succession of interval values correponding to intervals between QRS complexes of successive cardiac cycles, and said timing signal circuitry means includes means for generating each said timing signal at a time subsequent to the QRS complex for that cardiac cycle equal to a constant value plus a portion of the interval value for the next previous cardiac cycle.

9. The system of claim 8 wherein said portion is between 15 and 30% to cause said timing signal to represent systole.

10. The system of claim 8 wherein said portion is between 75 and 90% to cause said timing signal to represent diastole.

11. The system of claim 6 wherein said timing signal circuitry means includes means for changing in successive cardiac cycles the fraction of said interval value upon which the respective timing signal is based.

12. The system of claim 2 further comprising arrythmia detection circuitry means effectively connected to said cardiac input circuitry means and to said logic circuitry means for detecting cardiac arrythmia by comparison with cardiac cycles expected on the basis of said cardiac timing signals.

13. The system of claim 1 wherein said respiratory timing circuitry means includes means for generating values respectively representative of maximum and minimum expiration within a respiratory cycle of said subject, and respiratory state definition circuitry means for generating said windows as a function of both said values.

14. The system of claim 13 wherein said means for generating values comprises peak detectors.

15. The system of claim 14, wherein said peak detectors include means for storing values therein and for causing said stored values to decay over time.

16. The system of claim 14 wherein said respiratory state definition circuitry means includes threshold detection circuitry means effectively connected to said peak detectors and to said input circuitry means.

17. The system of claim 16 wherein said threshold detection circuitry means includes means for preventing its output from changing despite variations in the respiratory signal from said respiratory input circuitry smaller than a preselected limit.

18. The system of claim 1 further comprising digital offset correction circuitry means effectively connected to said respiratory input circuitry means for automatically causing said electrical signals representative of respiratory cycles to be within a predetermined range.

19. The system of claim 18 wherein said correction circuitry means includes limit detection means effectively connected to said respiratory input circuitry for providing a signal when the respiratory signal is outside said range, digital means effectively connected to said detection means for providing digital pulses in the presence of a signal from said detection means, a counter effectively connected to said digital means for counting said pulses, and offset generator means effectively connected to said respiratory input circuitry means for generating an offset voltage dependent upon the count in said counter.

20. The system of claim 19 wherein said detection means includes upper and lower limit detectors for respectively incrementing and decrementing said counter when the respiratory signal is above and below said range.

21. The system of claim 19 further comprising means for periodically automatically changing the count in said counter to cause said respiratory signal to drift in a predetermined direction.

22. A system for timing biological imaging, measuring or therapeutic apparatus in accordance with selected physiological states of a subject, comprising cardiac input circuitry means for providing electrical signals representative of the cardiac cycle of said subject, cardiac timing circuitry means effectively connected to said cardiac input circuitry means for producing a succession of timing signals corresponding to selected predicted cardiac events in successive cardiac cycles, said timing circuitry means including interval circuitry means for generating a succession of interval values corresponding to intervals between QRS complexes of successive cardiac cycles, and timing signal circuitry means effectively connected to said interval circuitry means for generating each said timing signal at a time subsequent to the QRS complex for that cardiac cycle equal to a time constant related to the refractory time of the heart muscle minus half the width of said timing signals plus a fraction of the interval for the next previous cardiac cycle, to cause each said timing signal to surround said predicted cardiac event, and means for effectively connecting said system to said apparatus to be controlled.

23. The system of claim 22 wherein said portion is between 15 and 30% to cause said timing signal to represent systole.

24. The system of claim 22 wherein said portion is between 75 and 90% to cause said timing signal to represent diastole.

25. The system of claim 22 wherein said timing signal circuitry means includes means for changing in successive cardiac cycles the fraction of said interval value upon which the respective timing signal is based.

26. The system of claim 22 further comprising arrythmia detection circuitry means effectively connected to said input circuitry means and to said cardiac timing circuitry means for detecting cardiac arrythmia by comparison with cardiac cycles expected on the basis of said cardiac timing signals.

27. The system of claim 22 wherein said time constant is between 50 and 150 milliseconds.

28. A system for timing biological imaging, measuring or therapeutic apparatus in accordance with selected physiological states of a subject, comprising input circuitry means for providing electrical signals representative of a physiological cycle of said subject, output circuitry means effectively connected to said input circuitry means for providing a succession of timing signals at selected portions of said physiological cycles, and digital offset correction circuitry means effectively connected to said input circuitry means for automatically causing said electrical signals representative of physiological cycles to be within a predetermined range, said correction circuitry means including limit detection means effectively connected to said input circuitry for providing a signal when the physiological signal is outside said range, digital means effectively connected to said detection means for providing digital pulses in the presence of a signal from said detection means, a counter effectively connected to said digital means for counting said pulses, said detection means including upper and lower limit detectors for respectively incrementing and decrementing said counter when the physiological signal is above and below said range, and offset generator means effectiveLy connected to said input circuitry means for generating an offset voltage dependent upon the count in said counter, and means for effectively connecting said system to said apparatus to be controlled.

29. A system for timing biological imaging, measuring or therapeutic apparatus in accordance with selected physiological states of a subject, comprising input circuitry means for providing electrical signals representative of a physiological cycle of said subject, output circuitry means effectively connected to said input circuitry means for providing a succession of timing signals at selected portions of said physiological cycles, and digital offset correction circuitry means effectively connected to said input circuitry means for automatically causing said electrical signals representative of physiological cycles to be within a predetermined range, said correction circuitry means including limit detection means effectively connected to said input circuitry for providing a signal when the physiological signal is outside said range, digital means effectively connected to said detection means for providing digital pulses in the presence of a signal from said detection means, a counter effectively connected to said digital means for counting said pulses, offset generator means effectively connected to said input circuitry means for generating an offset voltage dependent upon the count in said counter, and means for periodically automatically changing the count in said counter to cause said physiological signal to drift in a predetermined direction, and means for effectively connecting said system to said apparatus to be controlled.