CARDIAC OUTPUT COMPUTER

• US 3,651,318 A
• Filed: 01/26/1970
• Issued: 03/21/1972
• Est. Priority Date: 01/26/1970
• Status: Expired due to Term

• Current Assignee: Jan A. Czekajewski
• Original Assignee: Jan A. Czekajewski
• Inventors: Czekajewski, Jan A.
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Gruber, Felix D.
• Application Number:
  US05/005,888
• Time in Patent Office: 785 Days
• Field of Search: 235/183,92FL 328/127 128/2.5F,2.5R,2.1
• US Class Current: 600/431
• CPC Class Codes: A61B 5/0275 using tracers, e.g. dye dilution
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: G01F 1/704 using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter G01F1/76, G01F25/00 take precedence
• CPC Class Codes: G06G 7/186 using an operational amplifier comprising a capacitor or a resistor in the feedback loop
• CPC Class Codes: G06G 7/60 for living beings, e.g. their nervous systems ; for problems in the medical field

Abstract

A method and apparatus for determining the rate of flow of a substance such as blood in a closed circulatory system whereby a detectable indicator substance is injected into the blood upstream of the heart and the density of that substance in the blood downstream measured and integrated in time to determine the flow of blood pumped through the heart in volume units per time. Distortion of the density waveform by recirculation and consequent error in the calculated flow rate is avoided by detecting two points on the exponential decay from the density peak and extrapolating the integral of the remainder of the wave form from these points. In contrast to prior art techniques, an analogue signal reflecting the integral of the waveform is produced and employed to obtain the flow of blood through the heart.

Claims

1. Apparatus for determining the rate of flow of fluid in a closed circulatory system whereby a detectable indicator is injected into the system at a first point and the density of the indicator is detected at a second point to generate an electrical waveform which rises to a peak value and decays thereafter substantially exponentially toward zero until recirCulated indicator distorts the exponential tail comprising:

means for receiving said waveform and producing an output level substantially equal to said peak value after said waveform passes said peak value, first means for dividing said output level by a given factor to produce a first level, second means for dividing said output level by a given factor to produce a second level, first means for comparing said waveform with said first level and producing a first signal when the amplitude of said waveform during the exponential decay is substantially equal to said first level, second means for comparing said waveform with said second level and producing a second signal when the amplitude of said waveform during the exponential decay is substantially equal to said second level, integrating means for receiving an input and producing a continuous integral of said input in the form of a continuous electrical signal, and means for transmitting said waveform to said integrating means so that said integrating means integrates said waveform, including means for disconnecting said integrating means from said waveform and connecting said integrating means to said first dividing means so that said integrating means thereafter integrates said first level when said first comparing means produces said first signal and means for disconnecting said integrating means from said first dividing means when said second comparing means produces said second signal.

2. Apparatus as in claim 1 wherein said disconnecting and connecting means includes switch means having a first position connecting said waveform to said integrating means and a second position connecting said first dividing means to said integrating means and means connected to said first comparing means for shifting said switch means from said first to said second position when said first signal is produced.

3. Apparatus as in claim 2 wherein said disconnecting means includes second switch means connecting said first switch means to said integrating means, and having an open and closed position and means connected to said second comparing means for shifting said second switch means from said closed to said open position when said second signal is produced.

4. Apparatus as in claim 1 including means for receiving said output level and said peak value, for comparing said output level and said peak value with the preset constant value and generating a malfunction signal when said comparison indicates equivalence.

5. Apparatus as in claim 1 including means connected to said output level receiving and producing means for receiving said output level and disabling said first and second comparing means when said output level is less than a given preset value.

6. Apparatus as in claim 1 including means connected to said first level producing means for receiving said first level and multiplying it by a given factor before said first level is integrated.

7. Apparatus as in claim 1 including means connected to said output level receiving and producing means for dividing said output level into a signal representing the amount of indicator injected so as to generate a signal indicating said rate of flow.

8. Apparatus as in claim 7 wherein said output dividing means includes means connected to said output level receiving and producing means for multiplying said output level by a first factor means for dividing said output by a second factor and means for varying said second factor.

9. Apparatus as in claim 1 further including means for calibrating said apparatus.

10. Apparatus as in claim 9 including means for receiving and amplifying said waveform and wherein said calibrating means includes meter means connected to the output of said amplifying means, means for applying a given voltage to said meter means so that when said amplifying means receives a given calibrating input signal said meter means will deflect to a given point, and means for adjusting the gain of said amplifying means.

11. Apparatus as in claim 1 including means connected to said output level receiving and producing means for using said output level to determine said rate of flow and means for displaying said rate of flow.

12. Apparatus for determining the rate of flow of fluid in a closed circulatory system whereby a detectable indicator is injected into the system at a first point and the density of the indicator is detected at a second point to generate an electrical waveform which rises to a peak value and decays thereafter substantially exponentially toward zero until recirculated indicator distorts the exponential tail comprising:

means for receiving said waveform and producing an output level substantially equal to said peak value after said waveform passes said peak value, first means for dividing said output level by a given factor to produce a first level, second means for dividing said output level by a given factor to produce a second level, first means for comparing said waveform with said first level and producing a first signal when the amplitude of said waveform during the exponential decay is substantially equal to said first level, second means for comparing said waveform with said second level and producing a second signal when the amplitude of said waveform during the exponential decay is substantially equal to said second level, integrating means for receiving an input and producing a continuous integral of said input in the form of a continuous electrical signal, means for transmitting said waveform to said integrating means so that said integrating means integrates said waveform, means for disconnecting said integrating means from said waveform ans connecting said integrating means to said first dividing means so that said integrating means thereafter integrates said first level when said first comparing means produces said first signal, means for disconnecting said integrating means from said first dividing means when said second comparing means produces said second signal, means for dividing said output into a signal representing the amount of indicator injected so as to generate a signal indicating said rate of flow, means for receiving said output and said peak value for comparing said output and said peak value with the constant value for generating a malfunction signal when said comparison indicates a malfunction, means for receiving said first level and multiplying it by a given factor before said first level is integrated, and means for calibrating said apparatus.

13. A method of determining the rate of flow of fluid in a closed circulatory system whereby a detectable indicator is injected into the system at a first point and the density of the indicator is detected at a second point to generate an electrical signal the waveform of which rises to a peak value and decays thereafter substantially exponentially toward zero until recirculated indicator distorts the exponential tail comprising:

receiving said waveform and producing an output level substantially equal to said peak value after said waveform passes said peak value, dividing said output level by a given factor to produce a first level, dividing said output level by a given factor to produce a second level, comparing said waveform with said first level and producing a first signal when the amplitude of said waveform during the exponential decay is substantially equal to said first level, comparing said waveform with said second level and producing a second signal when the amplitude of said waveform during the exponential decay is substantially equal to said second level, integrating said waveform until said first signal is produced, and integrating said first level after said first signal is produced and until said second signal is produced and terminating the integration when said second signal is produced.

14. A method as in claim 13 including the steps of receiving the integrated waveform and the integrated first level and said peak value, for comparing said integrated waveform and said integrated first level and said peak value with the constant value and generating a malfunction signal when said comparison indicates equivalence.

15. A method as in claim 13 including the steps of receiving said integrated waveform and said integrated first level and preventing comparing when said output level is less than a given preset value.

16. A method as in claim 13 including the steps of receiving said first level and multiplying it by a given factor before said first level is integrated.

17. A method as in claim 13 including the steps of dividing said output level into a signal representing the amount of indicator injected so as to generate a signal indicating said rate of flow.

18. A method of determining the rate of flow of fluid in a closed circulatory system comprising the steps of:

injecting a detectable indicator into the system at a first point, detecting the density of the indicator at a second point to generate an electrical waveform which rises to a peak value and decays thereafter substantially exponentially toward zero until recirculated indicator distorts the exponential tail, receiving said waveform and producing an output level substantially equal to said peak value after said waveform passes said peak value, dividing said output level by a given factor to produce a first level, dividing said output level by a given factor to produce a second level, comparing said waveform with said first level and producing a first signal when the amplitude of said waveform during the exponential decay is substantially equal to said first level, comparing said waveform with said second level and producing a second signal when the amplitude of said waveform during the exponential decay is substantially equal to said second level, integrating said waveform until said first signal is produced, and integrating sad first level after said first signal is produced and until said second signal is produced.