Control of life support systems

• US 6,027,498 A
• Filed: 01/06/1997
• Issued: 02/22/2000
• Est. Priority Date: 03/15/1994
• Status: Expired due to Term

• Current Assignee: Biovar Life Support Inc.
• Original Assignee: University of Manitoba
• Inventors: Mutch, William Alan C., Lefevre, Gerald Robin
• Primary Examiner(s): Dvorak, Linda C. M.
• Assistant Examiner(s): ROLLINS, ROSILAND STACIE
• Application Number:
  US08/714,116
• Time in Patent Office: 1,142 Days
• Field of Search: 604/4, 604/7, 604/8, 604/9, 604/19, 604/27, 604/28, 604/30, 604/31, 604/66, 600/16, 600/17, 600/18, 128/898, 623/3
• US Class Current: 606/16
• CPC Class Codes: A61M 1/36 Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 60/113 in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/117 for assisting the heart, e.g. transcutaneous or external ventricular assist devices
• CPC Class Codes: A61M 60/279 Peristaltic pumps, e.g. roller pumps
• CPC Class Codes: A61M 60/31 for enhancement of in vivo organ perfusion, e.g. retroperfusion
• CPC Class Codes: A61M 60/37 Haemodialysis, haemofiltration or diafiltration
• CPC Class Codes: A61M 60/515 Regulation using real-time patient data
• CPC Class Codes: A61M 60/531 using blood pressure data, e.g. from blood pressure sensors
• CPC Class Codes: A61M 60/562 for making blood flow pulsatile in blood pumps that do not intrinsically create pulsatile flow
• CPC Class Codes: A61M 60/585 User interfaces

Abstract

The flow of a biological fluid to an organ is computer controlled so that natural variation of such flow is simulated. Specifically described are control of a blood pump flow output during CPB to mimic normal pulsatile blood flow from the heart and control of a ventilator output To mimic normal breathing of healthy lungs. A pattern of variation over Time of instantaneous flow of a biological fluid to an organ of a mammalian species is established, a variable control parameter for regulation of flow of the biological fluid to the organ is generated in accordance with the pattern, and the flow of biological fluid is to the organ is controlled in accordance with the variable control parameter.

Claims

1. A method of controlling flow of a biological fluid to an organ during controlled life support conditions, which comprises:

establishing a predetermined pattern of variations over time of instantaneous changes in flow of a biological fluid to an independently-functioning normal organ of a mammalian species,

generating a variable control parameter for regulation of flow of said biological fluid to an organ during controlled life support conditions in accordance with said predetermined pattern, and

controlling said flow of said biological fluid to said organ during controlled life support conditions in accordance with said variable control parameter.

2. A method of controlling flow of blood by a pump to a body during cardiopulmonary bypass, which comprises:

establishing a predetermined pattern of variation over time of instantaneous blood pressure and heart rate of an independently-functioning healthy heart of mammalian species,

generating a signal corresponding in value to an individually-determined blood pressure for a period of time corresponding to the heart rate for the difference between said individually-determined blood pressure and the next individually-determined blood pressure of said predetermined pattern,

generating a control voltage corresponding in magnitude to said signal,

applying said control voltage to said pump to provide an output of blood from said pump to the body during said cardiopulmonary bypass of a pressure proportional to the magnitude of said signal for said period of time, and

repeating said steps of generating a signal, generating a control voltage and applying said control voltage to said pump for each next individually-determined blood pressure of said predetermined pattern, whereby a pulsatile flow of blood from the pump during said cardiopulmonary bypass is provided to the body which mimics normal pulsatile blood flow from a healthy heart.

3. Apparatus for controlling the flow of a biological fluid to an organ, which comprises:

means for establishing a predetermined pattern of variations over time of instantaneous changes in flow of a biological fluid to an independently-functioning normal organ of a mammalian species,

means for generating a variable control parameter for regulation of flow of the biological fluid to an organ during controlled life support conditions in accordance with the predetermined pattern, and

means for controlling the flow of the biological fluid to the organ during controlled life support conditions in accordance with the variable control parameter.

4. The apparatus of claim 3 for use in controlling the flow of blood by a pump to a body during cardiopulmonary by-pass wherein said means for establishing a predetermined pattern comprises means for establishing a predetermined pattern of variation over time of instantaneous blood pressure and heart rate of an independently-functioning heart of a mammalian species;

said means for generating a variable control parameter comprises means for generating a signal corresponding in value to an individually-determined blood pressure for a period of time corresponding to the heart rate for a difference between such individually-determined blood pressure and the next individually-determined blood pressure of said predetermined pattern and means for generating a control voltage corresponding in magnitude to said signal; and

said means for controlling the flow of the biological fluid comprises means for applying said control voltage to said pump to provide an output of blood from said pump to the body during cardiopulmonary bypass of a pressure proportional to the magnitude of the signal for said period of time and means for repeating the steps of generating a signal, generating a control voltage and applying the control voltage to the pump for each next individually-determined blood pressure of said predetermined pattern.