Automated infusion apparatus for blood pressure control and method

• US 4,080,966 A
• Filed: 08/12/1976
• Issued: 03/28/1978
• Est. Priority Date: 08/12/1976
• Status: Expired due to Term

• Current Assignee: Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Original Assignee: Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Inventors: McNally, Robert T., Engelman, Karl, Noordergraaf, Abraham
• Primary Examiner(s): Truluck, Dalton L.
• Application Number:
  US05/713,645
• Time in Patent Office: 593 Days
• Field of Search: 128/2.05 D, 128/214 E, 128/214 F, 128/DIG. 12, 128/DIG. 13, 128/213, 128/227
• US Class Current: 604/505
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: G05D 16/2066 using controlling means acting on the pressure source
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A reliable and inexpensive method has been developed to continually regulate the blood pressure of mammals at virtually any desired level. The pressure thus regulated may be maintained within 10 mm Hg tolerances. The method may be carried out by a closed loop apparatus with which (1) the actual blood pressure is continually measured, (2) a function of the actual blood pressure is compared with a desired blood pressure, (3) any difference between the blood pressure expressed by the function of the actual blood pressure and the desired blood pressure is converted into an error signal, (4) the error signal is converted into proportional and derivative functions which in turn (5) control the rate of pumping of a supply of a liquid hypertensive agent or a hypotensive agent into the circulatory system of the mammal.

Claims

1. Apparatus for infusing drugs into a patient to achieve a desired blood pressure level comprising:

means for developing a representation of said desired level;

transducer means for evaluating the present blood pressure of the subject, and for developing a signal in correspondence therewith;

control means, responsive to the difference between said representation of said desired pressure and the signal in correspondence with said present pressure, and to the derivative of said difference, for developing an infusion control signal; and

pump means, responsive to said infusion control signal, for injecting said drugs into the patient.

2. Apparatus for infusing drugs into a patient to achieve a desired blood pressure level comprising:

means for developing a representation of said desired level;

transducer means for evaluating the present blood pressure of the subject, and for developing a signal in correspondence therewith;

control means, responsive to the difference between said representation of said desired pressure and the signal in correspondence with said present pressure, and to the derivative of said difference, for developing an infusion control signal;

pump means, responsive to said infusion control signal, for injecting said drugs into the subject; and

wherein said transducer means includes filter means for developing a signal representative of mean arterial pressure, said control means operating responsively to the difference between said representation of said desired pressure and said signal representative of mean arterial pressure, and to the derivative of said difference between said representation of said desired pressure and said signal representative of said mean arterial pressure.

3. Apparatus as described in claim 2, wherein said filter means includes means for integrating the evaluated present blood pressure from said transducer.

4. Apparatus for infusing drugs into a patient to achieve a desired blood pressure level comprising:

transducer means for evaluating the present blood pressure of the subject;

control means, responsive to the difference between said desired pressure and said present pressure, and to the derivative of said difference, for developing an infusion control signal; and

pump means, responsive to said infusion control signal, for injecting said drugs into the subject;

wherein said control means comprises means for developing a reference signal corresponding to said desired pressure level;

means for developing an error signal between said reference signal and a signal from said transducer means repesentative of present blood pressure;

means for scaling said error signal by a predetermined factor;

means for evaluating the rate of change of said error signal; and

said pump means being responsive to said rate of change and to the scaled error signal.

5. Apparatus as described in claim 4 wherein said control means further includes means for combining and for amplitude scaling the combination of said rate of change and said scaled error signal.

6. In a closed loop drug infusion system for controlling a subject'"'"'s measured blood pressure to a specified desired pressure, an improvement comprising:

means for developing measured pressure and the desired pressure;

means for integrating measured blood pressure to mean arterial pressure;

means for comparing said mean arterial pressure with the desired pressure, control being based on the results of said comparing; and

control means, responsive to said means for comparing, for regulating drug infusion based on a proportional plus derivative control mode.

7. A method of controlling infusion of drugs into a subject to bring present blood pressure to a desired pressure level comprising the steps of:

evaluating said present pressure and said desired pressure;

evaluating the error between the present pressure and the desired pressure;

developing a control signal based on said error and on the time rate of change of said error; and

regulating the infusion of drugs in response to changes in said control signal.

8. A method of controlling infusion of drugs into a subject to bring present blood pressure to a desired pressure level comprising the steps of:

evaluating said present pressure and said desired pressure;

evaluating the error between the present pressure and the desired pressure;

developing a control signal based on said error and on the time rate of change of said error;

regulating the infusion of drugs in response to changes in said control signal;

sensing the present blood pressure of the subject;

filtering the sensed present pressure to produce a representation of mean arterial pressure; and

comparing said representation with the desired pressure level, thereby producing a signal representative of said error.

9. A method as described in claim 8 wherein said filtering step includes integrating the sensed present pressure.

10. The method of controlling the blood pressure of a mammal which comprises the steps of:

(a) establishing a certain desired blood pressure;

(b) continuously sensing the mean arterial blood pressure of said mammal;

(c) continuously evaluating the difference between sensed mean arterial blood pressure and said desired pressure;

(d) continuously administering intravenously a drug effective to alter said mammal'"'"'s blood pressure in response to said difference in accordance with the following control relationship, ##EQU2## where A and B are predetermined scaling factors.