US 4,741,732 AGranted

Open-loop control of drug infusion

AssigneeThe University of Melbourne

InventorsDavid P. Crankshaw, Malcolm D. Boyd

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Abstract

A method of determining a generalised infusion rate profile for the delivery of drugs into the circulation comprising the steps of: (a) infusing a drug at arbitrary but known rates into a group of patients for each of whom the Lean Body Mass has been determined; (b) determining the plasma arterial concentration of the drug in each patient at a number of specific time intervals throughout each infusion period; (c) for each patient, estimating the rates of loss of drug from the circulation at a number of specific time instants by dividing the known infusion rates per Lean Body Mass of these instants by the plasma arterial concentrations of the drug at each of these instants; (d) calculating the average of the estimated rates of loss of drug from the circulation per Lean Body Mass unit at each specific time interval for the group of patients; (e) interpolating the successive average points between the specific time intervals to produce an infusion profile; (f) infusing said drug in accordance with said infusion profile determined from said interpolations into a group of patients for each of whom the Lean Body Mass has been determined, said infusion rate being scaled according to said Lean Body Mass of each patient, and (g) repeating steps (b) to (f) until a desired steady plasma arterial content of the drug is substantially maintained throughout the infusion period.

Claims29

Dependent claims

A method of infusion of a drug into a patient comprising the steps of:

(i) determining the Lean Body Mass of the patient;
(ii) selecting a predetermined profile for the rate of delivery of drug, which rate reduces with time and is configured to maintain a selected substantially steady plasma arterial content of the drug in the patient throughout an infusion period;
said profile being determined by:
(a) infusing a drug at arbitrary but known rates into a group of patients for each of whom the Lean Body Mass has been determined;
(b) determining the plasma arterial concentration of the drug in each patient at a number of specific time intervals throughout each infusion period;
(c) for each patient, estimating the rates of loss of drug from the circulation at a number of specific time instants by dividing the known infusion rates per Lean Body Mass of these instants by the plasma arterial concentrations of the drug at each of these instants;
(d) calculating the average of the estimated rates of loss of drug from the circulation per Lean Body Mass unit at each specific time interval for the group of patients;
(e) interpolating the successive average points between the specific time intervals to produce an infusion profile;
(f) infusing said drug in accordance with said infusion profile determined from said interpolations into a group of patients for each of whom the Lean Body Mass has been determined, said infusion rate being scaled according to said Lean Body Mass of each patient, and
(g) repeating steps (b) to (f) until a desired steady plasma arterial content of the drug is substantially maintained throughout the infusion period;
(iii) scaling said predetermined infusion profile by the determined Lean Body Mass of the patient and by the desired substantially steady plasma arterial content of the drug to be maintained in the system of the patient, and
(iv) administering the drug to the patient in accordance with said scaled profile by means of an infusion device which is controlled to deliver said drug at said scaled infusion rate profile.

9 more elements

An infusion system for regulating the delivery of a drug to a patient, including control means for controlling the operation of an infusion pump, said control means including pre-programmed means for varying the infusion rate with respect to elapsed time, said pre-programmed means varying the infusion rate in accordance with a profile which varies with time and which is adapted to maintain a desired substantially steady plasma arterial content of the drug throughout the infusion period;

said profile being determined by:
(a) infusing a drug at arbitrary but known rates into a group of patients for each of whom the Lean Body Mass has been determined;
(b) determining the plasma arterial concentration of the drug in each patient at a number of specific time intervals throughout each infusion period;
(c) for each patient, estimating the rates of loss of drug from the circulation at a number of specific time instants by dividing the known infusion rates per Lean Body Mass of these instants by the plasma arterial concentrations of the drug at each of these instants;
(d) calculating the average of the estimated rates of loss of drug from the circulation per Lean Body Mass unit at each specific time interval for the group of patients;
(e) interpolating the sucessive average points between the specific time intervals to produce an infusion profile;
(f) infusing said drug in accordance with said infusion profile determined from said interpolations into a group of patients for each of whom the Lean Body Mass has been determined, said infusion rate being scaled according to said Lean Body Mass of each patient, and
(g) repeating steps (b) to (f) until a desired steady plasma arterial content of the drug is substantially maintained throughout the infusion period;
and
operator adjustable scaling means for setting the desired concentration of said drug in the patient, for setting the Lean Body Mass of the patient, said scaling means causing modification of the pre-programmed infusion rate by a fixed proportion over each time period of operation of said infusion pump.

7 more elements

Dependencies are inferred from the claim text.