# US 9,750,430 B2 · Methods of intravenous drug monitoring

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- Number: US 9,750,430 B2
- Document ID: US9750430B2
- Status: Granted
- Kind: B2
- Application number: 13/173,809
- Filed: 2011-06-30
- Published: 2012-11-01
- Granted: 2017-09-05
- Earliest claimed: 2011-04-27
- Assignees: General Electric Company
- Applicants: Bo Li; Rui Chen; Xuefeng Wang; Hanna Elina Viertio-Oja
- Inventors: Bo Li; Rui Chen; Xuefeng Wang; Hanna Elina Viertio-Oja
- Web page: https://patentgrep.com/patent/US9750430B2

## CPC

- A61B 5/082: {Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath (A61B5/083, A61B5/091 take precedence)}
- A61B 5/0816: {Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00)}
- A61B 5/4848: {Monitoring or testing the effects of treatment, e.g. of medication}
- A61M 16/06: Respiratory or anaesthetic masks
- A61M 16/104: {specially adapted for anaesthetics (A61M16/18 takes precedence)}
- A61M 2016/1035: {the anaesthetic agent concentration}
- A61M 2202/0241: Anaesthetics; Analgesics
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## Abstract

A method of monitoring a concentration of an anesthetic drug using a patient's breath is provided. The method comprises forming a breath sample using the patient's breath; exposing one or more sensors to the breath sample; detecting one or more components of the anesthetic drug in the breath sample; measuring a concentration of at least one of the components of the anesthetic drug in the breath sample; and determining a concentration of the component in a plasma of the patient using a transfer function and the concentration of the component in the breath sample.

## Claims

### Claim 1

A non-invasive method of monitoring an anesthetic drug concentration in plasma of a patient using the patient's breath, comprising:
(a) administering an anesthetic drug to the patient using an infusion pump;
(b) collecting a breath sample using a breathing circuit connected to the patient, wherein the breath sample comprises a mixed gas comprising a combination of end-tidal gas, gas from dead-space, and inspiratory gas;
(c) exposing a system comprising a detector, a processor, and one or more sensors to the breath sample;
(d) detecting one or more components of the anesthetic drug in the breath sample using the detector;
(e) measuring a concentration of at least one of the one or more components of the anesthetic drug in the breath sample using the one or more sensors;
(f) measuring one or more parameters of the patient using the one or more sensors; and
(g) determining an anesthetic drug concentration in plasma of the patient based on the measured concentration of the at least one of the one or more components of the anesthetic drug in the breath sample and the one or more parameters of the patient using the processor, wherein the processor is configured to calculate the anesthetic drug concentration using a transfer function, and wherein the anesthetic drug concentration is a concentration of the one or more components of the anesthetic drug in the plasma of the patient; wherein the transfer function comprises an input value and an output value, wherein the transfer function comprises a non-linear equation that uses a second order or a higher order, and wherein the input value of the transfer function at least depends on a temperature parameter of the one or more parameters to normalize the measured concentration in the breath sample;
(h) providing a target range of the anesthetic drug concentration;
(i) comparing the anesthetic drug concentration with the target range;
(j) if the anesthetic drug concentration is outside the target range:
(1) generating an alarm;
(2) adjusting an anesthetic drug dosage to the patient;
(3) delivering the anesthetic drug to the patient; or
(k) if the anesthetic drug concentration is within the target range:
(1) delivering the anesthetic drug to the patient; and
(l) repeating steps (b) through (k) as needed until procedure is completed.

### Claim 2 (depends on 1)

The method of claim 1, wherein collecting the breath sample comprises use of two or more of filtration, concentration, differential permeation, dilution, desiccation, breath pressure control, breath temperature control, breath humidity control, breath flow rate control, or vapor density normalizing techniques.

### Claim 3 (depends on 1)

The method of claim 1, wherein collecting the breath sample is performed periodically or continuously.

### Claim 4 (depends on 1)

The method of claim 1, wherein the sensors are selected from two or more of pressure sensors, temperature sensors, flow rate sensors, humidity sensors, gas sensors, or drug vapor sensors.

### Claim 5 (depends on 4)

The method of claim 4, wherein the drug vapor sensors detect propofol in the breath sample.

### Claim 6 (depends on 1)

The method of claim 1, wherein at least one of the components of the anesthetic drug is propofol.

### Claim 7 (depends on 1)

The method of claim 1, wherein measuring the concentration of the at least one of the one or more components of the anesthetic drug in the breath sample is performed using every breath sample or an average of several breath samples over a determined period of time.

### Claim 8 (depends on 1)

The method of claim 1, wherein the input value of the transfer function depends on the anesthetic drug concentration in exhaled end tidal breath, carbon dioxide concentration in exhaled end tidal breath, pressure of exhaled breath, flow rate of exhaled breath, patient's body weight, patient's gender, age of the patient, body mass index (BMI) of the patient, lung function of the patient, or combinations thereof.

### Claim 9 (depends on 8)

The method of claim 8, wherein the input value of the transfer function depends on at least the measured anesthetic drug concentration in exhaled end tidal breath of the patient.

### Claim 10 (depends on 1)

The method of claim 1, wherein the method is a continuous real time process.

### Claim 11

A non-invasive method of monitoring a propofol concentration in a plasma of a patient, comprising:
(a) administering an anesthetic drug comprising propofol to the patient using an infusion pump;
(b) collecting a breath sample using a breathing circuit connected to the patient, wherein the breath sample comprises a mixed gas comprising a combination of end-tidal gas, gas from dead-space, and inspiratory gas;
(c) exposing a system comprising a detector, a processor, and one or more sensors to the breath sample;
(d) detecting propofol in the breath sample using the detector;
(e) measuring a concentration of propofol in the breath sample using the one or more sensors;
(f) measuring one or more parameters of the patient using the one or more sensors; and
(g) determining a propofol concentration in plasma of the patient based on the measured concentration of propofol in the breath sample and the one or more parameters of the patient using the processor, wherein the processor is configured to calculate the propofol concentration using a transfer function and the concentration of the propofol in the breath sample, wherein the transfer function comprises an input value and an output value, and wherein the transfer function comprises a non-linear equation that uses a second order or higher order, and the input value of the transfer function at least depends on a temperature parameter of the one or more parameters to normalize the measured breath drug concentration;
(h) providing a target range of propofol in the plasma of the patient;
(i) comparing the propofol concentration with the target range;
(j) if the propofol concentration is outside the target range:
(1) generating an alarm;
(2) adjusting a propofol dosage to the patient;
(3) delivering the anesthetic drug comprising propofol to the patient; or
(k) if the propofol concentration is within the target range:
(1) delivering the anesthetic drug comprising propofol to the patient; and
(l) repeating steps (b) through (k) as needed until procedure is completed.

### Claim 12 (depends on 11)

The method of claim 11, wherein the transfer function depends on the propofol concentration in exhaled end tidal breath, carbon dioxide concentration in exhaled end tidal breath, pressure of exhaled breath, flow rate of exhaled breath, patient's body weight, patient's gender, age of a patient, body mass index (BMI) of a patient, lung function of the patient, and combinations thereof.

### Claim 13 (depends on 11)

The method of claim 11, wherein the sensors comprise at least one sensor for measuring the concentration of propofol and at least one sensor for measuring other gases in the breath sample.

### Claim 14 (depends on 13)

The method of claim 13, wherein the sensors measure the concentration of propofol and a concentration of at least another gas in the breath sample.

### Claim 15 (depends on 14)

The method of claim 14, wherein the propofol concentration is determined by determining the concentration of the at least another gas in the end tidal gas and assuming a ratio of the concentration of propofol and another gas in the end-tidal gas and the ratio of the concentration of propofol and the at least another gas in the breath sample are same.

### Claim 16 (depends on 15)

The method of claim 15, wherein the propofol concentration is determined using the propofol concentration in the end-tidal gas.