Intravenous Flow Rate Controller

• US 20130083191A1
• Filed: 09/28/2012
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: ICU Medical Incorporated
• Original Assignee: Hospira Incorporated (Pfizer Inc.)
• Inventors: Lowery, Michael G., Markey, Brian G., Markey, James A.
• Granted Patent: US 9,134,736 B2
• Time in Patent Office: Days
• US Class Current: 348/135
• CPC Class Codes: A61M 2205/215 Tilt detection, e.g. for warning or shut-off
• CPC Class Codes: A61M 5/1411 Drip chambers A61M5/162, A61M5/1689, A61M5/40 take precedence
• CPC Class Codes: A61M 5/1689 Drip counters
• CPC Class Codes: G01F 1/56 by using electric or magnetic effects G01F1/66 takes precedence
• CPC Class Codes: G01F 1/72 Devices for measuring pulsing fluid flows
• CPC Class Codes: G01F 22/00 Methods or apparatus for measuring volume of fluids or fluent solid material, not otherwise provided for
• CPC Class Codes: G01F 3/00 Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow measuring a proportion of the volume flow G01F5/00
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: G06T 2207/20224 Image subtraction
• CPC Class Codes: G06T 7/62 of area, perimeter, diameter or volume
• CPC Class Codes: G16H 20/17 delivered via infusion or injection

Abstract

Tilting of a drip chamber from its vertical axis during fluid administration can have negative effects upon the accuracy of systems configured for drop counting and/or for volumetric measurement of individual drops passing through the drip chamber. To address these negative effects, in accordance with one embodiment of the present disclosure, a fluid delivery system that measures the flow volume of a fluid delivery system is disclosed, which includes an imaging apparatus that captures a first image of a drip chamber while a drop is falling therein and a second image of the drip chamber with no drop. Portions of each image that are in substantially the same position in each image are subtracted.

Claims

1. An apparatus for determining a rate of fluid flow in a fluid delivery system comprising a drip chamber and a length of tubing, the apparatus comprising:

a. a cradle configured to receive the drip chamber;

b. a valve configured to receive the length of tubing and to control a rate of fluid flow through the length of tubing; and

c. a flow rate determination element configured to determine a flow rate of fluid passing through the drip chamber, the flow rate determination element comprising, a camera for imaging activity within the drip chamber, a computing device, a memory storage coupled to the computing device, and a set of software instructions stored in the memory storage which when executed by the computing device causes the apparatus to carry out functions, the functions comprising;

detecting a presence of a drop of fluid falling within the drip chamber;

in response to the detecting, triggering the camera to capture a first image of the drip chamber with the drop falling therein;

capturing a second image of the drip chamber with no drop falling therein;

subtracting from the first image portions of the second image that appear in substantially the same position in each of the first and second images in order to create a drop image; and

determining a volume of the drop based on the drop image.

2. The apparatus of claim 1, wherein determining the volume of the drop comprises:

computationally rotating the drop image about an axis; and

determining a volume of a shape resulting from the computationally-rotated drop image.

3. The apparatus of claim 1, wherein detecting the presence of the drop in the drip chamber comprises:

detecting a change in a signal received from a detector having two electrically conductive metal plates, the change in the signal resulting from the presence of a drop within the drip chamber.

4. The apparatus of claim 3, wherein the cradle comprises a door operable between an open position in which the drip chamber can be placed into or removed from the cradle and a closed position in which the drip chamber is secured within the cradle, and wherein one of the two electrically conductive metal plates is mounted on the door.

5. The apparatus of claim 3, wherein the camera is positioned substantially perpendicularly to the metal plates.

6. The apparatus of claim 1, wherein the functions further comprise:

repeating the functions for successive drops detected in the drip chamber for a predetermined period of time; and

summing the determined volumes of drops falling within the drip chamber to generate a volume sum and dividing the volume sum by the predetermined amount of time to generate a flow rate for the predetermined amount of time.

7. The apparatus of claim 1, wherein detecting the presence of the drop in the drip chamber comprises:

detecting a change in a signal received from a beam emitter and a beam detector.

8. The apparatus of claim 7, wherein the cradle comprises a door operable between an open position in which the drip chamber can be placed into or removed from the cradle and a closed position in which the drip chamber is secured within the cradle, and wherein one of the beam emitter and beam detector is mounted the door.

9. A method for determining a flow rate of fluid delivered by a fluid delivery system, the fluid delivery system including a drip chamber, the method comprising:

detecting a presence of a drop in the drip chamber;

in response to the detecting, capturing a first image of the drip chamber and the drop falling therein;

capturing a second image of the drip chamber with no drop falling therein;

subtracting from the first image any portions of the second image that appear in substantially the same position in both the first and second images in order to create a drop image;

determining a volume of the drop based on said drop image;

repeating the preceding steps for successive detected drops over a predetermined period of time; and

summing the determined volumes of successive detected drops and dividing the sum by the predetermined period of time to provide a flow rate.

10. The method of claim 9, wherein detecting a presence of a drop in the drip chamber comprises:

detecting a change in a signal received from a detector having two electrically conductive metal plates, the change in the signal resulting from the presence of a drop within the drip chamber.

11. The method of claim 9, wherein detecting a presence of a drop in the drip chamber comprises:

detecting a change in a signal received from a beam emitter and a beam detector.

12. The method of claim 9, wherein the second image is captured after the first image is captured.

13. The method of claim 9, wherein the second image is captured before the first image is captured.