Infusion system using optical imager for controlling flow and method thereof

• US 9,603,999 B2
• Filed: 11/21/2013
• Issued: 03/28/2017
• Est. Priority Date: 10/19/2010
• Status: Active Grant

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Inventors: Hungerford, Roger L., Bui, Tuan
• Primary Examiner(s): Bosques, Edelmira
• Application Number:
  US14/086,561
• Publication Number:
  US 20140081233A1
• Time in Patent Office: 1,223 Days
• Field of Search: 604/251
• US Class Current: 1/1
• CPC Class Codes: A61M 2005/16868 Downstream occlusion sensors
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3379 Masses, volumes, levels of fluids in reservoirs, flow rates
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 5/1411 Drip chambers A61M5/162, A61M5/1689, A61M5/40 take precedence
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61M 5/16804 Flow controllers
• CPC Class Codes: A61M 5/1684 by detecting the amount of infusate remaining, e.g. signalling end of infusion
• CPC Class Codes: A61M 5/1689 Drip counters
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes

Abstract

A method of operating an infusion pump includes transmitting light through or around a drop of fluid suspended from an end of a drip tube for the infusion pump, the end of the drip tube located in a drip chamber for the infusion pump, wherein the drip tube is configured for connection to a source of the fluid; receiving, using an optical system for the pump, light transmitted through or around the drop; transmitting, to a specially programmed microprocessor and using the optical system, data regarding the received light; and, using the microprocessor to calculate a volume of the drop using the data.

Claims

1. A method of operating an infusion pump, comprising:

transmitting light through or around a drop of fluid suspended from an end of a drip tube for the infusion pump, the end of the drip tube located in a drip chamber for the infusion pump, wherein the drip tube is configured for connection to a source of the fluid;

receiving, using an optical system for the pump, light transmitted through or around the drop;

transmitting, to a specially programmed microprocessor and using the optical system, data regarding the received light;

using the microprocessor to calculate a volume of the drop using the data;

using the microprocessor, generating respective images of the end of the drip tube and the drop from the data;

locating an apex of the drop, the apex being a portion of the drop at a furthest distance from the end of the drip tube;

determining, using the location of the apex, an orientation of the drop with respect to the end of the drip tube; and

,

calculating, using the orientation of the drop with respect to the end of the drip tube, an orientation of the drip chamber.

2. The method of claim 1, wherein transmitting light includes:

using a telecentric lighting element including a telecentric lens and a first light source, wherein the telecentric lens bundles light rays from the first light source and directs the bundled light rays toward the drop;

using a structured lighting element including a second light source and a structural element placed between the second light source and the drop to block or alter light emanating from the second light source;

using a pair of laser light sources disposed at an acute angle with respect to each other to generate respective light beams that interact to form an interference pattern;

or, transmitting light through a projection lens, the lens having a pattern in or on a surface of the lens, to project the pattern onto the drop.

3. The method of claim 1, further including transmitting, to a specially programmed microprocessor and using the optical system, data regarding the received light;

and, calculating, using the processor, a position of a surface of the fluid using the data regarding the received light.

4. The method of claim 3 further comprising using the microprocessor to generate an empty bag alarm or an air-in-line alarm for an instance in which the light transmitted from the light source is not received by the optical system.

5. The method of claim 1 further comprising using the microprocessor to:

calculate, using the data, a boundary of the end of the drip tube; and

, calculate an orientation of the drop using the boundary as a reference plane.

6. The method of claim 1 further comprising:

using the optical system to control illumination properties of light illuminating the end of the drip tube and the drop; and

, using the microprocessor to;

identify respective boundaries of the end of the drip tube and the drop from the respective images;

fit a parametric function to the respective boundaries; and

, integrate the parametric function to obtain a volume of the drop.

7. The method of claim 1 further comprising using the microprocessor to:

compare the orientation of the drip chamber to a set point;

generate an out of bound condition alarm when the orientation equals the set point or varies from the set point by a specified amount, and adjust the infusion pump to correct any deviations between desired and measured flow rates.

8. The method of claim 1, further including using the microprocessor to:

generate, from the data, respective images of the drop and of the end of the drip tube;

calculate, using the respective images, a boundary of the end of the drip tube; and

, calculate a volume, shape, or location of the drop using the boundary as a reference plane.

9. The method of claim 8 further comprising using the microprocessor to:

identify a boundary of the drop from the respective images;

fit a parametric function to the boundary of the drop; and

, integrate the parametric function to obtain a volume of the drop.

10. The method of claim 1, further including using the microprocessor to generate an image of the end of the drip tube from the data;

determine, from the image, that a drop is absent from the end of the drip tube for a specified period of time; and

, generate an empty bag alarm or an air-in-line alarm.

11. The method of claim 10 further including using the microprocessor to:

create a plurality of temporally successive images of the drop from the data;

calculate a respective volume for the drop in each successive image;

identify changes in the respective volumes;

calculate a flow rate of fluid to the output tube based on the changes in the respective volumes, and control the infusion pump accordingly to achieve a desired flow rate.

12. The method of claim 10 further comprising using the microprocessor to:

calculate a respective boundary of the drop in each successive image; and

, calculate a respective volume for the drop in each successive image by;

fitting a parametric function to the respective boundaries of the drop; and

, integrating the parametric function to obtain the volume of the drop.

13. The method of claim 10 further comprising using the microprocessor to:

create a plurality of temporally successive images of the drop from the data;

calculate a respective volume for the drop in each successive image;

identify changes in the respective volumes;

calculate a flow rate of fluid to the output tube based on the changes in the respective volumes; and

, control the pumping mechanism to match the flow rate of fluid with a desired flow rate of fluid.