Infusion system using optical imager for controlling flow and method thereof

• US 8,622,979 B2
• Filed: 10/19/2010
• Issued: 01/07/2014
• 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): Sirmons, Kevin C
• Assistant Examiner(s): Bosques, Edelmira
• Application Number:
  US12/907,403
• Publication Number:
  US 20120095433A1
• Time in Patent Office: 1,176 Days
• Field of Search: 604/251, 604/253, 604203-206, 604/65
• US Class Current: 604/253
• 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

An infusion pump, including: a microprocessor; a drip chamber; a drip tube with an end in the drip chamber; and an illumination system: with a light source for transmitting light through the drip chamber to a drop of fluid suspended from the drip tube; and for controlling illumination properties of the light transmitted to the drop. The pump includes an optical system for: receiving light transmitted through the drop; and transmitting, to the microprocessor, data regarding the received light. The microprocessor: generates, using the data, an image of the drop; locates, using the image, an outer edge of the drop to define a boundary of the drop; integrates an area enclosed by the boundary; and calculates a volume of revolution for the drop with respect to an axis for the drop that intersects the end of the drip tube, assuming symmetry of the drop with respect to the axis.

Claims

1. An infusion pump, comprising:

a first specially programmed microprocessor;

a drip chamber for connection to an output tube;

a drip tube for connection to a source of fluid and with an end disposed in the drip chamber;

a drop suspended from the end of the drip tube;

an illumination system;

with a light source for transmitting light through a wall of the drip chamber to the drop of fluid suspended from the end of the drip tube; and

,

for controlling illumination properties of the light transmitted to the drop; and

,

an optical system for;

receiving light transmitted through the drop; and

,

transmitting, to the first microprocessor, data regarding the received light, wherein the first microprocessor is for;

generating, using the data, an image of the drop;

locating, using the image, an outer edge of the drop to define a boundary of the drop;

integrating an area enclosed by the boundary; and

,

calculating a volume of revolution for the drop with respect to an axis for the drop that intersects the end of the drip tube, assuming symmetry of the drop with respect to the axis.

2. The infusion pump of claim 1 wherein the first microprocessor is for:

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

,

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

3. The infusion pump of claim 1 wherein the first microprocessor is for:

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

identifying a respective circle within each temporally successive image, the respective circle partially defined by a respective outer boundary of said each temporally successive image;

identifying a respective center for each respective circle;

calculating a distance of each respective center from the end of the drip tube;

identifying first and second successive images of the drop in which the distance in the second image is less than the distance in the first image; and

,

calculating the volume of the drop using the first image.

4. The infusion pump of claim 1 wherein the first microprocessor is for:

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

calculating a respective volume for the drop in each successive image or calculating respective time periods between detachment of successive drops from the end of the drip tube; and

,

calculating a rate of increase for the volume of the drop using the respective volumes or the respective time periods.

5. The infusion pump of claim 4 wherein the first microprocessor is for:

generating a downstream occlusion alarm when the rate of increase is less than a second predetermined value.

6. The infusion pump of claim 5 further comprising a mechanism for controlling flow to the output tube, wherein the first microprocessor is for operating the mechanism to shut off flow to the output tube when the free flow alarm or the out of bound condition alarm is generated.

7. The infusion pump of claim 1 wherein the first microprocessor is for:

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

calculating a respective volume for the drop in each successive image or calculating respective time periods between detachment of successive drops from the end of the drip tube;

calculating a rate of increase for the volume of the drop or calculating a time interval between detachment of successive drops from the end of the drip tube; and

,

generating a free flow alarm or an out of bound condition alarm when the rate of increase exceeds a first threshold value or the time interval is less than a second threshold value, the infusion pump further comprising;

a mechanism for controlling flow to the output tube; and

,

a second microprocessor for operating the mechanism to shut off flow to the output tube when the free flow alarm or the out of bound condition alarm is generated.

8. The infusion pump of claim 1 wherein the microprocessor is for:

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

,

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

9. A method for operating an infusion pump, comprising:

suspending a drop of fluid from an end of a drip tube disposed in a drip chamber for the infusion pump;

transmitting light through a wall of a drip chamber for the infusion pump to the drop of fluid suspended from the end of a drip tube for the infusion pump, wherein the drip tube is for connection to a source of fluid;

controlling, using an illumination system for the infusion pump, illumination properties of the light transmitted to the drop;

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

detecting, using the optical system, an image;

transmitting, to a first specially programmed microprocessor and using the optical system, data regarding the image; and

,

using the first microprocessor to;

locate, from the data, an outer edge of the drop to define a boundary of the drop;

integrate an area enclosed by the boundary; and

,

calculate a volume of revolution for the drop with respect to an axis for the drop that intersects the end of the drip tube, assuming symmetry of the drop with respect to the axis.

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

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

,

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

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

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

identify a respective circle within each temporally successive image, the respective circle partially defined by a respective outer boundary of said each temporally successive image;

identify a respective center for each respective circle;

calculate a distance of each respective center from the end of the drip tube;

identify first and second successive images of the drop in which the distance in the second image is less than the distance in the first image; and

,

calculate the volume of the drop using the first image.

12. The method of claim 9 further comprising using the first 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 or calculate respective time periods between detachment of successive drops from the end of the drip tube; and

,

calculate a rate of increase for the volume of the drop using the respective volumes or the respective time periods.

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

generate a downstream occlusion alarm when the rate of increase is less than a second predetermined value.

14. The method of claim 9 further comprising:

controlling flow to the output tube, using a pumping mechanism for the infusion pump; and

,

using the first microprocessor to operate the pumping mechanism to shut off flow to the output tube when the free flow alarm or the out of bound condition alarm is generated.

15. The method of claim 9 further comprising:

using the first 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 or calculate respective time periods between detachment of successive drops from the end of the drip tube; and

,

generate a free flow alarm or an out of bound condition alarm when the rate of increase exceeds a first threshold value or the time interval is less than a second threshold value;

control flow to the output tube by controlling a pumping mechanism for the infusion pump; and

,

using a second specially programmed processor to operate the pumping mechanism to shut off flow to the output tube when the free flow alarm or the out of bound condition alarm is generated.

16. The method of claim 9 further comprising using the first processor to:

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

,

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

17. An infusion pump, comprising:

a first specially programmed microprocessor;

a drip chamber for connection to an output tube;

a drip tube for connection to a source of fluid and with an end disposed in the drip chamber;

a drop suspended from the end of the drip tube;

an illumination system;

with a light source for transmitting light through a wall of the drip chamber past the drop of fluid suspended from the end of the drip tube; and

,

for controlling illumination properties of the light transmitted past the drop; and

,

an optical system for;

receiving the light transmitted past the drop; and

,

transmitting, to the first specially programmed microprocessor, data regarding the received light, wherein the first specially programmed processor is for;

generating, using the data, an image of the drop;

locating, using the image, an outer edge of the drop to define a boundary of the drop;

integrating an area enclosed by the boundary; and

,

calculating a volume of revolution for the drop with respect to an axis for the drop that intersects the end of the drip tube, assuming symmetry of the drop with respect to the axis.