Fluid delivery system and flow control therefor

• US 8,672,876 B2
• Filed: 03/21/2008
• Issued: 03/18/2014
• Est. Priority Date: 06/21/2002
• Status: Expired due to Fees

• Current Assignee: Baxter International Inc.
• Original Assignee: Baxter International Inc.
• Inventors: Jacobson, James D., Bui, Tuan, Garchow, Stephen R., Yardimci, Atif, Slepicka, James S.
• Primary Examiner(s): Sirmons, Kevin C
• Assistant Examiner(s): GRAY, PHILLIP A
• Application Number:
  US12/053,120
• Publication Number:
  US 20080255502A1
• Time in Patent Office: 2,188 Days
• Field of Search: 604 65- 67, 6048901-9821, 604/131, 604151-155
• US Class Current: 604/67
• CPC Class Codes: A61M 2205/0244 Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
• CPC Class Codes: A61M 2205/0294 Piezoelectric materials
• CPC Class Codes: A61M 5/14236 Screw, impeller or centrifugal type pumps
• CPC Class Codes: A61M 5/16886 for measuring fluid flow rate, i.e. flowmeters
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: G05D 7/0676 by action on flow sources G05D7/0688, G05D7/0694 take precedence

Abstract

A fluid delivery system having a closed-loop control process for delivering a medical fluid to a patient. A fluid infusion system includes a pump for delivering a fluid to a patient via an administration tube. A flow sensor associated with the administration tube provides an indication of the actual flow rate of fluid in the administration tube. Such a flow sensor may comprise a positive displacement flow sensor constructed using micro-fabrication and/or micro-molding techniques. A reader reads the actual flow rate signal and provides an indication to a controller for controlling the pump. The flow rate information can also be used for providing status information, such as the existence of a blockage in the fluid delivery system.

Claims

1. A system for delivering a fluid at a desired pulsatile flow profile from a reservoir to a delivery point associated with a patient, the system comprising:

a delivery channel between the reservoir and the delivery point through which the fluid is delivered to the patient;

a pump including an actuator, the pump associated with the delivery channel for operatively delivering the fluid to the delivery point at an adjustable output rate;

a flow sensor physically separate from the pump and located along the delivery channel upstream or downstream from the pump for sensing a flow of the fluid in the delivery channel and for generating a flow rate signal indicative of a rate of flow of the fluid in the delivery channel, the flow sensor comprising a positive displacement flow sensor including;

(i) a housing in fluid communication with the delivery channel,

(ii) at least two rotors positioned within the housing so as to rotate in response to the flow of the fluid in the delivery channel,

(iii) a light source positioned outside the housing,

(iv) an optical detector positioned outside the housing, and

(v) at least a portion of the housing including a pattern that replicates a position of the at least two rotors relative to one another, the pattern being less reflective than the at least two rotors, wherein when the light source directs light at the housing, a reflection intensity detected by the optical detector varies as a function of an amount of the at least two rotors that is exposed to the light and a frequency of variations in reflection intensity denotes the rate of flow of the fluid in the delivery channel; and

a controller for controlling the pump, the controller causing adjustments to the output rate of the pump as a function of the flow rate signal such that the output flow rate has a generally pulsatile characteristic corresponding to the desired pulsatile flow profile.

2. A system as set forth in claim 1 wherein the controller provides a flow rate status signal and further comprising a status monitoring device providing an indication of an operating status of the desired pulsatile flow profile in response to the flow rate status signal.

3. A system as set forth in claim 1 wherein the flow rate status signal comprises a signal indicative of a blockage in the delivery channel and wherein the indication of the operating status of desired flow rate comprises an indication identifying that the delivery channel has a blockage.

4. A system as set forth in claim 1 wherein the pump is a peristaltic pump, a piezoelectric pump or a valve pump.

5. A system as set forth in claim 1 wherein the controller provides a closed-loop control path with the pump.

12. The system as set forth in claim 1 wherein the portion of the housing having the pattern has a darker color than the first rotor at least two rotors.

13. The system as set forth in claim 1 wherein a number of increases and a number of decreases in reflection intensity per revolution of each of the at least two rotors vary as a function of a number of lobes on each of the at least two rotors.

6. A system for delivering a fluid at a desired flow rate from a reservoir to a delivery point associated with a patient, the system comprising:

a delivery channel between the reservoir and the delivery point through which the fluid is delivered to the patient;

a pump including an actuator, the pump associated with the delivery channel for operatively delivering the fluid to the delivery point at an adjustable output rate;

a flow sensor located along the delivery channel physically separated upstream or downstream from the pump for optically sensing a flow of the fluid in the delivery channel and for generating a flow rate signal indicative of a rate of flow of the fluid in the delivery channel, the flow sensor comprising a positive displacement flow sensor including;

(i) a housing in fluid communication with the delivery channel,

(ii) at least two rotors positioned within the housing so as to rotate in response to the flow of the fluid in the delivery channel,

(iii) a light source positioned outside the housing,

(iv) an optical detector positioned outside the housing, and

(v) at least a portion of the housing including a pattern that replicates a position of the at least two rotors relative to one another, wherein when the light source directs light at the housing, the optical detector detects a frequency the at least two rotors are exposed to the light and the frequency denotes the rate of flow of the fluid in the delivery channel; and

a controller for controlling the pump, the controller providing a flow rate status signal indicative of a blockage in the delivery channel when the flow rate signal indicates the rate of flow of fluid in the delivery channel is less than a blockage threshold.

7. A system as set forth in claim 6 further comprising a status monitoring device responsive to the flow rate status signal for providing an alarm to a user and a communication channel for transmitting the flow rate status signal from the controller to the status monitoring device.

8. A system as set forth in claim 7 wherein the communication channel comprises a wireless spread spectrum communication channel operating in an unlicensed frequency band.

9. A system as set forth in claim 7 wherein the alarm comprises an audible alarm.

10. A system as set forth in claim 7 wherein the alarm comprises a visual alarm.

11. A system as set forth in claim 7 wherein the alarm comprises a vibrating alarm.

14. The system as set forth in claim 6 wherein the frequency varies as a function of a number of lobes on each of the at least two rotors.