Method of detecting occlusions in a solution pumping system

• US 5,292,306 A
• Filed: 01/29/1993
• Issued: 03/08/1994
• Est. Priority Date: 01/29/1993
• Status: Expired due to Term

• Current Assignee: Hospira Incorporated (Pfizer Inc.)
• Original Assignee: Abbott Laboratories
• Inventors: Wynkoop, Richard D., Wecker, Sheldon M., Ogden, John E.
• Primary Examiner(s): WEISS, JOHN
• Application Number:
  US08/011,062
• Time in Patent Office: 403 Days
• Field of Search: 604/49, 604/51, 604/131, 604/151, 604/152, 417/53, 417/63
• US Class Current: 604/505
• CPC Class Codes: A61M 5/16854 by monitoring line pressure

Abstract

A method of detecting occlusions in a solution pumping system includes monitoring and analyzing pressures within the system during selected portions of a pumping cycle. The pumping system of the illustrated embodiment includes a positive displacement pump operated by a reciprocable pump piston, with analysis of pressures within the system identifying those conditions which reflect the presence of an occlusion either upstream or downstream of the positive displacement pump. A suitable signal or alarm can then be activated to alert operating personnel.

Claims

1. A method of operating a solution pumping system including pump means which creates a positive liquid pressure at said pump means during a pumping stroke, and a negative liquid pressure at said pump means during a return stroke, said method comprising the steps of:

determining a pressure P₁ during a pumping stroke of said pump means corresponding to a peak pressure of said system;

waiting a predetermined time interval T_A after determination of said pressure P₁ ;

determining a pressure P₂ corresponding to the pressure of said system; and

providing a signal indicating occlusion of said system downstream of said pump means if P₂ exceeds a predetermined value.

2. A method of operating a pumping system in accordance with claim 1, including:

waiting a predetermined time interval T_B after completion of said one of said return strokes;

determining a pressure P₃ corresponding to the pressure of said system; and

providing a signal indicating occlusion of said system upstream of said pump means if the value of P₃ is equal to or greater than a predetermined value.

3. A method in accordance with claim 1, including:

determining an initial pressure P_I prior to operation of said pump means, and

determining said pressure P₂ by measuring a pressure P_SYS of said system, and subtracting therefrom the value of the initial pressure P_I of the system.

4. A method in accordance with claim 1, including:

comparing said pressure P₁ to a predetermined value P_REF.

5. A method in accordance with claim 4, wherein

the waiting step comprises waiting one of:

(1) a first predetermined time interval T_A(1) after determining said pressure P₁ if said pressure P₁ is less than P_REF, indicating a relatively non-viscous liquid, and (2) a second predetermined time interval T_A(2), greater than T_A(1), if said pressure P_I is greater than P_REF, including a relatively viscous liquid.

6. A method in accordance with claim 1, including

comparing said pressure P₁ to a predetermined value P_OCC, and

providing a signal indicating occlusion of said system downstream of said pump means if P₁ exceeds P_OCC.

7. A method of operating a solution pumping system including pump means which creates a positive liquid pressure at said pump means during a pumping stroke, and negative liquid pressure at said pump means during a return stroke, said method comprising the steps of:

measuring an initial pressure P_I prior to operation of said pump means;

measuring a peak pressure P_P during a pumping stroke of said pump means;

determining a pressure P₁, corresponding to a peak pressure of said system, by subtracting P_I from P_P ;

comparing pressure P₁ to a predetermined value P_REF ;

waiting one of;

(1) a first predetermined time interval T_A(1) after determining if said pressure P₁ is less than P_REF, indicating a relatively non-viscous liquid, and (2) a second predetermined time interval T_A(2), greater than T_A(1), if said pressure P₁ is greater than P_REF, indicating a relatively viscous liquid;

determining a pressure P₂ corresponding to the pressure of said system by measuring a pressure P_SYS of the system and subtracting therefrom the value of the initial pressure P_I of the system; and

providing a signal indicating occlusion of said system downstream of said pump means if P₂ exceeds a predetermined value.

8. A method in accordance with claim 7, including:

comparing said pressure P₁ to a predetermined value P_OCC, and

providing a signal indicating occlusion of said system downstream of said pump means if P₁ exceeds P_OCC.

9. A method in accordance with claim 7, including:

measuring a pressure P_R after said waiting step;

establishing completion of one of the return strokes of said pump means;

waiting a predetermined time interval T_B after completion of said one of said return strokes;

determining a pressure P₃ corresponding to the pressure of the system, and comparing P₃ to P_R ; and

providing a signal indicating occlusion of said system upstream of said pump means if the difference between P_R and P₃ is equal to or greater than a predetermined value.

10. A method of operating a pumping system including pump means which creates a positive liquid pressure at the pump means, comprising the steps of:

monitoring liquid pressure within said pumping system;

analyzing the monitored pressure within said system to identify an occlusion in said system; and

providing a signal indicating occlusion of system,

wherein said monitoring and analyzing steps include determining a pressure P₁ corresponding to a peak pressure of said system, waiting a predetermined time interval T_A after determination of said pressure P₁, and determining a pressure P₂ corresponding to the pressure of the system,

said step of providing a signal including providing a signal indicating occlusion of system downstream of said pump means if P₂ exceeds a predetermined value.

11. A method of operating a pumping system including pump means which creates a positive liquid pressure at the pump means, comprising the steps of:

monitoring liquid pressure within said pumping system;

analyzing the monitored pressure within said system to identify an occlusion in said system; and

providing a signal indicating occlusion of system,

wherein said pump means is operated to create a negative pressure in said system,

said pump means is operated to create a negative pressure in said system,

said monitoring and analyzing steps include measuring a pressure P_R prior to operating said pump to create said negative pressure, waiting a predetermined time interval T_B after operation of said pump to create said negative pressure, and determining a pressure P₃ corresponding to the pressure of the system, and comparing P₃ to P_R,

said step of providing a signal including providing a signal including occlusion of said system upstream of said pump means if the difference between P_R and P₃ is equal to or greater than a predetermined value.

12. A method of operating a pumping system including pump means which creates a positive liquid pressure at the pump means, comprising the steps of:

monitoring liquid pressure within said pumping system;

analyzing the monitored pressure within said system to identify an occlusion in said system; and

providing a signal indicating occlusion of system,

wherein said monitoring and analyzing steps include determining a pressure P₁ corresponding to a peak pressure of said system, and comparing said pressure P₁ to a predetermined value P_REF to determine the viscosity of liquid being pumped by said system.