Metering device for intravenous fluids

• US 4,493,709 A
• Filed: 01/25/1982
• Issued: 01/15/1985
• Est. Priority Date: 01/25/1982
• Status: Expired due to Fees

• Current Assignee: General Electric Capital Corporation (General Electric Company)
• Original Assignee: Quest Medical Incorporated (Atrion Corporation)
• Inventors: Smith, Gordon E.
• Primary Examiner(s): Pellegrino, Stephen C.
• Application Number:
  US06/342,100
• Time in Patent Office: 1,086 Days
• Field of Search: 604/33, 604/186, 604/237, 604/246, 604/250, 222/207, 222/212, 222/447, 222/450, 222/639
• US Class Current: 604/246
• CPC Class Codes: A61M 5/16809 by repeated filling and emptying of an intermediate volume pressure infusion using positive displacement pumps A61M5/142

Abstract

A metering device is disclosed which includes a metering chamber (14) divided into two compartments (22, 24) by a pressure transmitting member in the form of a flexible diaphragm (20). Fluid flow is alternately allowed into each of the two compartments (22, 24) with each compartment filling to the volume of the metering chamber (14) when full so that periodic pulses of intravenous fluid of that precise volume are sent to the patient. The volume of the metering chamber (14) is selected to match a standard intravenous set drop size, for example one-tenth, one-fifteenth, one-twentieth, or one-sixtieth milliliter.

Claims

1. A metering device for monitoring and controlling the flow of intravenous fluid at a preselected overall volumetric flow rate comprising:

a metering chamber (14) having a fixed accurately preselected volume equal to a standard drop size no greater than 0.1 milliliters;

a pressure transmitting member (20) dividing the metering chamber (14) into first and second compartments (22,

     24);

respective inlet and outlet tubes (28, 30, 36,

     38) connected to each of the first and second compartments (22,

     24) in the metering chamber (14);

valve means (32, 34, 42,

     44) connected to each of the respective inlet and outlet tubes (28, 30, 36,

     38) connected to each of the first and second compartments (22,

     24) in the metering chamber (14);

main inlet (26) and outlet (40) tubes, each of which connects to the respective inlet tubes (28,

     30) or outlet tubes (36,

     38) connected to the two compartments (22,

     24) in the metering chamber (14) the main outlet tube (40) being free from downstream rate-control occlusions; and

timing and valve operator means for controlling the operation of the valve means (32, 34, 42,

     44) so as to repetitively and alternatively allow fluid flow into and out of each of the two compartments (22,

     24) formed in the metering chamber (14) for a time period sufficiently long to allow the compartments to completely fill and empty alternatively, the volume of each of the compartments (22,

     24) being equal in volume to the volume of the metering chamber (14) when that compartment is filled so that a pulse of fluid precisely equal to the standard drop size in volume is introduced into the main outlet tube (40) and into the patient upon each switching of the valve means (32, 34, 42,

     44) by the timing and valve operator means;

the timing and valve operator means constructed so that the time period between valve means operations is equal to the quotient of the metering chamber volume divided by the preselected overall volumetric flow rate, the time period thus being independent both of the instantaneous flow rate and of the positioning of the pressure transmitting member.

2. A metering device as claimed in claim 1 wherein the pressure transmitting member (20) is a flexible elastic diaphragm stretched across the metering chamber (14) so as to divide it into two compartments (22, 24).

3. A metering device as claimed in claim 2 wherein the diaphragm (20) is formed of a silicone elastomer.

4. A metering device as claimed in claim 1 wherein the metering chamber (14) is constructed as a hollow cavity formed in the center of a cassette (12).

5. A metering device as claimed in claim 4 wherein the cassette (12) also includes therein the inlet and outlet tubes (28, 30, 36, 38), the main inlet and outlet tubes (26, 40), and the valve means (32, 34, 42, 44).

6. A metering device as claimed in claim 1 wherein the volume of the metering chamber (14) is equal to 0.1 milliliters.

7. A volumetric metering device for controlling the gravity flow of intravenous fluid in digital pulses at a preselected overall volumetric flow rate through a fluid path extending from a fluid supply to a patient comprising;

(a) a metering chamber having an accurately preselected volume no greater than about 0.1 milliliter, said chamber divided into first and second compartments by a pressure transmitting member, said first and second compartments each having valved inlet and outlet means, and the outlet means being free from downstream rate-control occlusions;

(b) control means for repeatedly driving the apparatus into four conditions sequentially as follows;

(i) inlet to first compartment and outlet from second compartment open;

outlet from first compartment and inlet from second compartment closed;

thus causing fluid to flow from the supply through the inlet to the first compartment to fill the first compartment, causing movement of the pressure transmitting member to empty the second compartment delivering a volume of fluid equal to the size of the metering chamber into the path to the patient;

(ii) fluid flow stopped following filling of first compartment by continued maintenance in the closed position of at least one of first compartment outlet and second compartment inlet, thus preventing movement of the pressure transmitting member and fluid flow;

(iii) inlet to second compartment and outlet from first compartment open;

inlet to first compartment and outlet from second compartment closed;

thus causing fluid to flow from the supply through the inlet to the second compartment to fill the second compartment, causing movement of the pressure transmitting movement to empty the first compartment delivering a volume of equal to the size of the metering chamber into the path to the patient;

(iv) fluid flow stopped following filling of second compartment by continued maintenance in the closed position of at least one of second compartment outlet and first compartment inlet, thus preventing movement of the pressure transmitting member and fluid flow; and

(c) timing means forming a part of the control means for selecting an overall volumetric rate of fluid flow to be delivered to the patient, completely independently of the instantaneous flow rate and the positioning of the pressure transmitting member, comprising means for setting a constant time lapse between the switching of valves for commencement of condition (i) and condition (iii) equal to the quotient of the chamber volume divided by the overall volumetric flow rate.

8. A method of supplying fluid on a volume controlled basis in digital pulses to a patient intravenously employing a supply of fluid elevated above the patient and connected to the patient by a fluid path free of downstream rate-control occlusions which contains a metering chamber of predetermined volume no greater than about 0.1 milliliter separated into first and second compartments by flexible membrane, the chamber having valve means controlling upstream entrance to, and downstream exit from, each of said compartments comprising:

(a) selecting an overall volumetric flow rate, but not an instantaneous flow rate, at which fluid is to be delivered to the patient over time;

(b) causing fluid to flow into the first compartment and from the second compartment by setting the valve means to a first state opening only the first compartment entrance to fluid from the upstream supply and opening only the exit of the second compartment to passage of fluid downstream toward the patient, whereby fluid from the supply fills the first compartment and forces the flexible membrane to move across the chamber delivering a volume of fluid equal to the size of the chamber from the second compartment toward the patient;

(c) stopping all flow of fluid after filling of the first compartment by maintaining in the closed position at least one of the outlet from the first compartment and the inlet to the second compartment, until a predetermined time period has elapsed from the setting of the valve means into the first state the time period being equal to the quotient of the volume of the metering chamber divided by the overall volumetric rate of flow selected;

(d) upon the lapse of such predetermined period of time from the setting of the valve means into the first state switching the valve means to a second state opening only the second compartment entrance to fluid from the upstream supply, and opening only the exit of the first compartment to passage of fluid downstream to the patient, whereby fluid from the supply fills the second compartment and forces the flexible membrane to move across the chamber delivering a volume of fluid equal to the size of the chamber from the first compartment toward the patient;

(e) stopping all flow of fluid after filling of the second compartment by maintaining in the closed position at least one of the outlet of the second compartment and the inlet of the first compartment until the identical predetermined period has elapsed from the setting of the valves into their second state;

(f) upon the lapse of such identical time period from the setting of the valve means into the second state, returning the valve means to the first state, and then continuing steps (b) through (f) until the overall volume of fluid desired for the patient has been delivered.