Pneumatically coupled fluid control system and process with air detection and elimination

• US 10,350,352 B2
• Filed: 05/22/2014
• Issued: 07/16/2019
• Est. Priority Date: 05/23/2013
• Status: Active Grant

• Current Assignee: Newiv Medical Corp.
• Original Assignee: Turnpoint Medical Devices, Inc.
• Inventors: Carlisle, Jeffrey A., Kuba, Lawrence M.
• Primary Examiner(s): Farrar, Lauren P
• Application Number:
  US14/285,314
• Publication Number:
  US 20140350511A1
• Time in Patent Office: 1,881 Days
• CPC Class Codes: A61M 2005/14208 with a programmable infusion control system, characterised by the infusion program
• CPC Class Codes: A61M 2005/14513 with secondary fluid driving or regulating the infusion
• CPC Class Codes: A61M 2039/242 designed to open when a predetermined pressure or flow rate has been reached, e.g. check valve actuated by fluid
• CPC Class Codes: A61M 2205/123 with incorporated reservoirs
• CPC Class Codes: A61M 2205/128 with incorporated valves
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3337 Controlling, regulating pressure or flow by means of a valve by-passing a pump
• CPC Class Codes: A61M 2205/3379 Masses, volumes, levels of fluids in reservoirs, flow rates
• CPC Class Codes: A61M 39/24 Check- or non-return valves
• CPC Class Codes: A61M 5/14224 Diaphragm type
• CPC Class Codes: A61M 5/1452 pressurised by means of pistons
• CPC Class Codes: A61M 5/14593 the diaphragm being actuated by fluid pressure
• CPC Class Codes: A61M 5/155 pressurised by gas introduced into the reservoir
• CPC Class Codes: A61M 5/16822 by controlling air intake into infusion reservoir needle sets with air inlet A61M5/162
• CPC Class Codes: A61M 5/16831 Monitoring, detecting, signalling or eliminating infusion flow anomalies low-level float-valves causing cut-off A61M5/40; indicating or recording presence, absence or direction of flow in general G01P13/0066
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: A61M 5/16859 Evaluation of pressure response, e.g. to an applied pulse
• CPC Class Codes: A61M 5/16881 Regulating valves on-off valves, e.g. clamps A61M39/28
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: A61M 5/365 : Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: A61M 5/385 : using hydrophobic filters

Abstract

A fluid control system for delivery of a liquid includes a pneumatic drive that incorporates a linear actuator to effect known volume changes in a gas reservoir. The gas reservoir is in fluid communication with a gas-side reservoir that is separated from a fluid-side reservoir by a flexible membrane. Movement of the linear actuator effects positive or negative volume differences on the gas in the gas-side reservoir, resulting in a decrease or increase in pressure of the gas that is transmitted to the fluid-side reservoir to draw fluid, primarily liquid, in from a source or deliver liquid out to a sink. In another aspect, a mechanism is provided for the detection and elimination of air bubbles in the fluid path.

Claims

1. A process for determining presence of air in an infusion of fluid from a fluid source to a liquid sink, comprising:

a) exerting a negative pressure on a gas reservoir in fluid communication with a gas-side chamber separated from a fluid-side chamber by a flexible membrane to draw liquid from the fluid source into the fluid-side chamber through a one-way inlet valve until the fluid-side chamber fills with fluid;

b) reducing a volume of the gas reservoir by an amount that exerts a positive pressure on the gas reservoir in fluid communication with the gas-side chamber such that said positive pressure is inadequate to deliver liquid in the fluid-side chamber to the liquid sink through a one-way outlet valve, wherein the inlet valve and the outlet valve each comprise a passive one-way check valve having a predetermined cracking pressure, and are each configured to open only when a pressure differential between upstream fluid and downstream fluid reaches the predetermined cracking pressure;

c) monitoring pressure in the gas reservoir during the step of exerting the positive pressure; and

d) determining volumes of fluid in the fluid-side chamber from incremental changes in volume of the gas reservoir and the gas-side chamber and any connecting dead space by an ideal gas law relationship, wherein P₁V₁=P₂V₂, wherein P₁ and P₂ are pressures measured at two times before and after volume changes and V₁ and V₂ are volumes at the two times;

e) determining a pressure trend from the step of monitoring the pressure over several time steps,

f) monitoring the pressure trend, the volume changes, or both for an indication of air in the fluid-side chamber.

2. The process of claim 1, wherein the indication of air comprises a decrease in pressure during the step of filling the fluid-side chamber.

3. The process of claim 1, wherein the indication of air comprises an increase in pressure during the step of delivering liquid that is below a normal pressure increase during the step of delivering liquid.

4. The process of claim 1, wherein the indication of air comprises a comparison of a determination of gas volume when the fluid-side chamber is fully filled with liquid to a subsequent determination of gas volume when the fluid-side chamber contains air.

5. A fluid control system for delivery of a fluid, comprising:

a fluid flow path comprising an inlet valve configured for fluid communication with a fluid source and an outlet valve configured for fluid communication with a fluid sink;

a chamber comprising a fluid-side chamber and a gas-side chamber, the fluid-side chamber and the gas-side chamber separated by a flexible membrane, the membrane configured so that there is substantially no pressure differential between the fluid-side chamber and the gas-side chamber across the membrane;

the fluid-side chamber disposed on the fluid flow path downstream of the inlet valve and upstream of the outlet valve such that pressure changes in the fluid-side chamber are communicated to the inlet valve and the outlet valve;

a pneumatically coupled drive in communication with the gas-side chamber configured to provide known incremental positive or negative volume changes that cause positive or negative pressure changes in the gas-side chamber, and wherein said pressure changes in the gas-side chamber are communicated to the fluid-side chamber via the flexible membrane, wherein the inlet valve and the outlet valve each comprise a passive one-way check valve having a predetermined cracking pressure, and are each configured to open only when a pressure differential between upstream fluid and downstream fluid reaches the predetermined cracking pressure; and

an air elimination mechanism comprising a hydrophobic filter comprising a first side disposed in communication with the fluid-side chamber, and a second side disposed in communication with a one-way air elimination check valve, the hydrophobic filter blocking flow of liquid therethrough and allowing passage of air therethrough.

6. The system of claim 5, wherein the one-way air elimination check valve comprises a cracking pressure sufficient to allow air to pass therethrough.

7. The system of claim 5, wherein the one-way air elimination check valve comprises a cracking pressure sufficient to prevent fluid from an ambient environment to enter the system.

8. The system of claim 5, further comprising:

a pressure sensor disposed to sense pressure in the gas-side chamber; and

a controller in communication with the pressure sensor to receive sensed pressure data in response to a known gas volume change and to compare a pressure change sensed when a volume change is effected to the fluid-side chamber filled with liquid without air to a pressure change sensed when a volume change is effected to the fluid-side chamber filled with liquid and air, whereby a quantity of air in the fluid-side chamber is determined.

9. The system of claim 5, wherein air that has been captured and stored between the hydrophobic filter and the one-way air elimination check valve under pressure equal to the cracking pressure of the one way valve air elimination check then passes back into the fluid-side chamber when subject to a negative pressure differential, thereby to clear the hydrophobic filter of liquid.

10. The system of claim 5, wherein the filter is disposed on a wall of the fluid-side chamber and the one way air elimination check valve opens to ambient.

11. The system of claim 5, wherein the filter is disposed on the flexible membrane and the one way air elimination check valve opens to the gas-side chamber.