Differential pressure based flow sensor assembly for medication delivery monitoring and method of using the same

A fluid-tight disposable assembly for removably coupling to a fluid impermeable reusable portion of a differential pressure based fluid flow sensor assembly, the disposable assembly comprising:

• a sealed body defining a fluid flow passage forming an inlet and an outlet;
• a flow restricting element positioned along the fluid flow passage between
• the inlet and the outlet, wherein the flow restricting element includes an orifice that defines a non-capillary fluid flow path;
• an impermeable upstream fluid pressure membrane sealing an upstream fluid chamber at a location in the fluid flow passage between the inlet and the flow restricting element;
• and
• an impermeable downstream fluid pressure membrane sealing a downstream fluid chamber at a location in the fluid flow passage between the flow restricting element and the outlet.

A method of determining a fluid flow rate in a fluid flow system comprising:

• providing a differential pressure based flow sensor assembly comprising:
• a fluid-tight disposable portion having:
• a sealed disposable body defining a fluid flow passage forming an inlet and an outlet;
• a flow restricting element positioned along the fluid flow passage between the inlet and the outlet, wherein the flow restricting element includes an orifice that defines a non-capillary fluid flow path;
• a disposable impermeable upstream fluid pressure membrane at a location in the fluid flow passage between the inlet and the flow restricting element;
• and
• a disposable impermeable downstream fluid pressure membrane at a location in the fluid flow passage between the flow restricting element and the outlet;
• and
• a fluid impermeable reusable portion including a housing removably coupled to the disposable portion and having:
• an upstream fluid pressure sensor to sense an upstream fluid pressure at an upstream location in the fluid flow passage between the inlet and the flow restricting element, the upstream fluid pressure sensor being positioned and adapted to interact with the upstream fluid pressure membrane and thereby generally determine the fluid pressure at the disposable upstream fluid pressure membrane;
• and
• a downstream fluid pressure sensor to sense a downstream fluid pressure at a downstream location in the fluid flow passage between the flow restricting element and the outlet, the downstream fluid pressure sensor being positioned and adapted to interact with the downstream fluid pressure membrane and thereby generally determine the fluid pressure at the disposable downstream fluid pressure membrane;
• directing a fluid through the fluid flow passage;
• calculating the fluid flow rate based on a pressure difference between an output of the upstream fluid pressure sensor and an output of the downstream fluid pressure sensor.

A fluid delivery system for delivering medication from a first source to a patient including measuring the flow rate of the fluid, the system comprising:

• an infusion pump that selectively varies a rate of flow of the first medication from the first source through a fluid line;
• a differential pressure based flow sensor assembly to determine the flow rate of the first medication within the fluid line, the sensor assembly comprising:
• a fluid-tight disposable portion having:
• a sealed disposable body defining a fluid flow passage forming an inlet and an outlet;
• a flow restricting element positioned along the first fluid flow passage between the inlet and the outlet, wherein the flow restricting element includes an orifice that defines a non-capillary fluid flow path;
• an impermeable disposable upstream fluid pressure membrane at a location in the first fluid flow passage between the inlet and the flow restricting element;
• and
• an impermeable disposable downstream fluid pressure membrane at a location in the first fluid flow passage between the flow restricting element and the outlet;
• and
• a fluid impermeable reusable portion having:
• an upstream fluid pressure sensor to sense an upstream fluid pressure at an upstream location in the first fluid flow passage between the inlet and the flow restricting element, the upstream fluid pressure sensor being positioned and adapted to interact with the upstream fluid pressure membrane and thereby generally determine the fluid pressure at the disposable upstream fluid pressure membrane;
• and
• a downstream fluid pressure sensor to sense a downstream fluid pressure at a downstream location in the first fluid flow passage between the flow restricting element and the outlet, the downstream fluid pressure sensor being positioned and adapted to interact with the downstream fluid pressure membrane and thereby generally determine the fluid pressure at the disposable downstream fluid pressure membrane;
• and
• a processor adapted to control the infusion pump by varying the rate of flow of the first medication based on information provided by the differential pressure based flow sensor assembly, the processor further being adapted to determine the amount of the first medication provided to the patient.

A method of delivering medication to a patient comprising:

• providing a differential pressure based flow sensor assembly to determine a flow rate of a first medication within a fluid line, the sensor assembly comprising:
• a fluid-tight disposable portion having:
• a sealed disposable body defining a fluid flow passage forming an inlet and an outlet;
• a flow restricting element positioned along the first fluid flow passage between the inlet and the outlet, wherein the flow restricting element includes an orifice that defines a non-capillary fluid flow path;
• an impermeable disposable upstream fluid pressure membrane at a location in the first fluid flow passage between the inlet and the flow restricting element;
• and
• an impermeable disposable downstream fluid pressure membrane at a location in the first fluid flow passage between the flow restricting element and the outlet;
• and
• a fluid impermeable reusable portion having:
• an upstream fluid pressure sensor to sense an upstream fluid pressure at an upstream location in the first fluid flow passage between the inlet and the flow restricting element, the upstream fluid pressure sensor being positioned and adapted to interact with the upstream fluid pressure membrane and thereby generally determine the fluid pressure at the disposable upstream fluid pressure membrane;
• and
• a downstream fluid pressure sensor to sense a downstream fluid pressure at a downstream location in the first fluid flow passage between the flow restricting element and the outlet, the downstream fluid pressure sensor being positioned and adapted to interact with the downstream fluid pressure membrane and thereby generally determine the fluid pressure at the disposable downstream fluid pressure membrane;
• sensing the flow rate of a first medication with the flow sensor assembly
• controlling an infusion pump that selectively varies the flow rate of the first medication, wherein the controlling is based upon information the flow sensor assembly provides a processor;
• and
• determining an amount of the first medication delivered to the patient, wherein the determining is based upon information the flow sensor assembly provides the processor.