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Publication Number
US-9949321-B1
Publication Date
2018-04-17
Expiration Date
Abstract
The present invention is generally a radio frequency apparatus for warming fluids such as IV fluids. In exemplary embodiments, a uniform warming of fluids is achieved by exposing a fluid-carrying tube to Radio Frequency (RF) energy. The RF energy may be supplied by an RF generator, which is coupled to a waveguide. The waveguide typically includes an inlet into which a fluid tube may be introduced. Inside the waveguide, a pathway may be formed wherein the fluid tube may rest in a predetermined position. In exemplary embodiments, the pathway guides the positioning of the tube along a transmission-line length of the waveguide, in a manner such that the tube gradually approaches an electromagnetic field inside the waveguide and exits at a second terminal end of the waveguide. Having absorbed energy supplied from the RF generator, the fluid inside the tube exits the apparatus warmed to a desired temperature.
Core Innovation
The invention relates to a radio frequency fluid warmer apparatus in which therapeutic fluids are routed through a fluid-carrying tube positioned inside a waveguide. A source of electromagnetic energy is coupled to a first electromagnetic port, and a termination is coupled to a second electromagnetic port to preserve a matched waveguide condition. The tube is routed inside the waveguide between an inlet and an outlet during operation, with a second shell configured to register with the first shell and to include a structure including a pathway for positioning the tube inside the waveguide.
The problem addressed is avoiding heating with microwave cavity standing-wave hotspots and instead achieving uniform warming of therapeutic fluids by using travelling-wave electromagnetic concepts within a waveguide. The travelling-wave approach supports substantially constant RF energy absorption per unit length, with an exit at a target temperature, by coupling the fluid tube gradually to the travelling-wave electromagnetic field along the waveguide length. The matched and terminated waveguide configuration preserves matched transmission and avoids standing waves that would create hot-spots.
The document further describes optional non-invasive temperature monitoring and control using temperature sensors and a control module that can monitor fluid temperature. It also discusses how waveguide and tube positioning affect absorption through field pattern dependence and attenuation and insertion loss concepts, including that the absorption behavior is related to electromagnetic field terms. Enclosure structures and interface features are described, including clam shells and an electromagnetic choke at mating edges to prevent electromagnetic leakage, along with optional low-loss foam pathways for tube positioning.
Claims Coverage
The independent claims provide coverage for a radio frequency fluid warmer apparatus with a matched waveguide condition and tube positioning structure, and a system for warming intravenous fluids using radio frequency signals applied to a rectangular waveguide with a terminating matched condition. Across the independent claims, the inventive features focus on the waveguide, ports, termination arrangement, and the tube positioning pathway formed by a shell or pathway structure.
Shell-registered radio frequency waveguide with tube pathway positioning
A radio frequency fluid warmer apparatus comprising a first shell, a waveguide including first and second electromagnetic ports, an inlet for receiving a fluid, and an outlet for dispensing the fluid; a tube for routing the fluid inside the waveguide between the inlet and the outlet during operation; and a second shell configured to register with the first shell, wherein the second shell comprises a structure including a pathway for positioning the tube inside the waveguide.
Matched waveguide condition via termination at the second electromagnetic port
A radio frequency fluid warmer apparatus including a source of electromagnetic energy coupled to the first electromagnetic port; and a termination coupled to the second electromagnetic port for preserving a matched waveguide condition.
In-waveguide pathway for routing the fluid tube
A radio frequency fluid warmer apparatus comprising a first shell; a waveguide including first and second electromagnetic ports, an inlet, and an outlet for receiving a fluid tube that traverses the waveguide; a pathway situated inside the waveguide for routing the fluid tube between the inlet and the outlet; a radio frequency generator coupled to the first electromagnetic port; and a termination coupled to the second electromagnetic port for preserving a matched waveguide condition.
Enclosure system for warming intravenous fluids with RF signal control and matched termination
A system for warming intravenous fluids using radio frequency signals comprising a rectangular waveguide housed in a first compartment of an enclosure, the rectangular waveguide including first and second electromagnetic ports, an inlet situated substantially at a sidewall of the rectangular waveguide for receiving a fluid, and an outlet for dispensing the fluid; a control module housed in a second compartment of the enclosure configured to generate radio frequency signals from an energy source and apply the radio frequency signals to the first electromagnetic port; a tube for routing the fluid inside the rectangular waveguide between the inlet and the outlet during operation; and a termination coupled to the second electromagnetic port for preserving a matched waveguide condition.
The independent claim set centers on routing a fluid tube through a waveguide while applying radio frequency energy to a first electromagnetic port and preserving a matched waveguide condition using a termination at a second electromagnetic port, with a shell or pathway structure for positioning the tube inside the waveguide. A further independent system claim specifies a rectangular waveguide in an enclosure with a control module generating and applying RF signals to the first port, while maintaining the matched termination at the second port.
Stated Advantages
Uniform warming of therapeutic fluids by using a travelling-wave approach in a waveguide to avoid microwave cavity standing-wave hotspots.
Substantially constant RF energy absorption per unit length with exit at a target temperature.
Preserves matched transmission and avoids standing waves that would create hot-spots.
Prevents electromagnetic leakage using an electromagnetic choke at mating edges.
Enables optional non-invasive temperature monitoring and control using temperature sensors and a control module.
Documented Applications
Warming intravenous fluids.
Warming therapeutic fluids including IV fluids, dialysate for peritoneal dialysis, and blood products.
Use related to peritoneal dialysis (PD) and critical care hypothermia.
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