Methods and devices for use of degassed fluids with fluid enhanced ablation devices

Inventors

Curley, Michael G.

Assignees

Thermedical Inc

Abstract

Devices, systems, and methods for degassing fluid prior to applying fluid to a treatment site during ablation therapy are provided. In one embodiment, an ablation system can include an elongate body, an ablation element, a heating assembly, and a fluid source. Fluid in the fluid source can be at least partially degassed prior to being provided as part of the system, or, in some embodiments, a degassing apparatus can be provided that can be configured to degas fluid within the system prior to applying the fluid to the treatment site. The degassing apparatus can include one or more gas-permeable and fluid-impermeable tubes disposed therein, which can allow gas to be removed from fluid passing through the apparatus. Other exemplary devices, systems, and methods are also provided.

Core Innovation

The invention relates to fluid-enhanced ablation systems in which an ablation element heats tissue adjacent to an elongate body while a fluid is delivered through an inner lumen. The system uses a fluid source separate from the elongate body, with the fluid source containing a volume of fluid that is at least partially degassed. The degassed fluid includes one or more dissolved gases having less than a predetermined partial pressure, so the fluid contains dissolved gases at a reduced partial pressure level.

A motivation for the degassing is that dissolved gas removal is driven by heating-driven bubble formation that increases system compliance and reduces flow reliability. The system addresses this by supplying at least partially degassed fluid to the ablation site, so that dissolved gases are reduced relative to expected equilibrium conditions based on partial pressure. Degassing is achieved using a pre-degassed reservoir and/or an integrated degassing apparatus connected with the fluid source.

In an apparatus embodiment, an integrated degassing apparatus includes gas-permeable and fluid-impermeable tubes and operates with a vacuum source or a controlled gas source, optionally using gas sensors. The document further describes an elongate body with outlet ports, an ablation element/electrode, a heating assembly in the lumen, a fluid reservoir, a pump, and a controller. Experimental results are described showing that degassed saline provides larger and less variable lesion diameters over varied temperatures and RF powers, thereby improving treatment reliability.

Claims Coverage

The document identifies one independent claim covering an ablation system that delivers at least partially degassed fluid through an inner lumen to tissue adjacent to an elongate body, where an ablation element heats the tissue. The independent claim is then refined by multiple dependent claims that add specific inventive features including dissolved-gas/oxygen partial-pressure constraints, an in-lumen heating assembly, and a mass-exchanger-based degassing apparatus, as well as additional structural delivery features.

Overall claim coverage centers on an ablation system that delivers at least partially degassed fluid—defined by dissolved gases having less than a predetermined partial pressure—from a separate fluid source through an inner lumen, with tissue heating by an ablation element. Dependent claim coverage specifies oxygen partial-pressure constraints, adds a heating assembly inside the lumen, introduces a mass exchanger to at least partially degas the fluid, and includes additional structural delivery features such as a tissue-puncturing distal tip.

Stated Advantages

Documented Applications