Cryoablation System Docking Station for Liquid Refrigerant
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Solution Overview
Problem
Current cryosurgical cooling systems using liquid nitrogen as a refrigerant face issues with rapid evaporation and vapor lock, making them impractical for cryoprobe applications due to the significant increase in volume and heat absorption, which clogs the cryoprobe and hampers effective tissue freezing.
Innovation Solution
A cryoablation system employing a docking station for thermally insulated containers that maintain a liquid refrigerant in a liquid state, utilizing a Pulse Tube Refrigerator to chill the refrigerant to cryogenic temperatures and a pump to deliver it to the cryoprobe while preventing evaporation, ensuring continuous liquid flow through the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid nitrogen is used as refrigerant in cryoprobe, then cryogenic temperatures can be achieved, but rapid evaporation causes vapor lock that clogs the cryoprobe
Solution Approach 1:
The system changes the physical state parameters of the refrigerant by maintaining it under pressure to prevent phase change from liquid to gas. The pressure control system adjusts parameters to keep the refrigerant in liquid state despite temperature variations, preventing vapor lock while achieving cryogenic temperatures.
Solution Approach 2:
A pressure control system acts as an intermediary between the refrigerant storage and the cryoprobe. This intermediary mechanism regulates pressure to prevent rapid evaporation, allowing the refrigerant to flow smoothly without forming vapor locks that would clog the probe.
2Use of energy by moving object
If liquid nitrogen flows through cryoprobe, then heat absorption from tissue occurs, but volume expansion clogs the cryoprobe
Solution Approach 1:
The system maintains pressure parameters within specific ranges to prevent the refrigerant from expanding in volume. By controlling pressure to stay above the vapor pressure at cryogenic temperatures, the refrigerant remains in liquid state with stable volume, enabling continuous heat absorption without clogging.
Solution Approach 2:
The pressure control system ensures continuous liquid flow of the refrigerant through the cryoprobe without interruption from vapor formation. This continuity maintains steady heat absorption from the tissue while preventing the discontinuous flow that would result from vapor lock and clogging.
3Temperature
If liquid refrigerant is cooled to cryogenic temperatures, then effective tissue freezing is achieved, but evaporation increases system complexity
Solution Approach 1:
A pressure regulation system serves as an intermediary component that adds minimal complexity to prevent evaporation. This relatively simple pressure control mechanism enables effective tissue freezing by maintaining the refrigerant in liquid state, avoiding the need for complex vapor management systems.
Solution Approach 2:
The refrigerant system is designed to self-regulate pressure to prevent evaporation. The closed-loop system with pressure sensors and control valves automatically maintains optimal pressure conditions, reducing the need for external intervention and simplifying operation while achieving reliable cryogenic temperatures for tissue freezing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively maintains the refrigerant in a liquid state, preventing vapor lock and ensuring efficient cooling of biological tissues without clogging, allowing for consistent and reliable cryosurgical procedures.
Implementation Method 1
A refrigerator chills liquid refrigerant to a predetermined cryogenic temperature (e.g. less than −100° C.). In one embodiment a Pulse Tube Refrigerator (PTR) provides the cooling energy to chill the refrigerant.
Implementation Method 2
The present invention pertains to cooling systems that use thermally insulated cryogen containers that are connectable to a cryoprobe for freezing biological tissues to cryogenic temperatures.
Implementation Method 3
Cooling is provided from a part of the cryoprobe (e.g., the cryoprobe tip) that will be in direct thermal contact with the target biological tissue to be treated.
Data Source
AI summary
A cryoablation system includes thermally insulated containers for holding liquid refrigerant. The containers are placed in a docking station that charges the containers with a liquid refrigerant at a cryogenic temperature suitable for carrying out a surgical procedure. The charged containers are detachably connectable with an inlet line of a cryoablation probe. When the cryoprobe is activated, the chilled liquid refrigerant is transported from a delivery container, through the cryoprobe, and to a recovery container. The recovery container is preferably identical in design to the delivery container. The refilled recovery container is then placed in the docking station to charge. In another embodiment, a cartridge includes a delivery container and recovery container combined as a single unit. Methods are also described.