Bi-directional Flow Heat Exchange Catheter Design
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Solution Overview
Problem
Existing heat exchange catheters have limited efficiency due to unidirectional flow of heat exchange fluid, which reduces heat transfer with blood and requires longer, thicker catheter shafts with longer inflow and outflow lumens, increasing pressure requirements and decreasing heat exchange rates.
Innovation Solution
Bi-directional flow heat exchange catheters with a heat exchange medium supply flow path and return flow path, where the heat exchange tube is laced through bores in the catheter shaft to form loops that protrude, allowing fluid to flow both distally and proximally, minimizing time within the catheter shaft and maximizing heat exchange with blood.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If unidirectional flow of heat exchange fluid is used, then the catheter shaft can be simpler in structure, but heat exchange efficiency is reduced and longer, thicker catheter shafts are required
Solution Approach 1:
The heat exchange tube is divided into multiple segments that are laced through bores in the catheter shaft, creating separate flow paths. This segmentation allows the fluid to flow through multiple sections of the heat exchange tube in series, increasing the effective heat exchange surface area without requiring a longer catheter shaft.
Solution Approach 2:
The heat exchange tube is nested within the catheter shaft structure, with the tube laced through bores in the shaft. This nested configuration allows the heat exchange tube to be positioned efficiently within the catheter, maximizing heat exchange surface area while maintaining a compact catheter shaft structure with shorter, smaller-diameter lumens.
2Device complexity
If unidirectional flow is used, then the flow path is simpler, but pressure requirements increase and heat transfer with blood is reduced
Solution Approach 1:
The flow path is segmented into multiple sections corresponding to different segments of the heat exchange tube. By distributing the flow through multiple smaller sections rather than one long continuous path, the pressure drop across each section is reduced, lowering overall pressure requirements while maintaining effective heat exchange.
Solution Approach 2:
The flow path is configured to move through multiple spatial dimensions by lacing the heat exchange tube through bores in the catheter shaft. This multi-dimensional arrangement creates a more efficient flow path that reduces the length of lumens required and decreases pressure requirements compared to a simple linear unidirectional flow.
3Ease of operation
If heat exchange fluid flows in single direction, then the system is easier to control, but heat exchange efficiency is limited
Solution Approach 1:
The heat exchange tube is segmented and laced through multiple bores in the catheter shaft, creating a flow path that passes through multiple sections. This segmentation allows the fluid to engage with blood across multiple discrete heat exchange zones, improving overall heat exchange efficiency while maintaining straightforward system control through the segmented architecture.
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
This design enhances heat exchange efficiency by allowing simultaneous co-current and counter-current flow, reducing pressure requirements, and increasing the rate of heat exchange, while allowing for a thicker-walled catheter shaft with shorter, smaller-diameter lumens.
Implementation Method 1
the heat exchange tube is laced through a series of bores in the catheter shaft such that portions of the heat exchange tube protrude from the catheter shaft... allowing thermal exchange medium to flow through the heat exchange tube... exchanges heat with blood flowing past the heat exchange in the blood vessel
Implementation Method 2
As the thermal exchange fluid circulates through the catheter's heat exchanger, it exchanges heat with blood flowing past the heat exchange in the blood vessel
Implementation Method 3
greater heat exchange efficiency is accomplished when the heat exchange fluid flows through the catheter's heat exchanger in a direction that is opposite the direction in which the blood is flowing through the blood vessel
Data Source
AI summary
Closed loop heat exchange catheters having bi-directional flow heat exchange regions and their methods of manufacture and use. The heat exchange region may be formed of expandable or non-expandable tubular conduit(s) that are configured in a series of loops or coiled configuration defining a supply flow path and a return flow path through which heat exchange medium is circulated. The individual loops of convolutions of the coiled configuration may be the same or different size. In some embodiments, the tubular conduit(s) may be passed through generally transverse bore holes formed in a catheter shaft so that the loops or convolutions of protrude from the catheter shaft.