Tracheal Catheter Multi-Lumen CO2 Washout Design
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Solution Overview
Problem
Current catheters for tracheal gas insufflation during ventilatory support face challenges in effectively ventilating CO2 from the lungs without increasing driving pressure, which can lead to barotrauma, and are unsuitable for nasotracheal insertion due to size and stability issues, especially during spontaneous breathing and movement.
Innovation Solution
A tracheal catheter with a tubular body and a distal ending segment featuring a terminal opening and side outlets, allowing for even gas flow distribution and reducing pressure buildup, designed for nasotracheal intubation with a flexible material and adjustable diameter to accommodate various patient sizes, ensuring effective CO2 washout without excessive pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high gas flow (4-12 l/min) is delivered through a thin catheter (1-2 mm diameter) to wash out dead space, then CO2 ventilation effectiveness is improved, but the driving pressure far surpasses 10 kPa which destroys lung parenchyma and causes barotrauma
Solution Approach 1:
The catheter is divided into multiple lumens (at least two lumens) with different functions: one lumen for delivering oxygen and another for removing CO2. This segmentation allows each lumen to operate at lower pressures while achieving the same overall ventilation effectiveness, thereby reducing barotrauma risk while maintaining CO2 washout capability.
Solution Approach 2:
The invention transitions from a single-lumen design to a multi-lumen configuration, adding a spatial dimension to the gas flow pathway. This dimensional change enables simultaneous inspiration and expiration through separate channels, reducing the pressure burden on any single pathway while improving overall ventilation efficiency.
2Object-affected harmful factors
If a catheter with larger diameter is used to reduce driving pressure, then barotrauma risk is reduced, but the catheter becomes unsuitable for nasotracheal insertion
Solution Approach 1:
The catheter is segmented into multiple thin lumens (each 1-2 mm diameter) that can be inserted nasotracheally, rather than using a single large-diameter catheter. The segmented structure maintains overall functionality while meeting the size constraints for nasal insertion.
Solution Approach 2:
Multiple lumens are nested within a common catheter body or introducer sheath, allowing thin individual lumens to be delivered through the nasal passage while providing the functional capacity of a larger system. The nested configuration enables easy insertion while maintaining low driving pressure capabilities.
3Ease of operation
If known catheters are inserted through the intubation cannula, then catheter placement is simplified, but dynamic resistance during expiratory phase is undesirably increased
Solution Approach 1:
The catheter design incorporates dynamic flow separation where inspiration and expiration occur through different lumens at different phases of the respiratory cycle. This dynamic configuration reduces expiratory resistance by providing a dedicated low-resistance pathway for CO2 removal that adapts to the breathing phase.
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 catheter effectively washes out CO2, reduces the risk of barotrauma, and supports ventilatory function during spontaneous breathing, maintaining low inspiratory and expiratory effort, even during high gas flows, while allowing for stable positioning and ease of insertion.
Implementation Method 1
The flows surpassing 10 l/min cause the positive pressure in trachea on the principle of nozzle - receiving channel; this holds for static and mainly for dynamic state.
Implementation Method 2
The pressure needed to drive the gases therefore far surpasses 10 kPa, which is a pressure that destroys the lung parenchyma and thus causes the barotrauma.
Data Source
Figure 1
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AI summary
Tracheal catheter from the flexible material has an ending segment (2) whose output forms a terminal opening (3) leaned in the direction of the axis of a body (1). Side outlets (4) are distributed on the circumference above the terminal opening (3); these side outlets (4) are leaning towards the terminal opening (3). The side outlets (4) are distributed equally angularly on the circumference of the ending segment (2) in such a way that the even flowing out of the breath gas towards the trachea's walls on the circumference is achieved. The surface of the terminal opening (3) is smaller than 90% of the surface of the flow cross-section of the body (1) and the total surface of the cross-section of the side outlets (4) is at least 10% of the surface of the terminal opening (3). The ending segment (2) can have an outer tightening towards the terminal opening (3), which is formed by transition from the diameter of the tubular body (1) towards the diameter of the terminal opening (3). The tightening can be gradual, stepless, and, for example, conical with the apex angle ranging from 30° to 90°. The catheter can be advantageously used for patients bordering on respiratory insufficiency or during the terminal disconnection of the patient from the lung ventilator.