Pulsatile Rotary Ventricular Pump Tubing Dynamics
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Solution Overview
Problem
Current cardiovascular roller pumps used in pediatric cardiopulmonary bypass surgeries are inefficient at low flow rates, cause hemodilution, and lack safety features to prevent venous reservoir drainage, leading to complications such as tubing leaks, air introduction, and increased blood product transfusions.
Innovation Solution
A pulsatile rotary ventricular pump with a flexible conduit having specific regions for fluid management, including a fill region, pressure region, and discharge region, designed to maintain constant speed and produce pulsatile flow profiles that mimic the human heart, reducing stress on tubing and enhancing safety by preventing reservoir drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If roller pumps are used to provide low flow rates (10-20 cc/kg/min), then flow accuracy is improved, but excessive roller forces are needed causing tubing stress and potential leaks
Solution Approach 1:
The pump transitions from static occlusion to dynamic compression, where the roller head rotates along the tubing rather than pressing against a fixed raceway. This dynamic motion allows effective low-flow pumping with reduced tubing stress
Solution Approach 2:
The traditional mechanical roller-raceway occlusion system is replaced with a rotating roller head that compresses and releases tubing dynamically, substituting a simpler mechanical system for the complex occlusive mechanism
2Productivity
If occlusive roller pumps are used to fully occlude tubing for low flow rates, then flow control is improved, but tubing wear and rupture risk increase
Solution Approach 1:
The roller head performs periodic compression cycles as it rotates, compressing the tubing to stop flow, then releasing to allow refilling. This periodic action provides precise flow control without continuous occlusion, reducing tubing wear
Solution Approach 2:
The system uses dynamic rotation and compression timing to control flow, replacing static full occlusion with a moving compression front that can be precisely timed and positioned
3Device complexity
If traditional roller pumps are used without safety features, then device simplicity is improved, but reservoir drainage and air introduction risks increase
Solution Approach 1:
The pump automatically detects reservoir level and stops operation when the reservoir is empty, eliminating the need for external monitoring systems while preventing air introduction
Solution Approach 2:
The pump incorporates feedback from reservoir level detection to control its operation, stopping automatically when the reservoir is empty to prevent air from being pumped to the patient
4Ease of operation
If roller pumps operate at constant speed, then operational simplicity is improved, but pulsatile flow generation is lost
Solution Approach 1:
The rotating roller head creates periodic compression and release cycles that generate pulsatile flow, automatically producing physiological flow patterns without varying motor speed
Solution Approach 2:
The mechanical dynamics of the rotating roller head on the flexible tubing automatically generate pulsations in the flow and pressure profiles, converting constant rotational motion into pulsatile output
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 pulsatile rotary ventricular pump achieves precise low-flow control, reduces hemodilution, and minimizes risks associated with tubing stress and air introduction, providing a safer and more effective perfusion method for pediatric patients by maintaining pulsatile flow and pressure profiles at constant rotor speed.
Implementation Method 1
a roller head (rotor) with three rollers and a conduit having an occlusive portion... The occlusive portion remains occluded as long as the pressure on the outside of the conduit is equal to or greater than the pressure on the inside of the conduit
Implementation Method 2
When the fluid inlet supply pressure exceeds the pressure acting on the exterior of the conduit, the occlusive segment will inflate and fill with fluid
Data Source
AI summary
A roller pump conduit defining a pump chamber is provided. The roller pump conduit includes a roller contact portion having a fill region and a delivery region. The fill region has a first taper configured to determine volume delivery per revolution of a roller head. The delivery region has a pressure region having a second taper and a discharge region having a third taper. The third taper has a lesser degree of taper than the second taper. The delivery region is configured to produce a pulsatile flow out of the conduit. Furthermore, a roller pump having a roller pump conduit is provided. The roller pump conduit of the roller pump has a fill region and a delivery region, the fill region having a first taper, and the delivery region having a second and third taper, wherein the third taper has lesser degree of taper than the second taper.