Absorbable Suture EtO Removal Using Supercritical CO2
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Solution Overview
Problem
Residual ethylene oxide on absorbable surgical sutures, left after sterilization, causes irritation, inflammation, and compromises mechanical properties, and is carcinogenic, necessitating its complete removal.
Innovation Solution
Treatment of absorbable sutures with supercritical carbon dioxide at pressures above 1099 psi and 31.1°C to remove residual ethylene oxide, using a reactor vessel with a stainless steel basket and stirring mechanism, allowing 1 second to 4 hours of exposure to the supercritical fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethylene oxide is used to sterilize absorbable surgical sutures, then sterilization effectiveness is improved, but residual ethylene oxide remains causing irritation, inflammation, and compromising mechanical properties
Solution Approach 1:
The patent applies extraction by introducing supercritical carbon dioxide to specifically remove and extract residual ethylene oxide from the suture material. The supercritical CO2 penetrates the suture packaging and absorbs the harmful residual EtO, then is depressurized to release the concentrated contaminant, effectively separating the harmful substance from the medical device while preserving the sterilized suture.
Solution Approach 2:
The patent utilizes parameter changes by transitioning carbon dioxide to a supercritical state (above 31.1°C and 73 atm pressure) to enhance its extraction capabilities. This phase change enables CO2 to achieve both liquid-like density for high solubility of EtO and gas-like diffusivity for deep penetration into packaged sutures, optimizing the removal process before returning to atmospheric conditions.
2Object-affected harmful factors
If residual ethylene oxide is removed completely, then patient safety and wound healing are improved, but additional processing steps and time are required
Solution Approach 1:
The patent implements continuous action by maintaining sutures in the supercritical CO2 environment for extended periods (1-4 hours) with continuous stirring, ensuring complete and thorough removal of residual ethylene oxide without requiring multiple discrete processing steps. This continuous exposure guarantees patient safety while streamlining the overall process.
Solution Approach 2:
The patent uses supercritical carbon dioxide as an intermediary substance that facilitates the removal of harmful ethylene oxide residues. The CO2 acts as a mediating agent that can be introduced and removed easily, carrying the contaminant away while requiring minimal additional equipment beyond standard sterilization infrastructure.
3Object-affected harmful factors
If supercritical carbon dioxide treatment is applied, then residual ethylene oxide is removed, but equipment complexity and operational procedures increase
Solution Approach 1:
The patent applies multi-functionality by designing the supercritical CO2 treatment system to serve multiple purposes: it removes residual ethylene oxide, sterilizes the suture packaging environment, and can be integrated with existing sterilization workflows. The same supercritical fluid system can potentially handle different medical devices and contaminants, reducing overall facility complexity.
Solution Approach 2:
The patent utilizes inexpensive carbon dioxide, a readily available and low-cost gas, as the treatment medium. The CO2 is consumed in the process (depressurized and vented after use), functioning as a disposable resource that eliminates the need for complex recovery and recycling systems, thereby simplifying equipment requirements despite the pressurization demands.
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
Effectively removes all residual ethylene oxide, as evidenced by cytotoxicity scores of 0, reducing irritation and ensuring compliance with stringent EU and Kyoto Treaty residual limits.
Implementation Method 1
treating absorbable sutures, after they are sterilized using ethylene oxide, with supercritical carbon dioxide to remove all residual ethylene oxide
Implementation Method 2
Carbon dioxide is then introduced into the reactor vessel while being pressurized and heated to supercritical levels above 1099 psi and 31.1 C
Data Source
AI summary
Treating absorbable sutures that have been sterilized using ethylene oxide with carbon dioxide at or near its supercritical pressure and temperature conditions to remove any residual ethylene oxide.