New technology can “sieve” argon, scarce surgical anaesthetic can be used again

Sick need surgery, which is the ideal anesthetic? In the past, this problem did not attract the attention of ordinary people, but the search for a small side effect, good anesthetic effect of the drug is really very elegant. Recently, Nanjing University of Technology Professor Gu Xuehong, Wang Xuerui and Professor Freek Kapteijn of Delft University of Technology in the Netherlands, developed a hollow fiber molecular sieve for modern medical anaesthetic xenon on-line reuse of new technology, can achieve the recycling of argon, saving more than 99% of the purchase cost of argon, It can also alleviate the problem of tight supply of argon market.

A diagram of hollow fiber molecular sieve technology for the online reuse of modern medical anaesthetic argon, for illustration by the Propaganda Department of Nanjing University of Technology

The results are published in the German Journal of Applied Chemistry.

When anaesthetic is also in short supply, it must rely on recycling to meet clinical needs. So, what kind of anaesthesis is argon? How do scientists prepare and recycle?

“The Nobles” of Inhalation Anesthetics

Xenon, because of its rarity and high cost, is known by the anesthesiologist as the “nobles” who inhale narcotic drugs.

Radon is an inert gas found in the earth’s air. The radon itself is non-toxic, and is discharged in its original form after inhalation, but has a suffocating effect at high concentrations. Xenon is anaesthetic, and a mixture of oxygen (20% argon and 80% oxygen) can be anaesthetized on the human body. Xenon is mainly anaesthetized by inhibiting the CENTRAL NERVOUS SYSTEM NMDA receptor and acetylcholine receptor.

Clinical research found that argon anaesthetic is strong, has a certain analgesic effect, the required auxiliary drugs are very few, especially anesthesia induction fast, wake up fast, not susceptible to the impact of biological transformation, is known to have the least cardiovascular impact on an anesthetic drug, so argon is an ideal anesthetic. Xenon can be used in a variety of surgical anesthesiology, such as general surgery, gynecology, orthopaedics and orthopaedic surgery.

However, argon is expensive. In clinical use, how to achieve argon with the patient’s breath ingress, continue to collect and recycle, has been a difficult problem to be solved.

In clinical surgery, the patient’s tissue metabolism is still normal during anesthesia, and the argon used as an anesthetic is constantly sucked in by the patient and then exhaled. While breathing argon, the patient also constantly exhales carbon dioxide, in this closed-circuit circulatory breathing anaesthetic device, when the concentration of carbon dioxide accumulates to a certain extent, it will cause carbon dioxide poisoning. The mixture of carbon dioxide and argon must therefore be regularly discharged to replace the fresh xenon.

“Currently, the only source of argon’s exploitability is air, which uses a high energy consumption in multi-stage deep-cold refining processes, while the concentration of argon in the air is extremely low, at 0.087ppm, and the market supply is extremely limited. Even if the worldwide production of high-purity argon is used in medical anesthesia, there are no more than 800,000 clinical cases available. “Thepaper newsletter author Gu Xuehong introduced.

Molecular sieve membrane “put the door” to stop the argon

“Our job is to put the molecular sieve into the anaesthetic closed-circuit circulation system, the human tissue metabolism during the anaesthetic process of carbon dioxide removed in a timely manner, so that argon can be recycled in it, do not need to replace the new argon, thereby reducing the amount of argon in the anaesthetic process and the cost of anesthesia.” Wang Xuerui, author of the paper newsletter and first author, said.

Molecular sieve film is a kind of silica alumina material with a regular hole structure, the effective aperture is determined by the structure of the porous channel of the molecular sieve, and is the ideal membrane material for precision separation of gas molecules. Nanjing University of Technology and other research institutes have successfully realized the industrial application of molecular sieve film in the separation of organic solvents and water, breaking the technological monopoly of a few countries such as Japan and Germany, and filling the technical gap in this field in China.

“We’ve been studying molecular sieve sieves for gas separation for 10 years. How to realize the large-scale industrial application of molecular membrane gas separation is a bottleneck that needs to be broken urgently, and it is also the focus of attention in the academic and industrial circles. Wang Xuerui introduced that the team developed a hollow fiber molecular sieve membrane for the modern medical anaesthetic xenon online reuse of new technology.

In the study, the team found that when the gas molecule penetrates through the molecular sieve membrane, the carbon dioxide molecule “runs” faster, and its penetration speed is two orders of magnitude faster than the argon molecule. Wang Xuerui explained: “Carbon dioxide molecules penetrate fast, the earliest entry into the molecular sieve and adsorption, but carbon dioxide molecules and molecular sieves are relatively weak interaction, it is easy to be more powerful xenon molecules ‘squeezed out’.” “

Using this technology, the recovery rate of xenon is more than 99%, the process energy consumption is very low, so this xenon on-line reuse technology, has obvious technical and economic advantages. At the same time, experts said that the membrane material can be continuously run in the simulation system for more than 300 hours, the performance is stable, it is expected to develop a new type of medical anesthesia equipment, serving the construction of China’s modern medical system.