Polymer membrane material and artificial organ

Polymer membrane materials and artificial organs Wang Qingrui, Chen Xueying, and He Chunju (The School of Materials Science and Technology at Donghua University, a national focal point for the modification of fiber materials, is a major breakthrough in the design of artificial kidneys. Blood flows from the end of the dialyzer into the hollow after flowing from the human artery. The inner cavity of the fiber flows out from the other end of the dialyzer and into the vein of the human body. The sterilized dialysate enters the side tube of the dialyzer, flows between the hollow fibers and flows out of the other tube. Waste, excess electrolyte and excess water enter the dialyzing fluid through the membrane, and is discharged along with the dialysate.The renal failure patients are dialyzed on average 2 times a week, about 5 hours each time, and each time the major disadvantage of urea 15 can be dialyzed from the blood. For this purpose, Donghua University successively developed modified polyacrylonitrile and polyethersulfone hollow fiber, and obtained good results through clinical trials.

In addition to the above film materials, synthetic polymer films such as polymethyl methacrylate, polyethylene, polysulfone, and ethylene-vinyl alcohol copolymers have also been developed.

4.2 Artificial Liver Hemodialysis The liver can be said to be a precision chemical plant in the human body. It is an important organ responsible for various functions, and is also an organ that mainly removes toxins in the human body. It may be damaged due to poisoning caused by overdose, allergies, acute hepatitis, etc., resulting in loss of detoxification function, increasing the concentration of harmful substances in the blood, causing neurological symptoms, lethargy, and ultimately death.

There are many kinds of artificial liver assist system, there are mainly two kinds: one is through the infiltration method, the other is through the adsorption method, such as using activated carbon to suck the potential toxic components, thus helping the liver failure comatose patients to cross Overcoming difficulties, fighting for time to regenerate liver cells and maintaining necessary liver function under new conditions. Although activated carbon can adsorb toxic substances in the blood, it also has serious drawbacks. For example, it can also absorb substances necessary for organisms such as platelets, clotting factors, epinephrine, and insulin, and sometimes it can cause serious complications such as bleeding. , DIC, etc. Therefore, although pure activated carbon blood lavage has been popular for a while, it has basically been abandoned. At present, granular activated carbon is often embedded in a polymer film to improve the selectivity of adsorption.

In recent years, membranes that are selective for dialysis have been favored, such as the use of polyacrylonitrile hollow fibers for assembly into artificial liver hemodialyzers. The first report of the blood export artificial kidneys hemodialysis machine structure schematic artificial kidney hemodialysis machine hollow fiber materials used are mostly regenerated cellulose or cellulose esters, such as ENKAGlanzstoff's copper amine (cuprophane), Cordis-DOW's acetate fiber Plain film, viscose cellulose and non-aqueous solvent cellulose membrane developed by Donghua University.

Patients who have long-term use of cellulose membrane dialysis can not excrete some toxic substances in the blood due to their molecular weight, and they will be concentrated for a long period of time. This can easily make patients suffer from another incurable disease. This is because the cellulose membrane is used to thicken ascites. Opolon, a French scholar of acrylonitrile dialysis, recently introduced a new therapeutic effect. After one day of treatment with artificial liver in three cases of fulminant hepatic coma (see class I K), the coma was significantly improved (level I) and completely awake on the third day. The artificial liver dialyzer developed by Donghua University and Ruijin Hospital has also passed the identification and has achieved good clinical results. As a hollow fiber membrane material for artificial liver hemodialysis, in addition to PAN, there is 4.3 hepatic ascites ultrafiltration and concentrating liver ascites, which is a common disease. Clinically, ascites is usually taken out of patients to relieve the disease. Since the protein in ascites can be discharged together with ascites and cause protein reduction in the patient, albumin must be returned to the patient. Albumin is separated from the blood and is expensive. It not only increases the economic burden on the patient but also exacerbates the blood. Contradiction between supply and demand may also cause infection.

Concentration and reinfusion of ascites is a new medical technique that concentrates the ascites in the body of a patient, removes water and substances that are useless to the body, and returns the protein to the patient. Britton et al. used an ultrafiltration membrane to inject a concentrated solution containing protein into a static state. 154. Membrane science and technology to control rapid ascites. The procedure of the *Rhodiascit* ascites concentrator produced by Rgone*Poulenc in France is shown in the flow chart. It uses multiple polyacrylonitrile flat membranes combined into an ultrafilter. Ascites is concentrated in a closed circuit and the ascites protein is returned to the body. The device can be used as a symptomatic method for cirrhosis refractory ascites. The polyacrylonitrile hollow fiber ascites ultrafiltration concentrator, developed by Donghua University, has been clinically applied in Shanghai Huadong Hospital and Zhongshan Hospital. The therapeutic effect is obvious. The ascites dialysis concentrator and its supporting equipment made by Donghua University and Shanghai Deyuan Science and Technology Development Co., Ltd. have been approved for production and application by the State Administration of Pharmaceutical Administration and the Shanghai Pharmaceutical Bureau.

Hepatic ascites concentrating and refeeding device process 44 Blood concentrator Blood dilution has been widely used in open heart surgery with extracorporeal circulation. The advantage of hemodilution is that there is less destruction of blood cells during extracorporeal circulation, and peripheral resistance is low, peripheral vascular perfusion can be improved, and blood is reduced. Destruction and use of blood, and can reduce serum hepatitis complications. However, hemodilution can cause organ edema, extracellular fluid and other disadvantages. Postoperative organ function is low, affecting the recovery of heart and lung function. In order to overcome the above disadvantages, diuretics have previously been used. The disadvantage is that the diuretic dose is not easily controlled, and electrolyte disturbances and secondary heart rate disorders are easily generated, and the effect on poor renal function is poor. Afterwards, centrifugation was used to separate the extra diluted blood into post-differentiated blood (mainly red cells), plasma, and water. The red blood cells were returned to the patient, and the plasma and water were discarded.

The blood concentrator was developed in the 1970s. Its structure is similar to that of an artificial kidney blood concentrator, but the material, structure and performance of the hollow fiber membrane material are different. The diluted blood enters from one end of the concentrator, is concentrated and then is drawn from the other end, enters the human body through the catheter, and low molecular substances such as water are eliminated through the membrane wall.

The membrane materials used as blood concentrators include cellulose and its esters, polyacrylonitrile, polymethyl methacrylate, polysulfone and the like. A large number of hydroxyl groups on the surface of cellulose membranes are likely to cause complement activation, so synthetic polymers are now used more often.

45 artificial lung gas exchanger should. Artificial lungs are mainly used for thoracic surgery and adjuvant therapy for people with poor breathing. Artificial lungs can be divided into two categories: artificial air bubbles and artificial artificial lungs. Bubble artificial lung is equivalent to a bubble tower, and oxygen is directly in contact with blood in the form of bubbles. In order to prevent air bubbles from entering the arteries of the body, it is necessary to add a defoaming chamber and a blood settling chamber coated with an antifoaming agent.

The direct contact of blood with air denatures proteins, and violent gas mixing can also cause destruction of red blood cells. Due to the above shortcomings of the bubble-type artificial lung, it is being replaced by a membrane-type artificial lung.

Membrane artificial lungs mainly use membrane enrichment method. The gas and blood are separated by membranes. Oxygen diffuses through the membrane and enters the blood side. Carbon dioxide passes through the membrane and enters the gas side. Membrane artificial lung can be divided into stratified, spiral and hollow fiber type. The appearance of the hollow fiber artificial lung is similar to that of an artificial kidney hemodialyzer.

4.6 Blood Filtration Fluids Another different method of blood purification is dialysis. It simulates the glomerular filtration principle of normal human kidneys, filtering and eliminating water and toxic substances in the bloodstream by convection. Hemodialysis involves the exchange of solute and water based on the diffusive effects of the concentration difference of the solution on both sides of the dialysis membrane and the osmotic pressure difference. Hemofiltration is a renal replacement therapy that is closer to normal glomerular filtration physiology.

4.7 hemodiafiltration filtration Another method of blood purification is based on hemodialysis, the use of high-throughput filters, mainly ultrafiltration, filtering out a large number of toxic substances and body fluids from the blood, while input A blood purification method of equal replacement fluid. Its purpose is to remove medium molecular weight toxic substances while eliminating small molecular weight toxins.

The common features of hemodiafiltration and hemodialysis are the diffusion and convection of solute, and also the ultrafiltration of water; the difference is that the removal of solute in hemodialysis mainly depends on diffusion, convection accounts for a minimum proportion, and the removal of HDF solute mainly depends on Convection; hemodialysis power is mainly the concentration difference, and the power of HDF is the pressure difference; the diameter of the hemodialysis membrane is small and can only remove small molecule toxins, while the HDF membrane has a larger pore size, not only can clear small molecules, but also Remove toxic substances in the molecule.

4.8 Simple ultrafilter The removal of water from the patient is one of the tasks of blood purification, which is achieved by ultrafiltration and accompanied by dialysis. Single super is a treatment method that removes moisture from whole blood through a semipermeable membrane through a convection transport mechanism. Unlike hemodialysis, patients undergoing a single timeout, hemodialysis and other body fluid electrolyte concentration and osmolality did not change; and when hemodialysis, due to diffusion and convection at the same time, so artificial oxygen using oxygen enrichment technology to keep the body oxygen For its electrolyte concentration and permeability have different degrees of change. As a single Wang Qingrui, etc.: polymer membrane materials and artificial organs. 155. Super-dialysis and dialysis are very different, in order to distinguish the difference between ultrafiltration and dialysis ultrafiltration without dialysis, the former is called single super.

The application of Shanchao significantly reduces hypotension, muscle cramps and other adverse reactions, and thus arouses people's interest and attention in this therapeutic technology. Its clinical application has been significantly expanded and applied to the treatment of the following conditions: renal insufficiency Patients with water sodium retention, refractory heart failure, acute and chronic pulmonary edema, respiratory failure, severe edema of nephrotic syndrome, treatment of dialysis-related ascites, dehydration in patients with peritoneal dialysis failure, severe headache during dialysis , Treatment of Cooley anemic cardiomyopathy and other heart failure.

4.9 plasma exchange) is one of the commonly used blood purification methods. Plasmapheresis involves taking blood from a patient, separating the plasma from cellular components, and removing the plasma. The cellular components and the albumin, plasma, and equilibrium fluids that must be supplemented are returned to the body to remove cancer-causing agents (such as denatured proteins). ). Selecting membrane materials with different structures can separate whole blood plasma and separate blood components, so as to selectively remove certain pathogenic substances, further improve curative effect and reduce complications. Some of the pathogenic factors present in human blood, these pathogenic factors can cause organ damage, and play an important role in the pathogenesis of some diseases.

The adaptability of plasma exchange is quite extensive, and it is mainly applied to the following diseases: Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome, Anti-glomerular basement membrane disease, Guillain*Barre syndrome, Acute renal failure of multiple myeloma , Hyperviscosity syndrome, autoimmune hemophilia, hypercholesterolemia, myasthenia gravis crisis, acute glomerulonephritis.

The new development trend of 410 hybrid artificial organs and artificial pancreatic artificial organs is the development of hybrid type artificial organs, immobilizing enzymes and biological cells on polymer materials, and preparing artificial organs with biological activity. Such as artificial liver in the hollow fiber membrane outside the immobilized protease, the synthesis of albumin can enter the blood through the membrane; as in the artificial kidney immobilized urease, glutamate dehydrogenase, glucose dehydrogenation Enzymes, etc., make the metabolite urea in the blood convert to ammonia under the catalysis of the enzyme, and react with glutamate under the enzymatic reaction with a-ketoglutarate to make the mixed artificial kidney more than the artificial kidney for detoxification. Advanced features.

The artificial pancreas is a mixed-type artificial organ. That is, islet cells are cultured on the outside of the hollow fibers, blood circulation is performed on the inner side, and the outer islet cells can measure the blood glucose concentration in the inner blood via the membrane wall, thereby controlling the secretion of insulin. Japan has been carrying out development work.