Blood purification refers to hemodialysis, hemofiltration, plasma exchange, and plasma perfusion. Bedside blood purification has specialized equipment, and the specific situations and modes used for different devices may vary. The most commonly used one is Braun.
1、 Hemodialysis
Hemodialysis is the process of simultaneously introducing the patient's blood and dialysate into the interior and exterior of a dialyzer. Solutes move through a semi permeable membrane from the high concentration side to the low concentration side, while water permeates through the semi permeable membrane from the low concentration side to the high concentration side, through the super effect of pressure gradient.
2、 Blood filtration
(1) Purification principle and method
The main method of blood filtration is a blood purification therapy designed to mimic the principles of glomerular filtration and tubular reabsorption. The specific method of blood filtration is to filter out a large amount of water and solutes through a blood filter under the action of grinding pressure. Equivalent to the filtration function of the glomerulus, and then supplemented with a solution similar in concentration to the extracellular fluid electrolyte through an infusion device, known as replacement fluid, this step is equivalent to the reabsorption function of the renal tubules. The excess displacement of ultrafiltrate is the difference in capacity between the two, which is the excess water excreted from the body. Toxic substances in the blood will be excreted together with a large amount of water, thus achieving the goal of blood purification.
（2） Indications for patients: Blood filtration is mainly suitable for patients with the following symptoms: 1. Patients with renal dysfunction and concomitant cardiac dysfunction. Two patients experienced hypotension during dialysis and were unable to undergo hemodialysis. There is fluid accumulation in the body cavity of three patients. Four patients also have refractory hypertension. 5 patients are accompanied by peripheral neuropathy. Six patients experienced severe edema.
（3） Advantages and disadvantages
Blood filtration is a blood purification method that can continuously remove water and solutes from the body. The changes in blood volume and solute composition are relatively slow, so the patient's cardiovascular function will be relatively stable. It can also avoid significant changes in osmotic pressure during the treatment process. This treatment method is easier to correct the patient's water overload than dialysis. Especially suitable for patients who are intolerant to hemodialysis.
The disadvantages of this blood purification method are also quite obvious. Firstly, the clearance rate of small molecule substances is relatively low. Secondly, the price is higher than that of hemodialysis. Thirdly, if the equipment is relatively simple, the operation will be time-consuming and laborious.
3、 Plasma exchange
(1) Purification principle and method
Plasma exchange is the process of extracting the patient's blood, separating plasma and cellular components, removing plasma, and then redeeming cellular components and new normal plasma or equivalent plasma substitutes back into the patient's body. This method is used to remove pathogenic factors in the body, such as self antibodies or immune complexes, as well as protein bound toxins, etc. Through this method, some diseases can be treated. There are three different types of blood purification methods, namely centrifugation, membrane filtration, and cold filtration.
（2） There are many symptoms that can be treated with plasma exchange as a blood purification method for patients. For example, kidney disease, neurological disease, hematological disease, or other diseases. Most kidney diseases can use this purification method, such as pulmonary hemorrhagic nephritis syndrome, progressive nephritis, membranous proliferative glomerulonephritis, lupus nephritis, hemolytic uremic syndrome, and so on. Neurological disorders include myasthenia gravis, Guillain Barr é syndrome, and multiple sclerosis, among others. Hematological disorders include autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura, and multiple myeloma, among others.
4、 Plasma perfusion
Plasma perfusion refers to the purification of blood by using extracorporeal circulation to remove exogenous or endogenous toxins from the blood through adsorption devices with broad-spectrum detoxifiers. The main process in the process of blood perfusion is that the blood flows through the perfusion device and comes into full contact with the adsorbent loaded in it. The toxins in the blood are adsorbed and then removed, so in this operation, the adsorbent plays a decisive role. There are two types of adsorbents used, one is activated carbon, and the other is synthetic resin.