The patient's blood and dialysate are introduced into the dialyzer at the same time (the flow direction of the two is opposite), and the semi-permeable membrane of the dialyzer (artificial kidney) is utilized to clear the excessive toxins and excessive water accumulated in the blood out of the body, and replenish the alkaline base in order to correct the acidosis, adjust the electrolyte disorders, and substitute for the excretory function of the kidney.
Hemodialyzer is commonly known as artificial kidney, there are hollow fiber type, coiled tubing type and plate type 3 kinds. The most commonly used is the hollow fiber type, composed of 1 to 15,000 hollow fibers, the wall of the hollow fiber is the dialysis membrane, with semi-permeable membrane properties. During hemodialysis, the blood flows into each hollow fiber, while the dialysis solution flows outside each hollow fiber. The flow direction of the blood is opposite to that of the dialysis solution, which removes toxins through the principle of semi-permeable membrane, and removes water through ultrafiltration and osmosis.
Indications and contraindications
The indications for hemodialysis include:① Acute renal failure. ② Acute drug or poison poisoning. Chronic renal failure. ③ Chronic renal failure. ④ Renal failure before renal transplantation or post-transplantation rejection reaction rendering the transplanted kidney non-functional. ⑤ Other diseases (liver failure, schizophrenia, psoriasis, etc.).
Relative contraindications to hemodialysis include: ① extremely critical condition, hypotension, shock. ② severe infection sepsis. ③Severe myocardial insufficiency or coronary heart disease. ④ within 3 days after major surgery. ⑤ Those with serious bleeding tendency, cerebral hemorrhage and severe anemia. (6) Those who are uncooperative in mental illness. The patient with malignant tumors.
General patients need hemodialysis 3 times a week, 4-5 hours each time. Dialysis should be started as early as possible to correct irreversible organ damage and metabolic disorders due to excessive accumulation of toxins, and should be started when the creatinine clearance rate decreases to 10-12mL/min. 15-60 years old patients have good and safe results of dialysis, but due to the continuous improvement of dialysis technology and the emergence of new dialysis equipment, patients over 70 years old can also get good results.
In order to ensure the quality of life of dialysis patients and to improve the recovery rate, hemodialysis patients should ensure the daily intake of protein 1.0-1.2 g/kg and 146.3 kJ/kg, and should consume enough water-soluble vitamins and micronutrients to replenish the amount of dialysis loss. The 5-year survival rate of dialysis patients varies from country to country, ranging from 50% to 80%, and a 10-year survival rate of more than 50% has also been reported.
When is hemodialysis appropriate
When is hemodialysis appropriate for kidney patients? There is no absolute contraindication to hemodialysis, but not all patients are suitable for hemodialysis. For patients over 70 years old or children under 4 years old, hemodialysis is often difficult to maintain, and peritoneal dialysis is preferred. Malignant tumors, Alzheimer's disease, cerebrovascular disease and other patients who can not sustain life for a long time; chronic liver disease, shock or cardiovascular function to withstand extracorporeal circulation; serious bleeding risk; patients with mental anomalies and uncooperative and family members do not agree to the patient can not do hemodialysis.
More than half of the patients with chronic renal failure are developed from chronic nephritis. Therefore, it is very important to protect the residual renal function of patients with chronic nephritis. Maintaining blood pressure at normal level is one of the main measures to protect residual renal function. Hypertension can lead to glomerulosclerosis, and blood pressure should be kept below 18.7-12.0 kPa. Antihypertensive treatment should be made to adhere to the rational use of medication, do not because the blood pressure down on everything, automatically stop taking medication, blood pressure rises and then re-administer medication. The fluctuation of blood pressure is very unfavorable to kidney function. Chronic nephritis patients with high blood pressure, mostly through rest, restriction of sodium intake and should look at the essence of the phenomenon, can achieve the purpose of lowering blood pressure. Some other patients also need to add nifedipine and mercaptopropionic acid and other drugs. In addition, high-quality low-protein, low-fat diet, adherence to the kidney series, while treating the complications of chronic nephritis, such as anemia, cardiac damage, infections, and to correct the water, electrolyte disorders, etc., can improve and slow down the process of development of renal function damage.
Indications for hemodialysis:
(1)Indications for chronic maintenance hemodialysis: those who have clinical manifestations of chronic renal failure, with blood urea nitrogen exceeding 20 mmol/L and blood creatinine exceeding 400 mmol/L can be put on maintenance hemodialysis.
(2)Indications for emergency dialysis: ① drug-uncontrollable hyperkalemia (more than 6.5 mmol/liter); ② drug-untreatable oliguria, anuria, high degree of swelling; ③ chronic renal failure combined with acute cardiac failure, pulmonary edema, cerebral edema; ④ drug-uncontrollable hypertension; ⑤ drug-uncorrectable metabolic acidosis; ⑥ concomitant bracturetitis, gastrointestinal bleeding and central nervous system symptoms. Symptoms. Peritoneal dialysis utilizes the peritoneum as a semi-permeable membrane and injects peritoneal fluid into the peritoneal cavity through a peritoneal tube to remove toxins, correct electrolyte and acid-base balance disorders through the principle of dispersion, and to achieve ultrafiltration and dehydration through the principle of osmosis (by adding glucose to the peritoneal fluid to increase the osmolality of the peritoneal fluid) to replace the excretory function of the kidneys.
Precautions
Peritoneal dialysis has simpler equipment than hemodialysis, can be operated at the bedside, and can avoid sudden changes in fluid balance.
Peritoneal dialysis is divided into continuous ambulatory peritoneal dialysis (CAPD, where the patient can move freely with the equipment), continuous cyclic peritoneal dialysis (CCPD, with the same advantages as CAPD, where the patient relies on the peritoneal wall dialysis machine to perform dialysis at night, and can still work in the daytime), and intermittent peritoneal dialysis (for acute patients). Generally, 4 to 6 PD sessions should be performed per day, with 2,000 mL of PD fluid infused into each session. Peritoneal dialysis is not dependent on machines, is easy to operate, and does not require special training of personnel, so it is inexpensive and can be carried out in primary care units. Although the indications of peritoneal dialysis and hemodialysis are the same, they have their own advantages and disadvantages, and cannot replace each other. Therefore, appropriate choices should be made according to the patient's primary etiology, condition, and medical and economic conditions, so as to maximize the benefits for the patient. The following conditions should be given priority to peritoneal dialysis: ① elderly, poor cardiovascular system function. ② the establishment of hemodialysis vascular access difficulties. ③Those with serious bleeding tendency who can not do hemodialysis systemic heparinization. ③ Those who have serious bleeding tendency and can't do hemodialysis with systemic heparinization. ④ Those who have diabetic nephropathy and uremia, adding insulin into the peritoneal cavity can make the blood sugar control better. The following conditions are contraindications to peritoneal dialysis: ① within 3 days after major abdominal surgery. ② Peritoneal adhesions or intestinal obstruction. (iii) Infection of the abdominal wall that cannot be colonized into the peritoneal dialysis tube. ④Abdominal tumors, intestinal fistula, diaphragmatic hernia and so on.
Aseptic operation is not strict can cause peritonitis, repeated episodes of peritonitis can make the peritoneal wall of the dialysis area is reduced, dialysis efficacy is reduced. In addition, due to the peritoneum on the membrane pore is larger than the aperture on the membrane of the hemodialysis apparatus, so the loss of nutrients from the peritoneal dialysis fluid is more serious than in hemodialysis. Therefore, strict aseptic operation as well as adequate nutrition is the guarantee for the success of peritoneal dialysis. The survival rate of peritoneal dialysis in the 1st, 2nd, 3rd, 4th, and 5th years is 90%, 80%, 70%, 65%, and 46%, respectively, with a decrease of about 10% per year, and there are some cases in the world that have been reported to have survived for 20 years.
Disadvantages
1. Infection induced: Because the catheter used for peritoneal dialysis has to be connected to the dialysis bag during fluid exchange, there is a possibility of peritoneal infection, so it is necessary to wash hands thoroughly when doing any steps related to peritoneal dialysis treatment. With current technology, the incidence of peritonitis has been dramatically reduced.
2. Increase in weight and blood triglycerides: Since the dialysis solution uses glucose to remove excess water, some glucose may be absorbed during dialysis, which may cause the patient to gain weight and increase blood triglycerides and other lipids, so proper exercise and reduction of sugar intake are needed.
3. Excessive protein loss: A small amount of protein and vitamins are lost during dialysis and need to be replaced with food. In addition to maintaining a normal diet, you can take more fish, meat, eggs, milk and other high-quality protein, and the best source of vitamins are fruits and vegetables, to replenish the body.