About hemodialysis

Hemodialysis is an in vitro hemodialysis device, which can replace part of renal function, remove harmful substances from blood, correct electrolytes in the body and maintain acid-base balance.

1 dialysis principle

Hemodialysis is commonly known as "artificial kidney", that is, blood and dialysate are placed on both sides of artificial semi-permeable membrane, and their different concentrations and osmotic pressures are used to diffuse and permeate each other. Hemodialysis can discharge excess water and metabolic waste from patients, and absorb electrolyte and alkali lacking in the body from dialysate to correct the balance of water, electrolyte and acid-base.

2, dialysis process

At the beginning of dialysis, the patient's blood is introduced into arterial pipeline, defoamer and analyzer through vascular access. Blood and dialysate are exchanged in countercurrent with the help of the semi-permeable membrane in the dialyzer, and the exchanged dialysate enters the waste liquid tank and is discarded, while the "purified" blood is reinjected into the patient through the defoamer and venous pipeline to achieve the purpose of "cleaning".

Step 3 instruct

(1) acute renal failure (see chapter on acute renal failure).

(2) Chronic renal failure (see chapter on chronic renal failure).

(3) Acute drug or poison poisoning.

4. Contraindications

(1) Severe cardiac insufficiency.

(2) Severe arrhythmia.

(3) There is obvious bleeding tendency.

(4) Shock or hypotension with systolic blood pressure lower than 10.6 kpa(80 mmhg).

(5) Patients who have undergone major surgery recently.

5. Establish vascular access

Generally, arteriovenous fistula and arteriovenous fistula are established. The use time can be 3 to 5 days after operation, and can be used immediately in case of emergency. Use it 3 to 6 weeks after operation, otherwise it is easy to form hematoma and shorten the service life.

The operation is simple and complicated, and puncture is needed for each dialysis.

Infection rate is easy to occur, and infection rarely occurs.

The service life is about 10 month.

Dangerous connection tube falling off will lead to massive bleeding and death. Excessive anastomotic shunt will increase the burden on the heart and cause heart failure.

6, the use of heparin

In the process of hemodialysis, heparin is a commonly used anticoagulant in clinic, which can prevent blood from agglutinating in extracorporeal pipes such as dialyzer. Heparin can produce systemic anticoagulation in 5 minutes after intravenous injection and will be exhausted in 4 ~ 6 hours. There are three usages in hemodialysis:

(1) Systemic heparinization: inject heparin 0.5mg/kg for the first time 10 minute before dialysis, then add 8 ~ 10 ml every hour, and stop heparin 30 ~ 60 minutes before dialysis, so as to keep the coagulation time in the body at 45 ~ 60 minutes (coagulation time by test tube method). This method is most commonly used and is suitable for patients without obvious bleeding. If there is obvious bleeding tendency, slowly inject protamine 30 ~ 50 ml to neutralize heparin.

(2) Heparinization in vitro: heparin is continuously injected from the arterial end of the dialyzer at the beginning of dialysis to maintain the coagulation time in the dialyzer at 40-60 minutes; At the same time, protamine was injected into the venous end of the dialyzer to neutralize heparin, so that the coagulation time in vivo was maintained within 65438 0.5 minutes. This can prevent coagulation in the dialyzer and prevent heparin from entering the human body too much to cause coagulation disorder. In fact, this method is only suitable for patients with obvious bleeding tendency or uremic pericarditis after recent surgery and trauma, and it is rarely used in clinic.

(3) Low-dose heparinization: Its indication is the same as heparinization in vitro. At the beginning of dialysis, low-dose heparin 5 ~ 10 mg was injected for the first time, and then 5 ~ 10 mg was injected every hour to keep the coagulation time in the body between 20 and 30 minutes.

7, monitoring in the process of dialysis

(1) Nursing before dialysis: Dialysis treatment is a non-physiological state, and patients will have psychological imbalance at this stage. First, they think their condition is getting worse. Second, they are afraid of hemodialysis itself and lose confidence in the prognosis. Therefore, psychological nursing is particularly important at this stage. Patients should be encouraged to overcome this psychological anxiety and pain, and fully explain the principle and effect of hemodialysis treatment to patients and their families. If necessary, please receive dialysis treatment for a long time and achieve good results. Although dialysis can maintain the life of patients, patients who insist on long-term dialysis treatment will gradually realize their physical condition, which will lead to some crises for other reasons. Nurses should bear the anxiety, anger or fear of patients and be the supporters of patients and their families.

Nurses must be familiar with the characteristics of each patient and make different nursing plans. The patient's diet, dialysis plan and medication form a related whole. If the diet changes, the dialysis plan should be changed accordingly. Weight, pulse, blood pressure, body temperature and respiration should be measured before each dialysis. Blood samples were taken to check K+, Na+, Cl-, blood urea nitrogen, blood creatinine, CO2CP, prothrombin activity and hemoglobin. To understand the state of heart, lung, liver and kidney function, anemia, infection and bleeding. If the patient's hemoglobin is 50g/L, blood transfusion is needed. If the blood pressure is low, dextran or blood transfusion can be injected intravenously, and hemodialysis can be carried out after correcting hypotension; Before dialysis, check whether all parts of the dialyzer are transported normally.

② Monitoring during dialysis:

① Patients should record their body temperature, respiration, pulse and blood pressure every 30 ~ 60 minutes, and critically ill patients should record it every 15 ~ 30 minutes, so as to find possible complications during dialysis and deal with them in time. At the same time, adjust the dialysis plan in time according to the recorded results. Serious complications may occur during dialysis, such as bleeding, palpitation, heart failure, respiratory arrest and myocardial infarction. Nurses should closely observe and make all preparations for cardiopulmonary resuscitation.

② During dialysis, we should closely observe the blood flow, venous pressure, blood stratification and the color of blood and dialysate. If stratification and coagulation occur, it means that the dose of heparin is insufficient, and the dose of heparin can generally be increased. The color of dialysate turns red, which means the membrane is broken. Stop dialysis immediately and replace the equipment.

(3) Monitoring after dialysis: Body temperature, respiration, pulse, blood pressure and weight must be measured after dialysis. Blood samples were taken to check creatinine, urea nitrogen, K+, Na+, Cl- and CO2CP. If necessary, check Ca2+ and P3- to determine the dialysis effect, whether there is electrolyte disorder, and make corresponding adjustments to prepare for the next dialysis plan. It is extremely important to accurately record the amount of fluid in and out between dialysis, so that patients can have proper fluid intake without excessively increasing the fluid load and leading to congestive heart failure. After starting dialysis treatment, patients often have a wrong understanding that hemodialysis can completely meet the needs of patients to remove metabolites, so their diet and drinking water are not limited. Therefore, when patients enter regular dialysis, their renal function, the number and interval of dialysis and the composition of dialysate should be considered to formulate a prescription suitable for patients. Provide a diet low in salt, potassium, vitamins, protein and calories. It is stipulated that hemodialysis patients should be given protein about 1g per kg body weight every day, of which 50% should be high-quality protein, and 35 kcal/ kg body weight can meet the needs of body activity and treatment. The intake of vegetables and fruits should be limited to avoid excessive potassium intake, but vitamin B 1 and B6 folic acid should be supplemented.

Although patients often have dialysis, it is still necessary to limit the amount of fluid. Generally speaking, the daily fluid intake of anuria patients is about 1000 ml. Weight change is a fairly accurate index to infer whether patients can follow the prescribed diet. Patients should not gain more than 0.5 kg every 24 hours. Excessive weight gain indicates excessive drinking water or excessive fluid retention in the body.

Due to the accumulation of toxic products and wastes, patients may have neuropsychiatric symptoms. Nurses should pay attention to observing the patient's conscious state and other neurological signs, and at the same time do a good job in the protection of encephalopathy, such as adding bed stalls and restraint belts. And do a good job in life care and psychological care of patients.

Hemodialysis patients use a lot of drugs, and most of them are excreted through the liver or kidney, so nephrotoxic drugs should be avoided.

In dialysis, aseptic operation technology should also be strictly implemented to prevent infection. Disinfect machines, instruments and dialyzers before and after dialysis; Keep the internal and external fistula local clean and dry; Non-dialysis personnel should wear masks and hats when picking up patients.

8. Nursing care of arteriovenous fistula

First of all, we should explain the location, importance, possible complications and how to protect the fistula to patients, and inform medical staff to deal with the problem in time. Keep the local area clean, be careful when doing various activities, don't wear too tight clothes, don't twist, press or separate the external fistula, and pay attention to whether there is bleeding or bleeding at the fistula. Nurses should also regularly check the tightness of the silicone tube and the connecting parts, and fix the uncooperative patients with splints to prevent the connecting tube from falling off and causing massive bleeding. Change dressing in time when there is oozing blood. If the test tube falls off, you can clamp the sliding end with sterile hemostatic forceps or put a tourniquet on it and apply pressure to wrap it. Please ask for surgical treatment in time.

Secondly, be careful not to transfuse blood or measure blood pressure on the limb where the fistula is located to prevent blockage. In the usual nursing process, we should always auscultate vascular murmur and observe the color of silicone tube. If the color is different, the serum separates, the fluctuation disappears, and the temperature is low, which indicates that the external fistula is blocked. Immediately flush the catheter with heparin and normal saline or slowly inject urokinase 10000u into the fistula in1000 ml normal saline, and suck it repeatedly, with each injection amount not exceeding 3ml. We should be very careful when dealing with venous end obstruction to prevent emboli from entering the body from venous end and causing embolism.

Third, keep the stoma local clean. If there is purulent secretion or local redness and swelling, it should be treated in time, local disinfection and dressing change should be carried out regularly, the spread of infection should be actively controlled to prevent sepsis, and blood culture should be done at the same time.

Every dialysis needs to puncture the fourth internal fistula, and the distance between the two puncture points should be about10 mm. Every puncture should avoid obvious scars, and you can choose a place close to the last puncture point. Press the puncture point for more than 20 minutes after needle drawing to avoid bleeding.

9. Nursing care of complications

(1) Dialysis reaction: During dialysis, the patient's heat source reaction usually starts 50 ~ 75 minutes after dialysis, and the patient feels cold discomfort, elevated body temperature, dizziness, headache, nausea and vomiting; Some patients get nervous before fluoroscopy. Therefore, in addition to symptomatic treatment, psychological care should also be paid attention to; At the beginning of dialysis, the dialysis time should be short and gradual, about 2 hours for the first time, and then gradually extended. After 1 ~ 2 weeks of induction, you can enter regular dialysis.

(2) Dialysis imbalance syndrome: It can occur before the end of dialysis or after dialysis. The main symptoms are headache, restlessness, nausea, vomiting and high blood pressure. In severe cases, blurred vision, convulsions, even convulsions and coma may lead to death. The cause of this disease is not completely clear. At first, it was thought that the metabolites in blood of hemodialysis patients decreased rapidly, while creatinine and urea nitrogen passed through the blood-brain barrier slowly, resulting in different osmotic pressure, brain edema, increased intracranial pressure and poor hydrogen ion concentration in blood and cerebrospinal fluid, which led to a series of central nervous system symptoms. Nursing measures are firstly to comfort patients, make them calm and stay in bed; Secondly, venous access was established, and glucose, dextran and fresh blood were dripped intravenously. In addition, symptomatic treatment is given, such as reducing intracranial pressure.

(3) Cardiovascular complications: The main cardiovascular complications of hemodialysis patients include arrhythmia, pericarditis, pericardial tamponade, heart failure, hypertension and cerebral hemorrhage. Patients may also have dialysis-related hypotension, which can be supplemented with normal saline, albumin and plasma. For other corresponding treatment methods, please refer to relevant chapters.