Overview
Blood purification technic
Main technology
Hemodialysis hemofiltration hemodialysis filter vascular filtration Peritoneal dialysis with perfusion replacement therapy
Hemodialysis
The hemodialysis system introduces the patient’s blood into the dialyzer, using the difference in solute concentration on both sides of the semi-permeable membrane. Filtration can eliminate metabolites and toxic substances, and correct the disorder of water and electrolyte balance.
Methods
1. Preparation of arteriovenous channels and their types Before dialysis, arterial and venous channels should be established first, and blood from the arterial end should be introduced into the dialyzer. After dialysis Function to purify the blood. The purified blood is then returned to the body through the venous end.
①The arteriovenous preserved intubation method. Generally, dorsal foot artery and medial malleolus saphenous vein cannulation are used; Seldinger dilatable catheters can also be used to puncture femoral arteries and veins. It is suitable for emergency dialysis patients with acute drug poisoning or acute renal failure.
②External arterial and venous fistula. The radial artery and its accompanying cephalic vein can be selected, and two silicone rubber tubes are inserted into the centripetal ends of the artery and vein respectively, and the skin is connected to form an external shunt. It is suitable for patients with acute and chronic renal failure who need long-term dialysis.
③External arterial and venous fistula. The radial artery and its accompanying veins can be used for side-to-side or end-to-side anastomosis; titanium wheel screws (with a diameter of 2.0 to 2.5 mm) can also be used for anastomosis. Two weeks after the anastomosis, puncture can be made at the venous arterialization for hemodialysis. Suitable for long-term dialysis patients.
④Subclavian vein catheterization method. The double-lumen catheter is inserted into the subclavian vein, the blood is sucked out through the side hole of the outer tube, after flowing through the dialyzer, and then returned to the body through the inner tube.
2. Type of dialyzer
①Standard flat dialyzer. The dialysis area is 1.0m2. Due to its large volume, it is easy to leak blood and air. Mostly use fixed (multilayer) small flat plate, with an area of 1.1～1.8m2, small size, and it has been commercialized.
②Hollow fiber dialyzer. Small size, high efficiency of ultrafiltration dehydration and dialysis, is the most commonly used one.
3. Application of heparin: Anticoagulation is required during dialysis. The method of anticoagulation depends on whether the patient has a bleeding tendency. Optional:
①The whole body heparinization method is a conventional method. 5 minutes before dialysis, give heparin 0.5 to 0.8 mg/kg intravenously; add 10 mg of heparin every hour after the start of dialysis; stop heparin 1 hour before the end of dialysis.
②Local (in vitro) heparinization method. A heparin pump was used to continuously inject heparin into the arterial tube at a rate of 0.25 mg/min, while protamine was injected into the intravenous tube at a rate of 0.25 mg/min to neutralize the heparin. 3 hours after the end of dialysis, protamine 30-50mg is injected intravenously to prevent heparin from rebounding.
③Marginal heparinization method. The first dose of heparin is 0.5 to 0.7 mg/kg, and thereafter 5 to 7 mg of heparin is replenished every hour to keep the blood clotting time in the dialyzer at about 30 minutes, and heparin is stopped 10 minutes before the end of dialysis.
4. Dialysis fluid composition: According to the condition of the disease, No. Ⅰ or Ⅱ dialysate can be selected.
Formula of No.1 dialysate: per liter containing 6.6g sodium chloride, 0.3g potassium chloride, 0.185g calcium chloride, 0.1g magnesium chloride, 2.5g sodium bicarbonate, 2.2g glucose, osmotic pressure 314mosm/L.
No. Ⅱ dialysis formula: each liter contains 6.0g sodium chloride, 0.3g potassium chloride, 0.185g calcium chloride, 0.1g magnesium chloride, 4.48g sodium acetate, 2.2g glucose, and osmotic pressure 300mosm/ L.
5. Monitoring during dialysis During each dialysis process, the patient's blood pressure, heart rate, respiration and body temperature should be recorded. Monitor the dialysate flow, temperature, negative pressure, blood flow in the catheter, pay attention to whether there is blood leakage, hemolysis, and coagulation, and prevent the dialysis catheter from coming out and causing hemorrhage.
Illness treatment
1. Dialysis imbalance syndrome is a common complication. It is more common in the initial dialysis, rapid dialysis or shortly after the end of dialysis. Manifestations of anxiety, irritability, headache, nausea, vomiting, and sometimes increased blood pressure; moderate patients still have myoclonus, tremor, disorientation, and lethargy; severe patients may have epileptic seizures, coma, and even death.
Precautions: The first dialysis time should not exceed 4 hours, the sodium concentration in the dialysate should not be too low, and the ultrafiltration dehydration should not be too fast. When symptoms occur, give 50% glucose solution 50-100ml intravenously for mild cases and 25mg promethazine intramuscularly; for severe cases, give mannitol or albumin to reduce the negative pressure and flow in the dialyzer.
2. Fever. Early fever during dialysis is mostly caused by poor flushing of the dialysis system, the presence of pyrogens or the rapid entry of prefilled blood into the body to produce a blood transfusion reaction; if the body temperature continues to rise after dialysis, it often indicates infection, and the cause of fever should be searched for and dealt with accordingly.
3. Cardiovascular complications. Such as hypotension, hypertension, progressive enlargement of the heart, heart failure, pericarditis, arrhythmia, etc.
4. Anemia. Uremia has anemia that is not easy to correct, and the need for repeated blood tests during dialysis and the loss of residual blood in the dialyzer can aggravate anemia. Therefore, blood loss due to various reasons should be reduced, iron, folic acid, or appropriate blood transfusion should be reduced.
5. Dialysis bone disease.
6. Infection. To prevent arteriovenous fistulas, lung and urinary tract infections.
Indications
1. Dialysis indications for acute renal failure are acute pulmonary edema and hyperkalemia. Serum potassium is above 6.5mmol/L; anuria or oliguria for more than 4 days; carbon dioxide binding capacity is below 15mmol/L. Blood urea nitrogen>28.56mmol/L (80mg/dl), or daily increase>10.7mmol/L (30mg/dl); anuria or oliguria for more than 2 days, accompanied by one of the following conditions: continuous Vomiting, excessive body fluids, galloping rhythm or continuous central venous pressure higher than normal; irritability or lethargy; blood creatinine> 707.2μmol/L (8mg/dl) and electrocardiogram showing high potassium pattern.
2. The general dialysis indication for chronic renal failure is those with blood urea nitrogen reaching 36mmol/L (100mg/dl) with obvious uremia; blood creatinine 707.2μmol/L (8mg/dl) or higher: endogenous creatinine clearance rate <10ml /Min; patients with congestive heart failure or uremic pericarditis; obvious neurological symptoms; uremic patients who require major surgery, hemodialysis can be used to improve their overall condition.
3. Acute poisoning drugs or poisons that can pass through the dialysis membrane, such as barbiturates, melanoplasts, hymenin, paraaldehyde, chloral hydrazine, chloral hydrate, isoniazid, arsenic, mercury, copper, chloride, bromide , Ammonia, endotoxin, boric acid, muscarinic acid, carbon tetrachloride, trichloroethylene and streptomycin, kanamycin, neomycin, vancomycin, polymyxin, etc. The above-mentioned acute poisoning can be treated with dialysis.
Contraindications
There are no absolute contraindications, but dialysis should be avoided in the following situations to avoid accidents.
Shock or low blood pressure, difficult to control bleeding, significant heart enlargement accompanied by severe myocardial damage, severe arrhythmia. Uncontrolled severe diabetes, cerebral hemorrhage, and persons older than 70 years old.
Hemofiltration
HF is a simulation device designed according to glomerular filtration function. HF equipment consists of three parts: hemofilter, blood pump, and negative pressure suction device.
Method
1. Establish arteriovenous and vascular channels and heparinization method: same as hemodialysis.
2. Hemofiltration device: commonly used polyacrylonitrile membrane multilayer small flat filter (such as RP6 filter), polysulfone membrane hollow fiber filter (such as Diafilter TM30 Amicon), polymethyl methacrylate membrane filter Filter (such as Filtryzer B1, Gambro MF202), etc.
3. Connect the patient's arterial and venous ends to the arteriovenous pipelines of the hemofilter, rely on the blood pump and the filter venous pipeline clip to generate 13.33～26.66kpa (100～200mmHg) positive pressure on the blood side of the filter, and adjust the negative pressure device , Make the negative pressure reach 26.66kpa, you can get 60-100ml/min of filtrate, and at the same time replenish the replacement fluid. If it is required to remove 1000ml of fluid from the body each time, the total amount of filtrate minus 1000ml is the input volume of replacement fluid.
4. The composition and input method of the replacement solution: Na+140mmol/L, k+2.0mmol/L, Ca++1.85mmol/L, Mg++0.75～1.0mmol/L, Cl－105～110mmol/L, lactate 33.75mmol/L dubbed. It can be input through the arterial pipeline of the filter (pre-dilution type) or through the venous line (post-dilution type).
5. According to the patient's condition, HF is 2 to 3 times/week, 4 to 5 hours/time.
Clinical significance
1. HF is slightly inferior to HD in the removal of small molecular substances such as urea nitrogen and creatinine, but it is better than HD in the removal of middle molecular substances, correction of water, electrolyte and acidosis, and treatment of renal failure, pulmonary edema, pericarditis, and cerebral edema.
2. Can significantly improve anemia and triglyceridemia, easy to control high blood pressure.
3. The combination of HD and HF is called hemofiltration dialysis, which can improve the efficiency of blood purification and shorten the time of dialysis.
4. The input of a large amount of replacement fluid is easy to contaminate and cause fever and sepsis, so attention should be paid to it.
Vascular filtration
Continuous Arteriovenous Hemofiltration (CAVH), CAVH uses the normal pressure gradient difference between the arteriovenous pressure to continuously pass blood Small filter to achieve hemofiltration. Its characteristics are: low filtration rate, no need to use hemofiltration machine and replenish a large amount of replacement fluid. Especially suitable for on-site rescue of acute renal failure.
Method
1. Establish arterial and venous passages and heparinization method: same as hemodialysis.
2. Filter: Commonly used are polysulfone membrane hemofilter, polyamine membrane hemofilter and so on.
3. Connect the patient's arterial and venous ends to the arterial and venous pipelines of the hemofilter, place the container for collecting the ultrafiltrate at the lowest part of the bed, and make the negative pressure 392.15Pa (40cmH2O) to obtain the filtrate 300～500ml/hour.
Hemoperfusion
HP is a hemoperfusion device that introduces the patient’s arterial blood into a hemoperfusion device that stores adsorbent materials, and makes the poisons and metabolites adsorbed and purified by contact with the blood, and then return Lost in the body.
Method
1. Establish arterial and venous passages and heparinization method: same as hemodialysis.
2. The hemoperfusion device is composed of a perfusion tank, an adsorbent, and a microcapsule membrane. The main types used in clinical practice are albumin collodion coated activated carbon, acrylic hydrogel coated activated carbon, and acetate fiber coated activated carbon. Activated carbon is usually coconut shell charcoal of 8 to 14 mesh.
3. Connect the patient's arteries and veins to the arterial and venous pipelines of the hemoperfusion device, and use a blood pump to maintain a blood flow rate of about 200ml/min. Once a day or every other day, every 2 to 3 hours, until the clinical symptoms improve.
Clinical significance
HP can effectively remove blood creatinine, uric acid, mid-molecular substances, phenols, guanidines, indole, organic acids and many It is a kind of medicine, but it cannot remove urea, phosphate, water and electrolytes. Therefore, when treating uremia, it should be combined with HD or HF.
Replacement therapy
Plasma Exchange therapy (Plasma Exchange therapy, PE)
PE introduces the patient’s blood into the plasma exchange device, The separated plasma is discarded, and a certain amount of plasma is replaced to eliminate antibodies in the patient's plasma and activate the immune response mediator and immune complexes.
Method
1. Establish vascular channel and heparinization method, same as hemodialysis.
2. Plasma separation device: Hollow fiber separators made of cellulose acetate membrane, polymethyl methacrylate membrane or polysulfone membrane are mostly used. The membrane area is 0.4-0.6m2, the pore size is 0.2-0.6μm, and the maximum cut-off molecular weight is 300 Daltons.
3. Connect the patient's arteries and veins to the blood plasma separator arterial and venous pipelines, adjust the speed and negative pressure of the blood pump, maintain the blood flow rate of 200ml/min, control the amount of ultrafiltered plasma 30-60ml/min, and the installation time is 90-120 minutes , 2 times/week, the total amount of ultrafiltration plasma is about 4 liters each time. Infuse 3.8 liters of 4% human albumin Ringer's solution from the venous end of the plasma filter (that is, 400 to 800 ml of 20% albumin, and the rest is compound sodium chloride solution).
Indications
①Immune complex glomerulonephritis and anti-glomerular basement membrane glomerulitis, such as pulmonary hemorrhage-nephritis syndrome Etc. Rheumatic diseases and systemic lupus erythematosus. Nodular periarteritis and rheumatoid arthritis.
③Autoimmune hemolytic anemia, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, etc.
④Myasthenia gravis, Guillain-Barre syndrome.
⑤Hepatic coma.
⑥Mushroom poisoning.
⑦Severe psoriasis.
⑧Acute rejection after kidney transplantation.
⑨Hyperlipidemia.
Peritoneal dialysis
Peritoneal dialysis uses the peritoneum as a semi-permeable membrane. According to the principle of Donan’s membrane balance, the prepared dialysate is infused into the patient’s peritoneal cavity through a catheter. In this way, There is a difference in the concentration gradient of the solute on both sides of the peritoneum. The solute on the high-concentration side moves to the low-concentration side (diffusion); the water moves from the hypotonic side to the hypertonic side (osmosis). The peritoneal dialysate is continuously replaced to achieve the purpose of removing metabolites and toxic substances in the body and correcting the disorder of water and electrolyte balance.
Methods
1. Selection of peritoneal dialysis method
①Emergency peritoneal dialysis. Continuous dialysis for a whole day in a short period of time. It is mostly used as a rescue measure for acute renal failure and acute drug poisoning.
②Intermittent peritoneal dialysis. Dialysis is performed for 5 to 7 days a week, with 6000 to 10000 ml of dialysate per day, 4 to 8 times into the abdominal cavity, indwelling for 1 to 2 hours each time, and 10 to 12 hours of dialysis per day. For chronic renal failure with obvious fluid retention.
③ Ambulatory continuous peritoneal dialysis (CAPD). Dialysis for 5-7 days a week, dialysis 4 to 5 times a day, 1500-2000ml of dialysate each time, infused into the abdominal cavity, replacement every 3 to 4 hours, once at night can be left in the abdominal cavity for 10 to 12 hours. After instilling dialysate into the abdominal cavity, clamp the infusion tube, fold the original dialysate bag and put it in the waist pocket, take it out when discharging the fluid, place it in a low place, and let the dialysate flow out of the abdominal cavity through the peritoneal dialysis tube , And then replace the peritoneal dialysate bag with a new one. The patient does not need to stay in bed during dialysis, and the patient can move freely.
④Continuous circulatory peritoneal dialysis (CCPD). It is an automatic circulation peritoneal dialysis machine controlled by a computer program. When the patient sleeps at night, the end of the peritoneal dialysis tube left in the abdominal cavity is connected to the automatic circulating peritoneal dialysis machine, and 6-8 liters of dialysate is used for continuous dialysis for 9-10 hours. During the day (10-14 hours), the dialysate is not changed, and the patient can move freely during the day.
2. Peritoneal dialysis tubing "There are three types of silicone rubber peritoneal dialysis tubing commonly used: single-cuff, double-cuff and no-cuff.
3. Tube placement method Use a trocar to puncture 1/3 of the umbilical and phalangeal joint line, and then send the dialysis tube into the abdominal rectum and bladder fossa through the trocar, or surgically cut the peritoneum in layers, and insert the peritoneal dialysis tube into the rectum and bladder In the nest, dialysis can be performed. For chronic renal failure requiring long-term peritoneal dialysis, a tunnel can be made under the abdominal wall, and a peritoneal dialysis tube with a wool sleeve can be used to pass through the tunnel and out of the skin to aid in fixation.
4. The formula of dialysate dialysate can be temporarily self-prepared or use commercial dialysate.
Temporary dialysate formula: 5% glucose solution 500ml, normal saline 1000ml, 5% sodium bicarbonate 100ml, 5% calcium chloride 12ml, osmotic pressure 359.4mmol/L.
Shanghai Changzheng Pharmaceutical Factory Dialysis Formula: Sodium Chloride 5.5g, Calcium Chloride 0.3g, Magnesium Chloride 0.15g, Sodium Acetate 5.0g, Sodium Metabisulfite 0.15g, Glucose 20g, add water to 1000ml, osmotic pressure 374.3mmol/L.
5. Precautions for dialysis should be strictly aseptic, pay attention to whether there is wound leakage: record the input and outflow of dialysate (if outflow
treatment of symptoms
1. Peritonitis is the most important complication. Bacterial peritonitis is more common. Infected bacteria can come from wounds, operation and dialysate contamination. If there is abdominal pain, fever, dialysate color becomes cloudy and white blood cell count increases to 100/mm3 The diagnosis can be confirmed when the bacteria in the dialysate is positive (note that anaerobic infection). Peritonitis can cause severe protein loss, adhesion and thickening of the peritoneum, leading to failure of peritoneal dialysis, blockage of the catheter, and even life-threatening. It should be used when peritonitis occurs. Appropriate antibiotics, such as gram-positive cocci, can use methicillin (100mg/L in dialysate) or cephalosporin (50mg/L in dialysate; gentamicin (dialysate) Internal concentration 8mg/L) or tobramycin (dialysis solution internal concentration is 8mg/L) and increase the frequency of dialysis. Generally, it can be controlled within a few days to 1 week. If the treatment is ineffective, the condition will become more serious or those with abdominal cavity mold infection , You should consider removing the dialysis tube and switch to other dialysis therapies. In addition, improper dialysate formulation or high glucose concentration can also cause abdominal pain. The number of white blood cells in the dialysate increases, the protein increases, and the color becomes turbid, which resembles peritonitis (chemical peritonitis). ) But the bacterial test of the dialysis fluid is negative, which can be used for identification.
2. Abdominal pain, hypertonic dialysis fluid, dialysis fluid temperature is too low or too high, the amount of fluid injected into the abdominal cavity is too much or too much air enters, Improper dialysate PH, abdominal cavity infection, catheter displacement stimulation, etc. can cause abdominal pain. The cause should be removed in the treatment, and 1% to 2% procaine 3 to 10ml can be added to the dialysate. If it is invalid, reduce the dialysis Number of times.
3. Causes of poor drainage of the dialysis tube include displacement or twisting of the catheter, obstruction by fibrin, blood clots or omental fat, excessive gas in the intestinal cavity or abdominal cavity, intestinal adhesions after dialysis, dialysis Some of the small holes at the end of the tube are exposed on the surface of the liquid in the abdominal cavity, causing the siphon effect to disappear. Change the position or take a semi-recumbent position, massage the abdomen, or inject saline, heparin or urokinase solution into the dialysis tube, and leave it for 30～ 60 minutes; if the abdominal distension is obvious, give a small dose of neostigmine; inject 500ml of dialysate into the abdominal cavity, and then take the semi-recumbent position to restore the siphon effect. If it is invalid, it can be sent into the rigid dialysis tube core under strict disinfection , Unblock the dialysis tube; if unable to reopen, re-implant the dialysis tube.
4. Excessive water or pulmonary edema: the patient has obvious azotemia in the early stage of dialysis, such as continuous use of high concentration The glucose dialysate is dehydrated. At this time, the plasma osmotic pressure is often higher than that of the dialysate. Once changed to conventional dialysate, water retention and even pulmonary edema may occur.
Indications
Same as hemodialysis.
Contraindications
Not suitable for dialysis:
① Extensive peritoneal adhesions, abdominal visceral trauma, short-term major abdominal surgery, colostomy or stool Fistulas, widespread abdominal wall infections or cellulitis, diffuse malignant tumors or unknown lesions in the abdominal cavity.
②Diaphragmatic hernia, severe lung disease and dyspnea.
③Pregnancy.