I. Knowledge about hemodialysis
1.Catharsis after heparin anticoagulation
Due to the rebound effect of heparin, there is still coagulation disorder after the end of dialysis. Patients should be told to avoid collision, abrasion, fall and other trauma. In case of inadvertent trauma, local pressure can be applied to stop bleeding; in case of subcutaneous hematoma, ice bags can be applied externally; in case of heavy bleeding, after the above treatment, patients should go to hospital immediately. Traumatic examination and treatment after hemodialysis should be carried out after 4-6 hours, such as after intramuscular (subcutaneous) injection which is likely to cause hip hematoma or petechiae, local pressure should be applied for 20-30 minutes after injection; patients performing tooth extraction usually need to be carried out after 1 day of dialysis. Tell the patient to avoid eating too hot and hard food, keep the stool unobstructed, and do not force to relieve the stool to prevent causing gastrointestinal bleeding. Observe for bleeding at the puncture site. If the bleeding at the puncture site of the internal fistula does not stop, local pressure can be applied to stop the bleeding.
Low molecular heparin: good effect and less side effects, but expensive.
Heparin-free dialysis: choose to use when there is active bleeding or bleeding tendency, routinely use dilute pre-fill and then flush with saline quickly at regular intervals.
2.Safety protection of intravenous indwelling double-lumen catheter during hemodialysis
When a patient undergoes hemodialysis for the first time, or when there is no internal fistula for multiple reasons, the physician will puncture a venous indwelling tube in the neck or the root of the thigh to facilitate hemodialysis treatment, depending on the patient’s condition. It is important that this tube is secured. Before and after each hemodialysis session, the staff will carefully clean and disinfect the punctured local skin, bandage and properly fix the tube as required, but during non-dialysis sessions, the patient needs to protect himself/herself and is advised to take the following precautions.
(1): Develop good hygiene habits, keep the area dry and clean, and avoid showering as much as possible to avoid infection after getting wet. Pay special attention when putting on and taking off clothes to avoid pulling out the catheter. Do not unwrap the wrapped gauze by yourself to avoid causing local infection of the puncture. If local redness, swelling, heat, pain or discomfort such as fever and chills appear once, you may have developed infection and should go to the hospital promptly.
(2): Except for the femoral vein indwelling catheter, which should not be moved too much, all other activities are not restricted, but also should not be strenuous to prevent the indwelling catheter from slipping out, once slipping out, pressure should be applied to stop the bleeding, please use clean gauze or towel to press the puncture opening to stop the bleeding immediately and go to the hospital immediately.
(3): Patients who choose femoral vein puncture should minimize walking, prolonged sitting, frequent squatting toilets and avoid prolonged knee flexion of the punctured side limb when lying down to avoid bending or blockage of the indwelling catheter.
(4): Patients should be careful not to inadvertently remove the indwelling tube during sleep because of local itching at the puncture site, resulting in bleeding and blood loss events.
(5): The indwelling catheter in the jugular (or femoral) vein of hemodialysis patients should not be used for other purposes, such as blood sampling and infusion, etc. If it must be used (e.g., the patient needs a lot of rehydration or there is no other infusion access, etc.), the catheter must be sealed after use according to the requirements for handling the catheter after hemodialysis to prevent blockage.
(6): Avoid distortion of the line under pressure, otherwise it will easily cause thrombosis leading to blockage of the catheter and make sure that the switch clip of the indwelling catheter is closed and the heparin cap at the end of the tube is tightened to avoid the occurrence of bleeding.
(7): Temporary central venous catheter is easy to break the suture because of the long retention time or the rejection of the foreign body (suture) by human skin, which makes the suture detach from the skin and causes the catheter to slip out, and the catheter to come out can cause bleeding, especially the femoral vein indwelling catheter. In case of suture breakage, you should go to the hospital promptly.
(8): A certain concentration of heparin in the lumen of the indwelling catheter is to prevent blockage of the lumen. If your dialysis interval is more than four days, you are recommended to come to our center for medication change and reseal the catheter with heparin halfway.
3.What is dry weight?
The weight at which the patient feels most comfortable without excess water retention after dialysis, without hypotension, convulsions and other symptoms.
4.What are the symptoms of too little water removal?
If the dry weight of dialysis patients is not accurately evaluated or fails to reach the dry weight for a long time, it will cause the patient to have continuous excess water volume, which will clinically show the manifestations of left heart failure such as hypertension, chest tightness and breath-holding at night; it will easily cause lung infection; gastrointestinal edema will cause the patient to have reduced appetite or even nausea and vomiting; some patients will have edema; in severe cases, acute left heart failure will occur, and the patient will hold his breath, sit down to breathe, and The patient cannot lie down, the chest X-ray indicates pulmonary edema, the heart shadow is significantly enlarged, the cardiothoracic ratio exceeds 50%, and even pleural effusion occurs, often requiring emergency dialysis. In this case, water is often stored and the dry weight needs to be reduced. As for how much it is appropriate to reduce, it is necessary for the doctor to regularly assess the patient’s dry weight to determine.
5.What are the symptoms of excessive water removal?
Long-term hemodialysis patients tend to have two tendencies: one is always worried that they will store water in their body and lower their dry weight too low; the other is worried that they will be uncomfortable and always reluctant to remove more water. In fact, there is no need to go to extremes. It is appropriate for the dry weight to be appropriate and for the patient to feel more comfortable after dialysis. Generally, it is normal to feel a little weak on the day after dialysis. If you often feel weak, muscle twitching, thirst, dry skin, sunken eyes, dizziness, tinnitus, low blood pressure and other symptoms after dialysis, it is abnormal, and some patients will have fear of dialysis because of this. competent doctor, and adjust the dry weight appropriately.
6.Why is heparin anticoagulation used during hemodialysis?
Hemodialysis is actually an extracorporeal treatment and anticoagulants must be applied to prevent blood clotting during extracorporeal circulation, which is necessary to ensure the smooth performance of hemodialysis. At present, the anticoagulant commonly used in hemodialysis is heparin. How to use heparin and how much is appropriate? This is a frequent concern of patients. In general, systemic heparinization is used in dialysis, that is, an initial amount is given, and then a maintenance amount is given every hour. If the amount of heparin is not enough, extracorporeal coagulation will occur and a small amount of blood will be lost in each dialysis, which is one of the reasons for anemia in dialysis patients; if too much heparin is used, there is a risk of bleeding, and patients often complain of bleeding after several hours of pressure at the puncture eye, especially patients who have a tendency to bleed are more likely to aggravate the bleeding. This requires the nurse to strictly observe the dialysis equipment and pipeline for clotting and the degree of clotting, and to promptly communicate with the doctor to adjust the heparin dosage. Generally speaking, heparin is the most commonly used and safe anticoagulant for most dialysis patients. However, heparin has some adverse effects, including allergy, pruritus, osteoporosis, hyperlipidemia, thrombocytopenia, and excessive bleeding. Sensitivity to heparin varies from patient to patient, and sensitivity to heparin can vary over time in the same patient. For patients who have more adverse reactions with heparin, other anticoagulation methods can be considered.
7.Acute complications in hemodialysis
(1), First Use Syndrome (FUS)
Type A: Respiratory distress, fistula or generalized fever sensation occurs within minutes, and may be followed by sudden cardiac arrest or even death. In mild cases, there is only itching, measles, cough and lacrimation.
Type B: chest pain and back pain occur within a few minutes to an hour.
(2), Hypotension: early yawning, bowel movement, back pain, etc.
(3).Hypertension: It occurs mostly in the middle and late stages and has a tendency to gradually increase.
(4), imbalance syndrome (DS): divided into pulmonary type and cerebral type.
(5), nausea, vomiting early symptoms of hypotension, imbalance, pyogenic reaction, hypertension, etc.
(6), headache , hypertension, neurogenic headache, acetonate dialysis, etc.
(7), fever Causes include infection, pyogenic reaction, transfusion reaction, hyperthermia dialysis, unknown causes, etc.
(8), bleeding Heparinization in the body is the direct cause.
(9), Hemolysis, mechanical injury, heterogeneous blood, dialysis fluid abnormalities, disinfectant residues, high temperature dialysis.
(10), Spasm Appears in the middle and late stages, is common in the lower extremities and abdomen, and lasts about 10 minutes.
(11).Cardiac arrhythmia.
Second, the principle of hemodialysis
Hemodialysis is one of the safer, easy to perform and widely used methods of blood purification. Dialysis is the movement of solutes through a semi-permeable membrane from a highly concentrated solution to a low concentration. Hemodialysis includes the movement of solutes and the movement of water, i.e. blood and dialysis solution exchange substances in the dialyzer (artificial kidney) by means of semi-permeable membrane contact and concentration gradient, so that metabolic waste and excess electrolytes in blood move toward dialysis solution, and calcium ions and bases in dialysis solution move toward blood. If a mixture of albumin and urea is put into the dialyzer and the outside of the tube is soaked with water, then the urea in the dialyzer tube will move to the water outside the tube through the artificial kidney membrane pore, and albumin cannot pass through the membrane pore because of its large molecule. This phenomenon of material movement in which small molecules can pass but large molecules cannot pass through the semipermeable membrane is called diffusion. The clinical use of dispersion to separate and purify blood for purification purposes is the basic principle of hemodialysis.
The thickness of the semi-permeable membrane used in hemodialysis is 10-20 microns, and the average pore size of the membrane is 3 nanometers, so only small molecules with molecular weights of 15,000 or less and some medium molecules are allowed to pass through, while large molecules with molecular weights greater than 35,000 cannot pass through. Therefore, proteins, pyrogen, viruses, bacteria and blood cells are impermeable; most of the components of urine are water, so to replace the kidney with artificial kidney, a large amount of water must be removed from the blood, and artificial kidney can only use osmotic pressure and ultrafiltration pressure to achieve the purpose of removing excessive water. The artificial kidney used now is the hemodialysis device has these functions, so that the quality and quantity of blood can be regulated, so that it is close to the physiological state.