In hemodialysis, the patient’s blood is pumped into a dialysis chamber. This chamber consists of two fluid compartments, which are arranged either as a bundle of parallel Hohlfaserkapillarrohren or as a sandwich-like sheets of semipermeable membranes. In both forms, the blood along the one side of a semipermeable membrane is pumped into the first chamber, while a crystalloid solution (dialysate) along the other side is pumped into a separate compartment in the opposite direction.
(See also overview of the renal replacement therapy.) In hemodialysis, the patient’s blood is pumped into a dialysis chamber. This chamber consists of two fluid compartments, which are arranged either as a bundle of parallel Hohlfaserkapillarrohren or as a sandwich-like sheets of semipermeable membranes. In both forms, the blood along the one side of a semipermeable membrane is pumped into the first chamber, while a crystalloid solution (dialysate) along the other side is pumped into a separate compartment in the opposite direction. Concentration gradient of solutes between blood and dialysate lead to the desired exchange of dissolved substances in the serum of the patient, z. As a reduction of urea and creatinine, an increase of bicarbonate and equilibration of sodium, chloride, potassium and magnesium. The dialysate is opposed to the blood compartment under a negative pressure and has a higher osmolality to prevent filtration of the dialysate into the blood stream and to remove excess fluid of the patient. The dialyzed blood is then returned to the patient. The patient is anticoagulated systemically usually during hemodialysis to prevent the blood clots in the dialysis machine. However, hemodialysis can be performed (with heparin or trisodium citrate) or saline flush also regional anticoagulation of the dialysis circuit in which every 15-30 min with 50-100 ml saline, the dialysis circuit is free of any blood clots. The immediate aim of hemodialysis is the correction of electrolyte and fluid imbalance and the elimination of toxins. Longer-term objectives in patients with renal insufficiency should optimize functional status, well-being and blood pressure of the patient Prevent extend complications of uremia survival The optimal “dose” of hemodialysis is unclear. Most patients come with 3-5 hour dialysis 3 times / week good. One way to assess the effectiveness of the particular session is present in the measurement of the Harnstickstoffwerte and after each session. A ? 65% decrease in the urea nitrogen from the value before dialysis ([predialysis BUN – Postdialyse- BUN] / pre-dialysis BUN x 100% ? 65%) shows a successful meeting. Specialists may use other computationally intensive formulas such as KT / V ? 1.2 (wherein K is the urea clearance of the dialyzer in ml / min, T is the dialysis time in minutes and V is the volume of distribution of urea [that as the total body water equivalent] in ml) is. The Hämodialysedosis can be increased by increasing the dialysis treatment time of blood flow, the membrane surface and the membrane porosity. Nocturnal hemodialysis sessions (6-8 hours, 5-6 days / week) and short (1.5-2.5 h) daily meetings – if possible – be chosen selectively for patients in whom one of the following apply: Clinical Calculator: percentage of urea reduction in hemodialysis (PRU) Clinical calculator: volume of urea distribution (VDU) Clinical calculator: Kt / V dialysis dose formulas MultiCalc Excessive fluid gain between dialysis sessions Common hypotension during dialysis Poorly controlled blood pressure hyperphosphatemia, which is otherwise difficult to control this daily sessions are economically feasible if the patient through-hemodialysis at home s can. Clinical Calculator: Lean body mass (women) Clinical Calculator: Fat-free body weight (man) vascular access surgically created arteriovenous fistula (preferred) central venous catheter Hemodialysis is usually done through a surgically created arteriovenous fistula. A central venous catheter can be used for dialysis if an arteriovenous fistula has not been created or is not yet operational, or when creating an arteriovenous fistula is not feasible. The primary disadvantage of a central venous catheter is that this is a relatively low caliber has not a required clearance for the optimal blood flow is sufficient and the high risk of a catheter infection or thrombosis. CVC for hemodialysis is best done with the right internal carotid artery. Most saphenous vein-internal catheter remain usable for 2-6 weeks if strict aseptic skin care is guaranteed, and the catheter is used exclusively for hemodialysis. Catheter with a subcutaneous tunnel and a fabric sleeve have a longer shelf life (29 to 91% are still working after 1 year) and can be helpful for patients who no arteriovenous fistula can be created. Surgically created arteriovenous fistulas are better than central venous catheters because they are infected longer and less frequent. However, they are also prone to complications (thrombosis, infection, aneurysm or pseudoaneurysm). In a newly created fistula, it may take 2 to 3 months until it has matured and functional. However, additional time may be required to revise the fistula, so that fistula is best created 6 months prior to the expected dialysis in patients with chronic kidney disease. Operationally, the radial, brachial or femoral artery is in an end (Vene-) to-Since then (Arterie-) technique anastomoses with an adjacent vein. the adjacent vein for access is not suitable, an artificial vascular graft is used. For patients with poor venous provides the autologous saphenous vein graft an option. Complications in vascular access Among the complications of the vascular access infection stenosis thrombosis (often at a stenotic Passage) aneurysm or Pseudoaneurysa limit these complications the quality of hemodialysis, performed can be significantly one, increase the long-term morbidity and mortality and are common enough that patients and users should be alert for changes suggestive. The changes are reflected in the form of pain, edema, erythema, cracks in the skin overlying the access, lack of bruit and pulse in access, hematoma in the area of ??access and prolonged bleeding from the dialysis puncture channel. The infection is treated with antibiotics, surgery or both. The fistula may be monitored for signs of impending failure by “serial dilution Doppler blood flow measurements”, thermal or urea dilution techniques or by measurement of the static venous chamber pressures. It is recommended to perform these tests at least once a month. The treatment of stenosis, thrombosis, a pseudoaneurysm or aneurysm may take the form of angioplasty, stenting or surgical revision. Complications of Dialysis complications are listed in complications of renal replacement therapy. The most common complication of dialysis hypotension Hypotension many reasons:. To rapid dehydration, osmotic fluid shifts across cell membranes, acetate in the dialysate, thermally induced vasodilation, allergic reactions, sepsis or underlying changes (e.g., autonomic neuropathy, cardiomyopathy with low ejection fraction , myocardial ischemia, arrhythmia). Other complications include restless leg syndrome Cramps pruritus nausea and vomiting headache chest and back pain, in most cases, these complications arise inexplicably. but some may be part of a first-use syndrome (when the patient’s blood is exposed in the dialyzer a Cuprophan or cellulose membrane) be caused or by a dialysis disequilibrium syndrome, a syndrome which is believed that by too rapid removal of urea and other osmolytes arises from the serum and causes osmotic movement of the liquid into the brain. More severe forms of dialysis Dysäquilibriums manifest themselves in the form of disorientation, restlessness, blurred vision, confusion, seizures and even death. A dialysis-related amyloidosis develops in patients who undergo dialysis for years, and manifests with carpal tunnel syndrome, bone cysts, arthritis and cervical spondyloarthropathy. It is believed that a dialysis-related amyloidosis occurs less frequently with today’s widespread high-flux dialyzers as beta-2 microglobulin (the protein causes amyloidosis) more effectively with these dialyzers can be removed. Complications of renal replacement therapy type hemodialysis peritoneal dialysis Cardiovascular (air embolism) angina arrhythmia cardiac arrest (rare) pericardial tamponade hypotension * arrhythmia hypotension * pulmonary edema Infectious bacteremia colonization of temporary central venous catheters infection at the catheter exit site both “tunneled” as well as temporary central venous catheters endocarditis Meningitis Osteomyelitis sepsis cellulitis the Gefä access or abscess infection at the catheter exit site * peritonitis * Mechanical obstruction of the arteriovenous fistula by thrombosis or infection stenosis or thrombosis of subclavian vein or inferior vena cava by recurrent use of Subclavia- and vena jugularis-internal catheter obstruction of the catheter by blood clots, fibrin , omentum or fibrous sheath Dialysatleckage in the catheter area dissection of fluid in the abdominal wall hematoma in “pericatheter tract” perforation of an internal organ through the catheter Metabolically hypoglycemia in diabetics, insulin use hyponatremia or hypokalemia Hypernatremia iron loss Hypoalbuminemia hyperglycemia hyperlipidemia obesity pulmonary dyspnea due to an anaphylactic reaction to the hemodialysis hypoxia when azetatgepuffertes dialysate is used atelectasis Pleural effusion Pneumonia Other amyloid deposits Catheter-related hemorrhage fever due to bacteremia, pyrogens or superheated dialysate haemorrhage (gastrointestinal, intracranial, retroperitoneal, intraocular) insomnia muscle spasms * itching restlessness seizures abdominal wall and hernia catheter-associated intraabdomin ale bleeding hypothermia peritoneal seizures * The most common complications in total. Prognosis The overall annual mortality rate hämodialyseabhängigen patients is approximately 20%. The 5-year survival rate is lower in patients with diabetes than in patients with glomerulonephritis. Death is usually the result of cardiovascular disease, which followed by infection and deduction of hemodialysis. Dark-skinned people have a higher survival rate in all age groups. Nichthämodialysebedingte causes of mortality are comorbidities (eg. As hyperparathyroidism, diabetes mellitus malnutrition, other chronic diseases), age and later use of dialysis.