Hemodialysis System

Consider Figure 1, which depicts the conventional hemodialysis system in counter-current mode. This dlalyzer set-up maximizes the concentration difference across the membrane and thus ensures maximum solute transfer. However this configuration also maximizes the transmembrane hydrostatic pressure difference and thus, maximizes the water flux. During hemodialysis the hydrostatic pressure of the blood must always be higher than the pressure of the dialysate to ensure sterility in the event of a membrane rupture. One has the following constraints during... 

Kidney. The device called an artificial kidney is actually an external hemodialysis system, first developed in the early 1940s, that washes the blood and removes waste products from the body. Over 40,000 patients are maintained by this device each year in the United States, and there are over 100,000 people worldwide undergoing routine dialysis. In addition, many others are placed on the hemodialysis unit for short-term treatment. 

Biomedical materials include metals, ceramics, natural polymers (biopolymers), and synthetic polymers of simple or complex chemical and/or physical structure. This volume addresses, to a large measure, fundamental research on phenomena related to the use of synthetic polymers as blood-compatible biomaterials. Relevant research stems from major efforts to investigate clotting phenomena related to the response of blood in contact with polymeric surfaces, and to develop systems with nonthrombogenic behavior in short- and long-term applications. These systems can be used as implants or replacements, and they include artificial hearts, lung oxygenators, hemodialysis systems, artificial blood vessels, artificial pancreas, catheters, etc. 

B. Hemodialysis. Blood Is taken from a large vein (usually a femoral vein) with a double-lumen catheter and is pumped through the hemodialysis system. The patient must be anticoagulated to prevent clotting of blood In the dialyzer. Drugs and toxins flow passively across the semipermeable membrane down a concentration gradient Into a dialysate (electrolyte and buffer) solution. Fluid and electrolyte abnormalities can be corrected concurrently. 

The long-term consequences of adding the adsorption device to the conventional hemodialysis system in treating renal patients still remain to be evaluated. For many decades, hemodialysis has been the most effective method of supporting patients with renal failure. In the United States alone in the year 2000, over ISbiUion dollars was spent on patients with chronic kidney failure. The cost of the dialysis treatment represents only... 

The combined use of different natural fluorescence techniques, such as steady-state fluorometry, fluorescence anisotropy and time-decay fluorescence, has been revealed to be quite powerfiil. The use of these techniques in an integrated mode for the monitoring of membrane-protein interactions is only in its infancy. These techniques offer not only the possibility to study the interaction of proteins with membranes, under convective and diffusive conditions, but also they may be easily extended to studies involving proteins and other porous materials such as chromatography media. The areas of application of these techniques will range from polypeptide and protein fractionation to the monitoring of hemodialysis systems. 

Keywords— Hemodialysis System, NIBP, Urea, Creatinine, HL7 standard, EMRs, e-Hospital, Patient ID. 

One unique appHcation area for PSF is in membrane separation uses. Asymmetric PSF membranes are used in ultrafiltration, reverse osmosis, and ambulatory hemodialysis (artificial kidney) units. Gas-separation membrane technology was developed in the 1970s based on a polysulfone coating appHed to a hoUow-fiber support. The PRISM (Monsanto) gas-separation system based on this concept has been a significant breakthrough in gas-separation... 

Grafts are also frequently employed in the upper part of the body to reconstmct damaged portions of the aorta and carotid arteries. In addition, grafts are used to access the vascular system, such as in hemodialysis to avoid damage of vessels from repeated needle punctures. Most grafts are synthetic and made from materials such as Dacron or Teflon. Less than 5% of grafts utilized are made from biological materials. 

Hexachloroethane that is absorbed appears rapidly in the systemic circulation. It is distributed widely throughout the body, with the highest concentration in fat and kidney and the lowest in the muscle (Fowler 1969b Gorzinski et al. 1985). There are no specific treatments available for reducing the body burden if hexachloroethane is absorbed. Because hexachloroethane causes renal injury, hemodialysis may be useful to reduce the plasma levels of hexachloroethane should renal failure occur in exposed persons. 

Creutzfeldt-Jakob disease (CJD) Alzheimer s disease (AD) Hemodialysis-related amyloidosis Primary systemic amyloidosis Secondary systemic amyloidosis Familial amyloid polyneuropathy I Familial amyloid polyneuropathy III Cerebral amyloid angiopathy Finnish hereditary systemic amyloidosis Type II diabetes Injection-localized amyloidosis Medullary thyroid carcinoma Atrial amyloidosis... 

Radiation Induced Reactions. Graft polymers have been prepared from poly(vinyl alcohol) by the irradiation of the polymer-monomer system and some other methods. The grafted side chains reported include acrylamide, acrylic acid, acrylonitrile, ethyl acrylate, ethylene, ethyl methacrylate, methyl methacrylate, styrene, vinyl acetate, vinyl chloride, vinyl pyridine and vinyl pyrrolidone (13). Poly(vinyl alcohols) with grafted methyl methacrylate and sometimes methyl acrylate have been studied as membranes for hemodialysis (14). Graft polymers consisting of 50% poly(vinyl alcohol), 25% poly(vinyl acetate) and 25% grafted ethylene oxide units can be used to prepare capsule cases for drugs which do not require any additional plasticizers (15). 

The systemic clearance of lepirudin is proportional to the glomerular filtration rate or creatinine clearance. Dose adjustment based on creatinine clearance is recommended (see Administration and Dosage). In patients with marked renal insufficiency (creatinine clearance less than 15 mL/min) and on hemodialysis, elimination half-lives are prolonged 2 days or less. 

Hemodialysis Topiramate is cleared by hemodialysis 4 to 6 times greater than in a healthy individual a prolonged period of dialysis may cause topiramate levels to fall below that required to maintain an antiseizure effect. To avoid rapid drops in topiramate plasma concentration during hemodialysis, a supplemental dose of topiramate may be required. The actual adjustment should take into account 1) the duration of the dialysis period, 2) the clearance rate of the dialysis system being used, and 3) the effective renal clearance of topiramate in the patient being dialyzed. 

Metabolism/Excretion - In the first 24 hours, approximately 75% of a dose is excreted in urine by glomerular filtration. Elimination half-life is 4 to 6 hours in adults and 2 to 3 hours in children. About 60% of an intraperitoneal dose administered during peritoneal dialysis is absorbed systemically in 6 hours. Accumulation occurs in renal failure. Serum half-life in anephric patients is approximately 7.5 days. Vancomycin is not significantly removed by hemodialysis or continuous ambulatory peritoneal dialysis, although there have been reports of increased clearance with hemoperfusion and hemofiltration. 

Hemoperfusion is like hemodialysis except that blood is circulated extracorporeally through a column with adsorbent material like resin or charcoal, which binds molecules electrostatically. The molecules likely to be removed are characterized as poorly dialyzable, lipid-soluble, protein bound. Among the indications for hemoperfusion in the management of poisoning include the presence of a poison in a patient with impairment of excretory system (i.e. damaged kidneys), intoxication of a drug known to produce delayed toxicity or metabolized to a more toxic metabolite (i.e. paraquat or methotrexate), deterioration of the clinical state of the poisoned patient despite conservative therapy (i.e. convulsions or cardiac arrhythmias following theophylline intoxication), or development of coma as a complication. 

Pharmacokinetics Well absorbed from fhe G1 fracf. Minimal absorption after ophthalmic administration. Protein binding 50%-60% (oral). Metabolized in liver. Primarily excreted in urine. Removed by hemodialysis. Half-life 12-22 hr (half-life is increased in the elderly and patients with impaired renal function). Ophthalmic Systemic absorption may occur. 

Rapidly, completely absorbed. Protein binding greater than 99%. Undergoes minor hepatic metabolism to inactive metabolite. Excreted unchanged in urine and in the feces through the biliary system. Not removed by hemodialysis. Half-life 9 hr. 

Completely absorbed from the G1 tract penetrates cornea after ophthalmic administration (may be systemically absorbed). Protein binding greater than 99%. Widely distributed. Metabolized in the liver. Primarily excreted in urine. Minimally removed by hemodialysis. Half-life 1.2-2 hr. 

Pharmacokinetics Low systemic absorption. Protein binding 98%. Metabolized in liverto more than 20 metabolites. Primarilyexcreted in urine minimal excretion in feces. Not removed by hemodialysis. 

Unlabeled Uses Cardiopulmonary bypass surgery hemodialysis pulmonary hypertension associated with acute respiratory distress syndrome, systemic lupus erythematosus, or congenital heart disease refractory CHF severe community-acquired pneumonia... 

Pharmacokinetics Rapidly absorbed after PO administration. Protein binding 98%. Undergoes first-pass metabolism in the liver to active metabolites. Excreted in urine and biliary system. Minimally removed by hemodialysis. Half-life 5-9 hr. 

Pharmacokinetics Well absorbed following subcutaneous administration. Protein binding Very high. Metabolized in the liver. Removed from the circulation via uptake by the reticuloendothelial system. Primarily excreted in urine. Not removedby hemodialysis. Half-life i-6hr. 

Slowly and incompletely absorbed from the GI tract. Protein binding 15%. Metabolized in the liver. Eliminated in urine and in feces by biliary system. Unknown if removed by hemodialysis. Half-life 2-4 hr. 

Mechanism of Action An HMG-CoA reductase inhibitor that interferes with cholesterol biosynthesis by preventing the conversion of HMG-CoA reductase to meva-lonate, a precursor to cholesteroh Therapeutic Effect Lowers serum LDL and VLDL cholesterol and plasma triglyceride levels increases serum HDL concentration. Pharmacokinetics Poorly absorbed from the G1 tract. Protein binding 50%. Metabolized in the liver (minimal active metabolites). Primarily excreted in feces via the biliary system. Not removed by hemodialysis. Half-life 2.7 hr. 

Pharmacokinetics Well absorbed from the gastrointestinal (Gl) tract. Protein binding 52%-57%. Crossesblood-brain barrier. Widely distributed. Metabolized in liverby microsomal enzyme system to inactive and active metabolites. Primarily excreted in urine. Not removed by hemodialysis. Half-life 15-40 hr. 

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