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  1. 1. IMPLANTABLE HUMAN KIDNEY REPLACEMENT UNIT (IHKRU) Referred-to also as an The Implantable Artificial Kidney (IAK) By C. Edward Jennings © COPYRIGHT 2004 This Patent Pending Implantable Human Kidney Replacement Unit (IHKRU or IAK) relates in general to a fully functional artificial kidney, made of inert anticoagulant materials. Smaller than an actual human kidney, this device will not only saves patients with end stage renal disease (ESRD) from being on dialysis for life, it will also provides them with an alternative to donor kidneys (allograft), without having to combat rejection by taking immunosuppressive agents, most always accompanied ARTIFICIAL KIDNEY (ACTUAL SIZE) WITH PATENT PENDING ARTIFICIAL KIDNEY, COMPARED EXPLODED-PICTURE IN BACKGROUND, SHOWING IN SIZE TO SINGLE DIALYSIS FILTER, SHOWN IN ALL TEN DOUBLE- MEMBRANE CARTRIDGES. BACKGROUND. by side effects and infection. This Human Kidney Replacement Unit whether worn outside the body (extracorporeal), or implanted in the body by transplant surgery, will provide patients with essential kidney functions, similar to those of real kidneys. The IHKRU implant procedure will be much simpler and require less time in surgery than required with donor kidneys. There will be no biological matching nor back table work with lengthy inspections nor biopsy and artery-vane-ureter prepping. With the HKRU time will not be a factor as with donor kidneys where the non-heart-beating (NHB) preservation time is only from 24 to 48 hours, with the kidney packed in a ice slush of Ringer’s Lactate or NaCl. With the IHKRU there will be no living donors going through tissue type antigen matching and nephrectomy surgery, sacrificing one kidney, putting themselves at risk in case they should some day loose the other kidney; also, donor kidneys, whether from a live donor or a cadaver, suffer a certain amount of irreversible damage, the extent of which is hard to determine during the back-table inspection. If a transplant surgeon does not think that the donor kidney is usable for anatomical/technical reasons, the kidney by all means should not be offered to anyone for transplant. 1
  2. 2. IMPLANTABLE HUMAN KIDNEY REPLACEMENT UNIT (IHKRU) Before getting into the technical aspects of the IHKRU, some history of kidney disease, renal failure and kidney function will be reviewed, to help those reading this text to understand the importance of the IHKRU in helping people with end stage renal disease lead near normal lives. There are currently more than 67,000 deaths in America each year as a result of end stage renal disease. Approximately 110 out of every 100,000 people in the U.S. are diagnosed with ESRD. Even as far back as 1997 the United States Renal Data System (USRDS) had estimated that more than 300,000 Americans at that time were living with ESRD, at an annual cost for dialysis of $11.8 billion. The surviving patients, combined with the current ESRD cases being treated right now at dialysis centers, have raised the annual cost to more than $20 billion, There is an increase of more than 60,000 new dialysis patients, each year, and steadily climbing. The ages of the patients range from 19 years old on up. Medical records indicate that 33.6% of these cases are caused by diabetes; although type-1 insulin-dependent diabetes mellitus accounts for 5 to 10 percent of all diagnosed cases of diabetes, type-1 accounts for 30 percent of all the kidney failure cases caused by diabetes. 22.9% are caused by high blood pressure (hypertension) adding more than 15,000 new cases of ESRD to the ever-growing list in the U.S. each year. What Causes Kidney Failure: Kidney abnormalities can be anatomic in origin. Many are hereditary and present at birth (congenital). Most all kidney diseases attack the nephrons, causing them to loose their filtering capacity. Chronic renal failure is characterized by progressive destruction of the nephrons. Kidney failure can be caused by polycystic kidney disease (PKD), others are caused by poisons and trauma. Diabetes is a disease that keeps the body from using glucose (sugar) as it should. If glucose stays in the blood instead of breaking down, it can act like poison and damage the nephrons in the kidneys. High blood pressure can also damage the small blood vessels in your kidney’s nephrons. The damaged vessels cannot filter poisons from your blood as they should. If the problems worsen and renal function drops below 10 to 15 percent “end stage renal disease”. In this case, you cannot live long without dialysis or transplantation. Broad terms that include different forms of damage to the kidney’s glomeruli are Glomerulonephristis and Glomerulosclerosis. Glomerulonephritis is the inflammation of the membrane tubule tissue in the kidney that serves as a filter separating wastes and extra fluid from the blood. Several different types of kidney diseases are grouped together under this category. Infection from bacterial diseases can stimulate the immune system and bring on sudden symptoms of swelling (edema), in the kidneys, causing reduced urine output (oliguria), as indicated by blood in the urine (hematuria). High blood pressure frequently accompanies reduced kidney function, and can escalate into kidney failure. Glomerulosclerosis is the scarring (sclerosis) or hardening of the tiny blood vessels within the glomeruli. In several sclerotic conditions, a systemic disease like lupus Erythematosus (SLE), or Lupus Nephritis can be responsible. A disease might belong in two or more categories as do some types of diabetes, causing both inflammation and scarring. This condition occurs when autoantibodies form, or are deposited in the glomeruli, causing inflammation. Ultimately, the inflammation may create scars, stimulated by molecules called growth factors which may be made by glomerular cells themselves or may be brought to the glomerulus by circulating blood that enters the glomerular filter. 2
  3. 3. IMPLANTABLE HUMAN KIDNEY REPLACEMENT UNIT (IHKRU) The waste product Blood Urea Nitrogen (BUN) buildup in the blood as the result of ESRD must be removed by dialysis. BUN is produced in the liver as the end product of protein metabolism (or degradation). During digestion, protein is broken down to amino acids. Amino acids contain nitrogen + ammonium ions while the rest of the molecule is used to produce energy etc. The ammonia is combined with other small molecules to produce urea, which makes its way into the blood and is removed in the filtrate Creatinine also poisons the system and must be removed from the blood. Creatinine Phosphate, is an energy storing molecule, produced largely from muscle breakdown, and is proportional to the muscle mass. High values, especially with high BUN levels, is a good indication that there are problems with the kidneys. Also, high values of uric acid excreted in the urine, is associated with kidney problems. Phosphorus is largely stored in bone, and is regulated by the kidneys, high levels may be due to kidney disease. The pH of plasma (the plasma’s acidity) is carefully controlled by the kidneys and should be within the neutral range of 6.8 to 7.7 The Human Urinary System is made up of the kidneys, the bladder, two ureters, and a single urethra. The kidneys are a pair of organs resembling large kidney beans. In the average adult, measure around 4” to 5” long and 2” to 3” wide, and are situated against the rear wall of the abdomen in the middle of the back, located on either side of the spine, beneath the liver on the right and the spleen on the left. Healthy Kidneys in the average adult process about 125 ml/min or 45 gallons (180 liters) each day to filter out about 2 quarts of waste product and extra water in the urine. The entire 7 to 8 liters in the average adult’s body gets filtered 20 to 25 times each day. The kidneys removing excess minerals and regulate the composition of the blood by keeping the relative concentrations of such inorganic ions as sodium, phosphorus, and chloride in the blood plasma at a nearly constant level. The kidneys help regulate the body’s calcium/vitamin D activation as well as performing all the other essential regulations. Potassium for instance, is controlled very carefully by the kidneys for proper functioning of the nerves and muscles, particularly those of the heart Three hormones are produced in healthy kidneys; Eerythropoietin (EPO), which stimulates the bone marrow to produce the proper number of red blood cells needed to carry oxygen to vital organs; Renin, which regulates blood pressure; and the active form of vitamin D, which maintains calcium for bones and for normal chemical balance in the body. When the kidneys are functioning properly, if the concentration of an ion in the blood, and hence in the glomerular filtrate exceeds its kidney threshold value, the excess in the filtrate is not reabsorbed but released in the urine, thus maintaining near constant levels. The same is so with excess protein. This is done by sophisticated mechanisms of osmosis, reverse osmosis and ion exchange filtration. 3
  4. 4. IMPLANTABLE HUMAN KIDNEY REPLACEMENT UNIT (IHKRU) When the Human Kidney Replacement Unit (IHKRU) is implanted instead of being worn outside the body (extracorporeal), the IHKRU encased in an inert cushioning saline filled bag is equipped with graft-able artery vein and ureter tubing, allowing the surgical procedure to be near the same as with a real human donor kidney. The following is a comparison of both procedures. KIDNEY TRANSPLANT (ALLOGRAFT) Procedure For Both the Donor Kidney and the IHKRU Kidney Transplant is an option offered to many people with ESRD. There are over 9,000 kidney transplants performed each year in the U.S. on patients with chronic kidney failure, or end-stage renal disease (ESRD). Kidney transplantation involves the surgical attachment of a functioning kidney (graft) from a donor, or the IHKRU to a patient with end-stage renal disease (ESRD). During the procedure, the surgeon makes an incision in the patient's flank and implants the new kidney above the pelvic bone and below the non-functioning kidney by suturing the kidney artery and vein to the patient's iliac artery and vein. The ureter of the new kidney is then attached directly to the bladder of the patient Preparation Without the IHKRU, patients with chronic renal disease who need a transplant but do not have a living donor register with United Network for Organ Sharing (UNOS) and are placed on a waiting list for a cadaver kidney transplant. UNOS is a non-profit organization that is under contract with the federal government to administer the Organ Procurement and Transplant Network (OPTN) and the national Scientific Registry of Transplant Recipients (SR). Kidney availability is based on the patient's health status. With the IHKRU the following does not apply, but with a donor kidney, the most important factor is that the kidney be compatible to the patient's body. A human kidney has a set of six antigens, substances that stimulate the production of antibodies. (Antibodies then attach to cells they recognize as foreign and attack them.) Donors are tissue-matched for 0 to 6 of the antigens, and compatibility is determined by the number and strength of those matched pairs. Patients with a living donor who is a close relative have the best chance of a close match. Without the IHKRU, potential kidney donors undergo a complete medical history and physical examination to evaluate their suitability for donation. Extensive blood tests are performed on both donor and recipient. The blood samples are used to tissue type for antigen matches, and confirm that blood types are compatible. A panel of reactive antibodies (PRA) is performed by mixing white blood cells from the donor and serum from the recipient to ensure that the recipient antibodies will not have a negative reaction to the donor antigens. A urine test is performed on the donor to evaluate his kidney function. In some cases, a special dye that shows up on x rays is injected into an artery, and x rays are taken to show the blood supply of the donor kidney (a procedure called an arteriogram). 4
  5. 5. IMPLANTABLE HUMAN KIDNEY REPLACEMENT UNIT (IHKRU) With the IHKRU there is no donor, but with a donor kidney, once compatibility is confirmed and the physical preparations for kidney transplantation are complete, both donor and recipient may undergo a psychological or psychiatric evaluation to ensure that they are emotionally prepared for the transplant procedure and aftercare regimen. This is omitted with the IHKRU. The surgical procedure to remove a kidney from a living donor is called a nephrectomy. The kidney donor is administered general anesthesia and an incision is made on the side or front of the abdomen. The blood vessels connecting the kidney to the donor are cut and clamped, and the ureter is also cut between the bladder and kidney and clamped. The kidney and an attached section of ureter is removed from the donor. The vessels and ureter in the donor are then tied off and the incision is sutured together again. A similar procedure is used to harvest cadaver kidneys, although both kidneys are typically removed at once, and blood and cell samples for tissue typing are also taken. Laparoscopic nephrectomy is a form of minimally-invasive surgery using instruments on long, narrow rods to view, cut, and remove the donor kidney. The surgeon views the kidney and surrounding tissue with a flexible videoscope. The videoscope and surgical instruments are maneuvered through four small incisions in the abdomen. Once the kidney is freed, it is secured in a bag and pulled through a fifth incision, approximately 3 in (7.6 cm) wide, in the front of the abdominal wall below the navel. Although this surgical technique takes slightly longer than a traditional nephrectomy, preliminary studies have shown that it promotes a faster recovery time, shorter hospital stays, and less post-operative pain for kidney donors. Once removed, kidneys from live donors and cadavers are placed on ice and flushed with a cold preservative solution. The kidney can be preserved in this solution for 24-48 hours until the transplant takes place. The sooner the transplant takes place after harvesting the kidney, the better the chances are for proper functioning. During the transplant operation, the kidney recipient patient is typically under general anesthesia and administered antibiotics to prevent possible infection. A catheter is placed in the bladder before surgery begins. An incision is made in the flank of the patient and the surgeon implants the kidney above the pelvic bone and below the existing, non-functioning kidney by suturing the kidney artery and vein to the patient's iliac artery and vein. The ureter of the new kidney is attached directly to the bladder of the kidney recipient. Once the new kidney is attached, the patient's existing, diseased kidneys may or may not be removed, depending on the circumstances surrounding the kidney failure. Since 1973, Medicare has picked up 80% of ESRD treatment costs, including the costs of transplantation for both the kidney donor and recipient. Medicare also covers 80% of immunosuppressive medication costs for up to three years, although federal legislation was under consideration in early 1998 that may remove the time limit on these benefits. To qualify for Medicare ESRD benefits, a patient must be insured or eligible for benefits under Social Security, or be a spouse 5
  6. 6. IMPLANTABLE HUMAN KIDNEY REPLACEMENT UNIT (IHKRU) or child of an eligible American. Private insurance and state Medicaid programs often cover the remaining 20% of treatment costs. Aftercare Kidney donors and recipients will experience some discomfort in the area of the incision. Pain relievers are administered following the transplant operation. Patients may also experience numbness, caused by severed nerves, near or on the incision. If the IHKRU is implanted, no immunosuppressants are used. But with the donor kidney, a regimen of immunosuppressive, or anti-rejection, medication is prescribed to prevent the body's immune system from rejecting the new kidney. Common immunosuppressants include cyclosporine, prednisone, and azathioprine. The kidney recipient will be required to take immunosuppressants for the life span of the new kidney. Intravenous antibodies may also be administered after transplant surgery. Daclizumab, a monoclonal antibody, is a promising new therapy that can be used in conjunction with standard immunosuppressive medications to reduce the incidence of organ rejection. Transplant recipients may need to adjust their dietary habits. Certain immunosuppressive medications cause increased appetite or sodium and protein retention, and the patient may have to adjust his or her intake of calories, salt, and protein to compensate. Risks As with any surgical procedure, the kidney transplantation procedure carries some risk for both a living donor and a graft recipient. Possible complications include infection and bleeding (hemorrhage). The most common complication for kidney recipients is a urine leak. In approximately 5% of kidney transplants, the ureter suffers some damage, which results in the leak. This problem is usually correctable with follow-up surgery. This is not the case with the IHKRU, but the biggest risk to the recovering transplant recipient is not from the operation or the kidney itself, but from the immunosuppressive medication he or she must take. Because these drugs suppress the immune system, the patient is susceptible to infections such as cytomegalovirus (CMV) and varicella (chickenpox). The immunosuppressants can also cause a host of possible side effects, from high blood pressure to osteoporosis. Prescription and dosage adjustments can lessen side effects for some patients. Normal results The IHKRU will start functioning immediately but the donor kidney may or may not start functioning immediately, or it may take several weeks to begin producing urine. Living donor kidneys are more likely to begin functioning earlier than cadaver kidneys, which frequently suffer some reversible 6
  7. 7. IMPLANTABLE HUMAN KIDNEY REPLACEMENT UNIT (IHKRU) damage during the kidney transplant and storage procedure. Patients may have to undergo dialysis for several weeks while their new kidney establishes an acceptable level of functioning. This is not the case with the IHKRU, but the success of a donor kidney transplant graft depends on the strength of the match between donor and recipient and the source of the kidney. Cadaver kidneys have a four-year survival rate of 66%, compared to an 80.9% survival rate for living donor kidneys. However, there have been cases of cadaver and living, related donor kidneys functioning well for over 25 years. Studies have shown that after they recover from surgery, kidney donors typically have no long-term complications from the loss of one kidney, and their remaining kidney will increase its functioning to compensate for the loss of the other. Abnormal results There is no way an IHKRU could be rejected by the immune system but a transplanted donor kidney may be rejected by the patient. Rejection occurs when the patient's immune system recognizes the new kidney as a foreign body and attacks the kidney. It may occur soon after transplantation, or several months or years after the procedure has taken place. Rejection episodes are not uncommon in the first weeks after transplantation surgery, and are treated with high-dose injections of immunosuppressant drugs. If a rejection episode cannot be reversed and kidney failure continues, the patient will typically go back on dialysis. Another transplant procedure can be attempted at a later date if another kidney becomes available. IMPLANTED ARTIFICIAL KIDNEY 1