Renal Failure

Kumud P Mehta
Management Of ARF
It consists of maintenance of fluid and electrolyte balance (strictly according to urine output, weight, presence of sodium and water retention), control of hypertension, treatment of hyperkalemia (with I. V. Calcium Gluconate + I.V. Sodium Bicarbonate + Glucose Insulin drip and use of ion exchange resin like kayexalate which exchanges potassium for sodium in G.I. tract and reduces blood levels of potassium. Albuterol inhalation is used for hyperkalemia recently.)

Dietetic restriction of protein, potassium, sodium and water is the backbone of conservative management of ARF. If these measures fail, peritoneal dialysis is the treatment of choice as renal replacement therapy (RRT). The main indications of peritoneal dialysis are emergency situations like:
- CNS manifestations of drowsiness/seizures
- Respiratory failure with pulmonary edema/CCF
- Bleeding from G. I. tract due to uremia.
Dialysis is advised if conservative therapy fails to control:
- Hyperkalemia with ECG changes of cardiotoxicity
- uncontrolled hypertension
- severe acidosis
- Anuria of more than one week
- Early dialysis in HUS, Crush injuries, myoglobinuria and in neonatal ARF (since normal neonates kidneys are immature).

- Diet
- Conservative therapy to reduce phosphorus, use of calcitriol, Erythropoietin in appropriate cases.

Conservative management can maintain good health for a few months to years. If GFR falls below 10 ml/ min/ 1.73 sq.metre, renal replacement therapy (RRT) needs to be initiated. RRT consists of (1) chronic maintenance hemodialysis (2) chronic ambulatory peritoneal dialysis (CAPD) (3) Renal transplantation which is a preferred mode of therapy.

Prevention of ARF can be done by rapid correction of shock, dehydration, hypoxic ischemic injury in a neonate and infants, by avoidance of drugs which are known to cause ARF, prevention of E. Coli gastroenteritis by avoiding uncooked food and contaminated milk and water because verotoxin producing E. Coli cause HUS. Prevention of CRF can be achieved by prevention and adequate treatment of recurrent urinary tract infection, by early detection of vesicoureteral reflux (VUR), correction of congenital anomalies like posterior urethral valves/pelviureteral obstruction/severe grades of VUR. Control of high BP, protein restriction in diet, use of ACE inhibitor to control proteinuria in diabetic or reflux nephropathy, use of drugs in dosage appropriate for the renal function are some of the measures known to prevent rapid progression of the disease.

Renal transplant is the preferred treatment for a patient with end stage renal failure when GFR falls bellow 5-10 ml/min/1.73sq metre. Transplanted kidney from a healthy living donor or cadaver can fulfill all the functions of kidney required for the normal growth and survival of a patient with ESRD.

Peritoneal dialysis is a procedure in which transfer of solutes like urea, sodium, potassium, creatinine and other metabolites and water from blood to dialysate fluid occurs across the peritoneum which serves as a semipermeable membrane. The dialysate fluid is instilled in the peritoneal cavity via a catheter which is specially designed for P.D. for infants and bigger children of various sizes. For patients with ARF, PD is required for 24-96 hours, whilst for CRF patients, chronic PD is required for which a special Tenckhoff catheter is surgically inserted in peritoneal cavity to create a permanent access. PD can be done 4-5 times/day via Tenckhoff's catheter for many years using special bags containing PD fluid.

Hemodialysis is done by creating arteriovenous connection by means of an AV shunt or fistula so that blood from the arterial side can flow alongside the dialysate fluid in a dialyser containing bundles of semipermeable membrane (cuprophane cellulose acetate etc). Mass transfer of solute and water occurs from blood of the patient into the dialysate fluid extracorporeally by diffusion and convection by means of a dialysis machine. Special sets of needles, tubings, dialysers are required for pediatric patients. Hemodialysis is technically difficult in young infants due to small sizes of vessels on long term basis .Hence peritoneal dialysis using Tenkchoff catheter is preferable for children with chronic renal failure. Advantages of CAPD are many viz. can be done at home after a short training by the parents, less chances of hemodynamic instability, no disruption of school/activity, less visits to hospital, no needle punctures and less disturbance to the family. Currently high cost of dialysate fluid, tubings etc. are responsible for less use of CAPD in Indian children with ESRD.

Role of erythropoetin is to correct erythropoetin deficiency which occurs in CRF. Erythropoietin is synthesized by kidney and by its action on bone marrow is responsible for erythropoiesis. In CRF because of nephron loss, EPO deficiency occurs and results in normocytic normochromic anemia requiring EPO administration for its correction.

Vit D in its active form (calcitriol) is required for the treatment of renal bone disease. 25 OH Vit D is hydroxylated to 1,25(OH)2 Vit D. in Kidney. This conversion is not possible in CRF resulting in demineralisation of bones, rickets and renal osteodystrophy. Oral or IV Calcitriol can heal the bones and prevent secondary hyperparathyroidism which is the other cause of renal bone disease.

Dietetic management is important in controlling accumulation of nitrogenous metabolites like urea, phosphorus, potassium, sodium and excess fluid in acute and chronic renal failure. Excess protein is harmful in chronic renal disease, as it can cause hyperfiltration and glomerulosclerosis. Protein restriction is an important measure to prevent progression of CRF. Coconut water, Fruit juices etc. contain potassium and hence to be avoided in ARF. Excess intake of salt and water can cause fluid and sodium retention with pulmonary edema in oliguric patients. Non vegetarian diet is rich in proteins, phosphorus and fat which are to be avoided in renal failure.

Drugs which are nephrotoxic and can induce renal failure are NSAIDS, cyclosporin A, aminoglycosides, cephalosporins, indomethacin, sulpha, anticancer drugs (like cisplatinum, ifosfamide), anti-fungal agents (like amphotericin B), antiviral (like acyclovir) and radio contrast medium. Minimum use of drugs in renal failure and modifying the dosage of drugs according to the GFR/ S. creatinine levels are very essential to prevent further damage to kidney.

A patient with acute renal failure needs frequent follow up with renal biochemistry, urine examination, BP monitoring at least once a week till all parameters normalise. Complete recovery may take few months to 1 year.

Chronic renal failure should be followed with growth monitoring, BP recording and renal function tests every 1-3 months to evaluate efficacy of conservative therapy, till the renal function stabilises or GFR falls to a level when renal replacement therapy needs to be initiated.

Renal Failure Renal Failure 01/10/2001
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