Dialysis Technology: Application of dialysis in acute renal failure !

Our kidneys are destined to perform excretory as well as regulatory function to maintain a state of homoeostasis in our body. Acute renal failure (ARF) is a syndrome defined as sudden or rapid loss of renal function (kidney function) leading to accumulation of urea and creatinine (nitrogenous waste compounds). If hyperbolic relationship between plasma creatinine or urea and glomerular filtration rate (GFR) is observed after investigations, the diagnosis is established as ARF. The early clinical signs of ARF/uremia are anorexia, nausea, vomiting, and sometimes pericarditis also. The ARF is an implication of loss of more than 50% of renal function. Dialysis should be instituted whenever early signs of uremia (elevated levels of urea in the blood) are present. Cases of metabolic acidosis as well as electrolyte and fluid imbalance also need dialysis for the reversal of hemodyanmics to normal.

Dialysis is a procedure for artificially purifying the blood of a patient through meticulous surgical intervention and electromechanical equipment. No specific elevated value of plasma creatinine or urea could be regarded as critical. The fluid intake and nutritional requirements are taken into consideration for deciding the timing and mode of dialysis. Cases of ARF should be put on dialysis without much delay for the successful recovery of their renal function. However, cases of chronic renal failure (CRF) may be kept in waiting. The dialysis procedure is of two types: i)  Hemodialysis (where patient's blood is passed through artificial kidney in conjunction with dialysis solution) and ii)  Peritoneal dialysis (where dialysis fluid is passed through the abdominal peritoneal cavity of the patient). The technique of dialysis was established long back in USA by Dr. Alan P Kendal, who also patented a 'suitcase kidney' in 1978.

Conventional hemodialysis remains the preferred and the best mode of dialysis. The hemodialysis is ideal for non-hypotensive and hemodynamically stable patients. Peritoneal dialysis is probably less effective in patients with hypercatabolic disorder and/or with undiagnosed abdominal disease. Peritoneal dialysis should be avoided in patients with recent abdominal surgery. The surgical intervention for hemodialysis can be in the following ways: i)  Continuous arteriovenous hemofiltration (CAVH), ii)  Continuous arteriovenous hemofiltration with/without concomitant dialysis (CAVHD), iii)  Continuous veno-venous filtration (CVVHD). These hemodialysis techniques are simpler, safe and very effective. The biochemical recovery is monitored during the dialysis for needful correction of fluid and electrolytes. After successive dialysis sessions the patient would return to normal health.

Various Causes of Acute Renal Failure

The cause and/or precipitating factor of acute renal failure (ARF) is always responsible for the effectiveness of therapy and supportive care techniques including hemodialysis. A rapid loss of renal function is exhibited through elevated levels of serum creatinine and blood urea due to fall in the clearance of these nitrogenous wastes by the kidneys in all cases of ARF. It has been observed that a loss of 50% of glomerular filtration rate (GFR) leads to significant elevation of the level of creatinine in the blood with a decrease in the urine output (oliguria). There could be three types of causes and implicating factors of acute renal failure: 1) Pre-renal, 2) Renal and 3) Post-renal. In pre-renal type ARF causes are the physiological factors or conditions which lead to poor renal perfusion and severe impairment of renal function. Hemorrhage in gastrointestinal tract (stomach and intestines) and other internal spaces, sepsis, hepatic failure (liver failure), over compliance of antihypertensive drugs or non-steroidal anti-inflammatory drugs (NSAID), arterial or venous thrombosis and intra-vascular hemolysis due to transfusion reactions, are the major pre-renal causes of ARF.

Acute tubular necrosis (ATN), rapidly progressive glomerulonephritis (RPGN), post infection glomerulonephritis and interstitial nephritis are some major renal causes of ARF. Pre-renal factors and use of nephrotoxic drugs may also be associated cause of ATN. Some viral infections, drugs, multiple myeloma, lymphoma and granuloma may cause interstitial nephritis leading to renal type ARF.

Post-renal type ARF is caused by intra-tubular obstruction due to fibrosis, stones or tumors. Every case of acute renal failure needs urgent investigations to establish the cause and efficient mode of supportive care and line of treatment. A comprehensive physical examination is required to look for possible causes of ARF and planning the investigations to classify the type of ARF. By timely diagnosis and treatment, renal function could be restored in majority of cases of pre-renal type acute renal failure.

Acute Renal Failure: Medical and Other Causes

If we look at the spectrum of acute renal failure (ARF), we find that in more than 65% of cases medical causes or ailments are associated. Around 20% of cases generally have obstetrical causes and 15% of cases of acute renal failure may have surgical or other causes. Diarrhoea, mismatched blood transfusion, intravenous hemolysis in glucose-6-phosphate dehydrogenate (G-6-PD) deficient patients, hemolytic uremic syndrome (HUS), severe glomerulonephritis, falciparum malaria, snake bite, insect stings, septicemia and copper sulphate, mercuric chloride and zinc phosphide poisoning are some medical conditions in which if effective treatment is delayed may lead to acute renal failure. Intake of nephrotoxic drugs can also cause acute renal failure. Obstetrical causes include toxemia of pregnancy, postpartum hemorrhage, puerperal sepsis and post abortal sepsis. Major surgery may cause ARF in some cases. Nephrotoxic drugs and sepsis could be compounding factors in cases ARF with surgical cause.

Acute gastroenteritis, septicemia and HUS may singly or in combination be the major cause of ARF in tropical countries. Rhabdomyolysis has been observed to play a significant role in causing ARF in a variety of conditions including toxemia of pregnancy, status asthmaticus, status epilepticus, hypothermia, burns, dermatomycosis, wasp and hornet strings, and copper sulphate, mercuric chloride and zinc phosphide poisoning. The main causative factors for intravenous hemolysis in G-6-PD deficient patients include the commonly used drugs like aspirin, chloramphenicol, chloroquine, quinine and phenylbutazone. Bilateral mucuromycosis has also been documented to cause ARF even in non-immunocompromized subjects. Sometimes nephrectomy may be required in cases of ARF due to mucuromycosis. The spectrum of community acquired acute renal failure and hospital acquired acute renal failure is almost similar throughout the world. Decreased renal perfusion in cases of hypothermia and hypotension (low blood pressure) may cause ARF if not treated well in time. Timely treatment and hemo-dialysis or peritoneal dialysis can definitely benefit the patient in restoration of renal function and reversal of acute renal failure.