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.

The Space Within and Outside Our Body

The space has a great role in our life. Our body is composed of five basic components: the earth, water, air, fire (heat or temperature) and the sky or space. The space within and outside our body is must for the existence of life. The outer space is composed of air (mixture of gases), vapours, finer particles, microorganisms, radiation, light, cold and heat. The composition of environment influences our breathing, metabolism and physiology. Our body reacts in a variety of ways to the external space and the environment possessed by it. In fact the particles floating in the air or transmitted through it may cause allergic reactions, infections, hot or cold skin burns or even skin cancer. All activities of human beings or animals are space oriented.

Just think of the life without space and you would understand its importance. Our body is like a tube open from both ends. You may appreciate space in your mouth (oral cavity), throat, nostrils, ears and lungs. In addition to these gross pockets of space there are hollow organs like heart (four chambers are there for blood flow regulation), gall bladder, urinary bladder and uterus (in females). Other examples of space within our body are cranial cavity, visceral cavity and cavities around all vital organs. There are micro-spaces in glandular tissues, alveoli of lungs, blood vessels and nephrons (glomeruli have capillary lumen and urinary space) in kidneys. In some of the renal disorders there are ultrastructural alterations in the areas/volumes of these micro-spaces within the kidneys leading to altered renal physiology and renal function. The figure-1 below illustrates normal urinary space (US) and capillary lumen (CL) or capillary space in a normal kidney; and figure-2 illustrates congestion of capillary lumen (CL) due to deposition of subendothelial deposits (SeD) in a kidney affected by lupus nephritis.

Figure-1: Ultramicrograph of a capillary loop from a normal human kidney illustrating normal urinary space (US) and capillary lumen (CL) with normal thickening of glomerular basement membrane (GBM); Uranyl acetate and Lead citrate stain.

Figure-2: Ultramicrograph of a capillary loop from human kidney affected by lupus nephritis, illustrating congestion of capillary lumen (CL) due to deposition of subendothelial deposits (SeD) with normal urinary space (US) but irregular thickening of glomerular basement membrane GBM); Uranyl acetate and Lead citrate stain.

In the illustration cited above you have seen the alteration in the space within the renal glomerulus. Abdominal tumors, brain tumors, polyps in the uterus, enlargement of spleen and liver, all these lead to functional as well as physiological changes in the body of a patient due to impact on space within the body.

Reversible Renal Failure

When we come across the term reversible renal failure, it indicates that there was a scope for the repair of renal lesions or complete recovery of renal function. Reversible renal failure is of great importance for the clinician/nephrologist attending to the patient, because he/she could be able to do something for the well being of the patient. Clinical end picture may be same in many renal disorders though the origins are so different. Acute stage is characterized by pain in back, fever and edema, a rise in blood pressure and such urinary changes as oliguria (low output of urine), high specific gravity of urine with high coloration. Presence of albumin, red blood cells (RBCs) and casts have also been observed in urine with low urea content. It has been observed that reversible renal failure is generally extra-glomerular in origin, but it may be nephritic type. Most of the cases with acute glomerulonephritis also make a complete recovery with therapy and dialysis.  Tubular damage may also be repaired, as has been in the cases of mercuric chloride poisoning. Accumulation of nitrogenous waste products in blood is observed in these patients without any renal lesion on blood biochemistry and kidney biopsy evaluation. The condition may also be termed as extra-renal uremia or azotemia without corresponding renal lesion.

Renal Function in Infants

We know that the main function of kidneys is their ability to produce the glomerular filtrate and thereby concentrating the urine by way of absorption of water from the glomerular filtrate. The ability to concentrate urine is not well developed in infants. Indeed the ability to concentrate urine is partially developed after three months of life and fully developed renal function is acquired by the end of first year of life. The lack of concentrating urine is because the kidneys are not adapted to the action of antidiuretic hormone (ADH) of pituitary gland. The kidneys gradually start responding to the ADH and acquire full ability within one year. If the infants are not given sufficient fluids during the first five days of life they are sure to loose 10% of their body weight. Adults with well developed renal function are capable of conserving fluid by reabsorption. The lack of concentrating power in the kidneys of infants is probably due to imperfect development of loop of Henle. In infants the tubular function is lower than the glomerular filtration rate (GFR). The reabsorption of water in infants is 70% to 80% less than the adults. An infant, therefore, has a narrow margin of defense against the factors which decrease body fluids. The renalfunction in infants is helpless to regulate water balance when water is lost by any reason like fever, vomiting or diarrhea and leads to clinical implications. Infants need special care during fever, vomiting or diarrhea to offset any dehydration.