RENAL SYSTEM

Renal Replacement Therapies

Dialysis• Dialysis is the diffusion of solute molecules through a

semipermiable membrane, passing from higher concentration to that of lower concentration. It is the process of separating colloids and crystalline substances in solution by the difference in their rate of diffusion through a semi permeable membrane.

• The purpose of dialysis is to remove endogenous and exogenous toxins and to maintain fluid electrolyte and acid- base balance till the renal function recovers. It is a substitute for some excretory functions of kidneys but does not replace the endocrine and metabolic functions.

GENERAL PRINCIPAL:

Movement of fluid and molecules across a semi permeable membrane from one compartment to another

INDICATIONS

• Uremic symptoms with neurologic abnormalities

• Persistent hyperkalemia, above 6.5 mEq/L• Blood urea level more than 150 mg./dl• Severe acidosis, pH less than 7.2, TCO2 less

than 10-12 mEq/L• Hyperphosphatemia• Pulmonary edema and CCF

METHODS OF DIALYSIS

1. Hemodialysis2. Peritoneal dialysis– Continuous ambulatory peritoneal dialysis– Continuous cycling peritoneal dialysis

3. Haemofilteration– Continuous venovenous hemofiltration– Continuous venovenous hemodialysis– Continuous venovenous hemodiafiltration

1.Hemodialysis

Pediatric hemodialysis is referred to extracorporeal renal replacement therapy in children under the age of 15 years. The neonates, infants and smaller children have special requirements for dialysis. Pediatric dialysis program could start even from a neonate who is less than 1 kg. The treatment requirements almost are similar to adults but there are certain differences as:– Renal replacement therapies– Growth and development– Psychological demands.

SPECIFIC CONSIDERATIONS:

1. The extracorporeal circuitThe amount of blood occupied by the

blood vessels and the dialyser should not exceed more than 10% of the total blood volume of the child. If the child is severely anaemic ( Hb < 5-6g/dL) the extracorporeal circuit volume should not exceed 7%. The total blood volume can be calculated by multiplying the child’s weight by 80mls.

2. Blood lines and dialysers-The surface area of the dialyser should not exceed the body surface area (BSA) of the child.-BSA (Mostellar equation) =Multiply the height by weight

Divide the result by 3600 Determine the square root of

result-i.e., SA(m2)= √([Ht in cms x Wt in kgs]÷3600)

3. Blood flow rateIt is determined by the child’s size, blood volume,

blood pressure and tolerance for dialysis.-Blood flow rate should not exceed 2.5 x weight (kg) ÷ 100

Hemodialysis

AV Fistula Communication

AV Graph Access

Hemodialysis

Hemodialysis MachineHemodialysis Circuit

TREATMENT PARAMETERS:

• Fluid replacement for hypotension should not exceed a maximum of 10ml/kg body weight and may given in divided doses.

• Ultra filtration should not exceed 5% of total body weight for each dialysis session.

• Clearance rates for urea should not exceed 3 mls/min/kg body weight with 1.5 to 2ml/min/kg body weight for extremely uremic children.

VASCULAR ACCESS:Vascular access are of the three types:• Fistulas

Arterio vascular fistula is an access in which a vein and artery are connected surgically. The preferred site is the radial artery and a forearm vein that produces dilation and thickening of superficial vessels of the forearm to provide easy access for repeated venipuncture.

• GraftsSubcutaneous (internal) arteriovenous graft is a synthetic prosthetic graft for circulatory access made by the anastomosis of artery and vein.

• External vascular access For this percutaneous catheters are inserted in the femoral, subclavian or internal jugular veins. A central catheter into internal jugular vein is more permanent form.

COMPLICATIONS

• more prone to cardiovascular instability due to small blood volume.

• Excessive weight loss• Hypotension• Hypothermia in infants• Dialysis equilibrium syndrome

Dialysis equilibrium syndrome:Fluid removal and decrease in BUN during hemodilaysis

cause changes in blood osmolarity. These changes trigger a fluid shift from the vascular compartment into the cells. In the brain, this can cause cerebral edema, resulting in increase intracranial pressure and visible signs of decreasing level of consciousness.

Symptoms:Sudden onset of headache, nausea and vomiting, nervousness, muscle twitching, palpitation, disorientation and seizures

Treatment:Hypertonic saline, Normal salineIf immediate treatment for disequilibrium is not provided it leads to:– Convulsions– Coma– Cardiac arrhythmia

ADVANTAGES• suited for children who

do not have someone in family to perform home peritoneal dialysis

• easy for those who live near dialysis center

• achieves rapid correction of fluid and electrolyte abnormality

DISADVANTAGES• associated to the rapid

change, it can cause muscle cramping and hypotension

• school absence during dialysis

• strict fluid and dietary restrictions

• boredom for child during the session

2. Peritoneal dialysisPeritoneal dialysis is a technique that

employs the patient’s peritoneal membrane as a dialyzer. Excess body water is removed by an osmotic gradient created by the high dextrose concentration in the dialysate; wastes are removed by diffusion from the peritoneal capillaries into the dialysate.

Because peritoneal dialysis is not as efficient as hemodialysis, it must be performed daily rather than 3 times weekly as in hemodialysis.

3 steps..??

1st 2nd3rd

3 steps in peritoneal dialysisInfusion :A sterile, dialysis solution flows into your peritoneal cavity by gravity via a catheter or tube that has been surgically placed into the abdomen. The filling takes about 10 minutes. Once the filling is complete, the catheter is shut so that it does not leak.

Dwell :The lining of the peritoneal cavity called the peritoneum acts as a natural filter. It lets the waste products and excess fluids in the blood filter through into the dialysis solution, while holding back important substances that the body needs. The length of time varies from 3 - 6 hours. While the solution is in the body you can move about.

Drain :The dialysis solution containing the wastes is drained again by gravity from your body through the catheter into an empty bag. This takes about 10-20 minutes. A bag containing sterile dialysis solution replaces the bag containing waste products. The whole process is then repeated. Each of these replacements is called a ' Bag Exchange'.

hookup infusion Diffusion(fresh)

Diffusion(waste) drainage

TYPES

1. Continuous ambulatory peritoneal dialysis2. Automated peritoneal dialysis (Continuous

cycling peritoneal dialysis)a) Continuous Cyclic Peritoneal Dialysisb) Intermittent Peritoneal Dialysis

-Nocturnal intermittent peritoneal dialysis

1.Continuous ambulatory peritoneal dialysis

It is the most commonly used method of peritoneal dialysis. The filtration process occurs most hours of the day. The exchange usually take about 3 minutes 3-4 times a day and only require a solution bag with tubing attached to it that connects to the child’s blood stream. It gives freedom.

2.Automated Peritoneal Dialysis

a)Continuous Cyclic Peritoneal DialysisContinuous regimen means that the

dialysis solution is present in the peritoneal cavity continuously, with the exception of short significant periods between exchange.

It uses duel lumen catheterization, i.e., 2 catheters, one for inflow and other for outflow.

b)Intermittent Peritoneal Dialysis

• It means the dialysis sessions are performed several times a week.

• This technique uses one catheter for inflow and outflow. Flow is interrupted after both inflow and outflow during exchange.

- Nocturnal intermittent peritoneal dialysis

PROCEDURE

The abdomen is cleaned in preparation for surgery, and a catheter is surgically inserted with one end in the abdomen and the other protruding from the skin. Before each infusion the catheter must be cleaned, and flow into and out of the abdomen tested.

The warmed solution is allowed to enter the peritoneal cavity by gravity and remains a variable length of time (usually 10-15 minutes) according to the rate of solute removal and glucose absorption in individual patients. The total volume is referred to as dwell while the fluid itself is referred to as dialysate.

The dwell can be as much as 2.5 litres, and medication can also be added to the fluid immediately before infusion. The dwell remains in the abdomen and waste products diffuse across the peritoneum from the underlying blood vessels. After a variable period of time depending on the treatment (usually 4–6 hours), the fluid is removed and replaced with fresh fluid.

RISKS

• HTN & other cardiac complications• Seizure• Obstructed catheter• Dialysate leakage• Hyperglycemia• Increased triglyceride levels• Increased protein loss• Parental stress and burnouts

ADVANTAGES

• Ability to perform dialysis treatment at home• Technically easier than hemodialysis,

especially in infants• Ability to live a greater distance from medical

center• Freedom to attend school and after-school

activities• Less-restrictive diet• Less expensive than hemodialysis• Independence (adolescents)

DISADVANTAGES

• Catheter malfunction• Catheter-related infections (peritonitis, exit

site)• Impaired appetite (due to full peritoneal

cavity)• Negative body image• Caregiver burnout

3.Continuous Renal Replacement Therapies

It is useful in patients with unstable hemodynamic condition, sepsis etc. it is an extra corporeal therapy in which fluid and electrolytes are continuously removed from blood using a special pump-driven machine. It continuously pass patient’s blood across a highly permeable filter.

1. Continuous venovenous hemofiltrationLarge amount of fluid moves by pressure across the filter bringing with it by convection other molecules such as urea, creatinine, uric acid and phosphorus. It is replaced with desirable electrolyte composition similar to blood.

2. Continuous venovenous hemodialysisIt utilizes the principle of diffusion by circulating dialysate in a countercurrent direction on the ultra filtrate side of the membrane, no replacement fluid is used.

3. Continuous venovenous hemodiafiltrationIt employs both the replacement fluid and dialysate, offering the most effective solute removal of all forms of renal replacement therapies.

ADVANTAGES

• Hemodynamic stability– Avoid hypotension complicating hemodialysis– Avoid swings in intravascular volume

• Easy to regulate fluid volume– Volume removal is continuous– Adjust fluid removal rate on an hourly basis

• Customize replacement solutions• Lack of need of specialized support staff

DISADVANTAGES• Lack of rapid fluid and solute removal

– GFR equivalent of 5 - 20 ml/min– Limited role in overdose setting

• SLED – Developing role• Filter clotting

– Take down the entire system

RENAL TRANSPLANTATION

• Kidney transplantation is recognized as the optimal therapy for children with end-stage renal disease (ESRD

• The child may achieve 40 – 80 % renal function with the transplant and demonstrate improved growth, enhanceded cognitive development, and improved psychosocial development and quality of life.

INCIDENCE AND ETIOLOGY• Congenital, hereditary, and cystic diseases are

the cause in more than 52% of children 0 to 4 yr of age,

• Glomerulonephritis, focal segmental glomerulosclerosis account for 38% of cases in 10 to 19 yr of age.

• Structural disease (49%)• Various forms of glomerulonephritis (14%)• Focal segmental glomerulosclerosis (12%)

INDICATIONS

• Almost all children with ESRD

• Renal replacement therapy

DONOR SELECTION• Living related donor

Living related donor is preferred for a pediatric patient because it allows transplantation to be planned when the child ad donor is in optimal health. The suitable donors include parents, siblings, grandparents, uncles and aunts.

• Cadaveric donorA cadaveric transplant is placed when there is no

availability of a related living donor. A cadaver is a patient declared brain dead who had previously given consent for organ donation. After permission for donation is granted, the kidneys are removed and stored until a recipient has been selected.

PREPARATION FOR TRANSPLATATION

• A pre–emptive transplantation is preferred for children.

• Clinical and laboratory evaluation of kidney donor and recipient

- Blood Type Testing- Tissue Typing- Crossmatch- Serology

CONTRAINDICATIONS• Pre-existing metastatic malignancy or HIV• Patients with remission of malignancy off

maintenance treatment for a minimum of 2 yr may be reconsidered on an individual basis for transplantation, with close post-transplantation surveillance

• Patients with autoimmune diseases resulting in ESRD are candidates for transplantation after a period of immunologic quiescence of the primary disease for a period of at least 1 year before transplantation.

• Severe neurologic dysfunction

SPECIAL CONSIDERATIONS• Dialysis may be required for a period before transplantation to

optimize nutritional and metabolic conditions, to achieve an appropriate size in small children or to keep a patient stable until a suitable donor is available

• For young infants, a recipient may need to weigh at least 8-10 kg to minimize the risk for vascular thrombosis and to accommodate an adult-sized kidney. This can require a period of dialysis support until the child is at least 12 to 18 mo of age.

• It would be best match the recipient with an appropriately sized cadaveric kidney. But it increases the chance of vascular thrombosis. Sibling donors of same size are best suitable.

• Transplantation with an adult-sized kidney has been successful in children who weighed <10 kg or were <6 months of age.

• For children weighing 20kg or more, the kidney is placed extra peritoneally. Intraperitoneal approach is required for those weighing less than 20 kg and receiving adult kidney. If the donor is less than 2 years, the kidneys are transplanted ‘en-block’, together with donor aorta and venacava.

• Many surgeons prefer to remove the appendix at the time of transplantation as it will be difficult to differentiate between appendicitis and tenderness that accompanies acute rejection

PROCEDUREThis type of

operation is a heterotopic transplant meaning the kidney is placed in a different location than the existing kidneys. The kidney transplant is placed in the front (anterior) part of the lower abdomen, in the pelvis.

The original kidneys are not usually removed unless they are causing severe problems such as uncontrollable high blood pressure, frequent kidney infections, or are greatly enlarged.

The artery that carries blood to the kidney and the vein that carries blood away is surgically connected to the artery and vein already existing in the pelvis of the recipient. The ureter, or tube, that carries urine from the kidney is connected to the bladder.

POST TRANSPLANTATION COMPLICATIONS• Rejection– Hyperacute rejection: occurs within minutes to hours after

transplantation– Renal vessels thrombosis occurs and the kidney dies– There is no treatment and the transplanted kidney is

removed• Acute Rejection: occurs 4 days to 4 months after

transplantation- It is not uncommon to have at least one rejection episode-Episodes are usually reversible with additional immunosuppressive therapy

Signs: increasing serum creatinine, elevated BUN, fever, wt. gain, decrease output, increasing BP, tenderness over the transplanted kidneys

• Chronic Rejection: occurs over months or years and is irreversible.₋ The kidney is infiltrated with large numbers of T

and B cells characteristic of an ongoing , low grade immunological mediated injury

₋ Gradual occlusion renal blood vessels

Signs: proteinuria, HTN, increase serum creatinine levelsSupportive treatment, difficult to manageReplace on transplant list

• Infection• Hypertension• Malignancies (lip, skin, lymphomas, cervical)• Recurrence of renal disease• Retroperiotneal bleed• Arterial stenosis • Urine leakage

NURSING MANAGEMENT• Immediate post operative management:• Preventing rejection and promoting renal function• Administer immuno suppressants accurately on

time.• Focus on achieving graft functioning• Early mobilization• Monitor closely for few days with attention to fluid

and electrolyte replacement• Assess for rejection and infections.• Care should be given to central venous catheter,

arterial line, Indwelling urine catheter, Drain tube to collect leakage from anastomoses.

• Fluid balance and central venous pressure should be monitored to ensure appropriate renal perfusion

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