RENAL REPLACEMENT THERAPIES

IBRAHIM ALHASSAN

RENAL REPLACEMENT THERAPIES

• The use of renal replacement therapies becomes necessary when the kidneys can no longer
• Remove wastes
• Maintain electrolytes and regulate fluid balance.

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• This can occur rapidly or over a long period of time and the need for replacement therapy can be acute (short term) or chronic (long term).
• The main renal replacement therapies include the various types of dialysis and kidney transplantation.

Dialysis

• When a patient is in late stage chronic kidney disease (stage 4) or facing kidney failure (stage 5, end stage renal disease) he/she is referred to a dialysis and transplantation centre for kidney replacement therapy.
• It is usually initiated when the patient cannot maintain a reasonable lifestyle with conservative treatment.

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Dialysis cont.

• Types of dialysis include hemodialysis, CRRT, and Peritoneal dialysis.

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• Acute dialysis is indicated when there is a high and increasing level of serum potassium, fluid overload, or impending pulmonary edema, increasing acidosis, pericarditis, and severe confusion.
• It may also be used to remove medications or toxins (poisoning or medication overdose) from the blood.

• Chronic or maintenance dialysis is indicated in advanced CKD and ESRD in the following instances: the presence of uremic signs and symptoms affecting all body systems, hyperkalemia, fluid overload not responsive to diuretics.

• The decision to initiate dialysis should be reached only after thoughtful discussion among the patient, family, physician, and others as appropriate.

HEMODIALYSIS

• Hemodialysis prevents death but does not cure renal disease and does not compensate for the loss of endocrine or metabolic activities of the kidneys.
• Most patients receive intermittent hemodialysis that involves treatments three times a week with the average treatment duration of 3 to 4 hours in an outpatient setting.

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• The objectives of hemodialysis are to extract toxic nitrogenous substances from the blood and to remove excess water.

Haemodialysis Machine

Procedure for haemodialysis

• A dialyzer (also referred to as an artificial kidney) serves as a synthetic semipermeable membrane, replacing the renal glomeruli and tubules as the filter for the impaired kidneys.
• A solution called dialysate which has similar composition but different concentrations as the blood is infused into the dialyzer.

A dialyzer

Procedure for haemodialysis cont.

• In hemodialysis, the blood, laden with toxins and nitrogenous wastes, is diverted from the patient to a machine, a dialyzer, where toxins are filtered out and removed and the blood is returned to the patient.

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Procedure for haemodialysis cont.

• Diffusion, osmosis, and ultrafiltration are the principles on which hemodialysis is based.
• The toxins and wastes in the blood are removed by diffusion—that is, they move from an area of higher concentration in the blood to an area of lower concentration in the dialysate.
• The semipermeable membrane impedes the diffusion of large molecules, such as RBCs and proteins.

Procedure for haemodialysis cont.

• Excess water is removed from the blood by osmosis, in which water moves from an area of low concentration potential (the blood) to an area of high concentration potential (the dialysate bath).
• In ultrafiltration, water moves under high pressure to an area of lower pressure.
• It is accomplished by applying negative pressure or a suctioning force to the dialysis membrane.
• This force is necessary to remove fluid to achieve fluid balance.

Procedure for haemodialysis cont.

• The anticoagulant heparin is administered to keep blood from clotting in the dialysis circuit.
• Cleansed blood is returned to the body.
• By the end of the dialysis treatment, many waste products have been removed and the electrolyte balance has been restored to normal.

• Vascular Access
• Access to the patient’s vascular system must be established to allow blood to be removed, cleansed, and returned to the patient’s vascular system at rates between 300 and 800 mL/min.
• Several types of access are available.

Complications of Haemodialysis

• While hemodialysis can prolong life indefinitely, it does not alter the natural course of the underlying CKD, nor does it completely replace kidney function.
• The CKD complications will continue to worsen and require more aggressive treatment.
• With the initiation of dialysis, cardiovascular complications such as ;

Heart failure, coronary heart disease, angina, stroke and peripheral vascular insufficiency may occur

Cardiovascular disease remains the leading cause of death in patients receiving dialysis.

Complications of Haemodialysis

• Anemia is compounded by blood lost during hemodialysis.
• Patients with uremia report a metallic taste and nausea when they require dialysis.
• Vomiting may occur during the hemodialysis treatment when rapid fluid shifts and hypotension occur.
• Phosphorus deposits in the skin can occur and cause itching.

Complications of Haemodialysis

• Other complications of dialysis treatment may include the following:
• Episodes of shortness of breath often occur as fluid accumulates between dialysis treatments.
• Hypotension may occur during the treatment as fluid is removed. Nausea and vomiting, diaphoresis, tachycardia, and dizziness are common signs of hypotension
• Exsanguination may occur if blood lines separate or dialysis needles become dislodged.
• Dysrhythmias may result from electrolyte and pH changes or from removal of antiarrhythmic medications during dialysis.

Nursing Management

• The nurse in the dialysis unit has an important role in monitoring, supporting, assessing, and educating the patient.
• Monitoring
• During dialysis, the patient, the dialyzer, and the dialysate bath require constant monitoring because numerous complications are possible, including clotting of the circuit, air embolism, inadequate or excessive ultrafiltration hypotension, cramping, vomiting,etc.

2. Promoting Pharmacologic Therapy�

• Many medications are removed from the blood during hemodialysis; therefore, dosage or timing of the medication administration may require adjustment.
• Medications that are water soluble are readily removed during hemodialysis treatment and those that are fat soluble or adhere to other substances (like albumin) are not dialyzed out very well.
• This is the reason some drug overdoses are treated with emergency hemodialysis and others are not.

2. Promoting Pharmacologic Therapy cont.

• The patient must know when and when not to take the medication. For example, if an antihypertensive agent is taken on a dialysis day, hypotension may occur during dialysis, causing dangerously low blood pressure.

3. Promoting Nutritional and Fluid Therapy�

• Diet is important for patients on hemodialysis because of the effects of uremia.
• Maintain good nutritional status through adequate protein, calorie, vitamin, and mineral intake; and to enable the patient to eat a palatable and enjoyable diet.
• Restricting dietary protein decreases the accumulation of nitrogenous wastes, reduces uremic symptoms.
• Restriction of fluid is also part of the dietary prescription because fluid accumulation may occur, leading to weight gain, heart failure, and pulmonary edema.

4. Meeting Psychosocial Needs cont.

• Dialysis alters the lifestyle of the patient and family.
• The amount of time required for dialysis and physician visits and being chronically ill can create conflict, frustration, guilt.

PERITONEAL DIALYSIS

• The goals of PD are to remove toxic substances and metabolic wastes and to reestablish normal fluid and electrolyte balance.

Indication for PD

1. PD may be the treatment of choice for patients with renal failure who are unable or unwilling to undergo hemodialysis or renal transplantation.
2. Patients who are susceptible to the rapid fluid, electrolyte, and metabolic changes that occur during hemodialysis.
3. Patients with DM or cardiovascular disease, and those who may be at risk for adverse effects of heparin.

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Procedure

• In PD, the peritoneal membrane that covers the abdominal organs and lines the abdominal wall serves as the semipermeable membrane.
• Sterile dialysate fluid is introduced into the peritoneal cavity through an abdominal catheter at intervals.

• Once the sterile solution is in the peritoneal cavity, uremic toxins such as urea and creatinine begin to be cleared from the blood.
• Diffusion and osmosis occur as waste products move from an area of higher concentration (the blood stream) to an area of lesser concentration (the dialysate fluid) through a semipermeable membrane (the peritoneum).

• This movement of solute from the blood into the dialysate fluid is called clearance.
• Since substances cross the peritoneal membrane at different rates, adjustments in dwell time and amount of fluid used are made to facilitate the process.
• PD usually takes 36 to 48 hours to achieve what hemodialysis accomplishes in 6 to 8 hours.

Summary

• In peritoneal dialysis, dialysate is infused into the peritoneal cavity by gravity, after which the clamp on the infusion line is closed.
• After a dwell time (when the dialysate is in the peritoneal cavity), the drainage tube is unclamped and the fluid drains from the peritoneal cavity, again by gravity.
• A new container of dialysate is infused as soon as drainage is complete.
• The duration of the dwell time depends on the type of peritoneal dialysis.

Preparing the Patient�

• The nurse’s preparation of the patient and family for PD depends on the patient’s physical and psychological status, level of alertness, previous experience with dialysis, and understanding of and familiarity with the procedure.

Preparing the Patient� CONT.

• The nurse explains the procedure to the patient and assists in obtaining signed consent.
• Baseline vital signs, weight, and serum electrolyte levels are recorded.
• Evaluation of the abdomen for placement of the catheter is done to facilitate self-care.

Preparing the Patient cont

• Patient is encouraged to empty the bladder and bowel to reduce the risk of puncture of internal organs during the insertion procedure.
• Broad-spectrum antibiotic agents may be administered to prevent infection.

Performing the Exchange�

• The dialysate is infused by gravity into the peritoneal cavity.
• A period of about 5 to 10 minutes is usually required to infuse 2 to 3 L of fluid.
• The prescribed dwell, or equilibration, time allows diffusion and osmosis to occur.
• At the end of the dwell time, the drainage portion of the exchange begins.

• The tube is unclamped and the solution drains from the peritoneal cavity by gravity through a closed system.
• Drainage is usually completed in 10 to 20 minutes.
• The drainage fluid is normally colorless or straw-colored and should not be cloudy.
• Bloody drainage may be seen in the first few exchanges after insertion of a new catheter but should not occur after that time.
• The number of cycles or exchanges and their frequency are prescribed based on monthly laboratory values and presence of uremic symptoms.
• The removal of excess water during PD occurs because dialysate has a high dextrose concentration, making it hypertonic.

• Complications
• Most complications of PD are minor, but several, if unattended, can have serious consequences.

• Peritonitis
• Peritonitis is the most common and serious complication of PD.
• Leakage
• Leakage of dialysate through the catheter site may occur immediately after the catheter is inserted.

• Bleeding
• A bloody effluent (drainage) may be observed occasionally, especially in young, menstruating women.
• (The hypertonic fluid pulls blood from the uterus, through the opening in the fallopian tubes, and into the peritoneal cavity.)

• Hypertriglyceridemia is common in patients undergoing
• long-term PD, suggesting that the therapy may accelerate
• atherogenesis. Despite this, the use of cardioprotective
• medications is relatively uncommon, and many patients
• have suboptimal blood pressure control. Given the high
• burden of disease in these patients, beta-blockers and ACE
• inhibitors should be used to control hypertension or protect
• the heart, and the use of aspirin and statins should be considered.

• Other complications that may occur with long-term PD include
• Abdominal hernias because of continuously increased intra-abdominal pressure.
• The persistently elevated intra-abdominal pressure also aggravates symptoms of hemorrhoids.
• Low back pain and anorexia from fluid in the abdomen and a constant sweet taste related to glucose absorption may also occur.