Renal Replacement Therapy Flashcards
What are the normal functions of the kidney?
Excretion (of waste and foreign chemicals) Regulation of: Water and electrolyte balancer Body fluid osmolarity Arterial pressure Acid base balance
Erythrocyte production
Vitamin D production
What does dialysis do for the kidneys?
Excretion of metabolic waste products and foreign chemicals.
Control water and electrolyte balances
Acid base balance
What is the aim of RRT (renal replacement therapy)?
RRT mimics the excretory function of the normal kidney.
Eliminating nitrogenous waste
Maintaining normal electrolyte concentration
Preventing systemic acidosis
Maintaining a normal extracellular volume
When do you start dialysis?
Uraemic symptoms
Uncontrolled hyperkalaemia
Uncontrolled fluid overload
What are the renal replacement therapy options?
Haemodialysis
Peritoneal dialysis
Kidney transplantation
Conservative management
Haemodialysis
In haemodialysis an artificial kidney (haemodialyzer) is used to remove waste and extra chemicals and fluid from the blood stream.
How does a dialysis machine work?
Blood is pumped around an extracorporeal circuit through a semi-permeable membrane (dialyser) before being returned to the circulation. In a dialyser the dialysate flow in the opposite direction to blood.
What is the peritoneal membrane?
A semi-permeable fine layer of tissue that lines the peritoneal cavity covering the stomach, liver, spleen and intestines.
What are the benefits of peritoneal dialysis?
The peritoneal membrane has a rich blood supply that is ideal for filtering wastes and extra water from the blood.
Cause and example:
Pre-renal AKI
Cause: Poor perfusion
Example: Blood loss, sepsis, ACE inhibitors, NSAID’s
Cause and example:
Renal AKICause: tubular damage
Cause: tubular damage
Examples: Crush injury (myoglobin), mismatched transfusion (haemoglobin), poison (mercury, clostridium toxin). Diabetes / Hypertension
Cause and example:
Post-renal AKI
Cause: Obstruction
Examples: bilateral ureteric obstruction (stone, tumour, retroperionteal fibrosis or surgical injury) Unilateral obstruction of solitary kidney.
Crush syndrome
Crush injury - prolonged continuous pressure on muscle tissue
Muscle injury can cause large quantities of potassium, phosphate, myoglobin, creatine kinase and urate to leak into the circulation.
Give brief investigation of renal failure.
- Urine assessed for haematuria, proteinuria, looked at microscopically for casts
- USS, kidney size: hydronephrosis?
- X-ray: stones in UT
- RBC: microscopically
CAPD
Chronic abumlatory peritoneal dialysis
Describe how CAPD may be carried out?
Chronic abumlatory peritoneal dialysis
- Silicon catheter inserted into abdo cavity.
- Dialysate fluid runs through multiple holes into abdomen.
- Left for several hours
- Fluid allowed to drain out
When is CAPD not possible?
If patient has undergone lots of previous abdominal surgery with adhesion.
Complications of CAPD
Peritonitis. Hernia (incisional, inguinal, umbilical) Genital oedema Gram negative sepsis Staphylococcus Back pain Fluid retention
Describe haemodialysis
Blood from patient flows through dialysing membrane.
Solutes allowed to pass into dialysis fluid thus purifying blood.
How common is death by myocardial infarction (heart attack) in dialysis patients and why?
20x more likely in dialysis patients.
Due to:
- Hyperlipidaemia
- Hypertension
- Left ventricular hypertrophy
The immunocompromised nature of ESRF patients undergoing dialysis may lead them at risk of what?
Malignancy
Hepatitis
Tuberculosis
Describe the method dialysis
- Create peripheral fistula
- Creates large hypertrophied vessel that can repeatedly be needled allowing blood to be diverted into dialysis machine.
- OR permanent plastic catheter inserted into internal jugular or subclavian vein
Describe the formation of the arteriovenous fistula.
Artery and vein anastomosed.
Usually radial/ brachial artery and cephalic vein .
Creates large hypertrophied vessel.
What is the infection risk in haemodialysis?
Bacteraemia
What is the infection risk in peritoneal dialysis?
Peritonitis
In renal transplant what antigens are compared?
HLA - human leukocyte antigens
What is the target of the drugs in post transplant immunosupression?
Mainly the drugs are targeted at reducing T-cell proliferation.
Transplant complications
Primary non-function Delayed graft function Post-op, MI, CVA, pneumonia, DVT, PE, wound infection Acute rejection Ureteric problems Atypical infections • CMV • PCP Cancers • Skin • Lymphoprolifertive Diabetes Dyslipidaemia Hypertension Chronic rejection and CKD
Delayed graft function
Delayed graft function (DGF) is defined as failure of the renal transplant to function immediately, with the need for dialysis in the first post-transplantation week.
CVA
Cerebrovascular accident (CVA) is the medical term for a stroke.
Why is CMV infection a risk following renal transplantation?
For people with compromised immunity, especially due to organ transplantation, CMV infection can be fatal.
Why is conservative management of kidney failure an option?
Patient choice: quantity of extended life offered by dialysis is not matched by the perceived impact on the quality of their lives.
What is the leading cause of mortality in haemodialysis patients?
Cardiovascular disease
What is the ideal treatment for people with end stage renal disease.
Ideally ESRD patients should have a (pre-emptive) live donor transplant.
What is an alternative to using an arteriovenous fistula?
Permanent plastic catheter inserted into internal jugular vein or subclavian vein.
In a patient with stage 5 CKD when should peritoneal dialysis be considered as 1st choice for dialysis over haemodialysis?
Patient is <2yrs old
Patient has residual renal function
Adults without significant associated comorbidities
What are indications for dialysis in AKI?
- Uraemia - pericarditis, gastritis, hypothermia, encephalopathy.
- Fluid retention - pulmonary oedema
- Sever hyperkalaemia
- Serum sodium out of range
- Severe pH disturbance <7
Hyperkalaemia (mmol)
> 6.5mmol
Normal range for serum Na+
120-155mmol
Describe the process of haemodialysis.
- Blood is drawn from arteriovenous fistula.
- Blood circulates through the dialyser.
- Blood is returned to fistula.
What medication is infuse during dialysis?
Heparin to prevent clot formation.
What are complications of haemodialysis?
Hypotension Cardiac arrhythmia Nausea Vomiting Headache Fever
What is the difference between haemodialysis and haemofiltration?
Haemodialysis removes solutes by diffusion. Haemofiltration removes solutes by convection.
When is haemofiltration used over haemodialysis?
In the intensive care setting to treat AKI.
What is the significance of haemodialysis vs haemofiltration?
Diffusive therapy (hemodialysis) removes small solutes mainly, whereas convective therapies (hemofiltration and hemodiafiltration) may also eliminate larger molecules such as myoglobin or cytokines.
What else will patients with ESRF need other than dialysis?
Patients in the later stages of chronic kidney disease (CKD) will need medical supplements to compensate for the hormones their kidneys are unable to produce.
In CAPD what organism causes peritonitis?
Staphylococcus aureus
Autotransplantation
An organ is transplanted into a different site in the same individual.
Cyclosporine
Cyclosporine is used to prevent organ rejection in people who have received a liver, kidney, or heart transplant. It is usually taken along with other medications to allow your new organ to function normally.
Summary of Peritoneal dialysis.
- Dialysate is run into the peritoneal cavity, usually under gravity.
- Urea, creatinine, phosphate and other uraemic toxins pass into the dialysate down their concentration gradients.
- Water (with solutes) is attracted into the peritoneal cavity by osmosis, depending on the osmolarity of the dialysate. This is determined by the glucose or polymer (icodextrin) content of the dialysate. More hypertonic solutions (rising from around 1.5% to 4% glucose) will improve fluid removal.
- The fluid is exchanged regularly to repeat the process.
What are the specific complications of peritoneal dialysis?
• Bacterial peritonitis, presenting as fever, abdominal pain, and a cloudy peritoneal dialysate effluent.
