Principles of dialysis Dechu Puliyanda, MD Professor of Pediatrics Director, Pediatric Nephrology and Transplant Immunology Cedars Sinai Medical Center UCLA David-Geffen School of Medicine

What we will talk about today Causes of renal failure Indications for dialysis Modalities for dialysis Principles of dialysis Hemodialysis Peritoneal dialysis

Causes of renal failure in the African subcontinent Septicemia Malaria Glomerulonephritis Hemolytic Uremic syndrome Nephrotoxins Obstructive uropathies

Indications for dialysis Intractable acidosis Intractable Hyperkalemia Fluid overload Uremia Need for transfusion in a patient with oliguria Need for parenteral nutrition in a patient with oliguria Removal of dialyzable toxins

Principles of dialysis: passage of solutes across a semi permeable membrane

Modalities of dialysis Hemodialysis Peritoneal dialysis Continuous renal replacement therapy (CVVH)

Hemodialysis

Hemodialysis

Hemodialysis Need an access – either a catheter or fistula Need extracorporeal blood flow Needs to be done in a hospital setting Needs anticoagulation Rapid fluid and electrolyte shifts

Peritoneal dialysis

Cook’s catheter: inserted at bedside

Continuous Ambulatory Peritoneal Dialysis Patients will be required to be dialysed 3 – 5 times per day by themselves. Gravity will draw the dialysate in and out of the peritoneal cavity, through the connecting tubing and bags. CAPD requires the patient to connect tubing and a bag of sterile dialysate to the peritoneal catheter. The bag is elevated to shoulder level, allowing the solution to flow into the peritoneum. Waste products and excess fluid pass from the blood, through the patient’s peritoneal membrane (lining of the abdomen), which acts as a filter, and into the dialysate. Once this is completed, all fluid and waste from the patient’s peritoneal cavity are drained and exchanged with a fresh solution.

Automated Peritoneal dialysis Automated peritoneal dialysis (APD) is performed by a machine, called a cycler, while the patient is asleep. Like CAPD, APD uses the patient’s peritoneal membrane as a filter to draw waste and excess fluid from the patient’s blood into a dialysate solution. The APD machine automatically controls the timing of exchanges, drains the used solution and fills the peritoneal cavity with new solution; based on the prescribed number of exchanges. For extra treatment, dialysis solution remains in the patient’s peritoneal cavity during the day. The peritoneal cavity of most adults can comfortably hold two-to-three liters of fluid.

Advantages of Peritoneal dialysis Fit the dialysis treatment around the patient’s lifestyle; Patient independence; Fewer visits to the dialysis unit (usually once a month); Dialysis done during sleep time for some patients; therapy is gentler and more similar to natural kidney function; PD is portable and flexible; Less fluid and diet restrictions; No needles needed; and Better blood pressure control.

Disadvantages Patients need to be well trained; Permanent catheter access required; Some risk of infection; Some patients may show a slightly larger waistline (due to carrying fluid); and Storage space required in the patient’s home.

Dialysis solutions ( dialysate)

Complications of peritoneal dialysis Ineffective Peritoneal dialysis (omentum still being present or clots in catheter) Hernias Infections (peritonitis) Leaks

Factors that contribute to poor outcome Insufficient dialysis Undernutrition Infection Lack of appropriate interdialytic care: no erythropoeitin, no active Vitamin D etc

Prevention of ESRD is the best strategy Health education: avoid nephrotoxins Infection control: good teaching of PD and effective hand hygiene Antischistomal therapy Antimalarial therapy Vaccination against Tuberculosis, Hepatitis and pneumococcus Screening UA among school aged children??