Peritoneal dialysis Dr Ejaz Ahmed

Barrier to transport Mesothelium Interstitium Endothelium Does not hinder transport Interstitium Hinders transport to some extent Endothelium Main barrier

Peritoneal transport principles Diffusion Depends on concentration gradient Convection(filtration) Depends on hydrostatic pressure and osmotic pressure

Diffusion Dr=p×a×c Dr=diffusion rate P=solute permeability A=area of membrane C=concentration gradient

Ultrafiltration UFr=p×a×(Hp+Op) UFr=ultrafiltration rate P=permeability of water A=surface area Hp=hydrostatic pressure gradient Op=osmotic pressure gradient

Material of catheter Silicone rubber Polyurethane Milky white material Clear material

Catheter design Three portions Cuffs Intraperitoneal Extraperitoneal External Cuffs Dacron material One or two

Placement of catheter Open surgical placement Peritoneoscopic placement Blind placement

Proper location of catheter Intraperitoneal portion Directed towards pelvis Cuff Deep: within medial or lateral border of rectus sheath Superficial: about 2 cms from skin exit

Composition of peritoneal dialysis fluid Sodium(mmol/L) 132-134 Potasium(mmol/L) 0-2 Calcium(mmol/L) 1.0-1.75 Magnesium(mmol/L) 0.25-0.75 Chloride(mmol/L) 95-106 Lactate(mmol/L) 35-40 Bicarbonate(mmol/L) 34 Bicarbonate/lactate 25/15 Glucose(g/dl) 1.36-4.25 lcodextrin(g/dl) 7.5 Amino acids(g/dl) 1.1

Osmotic agents Low molecular weight High molecular weight Glucose- 1.5%,2.5%,4.25% Glycerol Amino acids High molecular weight Albumin Glucose polymer peptides

Clearance Theoretical concept “Volume of plasma from which all the substance has been removed and excreted into the urine per unit time” Amount excreted = Urine volume x urine concentration Excretion rate = Urine volume x urine concentration Time

Clearance Example Clearance of a substance x Excretion rate = 100 mg/ml x 1 ml = 100 mg/min 1 minute Concentration of substance x in plasma = 1 mg/ml Amount of plasma cleared per minute = 100 mg/min = 100 ml 1 mg/ml Clearance = U x V T x P

Principles of Clearance

Principles of Clearance

Clearance of Inulin

Substance (L/wk) kidney H D standard High flux CAPD Urea 750 130 70 Vit B12 1200 30 80 40 Inulin 10 20 β2 Microg 1000 300 250

Small solute clearance Urea clearance (Kt/V) Normalised to total body water Creatinine clearance (CrCl) Normalised to body surface area

Total clearance Sum of Residual renal clearance Peritoneal dialysis clearance

Method of calculating dialysate clearance of urea 24 hr collection of peritoneal dialysate effluent Measure urea concentration in dialysate Estimate total urea content Urea concentration × volume of effluent Calculate clearance Kt = Urea content in dialysate Serum urea level

Method of calculating renal clearance of urea Collect 24 hr urine Measure urea concentration in urine Estimate total urea content Urea concentration × urine volume Calculate renal clearence of urea Kt = Urea content in urine serum urea level

Total and normalised clearance Total clearance Dialysate clearance + renal clearance Normalised clearance (Kt/V) Total body water

Calculate clearance A 50 yr old man weighing 66 Kg has no urine output. He is on CAPD with four 2.5 L exchanges daily. His blood urea is 160 mg/dl and dialysate urea concentration of 24 hr collection is 140 mg/dl.calculate his daily clearance

Complications of peritoneal dialysis Mechanical complication of catheter Catheter obstruction/inadequate drain Perforation and laceration of organs Peritoneal catheter leaks Infectious complications Exit site infection Peritonitis

Clinical presentation of peritonitis (percentages) Cloudy fluid 98-100 Abdominal pain 67-97 Abdominal tenderness 62-79 Fever 34-36 Chills 18-23 Nausea 30-35 Vomiting 25-30 Diarrhoea 7-15

Route of entry for peritonitis Touch contamination Catheter related Enteric Haematogenous Gynaecological

Organisms causing peritonitis Gram-positive Staphylococcus epidermidis Staphylococcus aureus Streptococcus Enterococcus Gram-negative Fungal Mycobacterial

Differential diagnosis of cloudy effluent Infectious peritonitis Eosinophilic peritonitis Sclerosing peritonitis Chylous ascites Malignant ascites Pancreatitis Chemical peritonitis

Treatment of peritonitis Antibiotics Intraperitoneal route Continuous Intermitent Intravenous route Pain control

Outcome and sequelae Resolution-60-90% Abscess formation-1% Transfer to hemodialysis(technique failure)-30% Sclerosing peritonitis-1-2% Death-1-6%

Types of peritoneal dialysis Manual CAPD-Continuous ambulatory peritoneal dialysis Automated CCPD-Continuous cyclic peritoneal dialysis NIPD-Nocturnal intermittent peritoneal dialysis TDP-Tidal peritoneal dialysis

TYPE CAPD 2-3 1-2 1-3 CCPD 1 3-4 NIPD 3-5 TDP 20 1-1.5 Day exchange Night Volume of exchange CAPD 2-3 1-2 1-3 CCPD 1 3-4 NIPD 3-5 TDP 20 1-1.5

Peritoneal transport assessment PET test Concentration of creatinine in dialysis solution at four hrs Concentration of creatinine in plasma at same time Ratio of dialysate creatinine to plasma creatinine is calculated Subject is classified into different transporter group

Improving outcomes: equal or better survival in first 2–3 years Better preservation of RRF versus HD Higher haemoglobin levels; less erythropoietin use Preservation of vascular access for HD Provides continuous UF for improved blood pressure and volume control Better outcomes post-transplant Less risk of acquiring blood borne virus (hepatitis C) Patient benefits including more flexible holidays and travel and higher employment rates; better quality of life than maintenance HD Ability to expand patient numbers in a dialysis centre with limited need for resources and major capital investments Lower staff to patient ratio than maintenance HD Less costly than maintenance HD