Peritoneal dialysis

Question 1

Peritoneal dialysis

Answer 1

Need to have some residual renal function- some quality of urine output inc some waste products
Loss of residual renal function- inflammation, CV, uremi leads to anorexia cachexia syndrome leads to protein energy wasting, leads to increased testing hypermetabolism with reduced energy intake

Blood is purified inside peritoneum (membrane that lines the abdominal cavity). Abdomen is filled with dialysis fluid via a catheter. The fluid then removes toxins and water from the blood through the peritoneum

Question 2

PD diet

Answer 2

Energy: 146kj/kg/IBW including glucose from dialysate
Protein: min 1.2g/of IBW (>50% HBV) Acute illness >1.3g/kg/Ibw
Peritonitis 1.5g/kg IBW
Sodium: individual treatment (if restricted 80-119mmol/L)
Potassium: individual treatment (1mmol/kg/IBW)
Phosphorous: individual treatment (if restricted 800-1000mg/d)
Fluid: individual treatment: if fluid overloaded, 800ml + PDUO
Biochemical and clinical goals: stabilise urea and creatinine, aim normal albumin, lipids K 3.5-5.5mmol/L

Question 3

Peritoneal dialysis energy

Answer 3

Energy requirements 125-146kj/kg/d 
Energy from dialysate: 
- 120-130g/d glucose supplied during PD 
% absorption 
- APD 40% (shorter dwell times)=0.4 
-CAPD 60% (longer dwell times) =0.6 
Lcodextein 25-40% 
Glucose concentration dialysate 
1.5% = 15g/L 
Icodextrin 7.5% = 75g/L 

Sample calc:
APD regime: 2 x 6L 1.5% + 17kj/ g CHO
Therefore 15g/L x 12L x 0.4 x 16kj/ g = 1150kJ

Question 4

PD protein

Answer 4

1.2g/kg
High requirements due to losses 4-8g/ d (APD) and 5-15g/d CAPD - high transporter is at higher risk of losses (membrane)

AA losses relative to transperitoneal transport of small molecular weight solutes and dependent on the number of exchanges
25% AA losses are EAAd
Protein and AA losses increase in peritonitis
Strong correlation between transport status and protein losses
Intraperitoneal AAs can improve nutritional status (Alb, preAlb, transferring) in malnourished PD patients who fail to meet protein intake targets
Very expensive cf oral protein supplements

Question 5

PD peritonitis

Answer 5

During peritonitis protein losses increase 50-100%
Protein losses on average 15g/ 24 he and can remain elevated for 2-3 weeks after resolution of infection
Negative N balance, inflammation -> net reduction in albumin
Spontaneous energy and protein intakes decreased
Recurrent peritonitis can lead to decline in nutritional status, membrane permeability and technique failure

Question 6

PD practice tips

Answer 6

• potassium
  Hyperkalaemia less common in PF than HDX due to continuous nature of dialysis (some have hypokalaemia)
  Diet- not enough?
  Leaking into peritoneal and being removed by dialysis
• weight
  Wt gain common especially in first 12/12. May be beneficial in CKD patients who have lost weight prior to PD
• hyperglycaemia
  Common due to glucose in dialysate
  Dose modification for OHAs and insulin
  Intraperitoneal insulin?
  Usual diabetes recommendations are suitable but may reduce oral CHO load overall
• abdominal distension
  Initially may be related to fluid in peritoneum but this usually settles in first few weeks
• under dialysis- uremic toxicity

Question 7

PD cautions

Answer 7

• inflammation
  Presence of inflammation associated with reduced dietary energy and protein intake in PD patients strict fat restricted diets not indicated but general healthy eating principles apply
• constipation
  Common in fluid restricted populations
  Can affect the way dialysate fluid grains by placement of tenchkoff catheter
  Aim for 1-2 bowel movements per day encourage fruit and veg including dried fruits. High fibre breads and cereals also useful but should watch phosphate levels