Peritoneal Dialysis and Complications

Question 1

How does peritoneal dialysis work?

Answer 1

Sterile PD solution (PD fluid) contains balanced concentration of electrolytes and osmotically active agent, introduced into peritoneal cavity via PD tube.

PD fluid bathes expansive network of capillaries over the surface area of the peritoneum.

Diffusion process
PD fluid has no waste - body solutes move down concentration gradients across peritoneal capillaries into PD fluid over time until near-equilibirum of uraemic solute reached between blood and PD fluid.

Ultrafiltration process
PD fluid osmotically active, draws fluid via ultrafiltration

Drainage
Drainage of PD fluid (dialysate effluent) removes waste and excess fluid, completing a cycle/exchange.

Exchange: cycle of infusion -> dwell -> drainage

Question 2

What are the advantages of PD compared to HD?

Answer 2

1. Flexibility and lifestyle choices - home-suitable RRT
2. Continouous removal of waste and fluid (similar to kidneys)
3. Better preservation of residual kidney function (and survival)
4. More haemodynamic stability and balanced tissue perfusion
5. Lesser rapid transcellular shifts of fluids and electrolytes
6. Preserves vasculature for future access for HD

Question 3

Peritoneal membrane transport is a __ transport of __ and __ across __ of peritoneal membrane.

__ between peritoneal capillary blood and PD fluid drives net transport, however patients have variable characteristics and speed as determined by __

Membrane transport can be classified as __, __, __ or __ as per PET.
- Fast transport patients should have __ dwell times
- Slow transport patients should have __ dwell times

Answer 3

Bidirectional transport of solutes and water across capillary walls of peritoneal membrane

Solute concentration gradient, peritoneal equilibration test (PET)

Slow, slow average, fast average, fast

Fast transport - shorter dwell times
Slow transport - longer dwell times

Question 4

PET is a standardised procedure for accessing __ and __ of patient’s membrane to excahnge small solute and fluid.

Uses a series of __ and __ samples obtained over 4 hour period to measure:
- Solute equilibration (D/P creatinine)
- Rate of glucose absorption
- Net fluid removal (ultrafiltration)

Done with 2.5% solution, but using 4.25% solution produces near identical diffusive result and provides additional information about maximal UF capacity

Answer 4

Permeability and efficiency

Dialysate and plasma

Question 5

Three-Pore Model for fluid and solute transportation

Answer 5

1. Intracellular aquaporins (water channel) - exclusively permeable to water
2. Inter-endothelial cells or “small” pores - respond to crystalloid and colloid osmotic forces, permeable to water and solutes smaller than albumin
3. Large inter-endothelial cellular pores (0.01%) - unresponsive to osmotic forces. Occurs by hydrostatic pressure. Responsible for protein leakage into peritoneal cavity

Question 6

What are the different methods of PD catheter placement?

Answer 6

1. Mini laparotomy dissective technique under GA
2. Modified Seldinger technique - bedside, no need GA
3. Lapasoscopic with direct visualisation and insertion - superior result

Question 7

What are the contraindications to PD?

Answer 7

1. Diaphragmatic defect
2. Abdominal defect (unfixable hernia, acute diverticulitis)
3. Patient refusal, caregiver unwilling or unable to learn

Question 8

CAPD: __

Answer 8

Continuous Ambulatory Peritoneal Dialysis

• Manual infuse and drain 2-3L of PD fluid for 3-4 times a day
• PD fluid dwell in peritoneal cavity for 4-6 hours for x3 daytime exchanges; 8-10 hours during overnight x1 exchange with EN
• PD continously for 24 hours a day
• +/- dry period for comfort or convenience

Question 9

APD: __

Answer 9

Automated peritoneal dialysis

• Cycler assist in administration and drainage of PD fluid
• Administer several exchanges at night while sleeping
• Final filling in the morning before disconnecting device (last fill with EN) that will remain in peritoneal cavity during the day
  (Continous cyclic PD / CCPD)
• If no last fill programmed = dry day
  (Nocturnal intermittent PD / NIPD)
  > for patients with residual kidney function

Question 10

A cycler is a mechanised device to assist in __ and __ of PD fluid, its use is termed __.

Patients with __ peritoneal membrane transport have improved outcomes using APD compared to CAPD.

Advantages (3)

Answer 10

Administration and drainage, APD

Fast

Advantages:
1. Lower risk of contamination and peritonitis
2. Reduces manual labour
3. Better survival

Question 11

PD solution contains __ and __ to draw fluid via ultrafiltration

Describe the electrolyte composition:
Sodium, chloride, potassium, calcium, magnesium

Tradirional buffer: lactate (not bicarbonate) to prevent __
What is the overall pH? How is lactate PD solution metabolised?
What are the contraindications for lactate buffer PD solution?

New bicarbonate buffer - how is it stored?
What are the advantages?

Answer 11

Physiologically balanced electrolyres and osmotically active agent

Sodium: 132 mEq/L
Chloride: 95-105 mEq/L
Potassium: nil - can be manually added using sterile technique
Calcium: 2.5-2.5 mEq/L
Magnesium: 0.5 mEq/L

Lactate prevents precipitation of calcium and magnesium
Lactate 40 mEq/L
Overall pH 5.2 to 5.5

pH rapidly rises to physiologic level above 7 in about 15 minutes of infusion
Lactate is absorbed and converted to bicarbonate by healthy liver
Contraindicated in severe lactic acidosis, liver cirrhosis

New: bicarbonate base buffer with pH 7.4
Achieved by separating bicarb from Ca and Mg using dual chambered PD container, until just before infusion
Advantages: lesser pain during infusion, more physiologic

Question 12

D-glucose in PD solution
- Available concentration
- Mechanism of action in ultrafiltration
- Factors influencing gradient dissipation

What is biocompatible PD solution?

Answer 12

D-glucose in PD solution: 1.5%, 2.5%, 4.25%
(corresponding to 346, 396, 478 mOsm/kg)
(higher glucose % provides higher ultrafiltration)

Glucose increases osmolality to augment ultrafiltration via osmotic gradient
As glucose is absorbed by peritoneal capillaries, osmotic gradient dissipates over time

Factors influencing gradient dissipation:
1. Lower concentration of dextrose
2. Large peritoneal capillary network (fast membrane transport)

Most PD solutions are bioincompatible
- Glucose-containing, hyperosmolar, lactate buffered and below physiologic pH
- Contains glucose degradation products (GDPs)
–> Fibrotic and microvascular changes in peritoneal membrane over time of chronic exposure

Question 13

Lymphatic absorption of PD fluid is __ (rate __), which may exceed transcapillary UF, thus in long exchange dwell times it may lead to __ or even __

Answer 13

Constant (1-2mL/min), poor fluid removal, net negative fluid balance (PD fluid drained out lesser than when infused in due to absorption)

Question 14

Alternative osmotic agents in PD

Answer 14

1. Icodextrine (Extraneal EN)
   - Baxter patented
   - Very large molecular weight (increases oncotic pressure)
   - Osm 282, pH 5.2
   - Not absorbed (minimally absorbed via lymphatics), thus not attenuated over time
   - Ideal for long daytime APD or nighttime CAPD
2. Amino acids (Nutrineal NN)
   - Glucose free
   - Osm 365, pH 6.4

Question 15

Icodextrin and interference with blood glucose monitoring

Answer 15

Even though icodextrin is minimally absorbed via peritoneal lymphatics, it undergoes metabolism by amylase into maltose

Maltose metabolites do not return to baseline values for at least 2 weeks following complete cessation of icodextin use

Maltose may interfere and mask hypoglycaemia by providing falsely elevated blood glucose reading

BGM monitoring with glucose-specific POCT or laboratory test

Question 16

How to prescribe PD?

Answer 16

1. Method: CAPD or cycler APD
2. PD fluid content (glucose 1.5%, 2.5%, 4.25% or EN)
3. Total number of exchanges
4. Dwell duration
5. Fill volume
6. Dry day/night vs EN fill

Question 17

Tidal APD is a technique to retain __ in the cavity, with partial fill volumes delivered for subsequent cycles to reach prescribed total volume.

Usages (2)

Answer 17

Constant residual volume of PD fluid (eg: 200mL)

Usages:
1. Reduces draining pain by providing “cushion” of PD fluid between catheter and pelvic organs
2. Improves end PD drainage which may slow down due to pelvic structures impeding flow at low peritoneal fluid volumes

Question 18

Dietary modifications in PD

Answer 18

1. Liberal potassium intake (PD causes hypokalaemia)
2. High protein diet (PD catabolic effect and effluent loss 5-15g)

Question 19

PD exit site infection
PD tunnel infection
Prevention of PD site infection

Answer 19

PD exit site infection - purulent drainage with/without skin erythema around catheter exit site

PD tunnel infection - involvement of catheter tunnel beyond superficial cuff, with erythema, oedema, tenderness, fluid collection over subcutaneous course of catheter.

PD catheter is inflated with double balloon. The exit site to peritoneum is not very far apart.

Prevention of PD site infection
1. Proper placement of PD catheter
2. Exit site clearly seen by patient
3. Downward or lateral facing (to prevent funneling of dirt or cellular debris)
4. Not buried in panniculus or abdominal skinfold
5. Prophylactic antibiotics prior to placement
6. Avoid anchoring sutures
7. PD catheter covered, cleaned, dry and undisturbed
8. Staff and patient training, handling with aseptic technique
9. Mupirocin or gentamicin cream to exit site

Question 20

What are the common microorganisms causing exit site infection?
What is the appropriate antibiotics for exit site infection?

Answer 20

1. Staphylococcus aurues
2. CONS
3. Pseudomonas aeruginosa
4. Other gram negative organisms

Antibiotics should cover SA and P. aeruginosa, fungal
- First generation cephalosporin (gram positive)
- Quinolones (gram negative, antipseudomonal)
- Nystatin (antifungal) until 1 week after antibiotics

Question 21

What is peritonitis?
How are the organisms transmitted into peritoneum?

Answer 21

Inflammation of peritoneal membrane from infection or non-infectious cause. Presents as abdominal pain, fever and cloudy PD effluent

ISPD 2023 guideline: 2 out of 3 criterias
1. Clinical: cloudy dialysate, abdominal pain
2. PD cell count > 100 cells/uL, > 50% neutrophils - true for bacterial, TB
3. Positive culture

Portal of entry:
1. Touch contamination
2. Extension of infection from around PD catheter (exit site, tunnel tract)
3. Transluminal migration across bowel wall - constipation, bowel clearance, scopes
4. Haematogenous seeding from bacteraemia or sepsis

Question 22

What are the differential diagnoses of abdominal pain and cloudy effluent?

Answer 22

1. PD Peritonitis
2. Ruptured viscus
3. Diverticulitis
4. Cholecystitis
5. Ischaemic bowel
6. Pancreatitis

Question 23

How do you investigate the PD effluent?

Answer 23

Drain from existing PD fluid that has dwelled for > 2 hours
If existing fluid already drained, fill fresh PD fluid and dwelled at least 2 hours

1. Cell count/cytospin
2. Microscopy - budding yeast,hyphae (fungal peritonitis)
3. Gram stain and culture

Question 24

How do you diagnose PD peritonitis?

Answer 24

ISPD 2023 Guideline

1. Abdominal pain or cloudy effluent
2. PD fluid: > 100/mm3 leukocytosis with at least 50% PMN cells
3. Positive culture

Question 25

Prevention of peritonitis, management of peritonitis

Answer 25

_Prevention_ 1. Measures to reduce exit site infections 2. Flush before fill connectology 3. Avoid constipation - reduces transmigration 4. Dry day during procedures 5. Antibiotics prophylaxis before procedures 6. Vitamin D replacement _Treatment_ 1. IV or IP antibiotics - 3rd gen cephalosporin, aminoglycoside, vancomycin or 1st gen cephalosporin 2. Nystatin coverage until 1 week completion of antibiotics 3. Removal of catheter within 5 days if failure to clear

Question 26

What are the common fungal peritonitis? What is the treatment? What is the progosis?

Answer 26

_Fungal peritonitis_ 1. Candida albicans 2. Candida parapsilosis Predisposing: recent antibiotics treatment Diagnosis: microscopy or culture _Treatment_ 1. Initial IV amphotericin B -> tailored (ampho has poor penetration, chemical peritonitis) 2. PO flucytosine 1000mg/day 3. Oral nystatin up to 1 week completion of antibiotics - prevention of fungal peritonitis post-bacterial peritonitis 4. Removal of PD catheter _Prognosis_ Death in 25% affected High frequency of PD failure

Question 27

What are the indications for removal of PD catheter?

Answer 27

1. Refractory peritonitis (failure to clear after 5 days antibiotics) 2. Relapsing peritonitis (same organism within 4 weeks completion of therapy of previous episode) 3. Repeat peritonitis (same organism > 4 weeks after previous) 4. Exit site or tunnel infection failing to respond to treatment 5. Fungal peritonitis 6. Multi-enteric organism peritonitis (esp anaerobic)

Question 28

What are the causes of relapsing or repeat peritonitis?

Answer 28

1. Inadequate treatment (insufficient MIC) 2. Continued nidus of infection (catheter biofilm)

Question 29

Pericatheter leak occurs when __ is not confined to peritoneal cavity, __ around __ or __ crossed by PD catheter. Leakage around catheter exit site presents with __, while leakage around rectus muscle sheath or Scarpa's fascia results in __ Risk factors of pericatheter leak (3) Patent processes vaginalis, inguinal or periumbilical hernia can result in __ Tendinous defects in diaphragm can result in __, especially when positive __ and negative __ results in __ (condition) Consequences of pericatheter leak (4)

Answer 29

Dialysis fluid and ultrafiltrate, leaks around entrance site or across the abdominal wall tissue planes Moisture or clear fluid over exit site, pericatheter oedema Risk Factors 1. Median catheter placement 2. Excessive volume of PD fluid relative to timing of placement 3. Intrinsic abdominal weakness (children, physical straining, obesity, long term steroids) Genitalia oedema Collection of fluid within thoracic cavity, positive abdominal pressure and negative intrathoracic pressure, PD hydrothorax _Consequences of pericatheter leak_ 1. Decreased UF 2. Increased weight 3. Localised swelling 4. Shortness of breath

Question 30

Management of pericatheter leak

Answer 30

1. Hold PD for 1-2 weeks to allow more time for healing 2. Reduce dwell volume 3. Interim supine PD, abdomen dry while sitting, upright or ambulatory 4. Antibiotics prophylaxis 5. Transfer to HD temporarily 6. Surgical correction of PD catheter, diaphragmatic defect

Question 31

What are the causes of infusion pain? What are the causes of drainage pain? What are the management of infusion/drainage pain?

Answer 31

_Infusion pain_ 1. Inappropriately cool or warm PD solution 2. Peritoneal sensitivity to slightly acidic pH 3. Visceral pain to directed jet stream of PD fluid 4. Malpositoned PD catheter against viscera _Drainage pain_ 1. Siphoning effect on viscera / catheter positioning 2. Constipation - expanded intestinal diameter _Management_ 1. Use neutral pH PD solution or compartmented bicarbonate PD solution 2. Small residual volume at end of drain phase (tidal APD)

Question 32

Poor PD flow can be __ or __. Bidirectional flow problems are due to __ Unidirectional flow problems are due to __, __ Commonest problem: __ Fibrin or blood occlusion can be treated with __ or __ or __

Answer 32

Bidirectional or unidirectional Bidirectional: clot, fibrin, kink or bend in catheter Unidirectional: malposition, encumbrance of catheter drainage pores by tissue or viscera Commonest problem: constipation Heparin 500 to 2000 units/L added to dialysate Push-pull infusion with moderate pressure rtPA (anecdoctal evidence)

Question 33

Hypokalaemia is common in PD due to __ and __ It can be precipitated by __, __ Prevention of hypokalaemia with __ or __ (dose)

Answer 33

Continous nature of PD therapy, lack of potassium in PD fluid Poor oral intake, transcellular shift due to peritoneal glucose Liberal potassium diet or supplement, IP potassium up to 4mEq/L

Question 34

Hypoalbuminaemia is more profound in PD than HD due to __ Albumin is a __ thus it is important to evaluate for sources of inflammation in hypoalbuminaemia. Albumin may also be __, thus important to evaluate for volume overload

Answer 34

Loss of albumin 6-8g/day in effluent Negative acute phase reactant Diluted by expanded intravascular volume

Question 35

What procedures require prophylactic antibiotics in PD patients?

Answer 35

1. Colonoscopy, OGDS 2. Uteroscopy 3. Nasoendoscopy 4. Dental procedures 5. Surgical procedures, except eye Procedures that do not require antibiotics cover: - Vaginal exam, speculum, transvaginal ultrasound - Eye operation without significant blood exposure or trauma

Question 36

Fungal peritonitis prophylaxis in PD patients

Answer 36

Given if PD patient on antibiotics for 3 or more days **PO Nystatin 1,000,000 units (10mL) BD direct swallow** - until 1 week after completion of antibiotics (No need swish in mouth as not treating for oral thrush) (Do not give as 5mL QDS)

Question 37

What are the differentials of abdominal pain with clear PD effluent?

Answer 37

_PD cycle related_ 1. Inflow pain - cold acidic PD fluid 2. Drain pain - Omental or fallopian tube wrap - PD catheter malposition - Sensitive to APD suction _Non-PD cycle related_ 1. Strangulated hernia 2. Hydrocoele 3. Torsion 4. Surgical abdomen 5. Others

Question 38

Why do PD patients frequently have hyponatraemia?

Answer 38

PD fluid Na: 132mmol/L Serum Na is likely close or equilibrise to mild-moderate hyponatraemia if: - Patient is adherent to regular PD - Sodium intake restricted - Water intake not excessive - No significant residual kidney function to excrete sodium or water No need to investigate mild to moderate hyponatraemia (125-135) in PD patients, unless clinically indicated/symptomatic or very severe hyponatraemia (<120)

Question 39

What are the causes of primary PD peritonitis?

Answer 39

_Exogenous_ 1. Wet touch contamination during exchanges 2. Extension of PD catheter exit site/tunnel tract infection 3. Non-adherence to flush before fill procedure in CAPD 4. Non-adherence to topical antibiotics and exit site care _Endogenous_ 1. Constipation 2. Aggressive PEG use in constipation 3. Colonoscopy 4. Uteroscopy 5. OGD 6. Bacteraemia from other sites