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Nephrology > Peritoneal Dialysis and Complications > Flashcards

Peritoneal Dialysis and Complications Flashcards

1
Q

How does peritoneal dialysis work?

A

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

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2
Q

What are the advantages of PD compared to HD?

A
  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
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3
Q

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

A

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

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4
Q

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

A

Permeability and efficiency

Dialysate and plasma

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5
Q

Three-Pore Model for fluid and solute transportation

A
  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
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6
Q

What are the different methods of PD catheter placement?

A
  1. Mini laparotomy dissective technique under GA
  2. Modified Seldinger technique - bedside, no need GA
  3. Lapasoscopic with direct visualisation and insertion - superior result
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7
Q

What are the contraindications to PD?

A
  1. Diaphragmatic defect
  2. Abdominal defect (unfixable hernia, acute diverticulitis)
  3. Patient refusal, caregiver unwilling or unable to learn
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8
Q

CAPD: __

A

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
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9
Q

APD: __

A

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
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10
Q

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)

A

Administration and drainage, APD

Fast

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

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11
Q

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?

A

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

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12
Q

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

What is biocompatible PD solution?

A

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

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13
Q

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

A

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

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14
Q

Alternative osmotic agents in PD

A
  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
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15
Q

Icodextrin and interference with blood glucose monitoring

A

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

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16
Q

How to prescribe PD?

A
  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
17
Q

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)

A

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

18
Q

Dietary modifications in PD

A
  1. Liberal potassium intake (PD causes hypokalaemia)
  2. High protein diet (PD catabolic effect and effluent loss 5-15g)
19
Q

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

A

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

20
Q

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

A
  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

21
Q

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

A

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

22
Q

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

A
  1. PD Peritonitis
  2. Ruptured viscus
  3. Diverticulitis
  4. Cholecystitis
  5. Ischaemic bowel
  6. Pancreatitis
23
Q

How do you investigate the PD effluent?

A

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
24
Q

How do you diagnose PD peritonitis?

A

ISPD 2023 Guideline

  1. Abdominal pain or cloudy effluent
  2. PD fluid: > 100/mm3 leukocytosis with at least 50% PMN cells
  3. Positive culture
25
Q

Prevention of peritonitis, management of peritonitis

A

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

26
Q

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

A

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

27
Q

What are the indications for removal of PD catheter?

A
  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)
28
Q

What are the causes of relapsing or repeat peritonitis?

A
  1. Inadequate treatment (insufficient MIC)
  2. Continued nidus of infection (catheter biofilm)
29
Q

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)

A

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

30
Q

Management of pericatheter leak

A
  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
31
Q

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

What are the management of infusion/drainage pain?

A

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)

32
Q

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 __

A

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)

33
Q

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

A

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

34
Q

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

A

Loss of albumin 6-8g/day in effluent

Negative acute phase reactant

Diluted by expanded intravascular volume

35
Q

What procedures require prophylactic antibiotics in PD patients?

A
  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

36
Q

Fungal peritonitis prophylaxis in PD patients

A

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)

37
Q

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

A

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

38
Q

Why do PD patients frequently have hyponatraemia?

A

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)

39
Q

What are the causes of primary PD peritonitis?

A

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

Nephrology (9 decks)

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