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Boards: Urinary/Renal > Peritoneal Dialysis. Bersenas. 2011. JVECC > Flashcards

Peritoneal Dialysis. Bersenas. 2011. JVECC Flashcards

1
Q

What are the 3 physical properties used to to exchange fluid and solute in Peritoneal Dialysis?

A
  • diffusion
  • convection
  • osmosis
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2
Q

Explain how intravascular fluid is removed in peritoneal dialysis.

A

fluid exchange occurs by osmosis
* osmotic gradient between peritoneal capillary blood and dialysate in peritoneal space (i.e., dextrose)
* movement of water via osmotic gradient is referred to as “ultrafiltration”

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3
Q

Explain diffusion in peritoneal dialysis. What does it remove, how does it work?

A

waste products (solutes; e.g., Urea) are in higher concentration in the blood compared to dialysate and will therefore move into dialysate following its concentration gradient

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4
Q

What does the rate of diffusion in PD depend on?

A

solute diffusion across the peritoneum depends on the size, the charge, and the concentration gradient of the solute.

Urea, molecular weight 60 Daltons, diffuses faster than creat (113 Dalt)

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5
Q

How does convection remove solutes in PD?

A

Convection is the passive movement of solutes across a membrane with the water that is moving

quantities will be similar to that of plasma cc, additional removal

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6
Q

What are the indications for Dialysis?

A
  • A Acidosis, pH < 7.1
  • E Electrolytes, K > 6.5 mEq/L
  • I Intoxications
  • O overload with fluid, refractory to diuresis
  • U uremia, severe
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7
Q

What are advantages of PD over venovenous RRT?

A
  • technical simplicitiy
  • good cardiovascular tolerance
  • absence of extracorporeal circuit
  • decreased risk of bleeding
  • lower risk of dialysis disequilibrium syndrome, decline of uremic toxins more gradual
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8
Q

What are contraindications for PD?

A

absolute:
* peritonitis
* vascular leak states
* severe hypoalbuminemia
relative:
* recent surgery
* hernias
not recommended in:
* severe coagulopathy
* peritoneal fibrosis or adhesions*

*precluding solute exchange or preventing fluid distribution throughout abdomen

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9
Q

What does conventional PD solution contain?

A
  • glocuse (high osmolarity)
  • lactate
  • sodium
  • potassium
  • calcium

commonly low pH

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10
Q

Why has there been a trend towards increasing/neutrolizing the pH of PD dialysate and how is this achieved?

A

reactions/pain to PD solution infusion has been associated with the lower pH
* newere, pH neutral solutions containing lactate and/or bicarbonate has shown preservation of periotoneal cells and better tolerance by patients

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11
Q

Why are Plasmalyte A and Normosol R not recommended as base for PD dialysate?

A

contain acetate
* use of acetate has been discontinued because it is associated with loss of ultrafiltration and sclerosing peritonitis

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12
Q

What solute in the dialysate may be adjusted to increase or decrease fluid removal?

A

dextrose concentration to increase or decrease osmolarity and therefore water movement

use lowest dextrose concentration/lowest osmolarity meeting the fluid removal requirements of the patient

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13
Q

What are complications (other than long term) of too high dextrose concentration in the PD dialysate?

A
  • severe dehydration and hypovolemia (too much water pulled)
  • protein loss
  • causes short-lived ultrafiltration after absorption through peritoneal membrane
  • metabolic complications (hyperglycemia, hyperinsulinemia, low glucagon, hyperlipidemia, weight gain)
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14
Q

What are long term complicatios of dextrose in dialysate in chronic PD?

A
  • cytotoxic glucose degradation products (GDPs) accumulate
  • GDPs react with amino acids and produce advanced glycosylation end products (AGEs)
  • AGEs cause fibrosis of the peritoneal membrane
  • fibrosis of peritoneal membrane causes ultrafiltration failure
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15
Q

Name 2 alternatives to dextrose in PD dialysate solution and name their limitations

A

Icodextrin (colloid) has less absorption through peritoneal membrane
* limitations: slow ultrafiltration
Amino acids has assumed positive nutritional status
* limitations: low pH worsening acidosis, increased urea load

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16
Q

Why is normal saline (0.9% NaCl) not recommended for long-term PD but only for short-term PD

A

predisposes to the formation of peritoneal adhesions and fibrosis

17
Q

How much 50% dextrose do you add to a 1 L bag to create a 1.5, 2.5, or 4.25% dextrose solution?

A
  • 1.5% = add 30 mL
  • 2.5% = add 50 mL
  • 4.25% = add 85 mL
18
Q

What should be added additionally if 0.9% saline is used as a base fluid instead of LRS

A

add 30-45 mmol/L (mEq/L) of sodium bicarbonate as buffer

19
Q

What is the recommendation for heparin in PD dialysate

A

500 U heparin/L added during initial exchanges and up to 5 d thereafter
* added to decrease clot formation and improve dialysate outlfow

20
Q

What is the recommended dwell time?

A

20 min to 6 hours

in human medicine
depends on the renal status of the patinet

21
Q

What is the recommendation for dialysis-free period after catheter insertion?

A

10-15 days when possible

impractical in the setting of AKI when hemodialysis is not available
immediate catheter use is common, even in human medicine

22
Q

What is the dose for initial dialysate volume and how fast do you administer it?

A

10-20 mL/kg*
give by gravity flow or over 5-10 minutes with an IV infusion pump

*to decrease the risk of dialysate leakage and cardiovascular complications
during infusion monitor for discomofrt, nausea, respiratory compromise

23
Q

What is the initial dialysate dwell time?

A

author recommends 45 min, but other recommendations may say shorter (30-40 min)

24
Q

How do you drain dialysate fluid?

A

drain the fluid by gravity over ~ 15 min

25
Q

How frequently should you perform exchanges?

A

repeat infusion, dwelling, and drainage every hour until patient improves and stabilizes

26
Q

When do you increase the amount of infused dialysate?

A

after 24 hours of hourly 10-20 mL/kg the dialysate can be increased to 30-40 mL/kg

this may cause discomfort or respiratory distress, and close monitoring is required

27
Q

Explain why fluid removal is highest at the beginning of exchange and becomes less effective towards the end of the exchange

A

the osmotic gradient between dialysate and peritoneal capillary blood is highest initially and then dissipates due to absorption of glucose from dialysate and due to dilution of glucose in dialysate by movement of fluid into dialysate

28
Q

What are 3 ways you can utilize to increase the amount of fluid removal during periotenal dialysis?

A
  • increase the glucose concentration in the dialysate
  • increase the frequency of exchange
  • decrease the dwell time of exchanges
29
Q

What is the most important determinant of solute exchange?

A

The volume of dialysate administered

As the fill volume increases, more surface of the highly vascularized peritoneal membrane is available for solute exchange

30
Q

If large volume of dialysate is not tolerated how can solute removal be increased?

A

Increase the number of exchanges

31
Q

What is the general rule of thumb for infusate versus effusate volume depending on dextrose concentration

A

1.25% –> get as much back as you’re infusion
2.5% and 4.25% –> get back more than infused

32
Q

How do you trouble shoot reduced effusate compared to infusate volume

A
  • patient may be dehydrated –> rehydrate
  • check for catheter occlusion
  • reposition patient to allow for better drainage
  • in euhydrated patient can consider reinfusion one dose volume
33
Q

What are the contraindications to renal biopsies?

A
  • uncontrollable coagulopathy
  • severe anemia
  • hydronephrosis
  • uncontrolled hypertension
  • large or multiple renal cysts
  • perirenal abscess
  • extensive pyelonephritis
  • end-stage renal disease
34
Q

List complications from PD

A
  • catheter obstruction and migration
  • dialysate leak
  • inadequate dialysis
  • development of hypoalbuminemia
  • electrolyte abnormalities
  • pelvic limb edema
  • pleural effusion
  • catheter exit-site infection
  • periotonitis
35
Q

What are the causes of hypoalbuminemia in PD?

A
  • low dietary intake
  • gastrointestinal or renal protein loss
  • loss of protein into the dialysate
  • uremic catabolism
36
Q

How could parenteral nutrition impair peritoneal dialysis?

A

may lead to hyperglycemia which will reduce diffusion/ultrafiltration and solute clearance

37
Q

What is the earliest sign of probable peritoneal infection?

A

turbidity of effluent

38
Q

How is peritoneal infection empirically treated in PD patients?

A

additional of antimicrobials to dialysate
* intraperitoneal route is more effective than IV route in preventing treatment failure
* add first generation cephalosporin to dialysate as loading dose of 1,000 mg/L and then maintenance of 250 mg/L of dialysate

Boards: Urinary/Renal (14 decks)

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