Dialysis

Question 1

short term objectives of dialysis

Answer 1

• Correct electrolyte balance
• Correct metabolic acidosis
• Correct fluid state
• Remove toxins

Question 2

longer term objectives of dialysis

Answer 2

• Optimise the patients functional status
• Control BP
• Prevent uraemia and its complications
• Improve survival

Question 3

what medication must be given with dialysis

Answer 3

anti coagulation (usually heparin) to prevent thrombosis in the blood circuit

Question 4

how efficient is dialysis

Answer 4

• not very, a longer treatment is needed for better efficiency - can never have enough but must strike a balance with QOL

Question 5

minmum treatment

Answer 5

• 4h/3d/week
• Decreasing dialysis increases morbidity, and increasing it although having a potentially better survival, impairs QOL

Question 6

patient restrictions whilst on dialysis

Answer 6

• fluid restriction - 1l per day if anuric
• salt restriction - reduces thirst and helps with fluid balance
• low potassium diet
• low phosphate diet and phosphate binders - phosphate in particular is not well removed by dialysis

Question 7

gold standard dialysis access

Answer 7

• fistula - joins an artery and vein to make an enlarged thick walled vein called an arteriovenous fistula

Question 8

pros and cons of AV fistula

Answer 8

• pros: good blood flow and unlikely to cause infection
• cons:
  
  • requires surgery
  • needs to mature for around 6-12 weeks before use
  • can block
  • can cause steal syndrome

Question 9

steal syndrome

Answer 9

• ischaemia resulting from a fistula
• features: pale, pallor, reduced wrist-brachial index, dec pulse
• can cause ischaemic ulcers and necrosis

Question 10

tunneled venous catheter

Answer 10

• used in situations where immediate access is required eg acute deterioration from CKD
• catheter inserted into a large vein eg jugular, subclavian or femoral

Question 11

indications for emergency dialysis

Answer 11

• Bloods: severe resistant hyperkalaemia (>7), GFR<5, Ur>45, unresponsive acidosis
• Refractory fluid overload due to oliguria – pulmonary oedema
• Uraemic symptoms: nausea, seizure, pericarditis, bleeding
• Toxins/drugs

Question 12

cons of tunneled venous catheter

Answer 12

• high risk of infection - endocarditis, discitis
• can damage veins making replacements difficult
• can become blocked

Question 13

what tends to cause infections in haemodialysis, and management

Answer 13

• S. Aureus is a major concern, tends to be skin commensals
• Investigation: blood culture, FBC and CRP, exit site swab
• Management: ABx (vancomycin – is dialyzable, cleared by renal excretion), line removal or exchange

Question 14

potential complications of haemodialysis

Answer 14

• steal syndrome
• infection
• thrombosis
• stenosis
• hypotension
• fluid overload
• blood leaks
  
  • fistulas can rupture
• loss of vascular access
• hypo/hyperkalaemia and cardiac arrest

Question 16

how doe haemodialysis often lead to hypotension

Answer 16

removal of large volumes of water at a time can lead to under filling of the intravascular space and low BP

Question 17

myocardial stunning

Answer 17

• can occur on haemodialysis after hypotension causes low coronary perfusion
• cardiac dysfunction that persists after reperfusion in the absence of irreversible injury

Question 18

why is it important to gradually increase session length

Answer 18

• Risk of dysequilibrium syndrome if correction is too quick - can cause cerebral oedema and brain herniation
• Clinical signs of cerebral oedema are focal neurological deficits, papilloedema, decreased level of consciousness.

Question 19

peritoneal dialysis

Answer 19

• the peritoneal membrane is used as a semi permeable membrane
• water removal by osmosis is driven by the high glucose concentration in the dialysate fluid

Question 20

what are the consequences of glucose driven osmosis in peritoneal dialysis

Answer 20

• patients put on weight
• diabetic control worsens

Question 21

APD

Answer 21

• 1 bag of fluid stays in all day
• An overnight machine drains fluid etc. for 9-10 hours per night

Question 22

CAPD

Answer 22

• Requires 4 bag exchanges per day – fluid drained and fresh fluid instilled
• Each exchange takes around half an hour

Question 23

complications of PD

Answer 23

• infection - peritonitis or at exit site
• can be due to contamination (often from skin) or gut bacterial translocation
• managed with ABx, and may need to remove catheter

Question 25

membrane failure with PD

Answer 25

• inevitable after a few years
• patients become fluid overloaded and uraemic due to inability to remove enough water and urea
• must switch to HD

Question 26

hernias

Answer 26

• often occur in PD due to the increased intra abdominal pressure
• hernias require repairing and less volume will be used the next time to prevent recurrence

Question 27

when do most patients start dialysis

Answer 27

Patients tend to start when GFR reaches 10 or 15 if they are diabetics. Argument to leave it for as long as possible.

Question 28

what is the most common cause of death in RRT

Answer 28

• cardiovascular disease: 20%
  
  • MI and CVA are much more common in dialysis patients, thought to be due to hypertension and calcium/phosphate dysregulation.

Question 29

malignancy in dialysis patients

Answer 29

more common