Renal replacement therapy Flashcards
Renal disease is associated with higher gastrointestinal risk. T/F
False - higher CVS risk
Describe the very basics of dialysis
Diffusion through a semi permeable membrane down a concentration gradient until equilibrium is reached
Dialysis allows the removal of four main toxins, name them
Potassium
Sodium
Urea
Creatinine
What is given to patients during dialysis? Why is this given?
Bicarbonate infusion
Patients become acidotic as hydrogen cannot be secreted into the urine
How fast does blood flow through a haemodialysis machine? How is this relevant?
300ml/min
You can’t get this amount of blood through simple IV access
Which type of vascular access is needed in haemodialysis?
Arterovenous fistula
Tunneled venous catheter
How is hypoglycaemia avoided in haemodialysis?
Glucose is given to patients during dialysis
Describe the haemodialysis circuit
Water in –>
Reverse osmosis machine (purifies) –>
Dialysis through semi-permeable membrane –>
Waste removed and disposed
How is waste removed in haemodialysis?
Convection/filtration - movement of water across semipermeable membrane in response to a pressure gradient (negative pressure created by vacuum)
What is the GFR of patients on haemodialysis?
10-20 (i.e shitty)
What is the minimum time and frequency of haemodialysis?
3 times a week for four hours
Why are patients not given haemodialysis for longer?
Quality of life would be greatly reduced
What restrictions does haemodialysis put on patients?
1 litre fluid intake if anuric
Low salt diet (reduce thirst)
Low potassium diet
Low phosphate diet +/- phosphate binders with meals
Which foods are rich in potassium?
Banana’s
Chocolate
Potatoes
Avocado
Which foods are high in salt?
Baked beans
Bread
Processed food
What type of patients suffer the most from dietary restrictions on haemodialysis?
Diabetics (super restricted diet)
Which foods are high in phosphate?
High protein foods (i.e meats)
Diet coke
Ready made meals
List some phosphate binders
Calcium
Aluminium
Magnesium
Lanthanum salts
Are AV fistulas likely to cause infection?
Nope
How long do AV fistulas take to mature?
6 weeks
At which sites can a tunnelled venous catheter be placed?
Jugular
Subclavian
Femoral
What is the major risk with tunnelled venous catheters?
Infection (usually staph. aureus)
Which types of infections tend to arise from tunnelled venous catheters?
Endocarditis
Discitis
How is tunnelled venous catheter infection treated?
Vancomycin
Removal of line +/- replacement
How are suspected tunnelled venous catheter infections treated?
Blood cultures
FBC
CRP
Exit site swab
How do patients with tunnelled venous catheter infections present?
Rigors with dialysis
What are the complications of haemodialysis?
Fluid overload Blood leaks Loss of vascular access Hypokalaemia + cardiac arrest Intradialyic hypotension
What should NOT be given to haemodialysis patients with fluid retention? What should be done?
Frusemide (cannot produce urine or pee) or any other diuretic
Dialysis
Blood leaks from haemodialysis can cause what?
Massive haemorrhage and death
How does intradialyic hypotension arise?
Too much fluid removed from intravascular space on dialysis (not continuously as in normal kidneys)
Explain the basics of peritoneal dialysis
Solute diffuses down a concentration gradient through the peritoneal membrane
How is water removed in peritoneal dialysis?
Osmosis occurs because of high glucose concentration in dialysis fluid
What type of access is used in peritoneal dialysis?
Tenckhoff catheter
Which type of dialysis is more efficient - haemo or peritoneal?
Haemodialysis
Which two types of peritoneal dialysis are available?
Continous (CAPD)
Automated (APD)
How frequent is CAPD?
4 bag exchanges per day
How long does a bag exchange on peritoneal dialysis take?
30 minutes
How frequent is APD?
1 bag of fluid stays in all day
How long does APD take?
9-10 hours overnight
Which type of dialysis can be taken on holiday?
Peritoneal dialysis
What are the main complications of peritoneal dialysis?
Infection
Membrane failure
Hernia
What types of infections occur in peritoneal dialysis?
Peritonitis
Exit site infection
How does infection occur in peritoneal dialysis? Which bugs are typical?
Contamination (staph, strep, diptheroids)
Gut bacteria translocation (e.coli, klebsiella)
How is infection treated with respect to peritoneal dialysis?
Intraperitoneal antibiotics (vancomycin & gentamicin) \+/- removal of catheter
How is PD infection cultured?
Peritoneal fluid used
When is PD catheter removed with respect to infection?
Staph aureus
Pseudomonas
How does membrane failure present? What must be done?
Fluid overload
Switch to haemodialysis
How do hernias occur with respect to PD dialysis? How are they treated?
Increased intra-abdominal pressure due to fluid
Repair + smaller fluid volumes
Is survival better on haemodialysis or peritoneal dialysis?
Not much difference - PD tends to be better for younger patients and haemo tends to be better for older patients
What metabolic complications can arise from end stage kidney disease?
Bone mineral metabolism abnormalities
Anaemia
Sodium & water retention
Accelerated CVS risk
How might bone mineral metabolism abnormalities present biochemically in chronic kidney disease?
Phosphate retained
Low 1,25 vitamin D
Hypocalaemia
Raised PTH
How might anaemia present biochemically in chronic kidney disease?
Erythropoetin deficiency
Iron deficiency
Which two parameters will be taken into consideration with regard to the decision to begin dialysis?
Symptoms
Blood results
What abnormalities of blood results would trigger the start of dialysis?
Resistant hyperkalaemia
GFR 45
Unresponsive acidosis
Which symptoms might trigger the start of dialysis?
Fatigue Itch Unresponsive fluid overload Nausea Vomiting Loss of appetite
How is haemodialysis started?
Gradually build up (start at 2 hours then move on to 4)
What happens if you begin haemodialysis quickly?
Disequilibrium syndrome (cerebral oedema and seizures)
How is PD started?
Begin with small volumes then build up to 2/2.5 litres
Patients with short life expectancy +/- co-morbidities will still get dialysis. T/F
False - in most cases no (effect on QoL is too great)
When might withdrawal from dialysis be indicated?
Patient decision based on medical or social reasons
A young patient on dialysis will have the same life expectancy as an older patient. T/F
True - in most cases
