Dialysis Flashcards
Since the use of long term dialysis the …
UK renal replacement therapy population is increasing
what are the types of renal replacement therapy
- Haemodialysis
- Peritoneal dialysis
- kidney transplant
What is the function of the kidneys
- Salt removal
- Water removal
- Electrolyte balance
- Acid-base balance
- Toxin removal
- Make erythropeitin
- 1-α hydroxylate vitamin D
What can dialysis do that the kidney can also do
- Salt removal
- Water removal
- Electrolyte balance
- Acid-base balance
- Toxin removal
SWEAT
How do you replace the erythropoietin that the kidney makes
- can give EPO subcutaneously or intravenously to replace what the kidneys would have made
How can you give 1 alpha - hydroxylate vitamin D
Give oral 1 alpha hydroxylate vitamin D
Name the two types of dialysis
- Haemodialysis
- Peritoneal dialysis
where can you give Haemodialysis
• Can be done at home but (in the UK) is usually done haemodialysis units (either standalone or in hospital)
where can you give peritoneal dialysis
at home
What are the two types of peritoneal dialysis
Continuous ambulatory peritoneal dialysis (CAPD)
Ambulatory peritoneal dialysis (APD)
when is continuous veno-venous haemofiltration used
- Usually an inpatient treatment in a critical care setting
What is continuous veno-venous haemofiltration
Continuous Veno-Venous Hemofiltration (CVVH) is a temporary treatment for patients with acute renal failure who are unable to tolerate hemodialysis and are unstable
- used in critical care when HD is not possible due to low blood pressure
- not used for chronic RRT unless in combination with HD
How is haemodialysis done basically
• Blood is filtered across a membrane using a machine
How many times does haemodialysis have to be done a week and for how long
• Minimum of 4 hours three times per week
Describe the mechanism of action of haemodialysis
- Blood is exposed to fluid dialysate across a biocompatible membrane
• Small molecules pass through the pores, large molecules such as albumin do not
• A concentration gradient allows diffusion of molecules across the membrane, enabling removal of waste products and replacement of desirable molecules or ions
• Water is driven through the membrane by hydrostatic force (ultrafiltration or UF)
• UF can also clear some solutes via convection - pressure monitors keep an eye on the flow rate and any sign of pressure change which means bleeding
- dialyser - this is the membrane and where the diffusion takes place
what does haemodialysis require
– vascular access (a means of taking blood to and from the patient)
– Anticoagulation (prevent clotting in the circuit)
What should you take while you are on haemodialysis
– Anticoagulation (prevent clotting in the circuit)
What is the area in the dialysis machine where the semipermeable membrane is
- dialyser - this is the membrane and where the diffusion takes place
what are the three types of vascular access used in haemodialysis
- AV fistula - most common and most optimum
- AV graft
- Tunnelled catheter
Describe an AV fistula
- most common used
- most optimum
How do you form an AV fistula in the arm
- surgical procedure takes place between an artery and vein in the arm
Can be:
- Radial Cephalic fistula.
- Brachial Cephalic.
- Brachial Basilic Transposition.
What are the types of AV fistulas
Radial Cephalic fistula.
Brachial Cephalic.
Brachial Basilic Transposition.
Describe how an AV graft works
- when PTFE graft is placed between the artery and the vein and the graft can be used for dialysis
- plastic tube that links the artery and vein
described tunnelled Catheter
- Cather that sits in the central vessels
- tunneled under the skin and comes up in the chest wall
What is the advantages of AV fistulas and grafts versus tunnelled catheter
= Provide better dialysis
- safer
- used long term
- less complications
What is the advantages of tunnelled catheter versus AV fistulas and grafts
can be used immediately - don’t need to wait for it to heal and mature like the other two
What are the two main headings of complications of haemodialysis
access complications
dialysis complications
What are access complications in haemodialysis
- Thrombosis - all three
- Infection - more common in tunnelled catheters
- Failure of access - stenosis in the central vessels or thromboses or there is no option for AV fistula formation
- Aneurysm (AVF/G)
- Distal ischaemia (AVF/G) - stills syndrome
- Central venous stenosis (Tunnelled catheter)
what are the dialysis complications
- Hypotension - where the blood pressure drops during dialysis
- Reactions to dialysis (cramps, headache)
- Inadequate dialysis dose and doesn’t deliver adequately
How many times a day is peritoneal dialysis done
• Done every day
how does peritoneal dialysis work basically
- Dialysis solution is infused and drained via a catheter that is surgically placed in the peritoneal cavity
- The peritoneal membrane acts as the filter
- The action of draining and infusing dialysis solution is called an exchange
Describe how peritoneal dialysis works
- The semi-permeable peritoneal membrane lines the abdominal cavity and covers the abdominal viscera.
- The membrane allows (via diffusion) the passage of toxins and electrolytes into the dialysis solution.
- Ultrafiltration (removal of fluid) occurs via osmosis.
- A “steady state” of toxin clearance and fluid management is achieved due to daily performance of dialysis.
how many times a day do you have to do Continuous ambulatory peritoneal dialysis (CAPD)
• 4-5 exchanges a day
How does Continuous ambulatory peritoneal dialysis (CAPD) work
- Starts with fluid in peritoneal cavity
- DRAIN- through a closed system the fluid is drained by gravity
- FLUSH - small amount flushed into drain bag to clear line
- FILL – new fluid run into peritoneal cavity via the closed system
- DWELL – fluid dwells 4-6 hours before another exchange
How does ambulatory peritoneal dialysis (APD) work
- Alternative to CAPD
- Patient has a cycler machine
- Dialysis takes place over night usually ~8 hrs • Usually better for someone that works
what peritoneal dialysis is better for those that work
APD
• Dialysis takes place over night usually ~8 hrs • Usually better for someone that works
What are the complications of peritoneal dialysis
- Infection (usually peritonitis, exit site infection)
- Catheter dysfunction/malposition - because it is blocked or it is in the incorrect position in the abdominal caity
- Peritoneal leak - around the exit site or in the pleural space
- Pain - usually self-limiting and settles down
- Membrane failure - becomes thickened and less effective
- Inadequate dialysis
- Encapsulating peritoneal sclerosis
What is a rare by severe complication of peritoneal dialysis
• Encapsulating peritoneal sclerosis - thickened sclerosis’s peritoneal which causes malabsorption
- life threatening
- occurs after several years of dialysis or after recurrent episodes of peritoneum
Who cannot tolerate dialysis
Not everyone wants to tolerate dialysis
– Heart disease - health is unstable on haemodialsysis
– Terminal diagnosis with short prognosis - may not want it
– Frailty - can be difficult
– Quality of life
– Patient choice
What is the alternative management of symptoms to people who don’t want dialysis
medication
How do we decide which dialysis to use
- Patient and clinician shared care decision-making
- Lifestyle (eg travel)
- Personal choice
- Technical
• Patient factors
– Technical (eg PD not possible after major abdominal
surgery which would be a contraindication)
– Comorbidities (heart failure or instability)
– Frailty
What patient factors come into thought when determining which dialysis to use
– Technical (eg PD not possible after major abdominal
surgery which would be a contraindication)
– Comorbidities (heart failure or instability)
– Frailty
