(SYNOPTIC) Dialysis + Drugs Flashcards
What types of dialysis are there?
(1) Haemodialysis - HD
(2) Haemofiltration - HF
(3) Haemodiafiltration - HDF
(4) Peritoneal dialysis - PD
What is dialysate?
The filtered liquid in dialysis
What is haemodialysis?
Patient is connected to a haemodialysis machine to create a circuit
Thousands of hollow synthetic fibres
Dialysate flows in opposite direction of blood
What is haemofiltration?
Blood pumped through dialyser
Negative pressure applied to the dialysate, causing solutes to move across a pressure gradient
More aggressive than haemodialysis
What is haemodiafiltration?
Combination of haemodialysis and haemofiltration
Removes the middle molecular weight
Increases clearance of larger toxins
How can access to a patient’s blood be achieved in dialysis?
(1) Arteriovenous fistula
(2) Arteriovenous graft
(3) Central venous catheter (CVC)
What is an arteriovenous fistula?
Surgeon connects an artery to a vein
- usually in your arm
Which dialysis blood access method is the best for long term?
Arteriovenous fistula
- provides highest blood flow for dialysis
- less likely to become infected/ clot
- lasts longer
What is an arteriovenous graft?
Usually inserted if a patient’s veins are not suitable for a fistula
Strong artificial tube inserted by a surgeon underneath the skin
One end connects to an artery, one to a vein
Needs 2-4 weeks to mature
Prone to infection and blood clots
What is a central venous catheter (CVC)?
Pair of hollow tubes called catheters/ lines
Catheter is placed into the jugular vein in the neck
- ends of the tubes are left on the outside
How is the jugular vein found for insertion in CVC?
Ultrasound is used on the neck
What is a Tesio?
Branded name given to CVC tubes left in the neck
Used in dialysis
What timeframe are most Tesios used for?
Short term
Emergency use or bridging (waiting for AV graft/ fistula)
What are the two main ways patients can receive dialysis?
(1) Home dialysis
(2) Conventional dialysis
How often is conventional dialysis done?
3 times per week
3-4 hours for each treatment
What rate is blood drawn out through a tube in conventional dialysis?
200-400mL/min
What are some advantages of conventional dialysis?
- Efficient
- Improves compliance
- Allows professionals to manage complications more efficiently
What are some disadvantages of conventional dialysis?
- Strict diet/ fluid restrictions
- Aggressive strategy can cause drop in BP
- Aggressive strategy can cause muscle cramps (+pain, from fluid removal)
- 3x a week is limiting on freedom
What are some benefits of home dialysis?
Flexible schedule
What is the standard schedule for home dialysis?
3x per week OR every other day 3-5hrs
What is the daily schedule for home dialysis?
5-7 days per weak for 2-4hrs
What is the nightly schedule for home dialysis?
3-6 times per week
While you sleep
What are some advantages of home dialysis?
- Aids flexibility, improves quality of life
- Daily/ nocturnal dialysis is less aggressive (less muscle cramps/ hypertension)
- Allows a more normal diet
What are some disadvantages of home dialysis?
- Increased risk of infections, if poor aseptic technique
- Delayed access to healthcare staff if there are issues
- Risk of poor compliance
What is peritoneal dialysis?
Form of dialysis that occurs in the body
Sterile dialysate is pumped in through catheter
Catheter is surgically placed into the abdomen
Peritoneal membrane acts as a filter
Why is a filter not needed in peritoneal dialysis?
Peritoneal membrane acts as a natural filter
How does dialysate function in peritoneal dialysis?
Contains glucose
Creates an osmotic gradient
Removes excess waste and water
What are the types of peritoneal dialysis?
(1) Continuous Ambulatory Peritoneal Dialysis (CAPD)
2) Ambulatory peritoneal dialysis (APD
What is continuous ambulatory peritoneal dialysis?
Continuous + machine free
Bag containing the dialysate is attached to the catheter in the abdomen
Waste is then drained into a waste bag
Done 3-5 times a day
How does the dialysate enter the abdominal cavity in CAPD?
via gravity
From the bag
How often is CAPD done?
3-5 times a day
When do patients using CAPD tend to time their dialysis for?
During meal times + bedtime
What does CAPD stand for, with regard to kidney failure?
Continuous ambulatory peritoneal dialysis
What does APD stand for?
Ambulatory peritoneal dialysis
What is ambulatory peritoneal dialysis?
Similar to CAPD, but a machine is used to control the exchange of fluid
When is APD done?
Attached before going to sleep
How long is a patient using APD attached for?
8-10 hours
What are some advantages of peritoneal dialysis?
- Patient-centred
- Increased flexibility
- Less diet restriction
- Fewer side effects
- Most similar to kidneys
- Can be done at night (APD)
- Skilled HCP only required for initial training
What are some disadvantages of peritoneal dialysis?
- 4 exchanges a day
- Permanent external catheter
- Risk of infection
- Tied to machine at night (APD)
- Requires a self-motivated and competent patient
- Not as efficient as HD
- Greater loss of albumin
Which type of dialysis has a greater loss of albumin?
Peritoneal dialysis
What are some complications of peritoneal dialysis?
(1) Increased risk of infections within the peritoneum
(2) Developing diabetes (usually occurs due to high dialysate concentration of glucose)
(3) Sclerosing peritonitis
What is sclerosing peritonitis?
Thickening of peritoneum
Leads to partial/ complete small bowel obstruction
What type of dialysis leads to an increased risk of developing diabetes? Why?
(1) Peritoneal dialysis
(2) Dialysate has a high concentration of glucose
What are two hormones excreted by the kidneys?
(1) EPO - erythropoietin
(2) Renin
What are the two aims of dialysis?
(1) Removal of waste
(2) Removal of fluid
What is a dialyser?
Filtration tube used in dialysis
Comprising hollow fibres
What is an essential nutrient in the dialysate used in haemodialysis?
Sodium bicarbonate
What is a more aggressive form of dialysis, haemofiltration or haemodialysis?
Haemofiltration
Which type of dialysis improves clearance of larger toxins?
Haemodiafiltration
How does an arteriovenous fistula work?
Connect an artery to a vein by a surgeon
To thicken the walls of the vein over time, so that it can withstand dialysis
How long does an arteriovenous graft take to mature?
2-4 weeks
When does a CVC tend to be used in dialysis?
Short term for:
- Emergency
- Bridging (waiting for AV graft/ fistula)
Why does the dialysate of peritoneal dialysis contain glucose?
To create an osmotic gradient
To remove excess waste + water
What is a Tenchkoff catheter?
Catheter surgically inserted into the abdomen
In peritoneal dialysis
What type of dialysis does not require a machine?
Continued ambulatory peritoneal dialysis
Uses gravity
How many exchanges per day are required for peritoneal dialysis?
4
What is peritonitis?
Infection of the peritoneum
What is the treatment of peritonitis?
IV Abx
Hospital admission
Why are patients on peritoneal dialysis at a higher risk of diabetes development?
High glucose concentration of dialysate
Which type of dialysis is not suitable for diabetic patients?
Peritoneal dialysis
Due to high concentration of glucose in the dialysate
What is a good source to find out if a drug is dialysed or not?
Renal Drug Database
What factors are important to consider when deciding if a drug is dialysed or not?
(1) Type of dialysis
(2) Molecular weight of drug
- high = unlikely
- low = more likely
(3) Hydro/lipophilic
(4) Level of protein binding
(5) Is the drug renally cleared?
(6) Active/ toxic metabolites
- time metabolism of drug into metabolites so that toxic metabolites are removed by dialysis
(7) Therapeutic index of the drug?
- ideally wide
(8) OD vs multi-dose
- adjust around dialysis sessions
Is a drug that is highly protein bound likely to be dialysed?
No
Proteins are too large to be dialysed
Are drugs that are highly renally cleared likely to be removed by dialysis?
Yes
