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PM4B > dialysis > Flashcards

dialysis Flashcards

1
Q

what is dialysis

A

It is a process for removing waste products such as creatinine, urea, water plus excess water and minerals from the blood

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2
Q

how is it an artificial replacement?

A

cannot secrete hormones. artificial replacement for patients who have temporary or permanent lost kidney function due to renal failure

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3
Q

dialyser

A
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4
Q

describe haemodialysis

A

patient is connected to a dialysis machine to create a haemodialysis circuit
The patient’s blood is pumped through a dialyser within the circuit
The dialyser is composed of thousands of hollow synthetic fibres which act as a semi-permeable membrane
Blood flows through the fibres and the dialysis solution flows outside the fibres in the opposite direction

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5
Q

what diffuses in and out of the blood/dialysis solution?

A

Water, waste products and excess electrolytes move from the blood into the dialysis solution via diffusion
Essential nutrients from the dialysis solution enter the blood via diffusion e.g. sodium bicarbonate
The movement of solute across the semipermeable membrane is along a concentration gradient – from a high to low concentration
The filtered blood then re-enters the bloodstream

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6
Q

describe haemofiltration

A

The blood is pumped through a dialyser as in dialysis

However a negative pressure is applied to the dialysate causing solutes to move across a pressure gradient, as opposed to diffusion

More aggressive than HD and allows removal of several litres of water and more solutes from the blood

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7
Q

describe haemodiafiltration

A

Combination of haemodialysis and haemofiltration i.e. solutes move across the semi-permeable membrane via diffusion and along a pressure gradient

Compared with HD, HDF removes middle-molecular-weight solutes so increases the clearance of larger toxins
HDF: combination of HD and HF – both diffusion AND pressure gradient.

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8
Q

how can we get access to the patients’ blood supply allow connection to the dialysis machine

A
  • Arteriovenous (AV) fistula
    • Arteriovenous (AV) graft
    • Central venous catheter (CVC)
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9
Q

Arteriovenous (AV) fistula

A

A surgeon connects an artery to a vein, usually in your arm, to create a fistula
Connecting an artery to a vein makes the vein grow wider and thicker, making it easier to place the needles for dialysis
The AV fistula also has a large diameter that allows blood to flow out and back into the body quickly

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10
Q

pros and cons of AV fistula

A

Needs time to mature
An AV fistula is the best long-term access
- provides highest blood flow for dialysis
- is less likely to become infected or clot
- lasts longer

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11
Q

Arteriovenous (AV) graft

A

An AV graft is a strong artificial tube inserted by a surgeon underneath the skin of the forearm, upper arm or thigh
One end of the tube connects to an artery and the other end connects a vein

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12
Q

pros and cons Arteriovenous (AV) graft

A

Will need 2-4 weeks to mature
Prone to infection and blood clots
An AV graft is usually inserted if the patients’ veins are not suitable for an AV fistula

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13
Q

Central venous catheter (CVC)

A

A CVC is a pair of hollow tubes called catheters or lines
The catheter is placed into the large central vein in the neck – the internal jugular vein
The ends of the tubes are left on the outside of the body so they can be attached to the dialysis machine
An ultrasound machine will be used to find the central vein in the neck
The brand of catheter used of dialysis access is called “Tesio”

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14
Q

pros and cons Central venous catheter (CVC)

A

Most Tesio’s are used short-term – whether it is inserted for emergency dialysis or used a ‘bridging’ access whilst an AVF or AVG matures; some are used long-term if AVF or AVG not possible
Tesio lines are great for emergency access but they do have a tendency to become infected or to clot

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15
Q

two main “ways” that patient can receive their dialysis

A

Conventional (hospital) dialysis
Home dialysis

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16
Q

conventional dialysis

A

Usually done three times per week, for about 3-4 hours for each treatment

Patients blood is drawn out through a tube at a rate of 200-400ml/min

Blood is then pumped through the dialyser and then filtered

The filtered blood is pumped back into the patients bloodstream through another tube

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17
Q

conventional dialysis advanatages

A

Very efficient
Improves compliance
Allows healthcare professionals to manage any complications more efficiently
Allows healthcare professionals to monitor bloods and make adjustments if needed more efficiently
?support network for patients that benefit from that network

18
Q

conventional dialysis dis-advanatages

A

Strict diet and fluid restrictions
Aggressive fluid removal can cause dramatic drop in blood pressure during the session
Aggressive fluid removal can cause pain muscle cramps
3xweek = very limiting on freedom

19
Q

Home dialysis

A

Allows longer or more frequent dialysis, which comes closer to replacing the work healthy kidneys do

Allows for a flexible schedule:
- standard schedule: 3xweek or every other day for 3-5 hours
- daily schedule: 5-7 days per week for 2-4 hours
- nightly schedule: 3-6 times per week while you sleep

20
Q

Home dialysis ADVANTAGES

A

Home dialysis dramatically improves quality of life by aiding flexibility
Daily/nocturnal dialysis is less aggressive – less muscle cramps/hypotension
Daily/nocturnal dialysis allows more “normal” diet and fluid intake

21
Q

Home dialysis DISADVANTAGES

A

Increased risk of infections if poor aseptic technique
Delayed access to healthcare staff if there are any issues e.g. clotting
Risk of poor compliance for those that are less motivated
?potentially isolating
Home environment – storage space for dialysis fluids and the machine?

22
Q

Peritoneal dialysis (PD)

A

Form of dialysis that occurs inside the body

Catheter is placed into abdomen surgically

Sterile dialysate is pumped into the peritoneal (abdominal) cavity through a catheter

Peritoneal membrane acts as a natural filter

23
Q

how is PD different to the other types of dialysis

A

this occurs INSIDE the body. (the others were outside via a machine with a dialyser (tube)).

24
Q

describe the dialysate of PD

A

The dialysate contains glucose which comes in various concentrations – this creates an osmotic gradient to remove excess waste and water

The dialysate sits in the peritoneum where waste and excess fluids/minerals diffuses into the dialysate

This dialysate is then removed from the peritoneum via the catheter and discarded

25
Q

two types of PD?

A
  • Continuous Ambulatory Peritoneal Dialysis (CAPD)
    • Ambulatory Peritoneal Dialysis (APD)
      ONES CONTINUOUS ONES NOT
26
Q

Continuous Ambulatory Peritoneal dialysis (CAPD)

A

A bag containing the dialysate is attached to the catheter in the abdomen
The dialysate flows into the peritoneal cavity via gravity
The dialysate sits in the peritoneal cavity to allow waste and excess fluid to be drawn out of the blood, across the peritoneum lining
The dialysate is then drained into a waste bag
Usually done 3-5 times a day

27
Q

Benefits of CAPD

A

Continuous and machine-free
Patients tend to time their exchanges during mealtimes and at bedtime

28
Q

Ambulatory Peritoneal dialysis (APD)

A

Patient attaches a bag of dialysate to the APD machine before going to sleep
The machine performs a number of fluid exchanges
Patient will need to be attached to machine for 8-10 hours

29
Q

ADVANTAGES OF PD

A

Patient-centred
Increased flexibility – can be carried out at home or work
Less fluid/diet restrictions
Less side effects in comparison to HD/HF/HDF e.g. hypotension or muscle cramps
Most similar to kidneys
Can be done at night (APD)
Skilled nursing only required for initial training

30
Q

DISADVANTAGES OF PD

A

~ four exchanges per day
Permanent external catheter
Change of body image
Risk of infection
Will be tied to the machine at night (APD)
Storage space is needed for supplies
Requires self-motivated and competent patient
Not as efficient as HD
Greater loss of albumin

31
Q

COMPLICATIONS OF PD

A

Increased risk of infections within the peritoneum  peritonitis. Will require hospital admission and IV antibiotics

Developing of diabetes  usually occurs due to high glucose concentration of dialysate

Sclerosing peritonitis  thickening of peritoneum that encloses the small intestine. This can lead to partial or complete small bowel obstruction

32
Q

considering pharmacokinetics, when choosing What is the type of dialysis?

A

HDF more aggressive, more likely to clear the drug

33
Q

considering pharmacokinetics, when choosing What is the molecular weight of your drug?

A

Larger molecular weight  less likely to be cleared

34
Q

considering pharmacokinetics, when choosing Is the drug hydrophilic or lipophilic? What is the Volume of distribution?

A

High VoD  distributes to fatty tissue (lipophilic)  not as much in the blood  less likely to be cleared

35
Q

considering pharmacokinetics, when choosing What about the level of protein binding?

A

Highly protein bound  larger molecule  less likely to be cleared

36
Q

considering pharmacokinetics, when choosing Is the drug renally cleared?

A

If not usually renally cleared i.e 25-30% of total body clearance, then dialysis will not clear much of it either

37
Q

considering pharmacokinetics, when choosing Any active or toxic metabolites?

A

Toxic metabolites?  give before HD session so that HD removes the toxins

38
Q

considering pharmacokinetics, when choosing What is the drugs therapeutic index?

A

Care with narrow therapeutic index – may need to adjust timings in respect to dialysis

39
Q

considering pharmacokinetics, when choosing OD dosing Vs multi-dose regimens?

A

E.g. 5 times a day?  likely to be cleared by dialysis  does it exist in MR?

40
Q

considering pharmacokinetics, when choosing Regular dosing Vs STAT doses

A

Stat “one-off” doses are not affected too much by dialysis vs regular long term medication

PM4B (8 decks)

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