Lecture 16 - Renal Replacement Therapy Flashcards
Define end stage renal disease
Irreversible damage to a person’s kidneys so severely affecting their ability to remove/adjust blood wastes that, to maintain life, they must have dialysis or a transplant
Until what CKD stage can the patient remain asymptomatic?
4 or 5
What is the syndrome of advanced CKD called?
Uraemia
What are the two earliest and most common uraemic symptoms?
Malaise, fatigue
Define renal replacement therapy
Means by which life is sustained in patients suffering from ESRD
At what eGFR is RRT usually indicated?
<10ml/min
List the types of RRT
Renal transplant
Haemodialysis (home vs hospital)
Peritoneal dialysis (CAPD vs IPD)
Conservative kidney management
What does conservative kidney management involve?
Not starting dialysis or having a transplant but treating symptoms of uraemia with medication
Define dialysis
Process whereby the solute composition of a solution, A is altered by exposing solution A to a second solution, B, through a semipermeable membrane
What are the two main principles of dialysis?
Diffusion
Ultrafiltration
What is ultrafiltration?
A type of membrane filtration in which hydrostatic pressure forces a liquid against a semi permeable membrane
What are the 4 pre-requisites for dialysis?
Semipermeable membrane
Adequate blood exposure to the membrane
Dialysis access
Anticoagulation (just for haemodialysis)
What acts as a semipermeable membrane in haemodialysis?
Artificial kidney (dialysier)
What acts as a semipermeable membrane in peritoneal dialysis?
Peritoneal membrane
What blood is dialysed in haemodialysis?
Extracorpeal blood
What blood is dialysed in peritoneal dialysis?
Mesenteric circulation
What is the dialysis access in haemodialysis?
Vascular
What is the dialysis access in peritoneal dialysis?
Peritoneal
What are the two types of permanent haemodialysis access?
AV fistula
AV prosthetic graft
What are two types of temporary haemodialysis access?
Tunneled venous catheter
Temporary venous catheter
Describe how haemodialysis works
Create a dialysate of a composition such that you draw out from the blood exactly what you want to
Blood enters one end and the dialysate moves in the opposite direction to the blood coming in
What are the fluid restrictions for dialysis patients dependent on?
Residual urine output
Interdialytic weight gain
Foods high in which three ions should be avoided by dialysis patients?
Potassium
Sodium
Phosphate
(As these are the things that accumulate in ESRD)
Why must dialysis patients fluid restrict?
Because they fluid overload due to their ESRD, and this can be taken off during dialysis but it is not good for the heart to remove large volumes of fluid quickly
How long does haemodialysis tend to last?
4 hours
How often must patients get haemodialysis?
Usually 3x per wee
What happens in peritoneal dialysis?
Balanced dialysis solution instilled into peritoneal cavity via tunneled, cuffed catheter, using peritoneal mesothelium as a dialysis membrane
After a dwell time, fluid is drained and fresh dialysate instilled
What are the two types of peritoneal dialysis?
Continuous ambulatory PD (CAPD)
Automated PD
What is the most common osmotic agent used for the ultrafiltration of fluid in PD?
Glucose
Dwell times in PD need to be adjusted to what?
Transporter characteristics
Describe how CAPD is carried out
Usually done 4x a day with none during the night
Describe how APD is carried out
Machine that does instills fluid and drains it for you during the night
What are possible complications of PD?
Exit site infection/Tunnel infection PD peritonitis Ultrafiltration failure Tube malfunction (e.g. catheter blockage) Abdominal wall herniae Encapsulating peritoneal sclerosis Fluid retention Hyperglycaemia Back pain Constipation Malnutrition
What is a gram +ve PD peritonitis usually due to?
Skin contaminant
What is a gram -ve PD peritonitis usually due to?
Bowel organisms
What is a mixed PD peritonitis usually due to?
Suspect complication, e.g. peritonitis
Is the fluid coming out from PD is cloudy what does this mean?
It is infected, i.e. patient may have PD related peritonitis
What are indications for dialysis in ESRD?
Advanced uraemia (eGFR 5-10ml/min) Severe acidosis (bicarb <10mmol/l) Transient resistant hyperkalaemia (K>6.5mmol/l) Treatment resistant overload Clinical judgement
What is the usual restriction on fluid intake in dialysis patients?
Haemodialysis - 500-800ml/24h (urine output + insensible losses)
Peritoneal dialysis - usually more liberal as continuous ultrafiltration achieved
What drugs may those on dialysis need?
EPO injections/IV iron (anaemia) Activated vit D (e.g. calcitriol), phosphate binders with meals (CaCo3) (renal bone disease) Heparin Water soluble vitamins Antihypertensives?
What are complications of haemodialysis?
CV - intra-dialytic hypotension and cramps, arrhythmia, endocarditis, air embolus
Coagulation - clotting of vascular access, heparin related problems
Other - allergic reactions to dialysers/tubing
Catastrophic accidents rare
What are important factors in choosing a modality of dialysis?
Patient choice (education, shared decision making)
Patient related factors
Perception of effectiveness
What is involved in conservative kidney management?
Supportive care - manage symptoms, MDT approach, anticipatory care planning
What is the incidence of CKD?
1 in 8 (UK)
What % of those with CKD go on to develop renal failure?
10%
Define renal failure
GFR <15ml/min
The decision about which RRT option to pick should be made jointly by the patient and healthcare team taking into account what?
Predicted QoL
Predicted LE
Patient preference
Co-existing medical conditions
How long before haemodialysis begins should the patient get surgery to create the AV fistula?
8 weeks
Where is the most common site for an AV fistula?
Lower arm
How long does the exchange and dwell time in CAPD last?
Exchange - 30-40 min
Dwell - 4-8h
In APD how many exchanges tend to occur over how long?
3-5 exchanges over 8-10h
What is the average wait time for a kidney transplant?
3 years
Describe what happens in a renal transplant
Donor kidney inserted into groin with renal vessels connected to external iliacs
Failing kidneys not removed!
What must patients take life-long after a renal transplant?
Immunosupressants to prevent transplant rejection
What is the average lifespan of a donor kidney?
10-12 years from deceased donors
12-15 years from living donors
How long is the average life expectancy of a patient with ESRD that does not recieve RRT?
6 months
What are symptoms of renal failure that is not being adequately managed with RRT?
Breathlessness Fatigue Insomnia Pruritus Poor appetite Swelling Weakness Weight gain/loss Ab cramps Nausea Muscle cramps Headaches Cognitive impairment Anxiety Depression Sexual dysfunction
What are complications of renal transplant?
DVT/PE Opportunistic infection Malignancies - esp. skin cancer, lymphoma Bone marrow suppression Recurrence of original disease Urinary tract obstruction CV disease Graft rejection
What is the most common causative organism for PD related peritonitis
Coagulase negative staph, e.g. staph epidermis
