Renal Medicine 2 Flashcards
name the functions of the renal system
• Excretory function • Water and electrolyte balance • Acid base balance • Renal endocrine function ○ Erythropoietin ○ Calcium metabolism ○ Renin secretion
how is renal endocrine function treated
medically
- treated by managing blood pressure in other ways by giving patients supplements and injections
what is renal dialysis
• A passive process
Diffusion across concentration gradients
Allows intermittent correct of changes in plasma concentration of small molecules
Not true renal replacement
why is renal dialysis not true renal replacement
○ Significant lifestyle restrictions remain
§ Restricted in how much they can eat / drink / how much fluid and salt they can take in
§ Can only take in up to the limit of what can be achieved by dialysis
• Doesn’t restore normal kidney function as it cannot maintain what the kidney’s do constantly
Better than having no kidney function but really just keeps you ticking along
what are the 2 types of renal dialysis
• Haemodialysis
○ Outside the body
• Peritoneal dialysis
Inside the body
how does dialysis work
- Like clingfilm with tiny holes in it
○ Blood on one side
○ Solution on one side
○ Determines what passes through - Design membrane to allow electrolyte exchange but not allow protein or cellular exchange
- Solution on one side of the membrane is designed to have what you want to achieve in the blood
Eg if there is a high potassium level in the blood then you want the potassium to leave so make the concentration of potassium on low to create a concentration gradient and the potassium will diffuse
what happens in haemodialysis
- Hollow fibre dialysis
○ Blood passes down little straw like tubes to the bottom
○ These straw structures are surrounded by dialysing solution
○ Ensures the blood is constantly changing so there is a changing concentration gradient occurring as the dialysis occurs - Blood has to go around this several times before you have the electrolyte balance where you want it to be
A dialysis session can take 6-8 hours
how does a typical haemodialysis cycle affect the patient
have the dialysis one day
then have a good day
then have a bad day
then back to having dialysis
- When the dialysis stops, your electrolyte and fluid balance is where you want it to be
○ Then the stuff you don’t want starts to build up so
○ Cannot lose what you don’t want
Cannot gain what you do want
= bad day
how does peritoneal dialysis work
- Works in the same way as haemodialysis
○ The thin walls of the blood vessels behaves like the dialysing straws as diffusion can happen here to maintain the balance
○ Happens inside the body instead of inside the machine - The dialysing solution is the opposite of what you want the blood to be?
- Fluid goes into peritoneum (this is separated by the pelvis and internal organs as a little organ)
○ Peritoneum is a big bag that holds the guts after you pass the layers of skin, fat and muscles
○ It is a sealed bag that has the intestines inside
○ Put fluid into this bag and it won’t go anywhere else in the body - will remain within the gut loops
§ Remove the fluid when finished
§ Replace fluid
what are the steps in the exchange procedure of peritoneal dialysis
- connect y system (double bag to Tenckhoff catheter
- drain out from patient
- drain from bag
- fill abdomen
- disconnect
what role does an implanted catheter play in peritoneal dialysis
- When want to do dialysis = put the dialysing fluid in to the peritoneum
- When you want to stop the dialysis = suck the dialysing fluid out of the peritoneum
a valve below the surface of the skin with the tube positioned around inside the peritoneum
what are the advantages and disadvantages of peritoneal dialysis
> more flexible
- can have lots of different time patterns for when the dialysis occurs
- can go on holidays more easily
wont have the same good and bad days as haemodialysis, can be much more consistent in how they feel
> patients don’t like being responsible for their own like and death
what are the disadvantages of haemodialysis
> not flexible
- can only really go away for a day or so
- strict pattern
what does dialysis restore
- Excretory function
- Water and electrolyte balance
- Acid base balance
is dialysis a cure?
no
○ Limited to a litre a day
§ Used for everything you swallow
○ Can cause problems with dry mouth and paste issues
§ Due to issues with hydration
○ Restricts what they can eat
§ Avoid high salt contents
[these problems are more likely with haemodialysis than peritoneal dialysis]
more of a temporary treatment as a transplant is the most preferred treatment option
is dialysis suitable for children
no
does not support them during growth
children are high priorities
how is erythropoietin replaced in renal endocrine replacement
Replaced by EPO injections
Maintains red cell mass
how is bone mass maintained in renal endocrine replacement
Vitamin D supplementation
Osteoporosis prevention programme
how is hypertension controlled in renal endocrine replacement
Renin-angiotensin system inactive
Ace inhibitors may have limited use
what is the advantage of renal transplantation
Optimal treatment for end stage renal disease
Normal renal function
No dietary restrictions
Normal energy and fertility
why is transplantation not a cure
§ Temporary fix as a transplant won’t last more than 10-15 years and then you will need to get another transplant
§ Each time you get a kidney, there is less chance of getting another
§ A transplant is kind of like having chronic renal failure- When it fails you need another transplant
what is a problem with renal transplantation
shortage of donations
younger patients get priority
as you get older you are less likely to receive one
how is the transplant kidney inserted
the broken kidneys arent removed
the working kidney is usually put in the pelvis so it sits at the appendix in addition to the 2 not working kidneys
the new kidney is not as well protected so it is more vulnerable to be damage
contact sports are avoided
what are the problems that arise with transplants
• Rejection - acute or chronic
○ Complicated - can either happen very fast or can happen over many years
• Immunosuppression
○ Increased infection / malignancy
○ Patients take medication to reduce the immune system attacking the transplant organ
○ This means the immune system is prevented from recognising infections and cancer cells § There is a higher risk of undetected serious infections and cancers that otherwise would be removed by the immune system
• High cardiovascular mortality
○ ? An effect of transplant
○ ? Aetiological in renal disease
• Osteoporosis risk
