Alex: Dialysis Flashcards
What are 4 options for end stage renal disease?
- Hemodialysis
- Transplantation
- Peritoneal dialysis
- No treatment
What stage of CKD should the patient be referred to a nephrologist?
Stage 4 (GFR under 30)
What plants must be made as part of pre-dialysis assessment for hemodialysis?
- Dialysis access surgery
- Type of renal replacement therapy (RRT)
* Advanced planning is essential
What the decision to initiate RRT based on?
A variety of factors:
- Symptoms
- Signs
- Laboratory results
What GFR do the majority of patients start dialysis at?
Under 10cc/min
What are laboratory indicators for the initiation of renal replacement therapy?
- Unmanageable hyperkalemia
- Severe Metabolic acidosis
- Uremic Symptoms / Encephalopathy: Nausea, vomiting, altered mental acuity, seizures, anorexia
- Pericardial friction rub
- Unmanageable volume overload
Is there a specific BUN, creatinine, or GFR level that mandates immediate dialysis?
NO
What are the 3 options for RRT and associated %
- Hemodialysis: 65%
- Transplant: 25%
- Peritoneal dialysis: 10%
What 5 things are needed for dialysis?
- Vascular access to the circulation
- Dialysis filter
- Dialysis machine
- Nursing staff to establish the vascular access and monitor the dialysis procedure
- Dialysis facility
What are options for vascular access foe hemodialysis?
SHUNTS
- Fistula
- Graft
What is the angioacess of choice for dialysis?
A side-to-side arteriovenous fistula
What are the 2 sites where arteriovenous fistulas are usually placed?
- The radial artery and cephalic vein in the non-dominant arm*
- In the upper arm between the brachial artery and brachiocephalic vein (if necessary)
What can be placed in patients with poor vessels and in those whom previous AVF have failed?
An arteriovenous graft between the artery and vein
Forearm, upperarm, thigh
What are the 2 options for dialysis access?
- Arteriovenous fistula
2. Arteriovenous graft (synthetic material)
What is an arteriovenous graft also called and what is it made of?
GORE-TEX graft…it’s made of Teflon
In dialysis, what is the arterial line for?
Blood flow from the patient to the dialyzer
In dialysis, what is the venous line for?
Blood return from the dialyzer to the patient
What can inserted into the internal jugular vein and used for vascular access until proper access can be created?
A tunneled, cuffed double lumen catheter
Why is a tunneled catheter the least desirable alternative for dialysis access?
- Infection
- Thrombosis
- Inefficient dialysis
What should be avoided with a tunneled catheter?
Subclavian vein cannulation
What kind of lumen does a tunneled catheter have?
Double
What does the separate inner lumen do in a double lumen tunneled catheter?
It return blood back to the patient after dialysis
What do small pores in the catheter do in a double lumen tunneled catheter?
They allow blood to be pulled out and circulated through the dialyzer
What are 2 methods of hemodialysis clearance?
- Diffusion
2. Convection (ultrafiltration)
What is diffusion?
The rate of mass transfer between 2 compartment separated by a semi-permeable membrane
What is diffusion determined by?
- Characteristics of the membrane
2. Solute concentration gradient between the 2 compartments: Plasma and dialysate compartments
What is fluid filtration through a porous membrane with the clearance directly related to the volume of fluid removed?
Ultrafiltration: Convective mass transfer
In convection or ultrafiltration, what does positive pressure lead to?
Negative suction
What must be established in dialysis?
2 compartments separated by a semi-permeable membrane
What are the 2 compartments in dialysis?
- Blood
2. Dialysate
What is a synthetically created sterile solution containing electrolytes and glucose, but minimal K and no urea?
Dialysate compartment: Hollow fiber dialyzer
What are the levels of Na, K, Cl, HCO3, Glucose, and Ca in typical dialysate?
- Na: 140mEq/L
- K: 2.0mEq/L
- Cl: 100mEq/L
- HCO3: 36mEq/L
- Glucose: 200mg/dL
- Calcium: 2.5mEq/L
True or False: The K level in dialysate is adjustable?
True
Why is the HCO3 intentially higher than normal in the dialysate?
So it moves into the patient to neutralize the acidosis
What is the flow rate of blood in hemodialysis?
300-500cc/min
What kind of membrane is used in hemodialysis?
Semi-permeable
What is the flow rate of dialysate in hemodialysis?
800cc/min
How many gallons are required per patient, per treatment for hemodialysis?
40 gallons
What is in dialysate?
Purified sterile water and electrolytes
How many dialysis units are in the US?
Over 4000
What are 2 methods for hemodialysis clearance?
- Diffusion
2. Convection: Ultrafiltration
Are diffusion and convection (ultrafiltration) both clearance methods in the human kidney?
NO
What is normal glomerular filtration maintained by?
CONVECTION ONLY (ultrafiltration)
Does diffusion occur in a normal human kidney?
NOOOOOOO
For how long and how often are most patients treated with hemodialysis?
- 3-4 hours
2. 3 times a week (M-W-F or Tu-Th-Sa)
What is the proper dose of dialysis based on?
It is individualized, but an expected decrease in BUN by greater than 65% each treatment is desired (urea reduction ratio)
If the pre-dialysis BUN is 80, what should the post-dialysis BUN be?
28
Why is creatinine not used as a marker for renal function once the patient is on dialysis?
Creatinine is not toxic and therefore isn’t a reflection of nitrogenous waste
What lines the walls of the abdominal cavity and encapsulates internal organs (stomach, liver, spleen)?
Peritoneum
What is the overall adult peritoneal surface area?
Approximately 1.75 +/- 0.5 m^2
What kind of pores does the peritoneum contain?
- Large pores: 25mm
- Small pores: 5nm
- Ultra small pores: Involved in water transport
What is a virtual space normally without significant fluid (ascites)?
Peritoneal cavity
What happens to the peritoneal cavity if a dialysate solution is infused?
It will expand the space between the intestines and solid organs–> This increases the surface area for diffusion
In peritoneal dialysis, what is the solution infused similar to?
Dialysate
What sits in the peritoneum and allows diffusion of solutes across the blood vessels into the peritoneal cavity?
Infused solution used in peritonel dialysis
What allows for removal of uremic toxins in peritoneal dialysis?
Drainage of the dialysate and replacement with a fresh batch
What are the 2 options for peritoneal dialysis?
- CCPD: Continuous cycling peritoneal dialysis
2. CAPD: Continuous ambulatory peritoneal fialysis
How does CCPD work?
Cycle at night for 8-10 hours
About 10 liters is exchanged
How does CAPD work?
About 4 exchanges per day with 2-2.5 liters per exchange
Does CAPD require a machine?
No
In CAPD how many liters of fluid is infused and how may times a day?
1.5-3 liters of fluid is infused 4 times per day
What is the exchanging time in CAPD?
30-40 minutes
How is dialysate solution managed in CCPD?
It is exchanged by a machine at night (it’s automated)
What is the fill volume in CCPD?
2L
How many exchanges occur in CCPD?
There are 4-6 exchanges over 8-10 hours each night
What does the patient do during the day with CCPD?
They disconnect and are independent of any further exchanges until the next night
What are some reasons peritoneal dialysis an excellent choice for many independent patients?
- Can be used in rural locations without hemodialysis clinics
- Can be used in countries without good city water sources
- Can be used in young children
What are 3 potential problems with peritoneal dialysis?
- Ability to follow strict sterile techniques
- Previous abdominal surgery
- IBD, diverticulitis, recurrent hernias
What is the stronger clearance method in peritoneal dialysis?
Diffusion (over convection/ultrafiltration)
Who performs treatment in hemodialysis versus peritoneal dialysis?
- Hemodialysis: Staff performs treatment…leads to regular contact with people in the unit (social sturcture)
- Peritoneal dialysis: Patients is very involved in care and has control over their schedule and freedom
Which type of dialysis is diet and fluid intake restricted in?
Hemodialysis
Peritoneal dialysis has a less restricted diet
Which type of dialysis results in a more steady physical condition?
Peritoneal dialysis (hemodialysis has unstable physical conditions
What is the difference in terms of external access for the 2 types of dialysis?
- Hemodialysis has no external access required
2. Peritoneal dialysis requires a permanent external catheter
What can be an issue in hemodialysis?
HD access
What can be an issue with peritoneal dialysis?
The effectiveness of the peritoneaum
Which type of dialysis does infection affect?
Both hemodialysis and peritoneal dialysis
What offers a degree of independence for the patient, but requires greater patient involvement?
Peritoneal dialysis
What can be avoided with peritoneal dialysis?
- Potential problems of vascular access
2. Avoids the hemodynamic stress of HD
What is required in peritoneal dialysis?
A peritoneal cavity that is accessible and without extensive adhesions
When patients start dialysis, what is the GFR?
Usually under 10cc/min
What is the actual GFR during a 3-4 hour dialysis session?
300cc/min
Since dialysis is only 3 times a week, what is the average GFR of a dialysis patient?
20cc/min
HEMODIALYSIS DOE NOT RETURN THE GFR TO NORMAL
What stage of CKD does hemodialysis take a patient too?
Takes them from a stage 5 CKD to a stage 4 CKD
What happens because dialysis doesn’t correct the CKD?
The patient will continue to be exposed to uremic toxins and experience accelerated atherosclerosis and premature death
What stage of CKD does peritoneal dialysis put patients in?
Stage 4
Is there a survival advantage between the 2 types of dialysis?
NO…patient choice dictates what technique to use
What is the leading cause of death among ESRD patients?
CV disease
What contributes to CV disease being the leading cause of death among ESRD patients?
- HTN
- Hyperlipiemia
- Ca/phos deposition in vessels
- Large number of diabetics
Who is the incidence of ESRD 2-3 times higher in?
Black patients
Who is the rate of ESRD rising every year especially in?
Elderly
How many indicators are there for initiating dialysis?
5
Is GFR an absolute reason to begin dialysis?
No…but most patients start at a GFR under 10cc/min
What do hemodialysis and peritoneal dialysis use primarily for clearance?
Diffusion and come convection
What does the human kidney use for clearance?
Only convective (ultrafiltration)
What is the best vascular access?
AV fistula
Is there a survival advantage between one form of dialysis compared to another?
NO
What stage of CKD does dialysis put the patient into?
Stage 4 CKD
True or false: Overall death rates from CV disease remain much higher than the general population?
TRUE
