Burkart: Esrd

Front 1

Stage 5: definition

Back 1

Working Definition: Disease state where the patients native kidney function is no longer able to maintain health in terms of: solute removal, volume homeostasis or electrolyte balance
Typically the patients’ GFR less than 12 – 15 ml/min

caveat. - no specific laboratory value which states you MUST be on dialysis

Front 2

Indications for starting dialysis in patients with CKD

Back 2

Symptoms of uremia
-Nausea, vomiting
-Weight loss
Hyperkalemia not amenable to medical treatment
Volume overload not amenable to medical treatment
Uremic pericarditis
Bleeding due to platelet dysfunction

Front 3

Why worry about ESRD?

Back 3

Number of patients with treated ESRD is increasing
For > 80% of patients primary payor is Medicare
It costs Medicare (and us as taxpayors) a lot of money
There is a high mortality rate

Front 4

Genetic predisposition to ESRD

Back 4

There is an inherited risk for ESRD
-(or perhaps better stated -- progression to kidney failure)
More common in African Americans
Many dialysis patients have family members who are, were or are about to be on dialysis

Front 5

Who gets kidney failure

Back 5

Incidence is increasing the most in:
-The Elderly
-African Americans
-Patients with Diabetes
Patients with a family History of ESRD
Patients with multiple comorbidities
Patients with a failed transplant

Front 6

Options for patients with stage 5 disease

Back 6

Conservative therapy – death from uremia
Transplantation (living related or Deceased)
Hemodialysis (In a center or at home)
Peritoneal dialysis

Front 7

Hemodialysis: contraindications

Back 7

Absolute
-No access
-Fresh intracranial bleed?

Relative
-Hemodynamic instability/CVDz
-Carotid disease
-Difficult disease
-GI bleeding

Front 8

Hemodialysis: treatment overview

Back 8

Most patients go to a dialysis center (Center HD)
Frequency typically 3 or 4 times/week
Access = venous, extracorporeal
Membrane = artificial, extracorporeal
Typical treatment = 3 to 4 hours - 3 times/week
However, emergence of more frequent HD schedules –these are done at patients HOME
-Short Daily (5 or 6 days/week)
-Daily Nocturnal – 4 to 6 nights/week

Front 9

Peritoneal dialysis: contraindications

Back 9

Absolute
-Cannot/will not learn
-No partner, home not suitable
-Unusable abdomen (no PD surface area)

Relative
-Social instability, Malnutrition,
-Large body weight (BSA, V)
-Fresh intraabdominal foreign body (AAA graft)
-Inflammatory bowel disease
-Ostomy (colostomy>>ureterostomy)

Front 10

Peritoneal dialysis: treatment overview

Back 10

Usually a daily (7 days a week) therapy
Two major forms of PD:
-CAPD -- do all manual exchanges (3 during day, 1 overnight)
-APD -- use a cycler to do automated exchanges at night (3 exchanges) while sleeping with a daytime dwell
Blood Flow Independent
Blood supply - mesenteric vessels
Membrane - peritoneal, mesothelial cells capillaries

Front 11

Physics of dialysis

Back 11

Bring blood into close contact with dialysate
Blood separated from dialysate by semi-permeable membrane
Adjust wanted/needed solute in dialysate as indicated
Solute and excess water removed from patient
Acidosis treated -- need a buffer

Blood side
HD: extracorporeal, Blood pump mediated
PD: mesenteric blood flow
Urea, Creatinine, potassium, excess body water


Dialysate side
HD: non sterile, must be locally produced*
PD: sterile, shipped
Buffer, +/- Calcium

Front 12

PD and HD membranes

Back 12

PD
Living Membrane
Cannot be manipulated
Cannot be discarded need to protect it
Cannot “pick” membrane

HD Dialyzers
Artificial
Can be manipulated/modified
Is disposable if damaged – discard it
Can “pick” from a menu of membranes

Front 13

Solute removal by dialysis

Back 13

In Stage V CKD, Unwanted, accumulated solute removed by 2 processes:
-Diffusion
--Clearance is MW dependent, very efficient for removal of small solutes
--In PD, an equilibrium is eventually reached
-Convection (along with Ultrafiltration)

Front 14

HD small molecular weight solute removal

Back 14

To enhance small solute clearance:
Can pick different dialyzers (membranes, surface area) to augment clearance
Increase blood flow as tolerated
Increase time per treatment
Increase dialysate flow

Small solutes very readily removed by diffusion

Front 15

PD rate of diffusion

Back 15

Not same for every patient

Peritoneal equilibrium test required to adjust length of time fluid dwells or how much fluid is put in

Front 16

PD solute clearance

Back 16

All patients have different peritoneal membrane transport characteristics
You can not pick membrane type
Must adjust dwell time per exchange to match peritoneal membrane transport type
Increase instilled volume/exchange
Increase number of exchanges
These interventions are very helpful to increase small molecular weight solute removal

Front 17

Ultrafiltration

Back 17

Movement of body fluid (and salt) from blood side to dialysate side

PD is via osmolar differences:
-Add hypertonic PD fluid on the dialysate side and to equalize oncotic pressure water (and some solutes) move from blood side to dialysate side.
-Crystalloid or colloid

HD is by trans-membrane pressure differences.
-A negative or positive pressure is generated across the membrane to suck or pull fluid off.

Can occur independent of diffusion (of solute)
But solute often moves with water (Convection)

Front 18

Absorption of peritoneal fluid

Back 18

Direct lymphatic absorption
- 20% of intraperitoneal fluid absorption
- Mainly in sub-diaphragmatic area
- By pumping action via respiration
- Via direct movement into sub diaphragmatic stoma

Direct absorption into tissues
- fluid then removed by capillaries/lymphatics

Fluid removed by “bulk flow” - no sieving
In health can be up to 1/ml/min

Front 19

Convection

Back 19

Relatively more important for Middle Molecular weight solutes
Can increase convective clearance of Middle molecular weight solutes by increasing UF volume
In HD one can intentionally manufacture synthetic membranes with a high intrinsic ultrafiltration (UF) rates in order to optimize middle molecule removal – you can not do this with PD

Front 20

Dialysis associated morbidity

Back 20

Hemodialysis
-Predominantly access related:
--thrombosis, clot, infection
-Dialysis acquired amyloidosis

Peritoneal dialysis
-Non infectious related access complications rare
-Infectious complications
--(Exit Site Infection; PD related peritonitis)
-Membrane failure in long term patient

Both modalities:
-Cardiovascular problems
-Bone Disease

Front 21

Dialysis access related infections

Back 21

HD
-Can have exit site infections
-Can have bacteremia, line sepsis
--Highest risk Tunneled catheter > Graft > AVF
--Bacteremia occasionally complicated by endovascular infections (SBE) or joint infections

PD
-Can have exit site infection (1/6 years on average)
-Can get peritonitis (On average about 1 in 3.5 years)
--Almost never have bacteremia

Front 22

Does pretransplant modality influence allograft or patient survival

Back 22

PD predicted:
3% lower risk of graft failure
6% lower risk of recipient death
Data persist even if predominant pre-transplant modality (>50% of dialysis time was used rather than immediate)