Part 1 Dialysis Flashcards
Define hemodialysis
Perfusion of blood and a physiologic solution on opposite side of semi-permeable membrane
Blood removed from body
Define peritoneal dialysis
Peritoneal membrane serves as the semipermeable membrane
HD Dialysis access created:
GFR less than 25
SCr great than 4
1 year prior to anticipated need for dialysis
The need for dialysis is recommended if
GFR or CrCl less than 15
***Acute indications for dialysis
Acidosis Electrolytes (hyperK) Intoxication (drug over dose Fluid overload Uremia
***Chronic indications for dialysis
Signs of kidney failure (acid base, electrolyte imbalance, pruritus)
Inability to control volume status or BP
Deterioration in nutritional status
Cognitive impairment
Conventional or standard dialyzers
Small pores limit clearance to small molecules (urea or creatinine)
Low blood flow rate
High efficiency dialyzers
Large surface area (increased capacity to remove water, urea, small molecules)
High blood flow rate
High flux dialyzers
Large pores increase removal of high molecular-weight substances
High blood flow rate
Dialysate solution
Composed of purified water, glucose, sodium, K, Ca
Dialysis solution bases
Base is added to dialysate to neutralize acids
Acetate –> bicarbonate in liver (bicarb is more expensive)
Bicarbonate is
drug of choice in liver impairment and sever acidosis
Vascular access is:
major challenge for success and long-term feasibility of HD
Types of access
AV fistula
AV synthetic graft
Venous catheter
Advantages of AV fistula
Longest survival
Lowest complication rate
Increases survival and decreased hospitalization rate
Disadvantages of AV fistula
Take 1-2 months to mature
Difficult to create in elderly or PVD pts
Advantages of AV synthetic graft
Easily implanted
Longer survival than others
Disadvantages of AV synthetic graft
Short survival than fistula
Higher rate of complications
2-3 wks to endothelialize prior to use
Advantages of venous catheters
Immediate use
Easy to place and remove
(femoral, subclavian or internal jugular vein)
Disadvantages of venous catheters
Short survival
High risk of infection
May not provide adequate blood flow
Urea reduction ratio (URR)
Percentage of blood being cleared of urea
100X(predialysis BUN - postdialysis BUN)/predialysis BUN
>60% is adequate
Intermittent HD
3 sessions/wk
3-5 hrs/session
Sustained Low-Efficiency Dialysis (SLED)
PRN basis***
Continuous HD
Based on access
Advantages of HD over PD
Intermittent treatment
Effectiveness more easily measured
Low technique failure rate
Closer monitoring of pt
Disadvantages of HD
Loss of independence
Long adjustment time
Risk with vascular access
More rapid decline in renal function
PD Principles
Blood filled compartment: Blood vessels that supply and drain abdominal viscera, musculature and mesentery
Dialysate filled compartment: peritoneal cavity
Semipermeable membrane: peritoneal membrane
PD Effiacy is not as easily manipulated bc
Distance between compartments
Cannot regulate blood flow
No countercurrent flow
Cannot change permeability
Continuous Ambulatory Peritoneal Dialysis (CAPD)
Manual exchange every 4-8 hrs during the day
Requires about 20 minutes per exchange
No machine
CAPD Advantages and disadvantages
A: independence
D: infection risk
Automated peritoneal dialysis (APD)
Automatic cycler performs exchanges at night
APD Advantages and disadvantages
A: fever exchanges, sterility, convenience
D: machine in bedroom
Continuous cycling peritoneal dialysis (CCPD)
APD with “wet” day
Multiple exchanges at night with a long daytime dwell
Tidal peritoneal dialysis
Initial partial fill, then drain, then replacement
Creates tidal flow
Nightly intermittent peritoneal dialysis
APD with “dry” day
Multiple exchanges at night without a daytime dwell
Intermittent Peritoneal DIalysis
Reserved for acute pts
Operater can change concentration, volume, time
Disadvantages of Intermittent Peritoneal DIalysis
High cost and risk of infection
Advantages of PD over HD
Continuous removal of solutes
Improved clearance of larger solutes
Better preservation of renal function
Increased independence
Disadvantages of PD
Predisposition to malnutrition Excessive glucose load Continued aseptic technique Time consuming exchanges Injury prone peritoneum Peritonitis
