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Renal replacement therapy
RK
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Dialysis
Definition
Artificial process that partially replaces renal
function
Removes waste products from blood by
diffusion (toxin and solute clearance)
Removes excess water by ultrafiltration viaosmosis (maintenance of fluid balance)
Wastes and water pass into a special liquid
called dialysis fluid or dialysate
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Selection for HD/PD
Clinical condition
Age(PD prefer in young pt)
Lean body mass
Vascular access availability
Lifestyle
Patient competence/hygiene (PD - high risk of
infection) Affordability / Availability
Patient preferrence
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Indication for dialysis
Complication of uremia(uremic pericarditis,progressive neuropathy, uremic encephalopathy,cramps)
Volume overload unresponsive to diuretics
Hyperkalemia unresponsive to potassiumrestriction
Metabolic disturbances: severe progressive
metabolic acidosis, hyperkalemia,hyperphosphatemia, hyper/hypocalcemia
Removal of drugs causing acute renalfailure(gentamicin, lithium, aspirin overdose)
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Haemodialysis
Dialysis process occurs outside the body in amachine
The dialysis membrane is an artificial oneknown as dialyser
The dialyser removes the excess fluid andwastes from the blood and returns the filteredblood to the body
Haemodialysis needs to be performed threetimes a week
Each session lasts 3-6 hrs
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Requirements for HD
Good access to patients circulation
Good cardiovascular status (dramatic changes
in BP may occur)
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Hemodialysis Apparatus
Dialyzer (cellulose, substituted cellulose,synthetic noncellulose membranes)
Dialysis solution (dialysate water must remain
free of Al, Cu, chloramine, bacteria, andendotoxin)
Tubing for transport of blood and dialysis solution
Machine to power and mechanically monitor theprocedure (includes air monitor, proportioningsystem, temperature sensor, urea sensor tocalculate clearance)
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HD Unit in hospital
Specially designed Renal Unit within a hospital
Patients must travel to the Unit 3 times a week
Patients are unable to move around while on
dialysis; may chat, read, watch TV or eat
Nursing staff prepare equipment, insert the
needles and supervise the sessions
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HD Access
2 criteria for HD access:
Must provide good flow
Reliable access
A fistula: arterio-venous (AV)
Vascular Access Catheter: Internal jugular or
femoral vein
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AV Fistula Access
Matures in about 6 weeks
Ensure good working order
Avoid tight clothing or wrist watch on fistula arm
Assess fistula daily; notify immediately if not working
Avoid BP cuff on fistula arm
Avoid blood sampling on fistula arm
Avoid sleeping on fistula arm
Grafts (synthetic) may be used to create an AV fistula
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AV Fistula
Preferred form of dialysis access
Typically end-to-side vein-to-arteryanastamosis
Types Radiocephalic (first choice)
Brachiocephalic (second choice)
Brachiobasilic (third choice, requiressuperficialization of basilic vein, i.e. transposition)
Lower extremity fistulae are rare
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Dialysis - the Present
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AV Fistula
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Vascular Access Catheter
Double lumen plastic tube
May be placed in Jugular, Subclavian or Femoral
vein
May be temporary or permanent
Temporary awaiting fistula or maturation
Permanent poor vessels for fistula creation e.g.
children and diabetics Catheters must be kept clean, dry and dressed to
prevent infection
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Vascular Access Catheter
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Adv vs Disadv
Adv: max solute clearance, best treatment of
severe hyperkalemia, ready availability, limited
anticoagulation time, bedside vascular access
Disadv:hemodynamic instability, hypoxemia,
rapid fluid and solute shift, complex
equipment, need specialized staff, AV fistula
takes time to form
Eff t f HD Lif t l
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Effects of HD on Lifestyle Travel:
Cannot travel to long distance places/vacation because notavalaibility of dialysis centre or to book in advance with HD unitof places of travel
Responsibility & Independence:
Young patients may defaulted their dialysis leads to uremia
Family relationship Anxiety of living with renal failure affects relationship with
partner
Sport & Exercise:
Can exercise and participate in most sports Body Image:
Esp with fistula; patient can be very self conscious about it
C li ti f HD
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Complication of HD Rapid changes in BP
fainting, vomiting, cramps, chest pain, irritability, fatigue, temporary loss ofvision
Fluid overload esp in between sessions
Fluid restrictions
more stringent with HD than PD
Hyperkalaemia
esp in between sessions
Loss of independence
Problems with vascular access poor quality, blockage etc. Infection (vascular access catheters)
Pain with needles Bleeding and thrombosis
from the fistula during or after dialysis
Infections
during sessions; exit site infections; blood-borne viruses e.g. Hepatitis, HIV
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Peritoneal Dialysis (PD)
Fluid and solute exchange between the peritonealmembrane capillaries and dialysate in theperitoneal cavity
Access is by PD catheter, a soft plastic tube
Catheter and dialysis fluid may be hidden underclothing
Suitability
Cannot done in patients with prior peritoneal scarringe.g. peritonitis, laparotomy
And patients who unable to care for self
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PD principle
Fluid across the membrane faster than solutes;
therefore longer times are needed for solutetransfer
Protein loss in PD fluid is significant ~ 8-9g/day
Protein loss s during peritonitis PD patients require adequate daily protein
averaging 1.2 1.5g/kg/day
Other substances lost in the dialysate
Amino acids, water soluble vitamins, somemedications and hormones
Calcium and dextrose are absorbed from the
dialysate fluid into the circulation
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Dialysate content
Standard dialysis solution contains:
Na+
132 mEq/l Cl- 96 -102 mEq/l
Ca2+ 2.5 3.5 mEq/l
Mg2+ 0.5 -1.5 mEq/l
Dialysis solution buffer:
Sodium lactate
Pure HCo3-
HCo3- /Lactate combinations
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Types
Continuous Ambulatory Peritoneal Dialysis
(CAPD)
Automated peritoneal Dialysis (APD)
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CAPD
Dialysis takes place 24hrs a day, 7 days a week
Patient is not attached to a machine for treatment
Exchanges are usually carried out by patient after
training by a CAPD nurse
Most patients need 3-5 exchanges a day i.e.
4-6 hour intervals with 30 mins per exchange
May use 2-3 litres of fluid in abdomen No needles are used
Less dietary and fluid restriction
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CAPD Exchange
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APD
Uses a home based machine to perform exchanges
Overnight treatment while patient sleeps
The APD machine controls the timing of
exchanges, drains the used solution and fills theperitoneal cavity with new solution
Simple procedure for the patient to perform
Requires about 8-10 hrs
Machines are portable, with in-built safety
features and requires electricity to operate
PD A
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PD Access
Done under
LA or GA
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DIET
Managing the diet
a) can slow renal disease
b) need for dialysis can be delayed
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Foods to control are those containing: Protein
Potassium
Sodium
Phosphorous
Fluid
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Adv vs Disadv
Adv: simple to set/form, easy to use,
hemodynamically stable, no anticoagulation,
bedside peritoneal access,
Disadv: unreliable ultrafiltration, slow fluid
and solute clearance, drainage failure/leakage,
catheter obstruction, peritonitis,
hypoglycemia
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Lifestyle Changes with PD
Flexibility
Can be performed almost anywhere
Least impact on work / school life (esp APD)
Travel
Dialysis supplies can be delivered to most parts of the
world; travel more flexible. APD machines are portable;
will fit into a car boot, can be carried by train/air
Responsibility
Requires more responsibility from patient but more
independence
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Lifestyle Changes with PD
Sports/Exercise
Most are possible
Advice on swimming, lifting, contact sports
Family relationship
May affect relations based on patient anxiety
Delivery & Storage of Supplies
Home delivery and storage
A months supplies 40 boxes; space to store
Specially recruited and trained delivery staff
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Complication
Body Image Problems
Esp with a permanent catheter Abdominal stretching
Fluid Overload
Much less a problem than with HD
Dehydration
Less common than fluid overload
Abdominal Discomfort Bloated feeling
C li ti
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Complication Poor drainage
Catheter displacement/malposition/occlusion
Leakage
Fluid may leak around catheter exit site. (May leakinto scrotum)
Infections Exit site infections
Tunnel infection
peritonitis
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Complication
Hernia
Aggravation of pre-existing herniae after repair
development of new herniae
Declining effectiveness of the peritoneum
e.g. repeated infection
Effect of glucose in the dialysis fluid