Dialysis various modalities and indices used

DIALYSIS
VARIOUS MODALITIES AND INDICES USED

GUIDE :- DR. ATKAR SIR
STUDENT :- DR. ABHAY MANGE

Introduction

 Dialysis from Greek dialusis= dissolution.

 Dialysis is process by which the solute composition of a solution ―A‖ is altered by
exposing it to a second solution ―B‖ through a semi-permeable membrane .

 Is a process for removing waste and excess water from the blood

 Used as artificial replacement for lost kidney function

 The goal of dialysis is to remove accumulated fluid and toxins to maintain their
concentrations below the levels at which they produce uremic symptoms.

Initiation of dialysis in ESRD

 Preparation for kidney failure:

 CKD- stage 4 (estimated GFR < 30 mL/min/1.73 m2) should receive timely
education about kidney failure and options for treatment

 Timing of therapy:
 Stage 5 CKD ,estimated GFR < 10mL/min/1.73m2 in diabetics and GFR < 15
mL/min/1.73m2 nondiabetics, respectively.
 Particular clinical considerations and certain characteristic complications -
prompt early therapy

GENERAL PRINCIPLES OF DIALYSIS

 Diffusion
 Ultrafiltration

Diffusion

 Movement of solute Across
semipermeable membrane From
region of high concentration to low
concentration

 Diffusion depends on
 Concentration gradient
 Molecular wt. of solute
 Velocity of molecule in solvent
 Membrane resistance
 Membrane surface area
 Pore size and
 Duration

Ultrafiltration (UF)

 UF occurs when water driven by
either a hydrostatic or an osmotic
force is pushed through the membrane

 Those solutes that can pass easily
through the membrane pores are swept
along with the water called solvent
drag

 The rate of UF will depend on the total
pressure difference across the
membrane (TMP)

Hemofiltration and hemodiafiltration

 All ultrafiltered solutes below the
membrane pore size are removed at
approximately the same rate.

 This principle has led to use of a
technique called hemofiltration,
whereby a large amount of
ultrafiltration is coupled with infusion
of a replacement fluid in order to
remove solutes.

 Some times hemodialysis and
hemofiltration are combined. The
procedure is then called
hemodiafiltration

MODALITIES OF DIALYSIS

 Intermittent
1.Intermittent hemodialysis (IHD)
2 .SLED, sustained low efficiency/Extended Daily Dialysis (Hybrid therapies)

 Continuous
1.Peritoneal dialysis
2.Continuous renal replacement therapy
A . SCUF: Slow continuous UF
B .CAVH or CVVH: Continuous AV/venovenous hemofiltration
C .CAVHD or CVVHD: Continuous AV/venovenous HD
D .CAVHDF or CVVHDF: ContinuousAV/venovenous Hemodiafiltration

Hemodialysis apparatus

 Blood access
 Blood tubing
 Blood pump
 Dialyzer
 Air traps
 Air detectors
 Pressure monitors
“arterial monitor
“venous monitor,”
 Syringe pump
 Blood leak detector

The Hemodialysis Membrane:Dialyser

 In place of glomeruli and tubules the point of exchange for HD is the
membrane in the dialyzer

 Surface area, surface charge, and pore size are properties of the membrane
, govern the molecules that can diffuse from blood to the dialysate.

 Membranes that produce little interaction with blood components are
biocompatible.

 Reuse -should have a blood compartment volume not less than 80% of the
original or a urea clearance not less than 90% of the original clearance.

Dialyser

 The structural composing
dividing dialyzers into
1.Cellulosic-cuprophane and cellulose
acetate, use is in decline.
2.Semisynthetic, and
3.Synthetic - Polyacrylonitrile (PAN)
and polysulfone (PS)

 Dialyzers may be formatted as

1. Hollow fiber
2. Parallel-plate

Dialyser

 Dialyzers are classified as
 1.Conventional-
 Has a membrane that is homogenous and permits effective small solute
clearance, but its clearance of middle molecules is low
 Cellulose based and permit complement activation

 2. High-flux. –
 Constructed with pores that permit passage of molecules exceeding 10,000 D
or more with a clearance
 Significant binding of protein and peptides from the blood

 3.High-efficiency-
 When the high-flux membrane is chemically modified, hydraulic permeability
as well as the permeability to HMW substances is reduced, creating a high
efficiency membrane

Dialysate Circuit

 In some large units, dialysate is made as a batch and stored in tanks then
simply delivered to each dialysis station and connected to the machine.
 In other cases, water that has been treated to remove most elements is sent
to the HD machine and then mixed with a dialysate concentrate/Powder
 Two properties of the dialysate require constant monitoring:-conductivity
and temperature.

 Dialysate circuit
 Dialysate
 Dialysate tubing
 Water treatment system:

Water Treatment

 HD patients are exposed to 600 L of dialysis water a week

 Water treatment systems used by dialysis centers produce high-quality water
for safe dialysis,

 Essential Components of Water Purification
 Temperature-blending valves -mix incoming hot and cold water to provide
an optimum water temperature for downstream components.
 Water softeners- often sodium-containing cation exchange resins- remove
calcium, magnesium, and other polyvalent cations from the feed water
 Granular activated-carbon filters (GAC)- absorb chlorine,
chloramines,and other organic substances from the water
 Primary purification process-Reverse osmosis/Deionization

Hazards Associated with Dialysis Water

Microbiology of Hemodialysis Systems

 Primary contaminants are water bacteria,- gram-negative bacteria, and
non tuberculous mycobacteria

 Nontuberculous mycobacteria in particular are problematic.They do not
produce endotoxins, but they are more resistant to germicides than gram-
negative bacteria

 Pyrogenic reactions (PRs) - incident rate of 0.5% to 12%.

 PR can be defined as chills and/or fever (temperature>37.8°C ) in a
previously afebrile patient with no recorded signs or symptoms of infection
before dialysis.

VASCULAR ACCESS

 Planning for access in ESRD -when patients enter CKD stage -4

 Fistula should be placed at least 6 months before the anticipated start of
HD treatments.

 This timing allows for access evaluation and additional time for revision to
ensure a working fistula

 Exact timing of placement of vascular access will be determined by rate of
decline renal function

Types of Vascular Access

 Venous Access

 External shunt

 Internal shunt
 AV fistula
 AV graft

Arteriovenous Fistula

 Radio-Cephalic
 Brachio-cephalic
 Brachio-basilic
 Brachial-perforating vein fistula
(Gracz )

 Complications
 Stenosis,thrombosis,
 Ischemia and edema of limb,
 Pseudoaneurysm,infection,ccf

Arterio-venous Grafts

 If a primary AV fistula cannot be established,
a synthetic AV graft is the next preferred

 Made of ePTFE(Polytetrafluoroethylene)
also known as Gortex

 Procedure- graft to the artery, a tunneling
under the skin, and anastomosis to a vein.

 Can be used 2 wks after insertion

 Expected to last 3 to 5 years

 Complications:- clotting,aneurysms and
infection

Venous Catheters

 For less than 3 weeks duration
 Cuff/uncuffed
 For patients with AKI, poisoning, in the ICU
setting for CRRT
 Short-term bridge until more permanent access
in CKD
 Preferred site - right internal jugular vein
 Complications: Thrombosis, Infection, Risk of
permanent central venous stenosis or occlusion,
Discomfort and cosmetic , Lower blood flow
rates
 Use of subclavian venous catheters is generally
contraindicated in dialysis patients except as a
last resort.

Anticoagulation for Hemodialysis

 Interaction of plasma with the dialysis membrane produces activation of the
clotting cascade- thrombosis – dysfunction

 Dialyzer thrombogenicity is determined by
 Dialysis membrane composition
 Rate of blood flow through dialyzer and UF rate
 Length, diameter, and composition of blood lines

 Most widely used anticoagulant for dialysis is heparin

 Monitor - activated clotting time (ACT) /APTT

 Heparin administration usually ceases at least 1 h before the end of dialysis


 Systemic administration
 50 to 100 U/kg of heparin at the initiation followed by a bolus of 100 U/hr
 Target ACT is approximately 50% above baseline

 Fractional anticoagulation,
 Bolus of (10–50 U/kg), followed by an infusion of 500 to 1000 U/hr
 Utilized to achieve less intensive anticoagulation
 Target ACT is maintained at 25% (fractional) or 15% (tight fractional),
above the baseline
 These approaches generally reserved for patients with a higher risk of bleed.


 Regional anticoagulation,
 The extracorporeal circuit alone is anticoagulated by
 Administering 500 to 750 U/hr into the arterial line and by the parallel
administration of protamine(1 mg /100u) into the venous line
 Requires frequent checks of the ACT from the arterial and venous line
 Variant of regional anticoagulation
 Uses sodium citrate with dialysate containing no calcium,
 For patients at high bleeding risk,
 Dialysis without any anticoagulation.
 Using the saline flush technique
 HD is initiated at a high blood flow rate to reduce thrombogenicity, and the
 Dialyzer is flushed every 15 to 60 minutes with 50 mL of saline.
 Used in pericarditis,recent major surgery ,IC bleed/surgery


 Low-molecular-weight heparin (LMWH)
 Improvement of lipids,less osteoporosis,less pruritus,
 less hair loss,less blood transfusions compared with UFH

 Direct thrombin inhibitors
 Hirudin ,Lepirudin ,Argatroban -In HIT

DIALYSIS PRESCRIPTION

Components of the Dialysis Prescription

 Dialyzer (membrane, configuration, surface area)
 Time
 Blood flow rate
 Dialysate flow rate
 Ultra filtration rate
 Dialysate composition
 Dialysate temperature
 Anticoagulation

DIALYSIS PRESCRIPTION-
DIALYZER TYPE

 Capacity for solute clearance: Ideal dialyzer should have high clearance
of small- and middle-molecular weight uremic toxins and
 Negligible loss of vital solutes
 Biocompatibility:
 Cost
 Low blood volume compartment

 UF coefficient (KUF)-determines quantity of pressure that must be
exerted across dialysis membrane to generate a ultrafiltrate
 High-flux membranes are defined a having >UF coefficient 15 mL/h/mm
Hg

 Acceptable reuse parameters, the fiber bundle volume must be >80% of
the initial , UF rate must >20% of the manufacturer‘s stated value, and the
dialyzer should not leak .

THE DIALYSIS PRESCRIPTION-
Time and Blood flow

 Length of treatment
 Clearance of a HMW solute can be increased by lengthening HD

 Increasing time decreases LMW solute removal and does not result in
equivalent increases in LMW solute removal -diminishing return

 Blood flow

 As blood and dialysate flow rates increase,resistance and turbulence
within dialyzer also increase leads to decline in clearance per unit time

 Increase blood flow ,Efficacy of vascular access may affect solute
clearance due to recirculation

DIALYSIS PRESCRIPTION:
Dialysate flow /UF rate

Dialysate flow
 Practical upper limit of effective dialysate flow is twice blood flow rate,
beyond which gain in solute removal is minimal
 High flow rates should be confined to blood flows >300 mL/min

UF rate prescription.
 Goal is to achieve estimated dry weight
 Tolerance determined by vascular refilling
 UF modeling may reduce intradialytic complication
 On-line monitoring of blood volume changes may help prescription

Dialysate Composition

 Sodium-
 Standard to have a dialysate Na+ similar to plasma Na+
 Higher dialysate Na+- in patients prone to intradialytic hypotension
 Hyponatric dialysate- prevent interdialytic hypertension,exaggerated thirst,
and excessive interdialytic weight gain.
 Hyponatric dialysate, -interdialytic decline in plasma osmolality result in
dialysis disequilibrium,
 Sodium modeling or sodium ramping, in which the initial dialysate sodium
concentration is greater than or equal to 145 mEq/L and second half
session is abruptly reduced
 Historically,- hyponatric levels (130–135 mEq/L) to favor diffusive
sodium loss during the dialysis


 Potassium
 Dialysate K - 1-3mEq/L is used in most patients
 Low K+ should be used with caution due to association between use of
Low K+ dialysate with SCD

 Calcium.
 Patients with hypocalcemia, positive intradialytic calcium balance may be
desired for control of metabolic bone disease
 Standard dialysate calcium -2.5-3.0 mEq/L is used
 Dialysate calcium also affect hemodynamic stability during HD procedure


Buffer.
 Acetate:
 Biochemically more stable and less frequent bacterial contamination

 Associated with cardiovascular instability and intradialytic hypotension
due to slow conversion of acetate into bicarbonate
 Acetate accumulation also can cause nausea, vomiting, headache,
fatigue,decreased myocardial contractility, peripheral vasodilatation, and
arterial hypoxemia

 Bicarbonate:
 Replaced acetate as standard dialysate buffer
 Dialysate bicarbonate concentrations of 30-35 mEq/L now commonly used


 Chloride.
 Major anion in dialysate
 Dialysate chloride determined to maintain electrical neutrality

 Glucose.
 Osmotic agent for UF
 Optimal 100-200 mg/dL for most patients
 High dialysate glucose (>200 mg/dL)- increases risk for hyperosmolar
syndrome, postdialysis hyperglycemia and hyponatremia,and
hypertriglyceridemia
 Glucose-free dialysate may potentiate hypoglycemia (especially in DM)

 Magnesium
 Many centers use a dialysate magnesium concentration of 1 mEq/l

Composition of typical dialysis solution

COMPONENT meq/l

 Na+ 135-145
 K+ 0-4
 Ca ++ 2.5-3.5
 Mg++ 0.5-0.75
 Cl- 98-124
 Acetate 2-4
 Hco3- 30-40
 Dextrose 11 g
 PH 7.1-7.3

DIALYSIS PRESCRIPTION

 Temperature.
 Dialysate temperature is maintained between 36.5°C and 38°C at inlet of
dialyzer
 Lower dialysate temperature may reduce intradialytic hypotension and also
increase cardiac contractility, improve oxygenation,increase venous tone
 New accurate monitors allow isothermic HD

 Microbiological characteristics
 Medical Instrumentation standards

Rx: Acute hemodialysis

 Session length: Perform hemodialysis for 4 hours

 Blood flow rate: 350 mL per minute

 Dialyzer:-Dialyzer membrane: choice

 Dialysis solution composition (variable):

 Dialysis solution flow rate: 500 mL per minute

 Dialysis solution temperature: 35 to 36°C

 Fluid removal orders:-Use ultrafiltration control device/Remove 2.2 L over 4 hours at
a constant rate

 Anticoagulation orders

Measurement of dialysis dose/Adequacy

 Urea reduction ratio (URR)

URR= PREDIALYSIS BUN-POSTDIALYSIS BUN x 100
PREDIALYSIS BUN

 The fractional decrease in BUN during a single HD
 Simple to calculate
 K/DOQI guidelines suggest urea reduction ratio at least 65%

Measurement of dialysis dose

 Single-Pool urea kinetics.
= SP Kt
V
 K- is the dialyzer blood water urea clearance (L / hour),
 t - is the time on dialysis(hr)
 V- is the volume of total body water(L)

 Most commonly applied method for quantifying HD in clinical practice
 KDOQI-2006 adequacy guidelines = 1.2

INTRADIALYTIC COMPLICATIONS

 1.Hypotension-Most common (incidence, 15% to 30%)
 2.Muscle Cramps
 3.Dialysis Disequilibrium Syndrome
 4.Dialyzer Reactions First-use syndrome/ second-use syndrome
 5.Arrhythmia
 6.Cardiac arrest
 7.Intradialytic Hemolysis
 8.Hypoglycemia
 9.Hemorrhage
 10.Toxic water system treatment contaminants-
hemolysis/anemia/osteomalacia and encephalopathy/Fluoride bone
disease and cardiac arrhythmia
 11.Infectious complications

Chronic complications of HD

 Anemia
 Cardiovascular Disease
 Vascular Calcification
 Calciphylaxis
 Nephrogenic Systemic Fibrosis
 Nutrition
 Infection

Daily HD/Nocturnal HD

 Short daily HD (DHD)-
 Five to seven treatments/ week, each lasting 1.5 to 2.5 hours
 Using high-flux membranes at blood flow rates greater than 400 mL/min
and dialysate flow rates of 500 to 800 mL/min.
 This form of therapy is associated with a significant improvement in
serum albumin levels.

 Nocturnal HD (NHD)
 Five to seven times per week, each lasting 6 to 8 hours,
 Using biocompatible membranes at blood flow rates of 200 to 300 mL/min
and dialysate flows of 200 to 300 mL/min
 Personal preference is the major arbiter of this regimen selection
 Large interdialytic weight gains may benefit

SLED(D) : Hybrid therapy

 Conventional dialysis equipment
 Typically , use low blood-pump speeds of 200 mL/min and low
dialysate flow rates of 300 mL /min for 6 to 12 hours daily
 Excellent small molecule detoxification
 Cardiovascular stability as good as CRRT
 Reduced anticoagulation requirement
 11 hrs SLED comparable to 23 hrs CVVH
 Decreased costs compared to CRRT
 SLED allows units where CRRT equipment or personnel are unavailable
to offer a treatment modality that should achieve similar benefits as
CRRT

Clinical indication of HD

 HD for end-stage renal disease:
 Conventional HD
 Daily HD
 Short daily HD
 Nocturnal HD

 HD for acute renal failure:
 Conventional HD
 Slow low-efficiency dialysis (SLED)
 Continuous renal replacement therapy:

Continuous Renal Replacement Therapy

Introduction CRRT

 CRRT emerged as a viable modality for management of hemodynamically
unstable patients with ARF.
 ( as in septic shock , AMI , severe GI bleeding ,ARDS or condition with or
at risk for cerebral edema)
 Treatment occurring 24 hours a day
 Blood flow of 100 to 200 mL/min
 Dialysate flow of 17 to 40 mL/min
 CRRT membranes that are high flux - higherly permeable to water , LMW
solutes.
 Classified by access type and method of solute clearance.
 Current technology permits any of these treatments with the same machine

Indications for CRRT

 Hemodynamically unstable patients with the following diagnoses may
be candidates for CRRT:
 Fluid overload
 Acute renal failure
 Chronic renal failure
 Life-threatening electrolyte imbalance
 Major burns with compromised renal function
 Drug overdose

 Contraindications for CRRT
 Patient or family refusal of therapy
 Inability to establish vascular access

Advantages of using CRRT

 Suitable for use in hemodynamically unstable patients.
 Precise volume control, which is immediately adaptable to changing
circumstances.
 Very effective control of uremia, hypophosphatemia and hyperkalemia.
 Rapid control of metabolic acidosis
 Improved nutritional support (full protein diet).
 Available 24 hours a day with minimal training.
 Safer for patients with brain injuries and cardiovascular disorders
(particularly diuretic resistant CCF).

 Complications of CRRT
 The most common complications encountered include bleeding, infection,
fluid & electrolyte imbalances, hypothermia, and hemodynamic instability

The machine circuit in CRRT

 A double lumen catheter.
 Blood flow - usually set at 120ml/min.
 Anticoagulant – to prevent blood clotting on
the filter.
 Dialysis fluid, which runs in countercurrent
to the blood, standard rate is 1 L per hour.
 A bag to collect the ultrafiltrate.
 Replacement fluid

 MACHINE-Prisma and Prismaflex systems
from CGH Medical Inc.
 Fresenius USA

Slow continuous ultrafiltration (SCUF)

 In SCUF -volume ultrafiltration at a
rate of 100 to 300 mL/h is performed
to maintain fluid balance

 No fluids are administered either as
dialysate or replacement fluids,

 Indication include volume overload in
patients with CCF refractory to
diuretics.

 SCUF cannot be used to provide total
renal replacement therapy

Continuous Veno-Venous Hemofiltration
(CVVH)
 In CVVH, solute clearance occurs by convection
 No dialysate is used.
 Typically, hourly ultrafiltration rates of 1 to 2 L/h
are used
 Intravenous ‗‗replacement fluid‘‘ is provided to
replace the excess volume that is being removed and
replenish desired solutes,can be administered either
prefilter or postfilter.
 Effective method of solute removal and
 Indicated for uremia or severe acidosis or
electrolyte imbalance with or without fluid overload
 Major advantage is that solutes can be removed in
large quantities , maintaining a net zero or even a
positive fluid balance

Continuous Veno-Venous Hemodialysis
(CVVHD)

 CVVHD employs diffusion to replace renal function.
 Blood flow rate through the is similar to that for
continuous hemofiltration.
 Dialysate is run through the filter at 1 to 2 L/hr.
 This results in a urea clearance of 17 to 34 mL/min,
 One can futher increase the clearance of urea by
combining hemofiltration with the continuous HD
procedure.
 CVVHD is very similar to traditional hemodialysis,
 Effective for removal of small to medium sized
molecules

Continuous Veno-Venous Hemodifiltration
(CVVHFD)
 CVVHDF- the patient is placed on the CRRT
machine with dialysate running on the opposite
side of the filter and replacement fluid either
before or after the filter.

 Combines the benefits of diffusion and
convection for solute removal.

 The use of replacement fluid allows adequate
solute removal even with zero or positive net
fluid balance for the patient..

 In CVVHDF the amount of fluid in the effluent
bag equals the fluid removed from the patient
plus the dialysate and the replacement fluid.

Hemoperfusion

 Hemoperfusion is the method by which
anticoagulated blood is passed through a
column containing sorbent particles

 Activated charcoal particles and resin beads
contained in hemoperfusion devices have been
used

 Certain resins are most effective for removal
of lipid-soluble drugs Antibody- or antigen-
coated particle

 Hemoperfusion devices have been constructed
for the removal of specific toxins.

INTRODUCTION

 PD involves the transport of solutes and water across a membrane• that separates
two fluid-containing compartments.

 These two compartments are (a) the blood in the peritoneal capillaries, (b) the
dialysis solution in the peritoneal cavity

 Popularity because of simplicity, convenience, and relatively low cost.

 Peritoneal transport comprises three processes
 Diffusion, ultrafiltration, and absorption

 The amount of dialysis achieved and the extent of fluid removal depends on the
 Volume of dialysis solution infused ( dwell),
 How often this dialysis solution is exchanged, and
 Concentration of osmotic agent present

PERITONEAL MEMBRANE ANATOMY

 Surface area - ranges from 1 to 2 m2 in an adult.

 Visceral- 90% ,its blood supply from the superior
mesenteric artery, venous drainage via portal
system

 Parietal 10%, important in PD, receives blood
from the lumbar, intercostal, and epigastric and
drains into IVC
 Blood flow = 50 to 100 mL/min

 Lymphatic drainage via stomata in the
diaphragmatic peritoneum,

PERITONEAL MEMBRANE HISTOLOGY

 The peritoneal membrane is lined by
mesothelial cells . Mesothelium
 Under the mesothelium is the interstitium, - a
gel-like matrix , peritoneal capillaries and
lymphatics
 Peritoneal membrane - six resistances to solute Sub serosal loose zone
transport:
1. Stagnant capillary fluid film
2.Capillary endothelium itself, Blood vessels
3. Endothelial basement membrane,
4. Interstitium,
5. Mesothelium, and
6.Stagnant fluid film overlies mesothelium.

PERITONEAL TRANSPORT

 Three-pore model, used to develop the concept
of effective peritoneal surface area.
 Large pores - 20 to 40 nm,protein
 Small pores -4.to 6.0 nm. ,
Large number of these,
Transport of small solutes, such as Urea,
creatinine, sodium, Potassium, with water.
 Ultrapores (aquaporins) <0.8nm.
Transport of water only
 Effective peritoneal surface area is the area of
the peritoneal surface that is sufficiently close to
peritoneal capillaries to play a role in transport

PERITONEAL EQUILIBRATION TEST(PET)

 First described by Twardowski in 1987

 Standard test - to assess peritoneal transport

 High transporters –
 Low transporters-
 High-average and
 low-average transporter

PET: Sampling

 Blood sample glucose/ creatinine : 0,2,4 hour

 Dialysate sample:
 200 ml of dialysis solution is drained into the bag, mixed well, a 10 ml
sample is taken, and the remaining 190 ml is reinfused back
 after 2 and 4 hours, another sample is taken.

 Calculate –

1.D/P creatinine at 2 and 4 hours

2. D/D0 glucose at 2 and 4 hours

3.Volume of UF in the drainage bag

PET

 High transporters
 Achieve most rapid and complete equilibration for creatinine and urea,
because they have a relatively large effective peritoneal surface area or
high intrinsic membrane permeability .
 High transporters rapidly lose their osmotic gradient for UF because the
dialysate glucose diffuses into the blood through the highly permeable•
membrane.
 High transporters have the highest D/P Cr, values but have low net
ultrafiltration and low D/D0 G values.
 They also have higher dialysate protein losses and so tend to have lower
serum albumin values
 High transporters do best on PD regimens that involve frequent short-
duration dwells (e.g., APD),

PET

 Low transporters,
 Have slower and less complete equilibration for creatinine, reflecting low
membrane permeability or small effective peritoneal surface area. They
thus
 Have low D/P Cr, and high D/D0 G with good net ultrafiltration.
 Dialysate protein losses are lower, and serum albumin values tend to be
higher
 Low transporters should do best on regimens based on long-duration,
high-volume dwells, so that diffusion is maximized

 High-average and low-average transporters
 Have intermediate values for these ratios and for ultrafiltration and
protein losses

PERITONEAL CLEARANCE

 Clearance for a given solute is defined as the volume of plasma cleared of
that solute per unit time.

 Clearance is the net result of diffusion plus ultrafiltration minus absorption

 Peritoneal clearance can be increased by
 Maximizing time on peritoneal dialysis (i.e., no dry time),
 Maximizing concentration gradient (i.e., more frequent exchanges as in
and larger dwell volumes),
 Maximizing effective peritoneal surface area (i.e., larger dwell volumes),
 Maximizing peritoneal fluid removal

THE PERITONEAL CATHETER

Acute catheters-
 Straight or slightly curved, relatively rigid ,side holes at the distal end.
 A metal stylet or flexible wire -guide insertion
 Do not have cuffs to protect against incidence of peritonitis
 Increases prohibitively beyond 3 days of use.

Chronic catheters-
 Constructed from silicone rubber or polyurethane and
 Usually have two Dacron (polyester) cuffs
 Dacron cuffs provoke a local inflammatory response that progresses to
form fibrous and granulation tissue within 1 month and act as anchor.
 Chronic catheters function successfully for 2 or more years
 Implanted by surgical dissection or peritoneoscopy

PERITONEAL CATHETERS

 Straight Tenckhoff - deep and superficial cuff extrusion

 Curled Tenckhoff - designed to reduce omental obstruction of the catheter
and to minimize inflow pain. More difficult to reposition .

 Toronto-Western - silastic disc 5 cm apart at the tip of its intra-abdominal
part to stabilize it and prevent visceral wrapping, Impossible to reposition

 Missouri Swan-neck -less omental attachment and catheter migration, no
deep and superficial cuff , difficult to reposition

 No particular catheter is definitively superior to the standard silicon
Tenckhoff in terms of outcome
 Complications of peritoneal catheters ;-pericatheter leak, outflow failure
due to migration and omental attachment, and infection of the exit site or
catheter

PERITONEAL DIALYSIS SOLUTIONS

 CAPD solutions are available in volumes of 1.5, 2.0, 2.25, 2.5, or 3.0 L

 Constituents of PD solutions are

1. Osmotic agent
2. pH
3. GDP content,
4. Buffer used;
5. Calcium
6. Sodium
7. K+


1.Osmotic Agent
 Glucose , amino acids and polyglucose are available

A .Glucose.
 Standard dialysis solutions contain glucose as the osmotic agent.
 Glucose is safe, effective, readily metabolized, and inexpensive.
 Not an ―ideal‖ because of : rapid absorption; the potential for metabolic
derangements
 Studies have suggested more hypertonic glucose have more rapid
deterioration in peritoneal membrane function


B.Amino Acids.
 1.1% amino acid solutions results in ultrafiltration and solute clearance rates
similar to those using 1.5% dextrose solutions.
 for only one dwell daily because of potential to exacerbate uremia and
acidosis.

C. Icodextrin.
 This is a mixture of glucose polymers with a mean MW of about 20,000 kD.
 Icodextrin induces ultrafiltration by oncotic rather osmotic pressure
 Most useful for the long nocturnal dwell of CAPD and the APD
 Function in long-term PD patients is better preserved in those using
icodextrin as compared with glucose
 Use limited to one dwell a day, because of its time course of action, its
relatively high cost, and possible toxic effects


2.PH –
 Traditional lactate-based PD solutions is lowered to about 5.5 to minimize
generation of GDPs during heat sterilization
 Lowering pH further cause infusion pain in patients.
 A pH of 5.5 on infusion is normally well tolerated, and rises rapidly as
bicarbonate diffuses into the peritoneal cavity from the plasma.
 Dual-chamber bags

3.GDPs.
 Heat sterilization process leads to generation of GDPs, which have toxic
effects on the peritoneal membrane.
 The principal strategy to deal with this is the use of multicompartmental
solution bags where the glucose, having been heat-sterilized at a very low
pH


4.Sodium –
 sodium levels are set at about 132 to134 mM
 Higher sodium concentrations would lead to less diffusive removal of
sodium during dwells.
 Low-sodium solutions have been proposed as a means of augmenting
sodium removal but would likely lead to hyponatremia, as well as a
requirement for more glucose to maintain a given osmolarity

5.BUFFER-
 Bicarbonate-based PD solutions are increasingly used.
 Both pure bicarbonate solutions and bicarbonate/lactate mixtures are
available.


6.CALCIUM-
 CAPD solutions containing 2.0 to 2.5 mEq/L used
 goal of reducing the incidence of the hypercalcemia that is sometimes
associated with oral calcium and vitamin D administration

7. MAGNESIUM- levels of 0.5 or 0.25 mM and this can occasionally result
in magnesium depletion

8.TEMPERATURE. PD solutions are usually warmed to body temperature
prior to inflow.

THE PERITONEAL MODALITIES

1.CONTINUOUS AMBULATORY PERITONEAL DIALYSIS (CAPD)

2.AUTOMATED PERITONEAL DIALYSIS (APD)

 CONTINUOUS CYCLING PERITONEAL DIALYSIS (CCPD )
 NOCTURNAL INTERMITTENT PERITONEAL DIALYSIS (NIPD)
 TIDAL PD

3.HYBRID REGIMENS

 NIGHT EXCHANGE DEVICE
 PD PLUS

 ACUTE PD

CAPD

 CAPD, dialysis solution is constantly present in
the abdomen
 Usually involves 4 exchanges of 1.5 to 2.5 L of
solution daily, with the
 Night dwell 8 to 9 hours and day dwells 4 to 6
hours each
 Drainage and inflow of fresh dialysis solution
are performed manually,
 Control of body fluid volume achieved,
 Normalization of blood pressure is possible in
most patients.
 Disadvantage requirement for multiple
procedural sessions and peritonitis

AUTOMATED PERITONEAL DIALYSIS

 APD, using a cycler, is now the fastest-growing
modality
 Requires a cycling machine called a cycler
 Main advantage of CCPD is the ability to provide
continuous therapy without the need for on/off
procedures during the day.
 Therapy of choice for most patients who require
assistance in carrying out their dialysis (e.g., children,
the dependent elderly, nursing home residents
 Main disadvantages of CCPD are the need for a
cycler

CCPD

 Patient carries PD solution in the
abdominal cavity throughout the day but
performs no exchanges and is not attached
to a transfer set.
 At bedtime, the patient hooks up to the
cycler, which drains and refills the
abdomen with solution three or more
times in the course of the night.
 In the morning, the patient, with the last
dwell remaining in the abdomen,
disconnects from the cycler
 Patient free to go about daily activities.

NIPD

 Patient drains out fully at the end of the
cycling period, and so the abdomen is
dry day.
 Because of the absence of a long-
duration day dwell, clearances are
generally lower on NIPD than on CCPD,
 Indicated if there is good residual renal
function or
 If there are mechanical contraindications
to walking about with solution in the
abdominal cavity (e.g., leaks, hernias,
back pain).

Tidal peritoneal dialysis (TPD)

 TPD was designed to optimize solute
clearance by leaving a large volume of
dialysis solution in the peritoneal cavity
throughout the dialysis session.
 Initially, the peritoneal cavity is filled with a
volume of solution to be as large as possible
without causing discomfort-2 to 3 L.
 50% tidal volume common
 The peritoneal cavity is drained completely
only at the end of the dialysis session
 Indications - are poor catheter function or to
avoid drain pain

HYBRID REGIMENS

Night exchange device
 This system was designed to provide a single extra exchange for CAPD
patients, at a predetermined time,

 most often while the patient is asleep

 Enhances ultrafiltration, and so the device is useful for

 patients, typically high transporters, who have net fluid resorption after
long dwells

PD PLUS

 CCPD does not provide adequate clearances for
some patients once residual renal function is lost.
 Additional day exchanges may be required
 These additional day exchanges also improve
ultrafiltration as the single day dwell is too long
for effective net fluid removal.
 PD Plus,- patient returns to the cycler in the
afternoon drains the dialysate that has been in the
peritoneal cavity since that morning, and
 Then refills from the large-volume solution
containers (3 to5 L) that will used to provide
solution for cycling that night

CLEARANCE TARGETS

 TARGET Kt/V on peritoneal dialysis - 2 per week

 Kt = Total Kt = peritoneal Kt+ renal Kt

 Peritoneal Kt = 24-hour dialysate urea nitrogen content/serum urea

 Renal Kt = 24-hour urine urea nitrogen content/serum urea nitrogen

 Total Kt = peritoneal Kt+ renal Kt

CLEARANCE TARGETS

 CrCl (creatinine clearance)

 CrCl = total CrCl corrected for 1.73 m2 body surface area

 Total CrCl = peritoneal CrCl + renal CrCl

 Peritoneal CrCl = 24-hour dialysate creatinine content/serum creatinine

 Renal CrCl = 0.5 (24-hour urine creatinine content/serum creatinine + 24-
hour urine urea nitrogen content/serum urea )

Minimal Recommendations for PD Dose

DOQI
CAPD CCPD NIPD
Kt/V per wk 2.0 2.1 2.2
CrCl per wk 60 63 66

COMPLICATIONS OF PD

A . Infectious Complications B . Noninfectious Complications

 1.Peritonitis  1.Catheter Malfunction-Obstruction
 2.Relapsing Peritonitis -Malposition
 3. Exit-Site Infection  2. Pain-Pain on Inflow/ Outflow
 4.Tunnel Infection  3. Generalized Pain -Back Pain ,
-Shoulder Pain
 4. Abdominal Fullness
 5.Membrane-Related Complication
- Ultrafiltration Failure,
- Sclerosing Encapsulating Peritonitis
 6. Hernias and Abdominal Wall or
Genital Edema
 7.Metabolic

ACUTE PERITONEAL DIALYSIS

 Acute PD provides the nonvascular alternative for dialysis.

 PD like other CRRT used in the intensive care setting,

 Less efficient than hemodialysis in the treatment of acute problems

 May not be the dialytic therapy of choice for extremely catabolic

Indications for acute PD

 a. Uraemic encephalopathy

 b. Severe metabolic acidosis

 c. Diuretic resistant hypervolaemia with pulmonary oedema in patients
with cardiovascular compromise

 d. Uraemic neuropathy

 e. Hyperkalaemia not amenable to medical management

 f. Hypothermia

 g. Hemorrhagic pancreatitis

Contraindications for acute PD

 Absolute  Relative contraindications
contraindications
 Recent abdominal or cardiothoracic
 Recent surgery requiring surgery
abdominal drains;  Diaphragmatic peritoneo-pleural
connections
 Known fecal or fungal peritonitis  Severe respiratory failure
 Abdominal wall cellulitis
 Known pleuroperitoneal fistula.  Severe gastro-esophageal reflux
disease
 Low peritoneal clearances
 Life-threatening hyperkalemia
 Severe acute pulmonary edema
 Extremely high catabolysis

Peritoneal catheter -Acute PD

 Use of an uncuffed temporary catheter,

 Which will have to be replaced after 3 days is recommended

 Acute peritoneal dialysis has traditionally been done using manual
exchanges.

 Increasingly, automated cyclers are being used instead

Prescription of acute PD

 1.Length of the dialysis session

 2.Dialysate composition

 3.Exchange volume

 4.Exchange time -Inflow time /Dwell time /Outflow time

 5.Additive to dilaysate

 6.Monitoring


1.length of the dialysis session
 PD orders for only 24 hours at a time

2.Exchange volume
 Commonly 0.5 L – 2 L, adjusted

 Size of patient‘s peritoneal cavity

 Severity of uremic syndrome

 Start with small volume -minimal leak

 Lager volume grater clearance

 Hypercatabolic : high volume/cycle smaller patients,

 pulmonary disease,hernias volume reduced


3.Dialysis solution dextrose concentration
 Standard 1.5% dextrose - remove 50 to150 mL /hr 2-L exchange volume
 4.25% solution- can result in an ultrafiltration rate of 300-400 mL/ hour.
 Most effective during the initial 15 to 30 minutes, When require very rapid
fluid removal. Such patients can be treated initially with two or three in and
out (zero dwell time) 2-L exchanges of 4.25% solution.

4.Exchange time
 Combined time for inflow, dwell &drain commonly is 1 hour
 Inflow -10 min.( 200ml/min.) Depend on high-abdomen(manual)
 Dwell -Cataboic pt. : dwell 30 min. More stable pt.: longer dwell
(Continuous equilibration peritoneal dialysis ,CEPD)
 Drain( outflow) 20-30 min.


5.Additive to dialysate

1.Potassium: 3-5 mEq/L in PDF
2.Heparin – 1000-2000 u/2 L -prevent clot
3.Insulin -1.5%=8-10u, 2.5%=10-14, 4.5%=14-20 u
4.Antibiotics

6.Monitoring

 Fluid balance
 Clearance –Electrolyte –BUN/Cr –Glucose

Complications of acute PD

1.Mechanical complications
 Pain on inflow
 Localized outflow pain
 Visceral perforations •Bloody dialysate •dialysate leakage
 Abdominal distension & respiratory compromise

2.Infectious complications -Peritonitis up to 12% of cases
 Frequently developing within the first 48 hours

 Contamination during connection or disconnection of each new exchange

3.Medical complications
 Hypovolemia & Hypotension Hyperglycemia .hypernatremia

DIALYSIS IN TREATMENT OF POISONING

Indications
 Progressive deterioration despite intensive supportive therapy

 Severe intoxication with depression of midbrain function leading to
hypoventilation, hypothermia, and hypotension

 Development of complications of coma, such as pneumonia or septicemia

 Impairment of normal drug excretory function in the presence of hepatic,
cardiac, or renal insufficiency

 Intoxication with agents with metabolic and/or delayed effects (e.g., methanol,
ethylene glycol, )

 Intoxication with an extractable drug or poison, which can be removed at a rate
exceeding endogenous elimination by liver or kidney.

CHOICE OF THERAPY

 Peritoneal dialysis (PD)
 Is not very effective in removing drugs from the blood,
 When HD is difficult to institute quickly, such as in small children, .
hypothermic poisoned patient, PD maybe useful.

 Hemodialysis
 Therapy of choice for water-soluble drugs, especially those of LMW
along with a low level of protein binding,
 Examples - ethanol, ethyl glycol, lithium, methanol, and salicylates.
 HD not very useful in removing lipid-soluble drugs .

CHOICE OF THERAPY

 Hemoperfusion

 More effective than hemodialysis in clearing the blood of many protein-
bound drugs and lipid-soluble drugs

 Continuous hemodiafiltration, hemoperfusion. useful in drugs with
moderately large volumes of distribution and slow intercompartmental
transfer times to prevent post therapy rebound of plasma drug levels.

 Continuous hemoperfusion - in theophylline, and phenobarbital toxicity
and

 Continuous hemodiafiltration -in ethylene glycol and lithium toxicity

References

 Handbook of Dialysis- 4th Edition;-Daugirdas, John T.; Blake, Peter G.;
Ing, Todd

 Brenner and Rector;-The Kidney -8thEdition

Milestones in the development of Modern
Hemodialysis
 1861- The process of dialysis was first
described by Thomas Graham (Glasgow)

 1913-Artificial kidney developed
John Abel (Baltimore)

 1924-First human dialysis –------------------
GeorgeHaas(Giessen)

 1943-Rotating drum dialyzer - Dr. Willem
Kolff, a Dutch physician, constructed the first
working dialyzer in 1943 during the Nazi
occupation of the Netherlands

 1966-Internal AV fistula developed Brescia,
Cimino (New York)

 1977 -Continuous arteriovenous
haemofiltration described


3.Dialysis Disequilibrium Syndrome
 Characterized by nausea, vomiting, headaches, and fatigue
 Can result in life-threatening seizures, coma, and arrhythmias
 Pathogenesis from rapid rates of change in solute concentration and pH in
the central nervous system
 Most commonly occurs with high initial solute concentrations
 Treatment strategies
 Use of smaller surface area dialyzers
 Reduced rates of blood and dialysate flow
 Cocurrent (rather than countercurrent) dialysate flow
 High dialysate sodium
 Intravenous administration of diazepam


 Treatment of intradialytic hypotension
 Decreased ultrafiltration rate (1.5 L/h)
 Increased dialysate sodium
 Increased dialysate calcium concentration
 Variable sodium and/or ultrafiltration modeling
 Decreased dialysate temperature
 Use of biocompatible membranes
 Minimize short-acting antihypertensiveswithin 4 hours of dialysis
(especially vasodilators)
 Midodrine, 5 to 10 mg, administered 30 to 60 minutes before
hemodialysis


2.Muscle Cramps
 Occur with up to 20% of dialysis treatments
 Pathogenesis uncertain, but frequently related to acute extracellular
volume contraction
 Treatment of muscle cramps
 Decreased ultrafiltration rate
 Administration of normal or hypertonic saline
 Pharmacologic agents (quinine sulfate, diazepam,vitamin E, carnitine)
 Increased estimated dry weight

Measurement of Kt/V

 Peritoneal Kt/V is calculated by
 Performance of a 24-hour collection of dialysate effluent and
measurement of its urea content.
 This is then divided by the average plasma urea level for the same 24-hour
period to give a clearance term
 Residual renal Kt is calculated in the same way using a 24-hour collection
of urine

EXAMPLE 1
 A 50-year-old man weighing 66 kg has no residual renal function. He is on CAPD
with four 2.5-L exchanges daily, and his net UF is 1.5 L. His V by the Watson
formula is 36 L, and his BSA by the DuBois formula is 1.66 m2. Serum urea
nitrogen is 70 mg/dL (25 mmol/L), and serum creatinine is 10 mg/dL (885
mcmol/L). The urea nitrogen and creatinine (after correction for glucose) levels in
the 24-hour dialysate collection are 63 mg/dL (22.5 mmol/L) and 6.5 mg/dL (575
mcmol/L), respectively. Calculate his Kt/V and CrCl.

 Calculations using mg:
 Kt urea per day = 24-hour drain volume xD/P urea = 11.5 X 63/70 = 10.35 L per day.
 Daily Kt/V = 10.35 L/36 L = 0.288 L.
 Weekly Kt/V = 0.288 XSS 7 = 2.02 L.

 Creatinine clearance per day = 24-hour drain volume X D/P creatinine = 11.5 X
6.5/10 = 7.48 L per day.
 Corrected for 1.73 m2 BSA = 7.48 X 1.73/1.66 = 7.80 L per day.
 Weekly CrCl = 7.8 X 7 = 55 L per week

Anticoagulation in high risk

 Within 7 days of a major surgery or 14 days of intracranial surgery -
without heparin or by regional anticoagulation.
 Within 72 hours of a biopsy of a visceral organ -without heparin or
regional anticoagulation.
 >7 days past a major surgery or 72 hours past a biopsy - fractional
heparinization..
 Pericarditis -without heparin or by regional anticoagulation.
 Minor surgery within the previous 72 hours -fractional anticoagulation.
 Anticipated major surgery within 8 hours of HD -without heparin or
with tight fractional anticoagulation.
 If they are within 8 hours of a minor procedure,-fractional
anticoagulation is appropriate

Dialysis solution additives in acute
PD
 When injecting any additive into dialysis solution containers, meticulous sterile technique must be followed to prevent
bacterial contamination of the dialysis solution and peritonitis.
 Potassium. Standard peritoneal dialysis solutions contain no potassium, but when the patient is hypokalemic, potassium
chloride (3â€―5 mEq/L) can be added. Even in normokalemic patients, failure to add potassium chloride may result in
hypokalemia (especially with 60-minute exchanges) if the patient's total-body potassium content is normal or low and the
oral intake is poor. It must also be remembered that glucose absorption and correction of acidosis with peritoneal dialysis
promotes a shift of extracellular potassium into cells, lowering the serum concentration. If moderate to severe metabolic
acidosis is being corrected, addition of even 5 mEq/L of potassium to dialysis solutions may not prevent hypokalemia, and
parenteral supplementation may be required. Higher concentrations of potassium in the dialysis solution have been used on a
short-term basis, but caution is advised.
 Heparin. Sluggish dialysate flow from catheter obstruction by fibrin clots may occasionally be seen in acute peritoneal
dialysis. This is usually a result of the slight bleeding that may accompany catheter insertion or irritation of the peritoneum
by the catheter. Heparin (1,000 units/2 L) added to the dialysis solution can be helpful in preventing or treating this problem.
Because heparin is not absorbed through the peritoneum, there is no increased risk of bleeding.
 Insulin. Because glucose is absorbed from the dialysis solution, supplemental insulin administration may be required for the
diabetic patient undergoing acute peritoneal dialysis. Regular insulin may be added to the dialysis solution (Table 21-3)
before infusion. The blood glucose level must be monitored closely and the dose of insulin tailored to the needs of the
patient. To minimize the risk of hypoglycemia after dialysis has been stopped, insulin should not be added to the last
exchange of a treatment session.
 Antibiotics. Intraperitoneal administration of antibiotics is efficient and provides an alternative route for patients with poor
vascular access and for those with peritonitis (see Chapter 24). Intraperitoneal administration or P.383

more frequent IV or PO dosing may be required for antibiotics (e.g., aminoglycosides) whose clearances are enhanced by
peritoneal dialysis (see Chapter


6.Dialyzer Reactions
First-use syndrome
 Anaphylactoid reaction to new dialyzers made of cuprophane:
 Alternative pathway complement activation Ethylene oxide exposure
 Bradykinin generation through the kallikrein-kininogen pathway
 Treatment with epinephrine and steroids
Nonspecific type B dialyzer reactions
 The principal manifestations are chest pain, back pain.

 Complement activation has been suggested to be a culprit.

 Management is supportive. Dialysis can usually be continued,

 Prevention-dialyzer reuse or trying a different dialyzer membrane

Factors determining clearance in PD
patients
 Nonprescription factors
Residual renal function
Body size
Peritoneal transport characteristics
 Prescription factors
(a) CAPD:
Frequency of exchanges
Dwell volume
Tonicity of dialysis solution
(b) APD:
Number of day dwells
Volume of day dwells
Tonicity of day dwells
Time on cycler
Cycle frequency
Cycler dwell volumes
Tonicity of cycler solution


4 .Arrhythmia
 Changes in potassium concentration
 Can be precipitated by hypotension and coronary ischemia
 Treatment similar to that for patients with normal renal function
5.Cardiac arrest
 Uncommon in outpatient dialysis
 Related to day of week and dialysate potassium ,concentration
7.Intradialytic Hemolysis
8.Hypoglycemia
9.Hemorrhage

TAC Urea
 Lowrie et al, who published the National Cooperative
Dialysis study of 151 patients in 1981, thought that
following the BUN was not the best way to measure
adequacy
 Developed the time average concentration (TAC) of
urea
 Patients in the high TAC group had higher
hospitalization and more withdrawal from the study

 Lowrie EG et al N Eng J Med 1981; 305 (20) 1176

Why was urea chosen?

 Why not creatinine or beta2 microglobulin?
 Since the BUN is dependent on both dietary urea
production and dialysis removal, it was felt that this
would be the best metric
 It is also easy to measure


10.Toxic water system treatment contaminants
 Chloramine -hemolysis
 Copper -anemia
 Aluminum -osteomalacia and encephalopathy
 Fluoride bone disease and cardiac arrhythmia

11.Infectious complications
 Endotoxin exposure (pyrogenic reactions) from contaminated dialysate or
reuse
 Infectious outbreaks (eg, Mycobacterium chelonei) related to improper
dialyzer reuse

KT/V
 In this formulaDeveloped in 1985, as TAC urea was
not felt to be an adequate marker of adequacy

 Gotch FA; Sargent JA: A mechanistic analysis of the NCDS. Kidney Int
1985 Sept; 28 (3): 526-534

Calculation of KT/V

 KT/V = -ln (R – 0.03) + [(4 – 3.5R) times (UF
divided by W)]
 where UF is UF volume, W is the postdialysis
weight in kg and R is the ratio of post-dialysis to
pre-dialysis BUN

Post-dialysis BUN
 Both access and cardiopulmonary recirculation are
prominent at the end of dialysis, so the post dialysis
BUN should not be measured immediately during
high blood flow
 Both have pretty much dissipated by two minutes
after dialysis

Equilibrated (Double Pool) KT/V
 Measurement of post dialysis BUN at the very end of
dialysis overestimates the degree of urea removal, as
it takes about 30 minutes after dialysis for urea to
come out of cells and ―equilibrate‖ with the extra-
cellular content
 eKT/V is about 0.21 lower than sKT/V
 It is inconvenient to keep the patient an extra 30
minutes

 Step 1: Estimate the patient's V.
 Step 2: Multiply V by the desired Kt/V to get the required K Ã— t.
 Step 3: Compute required K for a given t, or the required t for a
given K.
 Estimate V. This is best done from anthropometric equations
incorporating height, weight, age, and gender as devised by Watson
(Table A-2). If the patient is African American, add 2 kg to the Watson
value for Vant. Alternatively, one can use the Hume-Weyers equations or
the nomogram derived from them (Table A-2, Figs. A-5 and A-6).
Assume that, in this case, the estimated V is 40 L.
 Compute the required K Ã— t. If the desired Kt/V is 1.5 and estimated
V is 40 L, then the required K Ã— t is 1.5 times V, or 1.5 Ã— 40 = 60
L.
 Compute the required t or K. The required K Ã— t can be achieved
with a variety of different combinations

Stop dialysate flow technique-for eKT/V

 In a study of 70 patients in Glasgow, the 30 minute
post dialysis BUN was compared with the stop
dialysate flow BUN
 Possible to estimate eKT/V by getting a BUN within
5 minutes of completion
 A regression equation was generated:
 30 min BUN = 1.06 times (5 min BUN) + 0.22

 Traylor JP et al. AM J of Kidney Dis 2002 Feb; 39(2): 308-314

Adequacy metrics
 URR-CMS says it should be greater than 65%; 70
% is more reasonable
 spKT/V-should be greater than 1.4 – 1.6
 eKT/V should be greater than 1.2 – 1.4-this is the
most accurate metric
 If a patient is getting metrics equal to or greater
than above, is that patient getting adequate
dialysis? Maybe not

 In NIPD (row 1 in Fig. 19-3),
 the patient drains out fully at the
end of the cycling period, and so
the abdomen is â€œdryâ€• all
day.
 Because of the absence of a
long-duration day dwell,
clearances are generally lower
on NIPD than on CCPD,
 its use may be indicated if there
is good residual renal function or
if there are mechanical
contraindications to walking
about with solution in the
abdominal cavity (e.g., leaks,
hernias, back pain).

Drug Preferred Method
Carbamazepine HP
Ethylene glycol HD
Lithium HD
Methanol HD
Methotrexate HF
Phenobarbital HP
Procainamide HF
Salicylate HD or HP
Theophylline HP or HD
Valproic acid HD or HP

Why weekly Kt/V and CrCl ?
 Uremic Sx No of
exchange
 Overall small MW clearance is
most closely related to uremic
toxicity

 CANUSA study
 680 CAPD patients
 weekly Kt/V 0.1 = 5% patient survival
 CrCl 5 L/1.73m2/wk = 7% patient survival
 No evidence of a plateau effect over the range of the clearance
 Kt/V = 2.1 Predicted 2-yr survival 78% CrCl = 70 L/1.73m2

Salicylate poisoning
 Indications for dialysis:
 severe metabolic acidosis
 serum level > 100 mg/dL (acute OD)

 level > 60 mg/dL (elderly, chronic OD)

 Note:
 check units!! (mg/dL vs mg/L)
 alkalinize serum and urine

 dialysis preferred: can correct electrolyte and fluid
abnormalities

THE PERITONEAL MODALITIES

 Continuous ambulatory PD
(CAPD))
 Continuous Cycler-assisted
PD (CCPD)

 Nightly PD (NPD)
 Intermittent PD (IPD)
 Tidal PD

Theophylline poisoning
 serum level > 100 mg/L (acute OD)
 level > 60-80 mg/L? (chronic)

 seizures

 Notes:
 HP or high-flux HD
 Control Sz w/ phenobarbital

 Rx hypotension w/ beta blockers

Methanol, Ethylene Glycol
 elevated level > 50 mg/dL
 severe acidosis

 increased osmolal gap > 10-15 mmol/L

 Notes:
 HD only - not adsorbed to AC
 give blocking drug (EtOH, 4-MP) - Note: need to
increase dosing during dialysis

Weekly Kt/V & CrCl

 Peritoneal Kt = DUN / BUN x PD drain vol -- (2)
 Renal Kt = UUN / BUN x 24H Urine vol -- (3)
 Weekly Kt = { (2) + (3) } x 7 -- (4)
 Kt / V = (4) / (1)

 Peritoneal Clcr = Dcr / Pcr x PD drain vol -- (5)
 Renal Clcr = { ( Ucr/Pcr + UUN/BUN) / 2 } x 24h UV -- (6)
 Weekly Clcr = { (5) + (6) } x 7 x ( 1.73 / BSA )

Phenobarbital
 level > 190-200 mg/L
 failure of supportive care (ie, intractable hypotension)

 Notes:
 rarelyseen anymore
 HP > HD

 repeated dose AC shortens half-life but not length of
coma

Lithium
 serum level > 6? 8? 10? (acute OD)
 level > 4 ? (chronic)
 level 2.5-4 with severe Sx?

 Notes:
 2-compartment model, very slow redistribution from
tissues
 patients rarely get quick improvement
 difficult to evaluate need and benefit
 IV saline ―diuresis‖ may be nearly as effective

continuous veno-venous
hemodialysis
 In continuous venovenous hemodialysis, a dialysate solution runs countercurrent to the flow
of blood at a rate of 1 to 2.5 L/h (Fig. 6).
 Solute removal occurs by diffusion.
 Unlike IHD, the dialysate flow rate is slower than the bloodflow rate, allowing small solutes
to equilibrate completely between the bloodand dialysate.
 As a result, the dialysate flow rate approximates urea and creatinineclearance.
 Ultrafiltration is used for volume control but can allow for some convective clearance at
high rates.
 Continuous venovenous hemodiafiltration(Fig. 7) combines the convective solute removal of
CVVH and the diffusivesolute removal of continuous venovenous hemodialysis. As in
CVVH, the highultrafiltration rates used to provide convective clearance require the
administrationof intravenous replacement fluids. Replacement fluids can be administered
prefilter or postfilter. Postfilter replacementfluid results in hemoconcentration of the filter
and increased risk of clotting, especially when the filter fraction is greater than 30%. The
filtrationfraction is the ratio of ultrafiltration rate to plasma water flow rate and is
dependenton blood flow rate and hematocrit [17]. Prefilter replacement fluiddilutes the blood
before the filter, resulting in reduced filter clotting. Dilutionof solutes before the filter
reduces solute clearance by up to 15% by loweringthe diffusion driving force and convective
concentration.

Acute Peritoneal Dialysis Orders

 Nursing orders:
 Dialysis to run_________hours
 Exchange volume:_________L
 Warm dialysis fluid to 37Â°C.
 Exchange time: Inflow 10 minutes
Dwell_________minutes
Outflow 20 minutes or as long as fluid drains freely
DO NOT LEAVE FLUID IN ABDOMEN
 Strict intake and output to be kept on fluid intakeâ€―output record.
 Dialysate balance to be recorded on peritoneal dialysis record.
 Dialysis fluid running balance to be maintained at:_________L.
 Dialysate solution:_________%
 Additives to dialysate:
Medication Dose Frequency
_________ _________/2 L q exchange or Ã—_________exchanges
_________ _________/2 L q exchange or Ã—_________exchanges

Selection for HD/PD
 Clinical condition
 Lifestyle
 Patient competence/hygiene (PD - high risk of
infection)
 Affordability / Availability

Physiology of peritoneal transport
 depends on the following factors
1. The concentration gradient,
2. Effective peritoneal surface area,
3. Intrinsic peritoneal membrane resistance ,
4. Molecular weight of the solute concerned,( Mass transfer area coefficient
,Peritoneal blood flow)
B. Ultrafiltration depends on
 Concentration gradient for the osmotic agent (i.e., glucose)

 Effective peritoneal surface area

 Hydraulic conductance of the peritoneal membrane

 Sieving. Sieving occurs when solute moves along with water across a
semipermeable membrane by convection, but some of the solute is held back, or
sieved.
C. Fluid absorption- occurs via the lymphatics
1. Intraperitoneal hydrostatic pressure
2. Effectiveness of lymphatics

Hemodialysis
:
Thomas Graham (1805-1869) The First Hemodialysis Experiment 1913

Hemodialysis
George Haas used a collodion
tube arrangement to successfully George Haas
dialyze human subjects

Dialysis various modalities and indices used

Dialysis various modalities and indices used

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