Advances in dialysis technology

Report
ADVANCES IN DIALYSIS
TECHNOLOGY
Dr Dhanesh Vaidya
Surat
INTRODUCTION

Hemodialysis machine has evolved over the
history of dialysis;


Increasing significantly in safety and reliability
aspects
Dialysis technology

Highly specialized field of nephrology
INTRODUCTION

In clinical practice settings,


Dialysis technologists provide dialysis treatment
under the supervision of a physician
Clinical staff are required to

Understand functioning of hemodialysis (HD)
machines in order to manage it safely in delivering
the dialysis care delivery for patients
NEWER TECHNOLOGIES
Dialysis as more physiological and safe treatment
due to
 Newer technologies like

Membrane technology
 Water treatment
 Microprocessor technology
 Computer and software engineering

NEWER TECHNOLOGIES

Newer modules which improve safety and
efficacy of dialysis procedure are
Online clearance monitor (OCM)
 Blood Volume Monitor (BVM)/Citline,
 Blood Temperature Module


Also

Haemodiafiltration (HDF) and Haemofiltration (HF)
which
Simulates excretory function of natural kidney more closely
and
 Demonstrates clear cut advantage over standard HD

OCM (ONLINE CLEARANCE MONITOR)

Uses conductivity sensors to measure the pre and
post dialyzer change in the sodium concentration
of dialysate to determine the effective dialyzer
urea clearance
OCM (ONLINE CLEARANCE MONITOR)

Offers a visual assessment of
the adequacy of the treatment
provided

Projected adequacy goal
attainment is graphically
presented on the OLC (online
clearnace) screen

If the Kt/V drops below a target,
the clinician is alerted

This visual aid allows staff to
reassess patient condition
OCM (ONLINE CLEARANCE MONITOR)
Kt/V
 For about 30 years, the individual dose of dialysis
(Kt/V) has been defined as the


Product of urea clearance (K) times the length of
treatment time/dialysis time (t) in relation to the
urea distribution volume (V) of the patient

[K – clearance determined. The clearance for a
certain solute is the (theoretical) flow K cleared
completely from this solute]

Comparison of pre- and post-dialysis urea
concentration-based methods and on-line
monitoring methods
OCM (ONLINE CLEARANCE MONITOR)

Advantages
Provides safe and accurate tool for continuous
online monitoring of total urea clearance
 Does not require blood sample
 Inexpensive
 Improves and monitoring efficacy of HD
treatment

HEMOFILTRATION

Hemofiltration





Renal replacement therapy similar to hemodialysis
Almost exclusively used in the intensive care settings
Nearly always used in in cases of acute renal failure
Slow, continuous procedure, usually requiring 12 to
24 hours per session
Usually performed daily for as long as necessary
HEMOFILTRATION

During hemofiltration, a patient’s blood is passed
through a set of tubing (a filtration circuit) via a
machine to a semipermeable membrane (the
filter)
Where waste products and water are removed
 Replacement fluid is added and
 Blood is returned to the patients

HEMOFILTRATION - PRINCIPLE
Hemofiltration mainly differs from dialysis in the
method of filtration
 Both procedures use a semi-permeable
membrane to filter the blood, but hemofiltration
uses convection along with diffusion, while
dialysis uses diffusion alone
 Convection allows positive fluid pressure to drive
water and solutes through the filtering
membrane
 Diffusion is simply the random motion of
particles in the blood, so larger solutes are not
filtered as quickly as smaller ones because they
move more slowly

HEMOFILTRATION - PRINCIPLE

The convection method solves the problem
inherent in diffusion alone, allowing solutes of all
sizes to be filtered at a similar rate
MECHANISMS OF SOLUTE CLEARANCE

Diffusive transport


Blood from the patient flowing within the dialysis
apparatus interfacing with dialysate fluid via pores
located within each fiber of the dialysis membrane
Convective transport

In this mechanism, solutes are effectively dragged
along with fluid as it moves across the membrane
depending upon their size relative to the size of the
membrane pores.
TERMINOLOGY

Hemodialysis


Hemofiltration


transport process by which a solute passively diffuses
down its concentration gradient from one fluid
compartment (either blood or dialysate) into the other
use of a hydrostatic pressure gradient to induce the
filtration (or convection) of plasma water across the
membrane of the hemofilter.
Hemodiafiltration


dialysis + filtration.
Solute loss primarily occurs by diffusion dialysis but 25
percent or more may occur by hemofiltration
HEMODIALYSIS
DIFFUSION
HEMOFILTRATION :
Convection
SOLUTE CLEARANCE
Blood
Membrane
Dialysate/Ultrafitrate
DIFFUSIVE SOLUTE CLEARANCE
Blood
Membrane
Dialysate/Ultrafitrate
DIFFUSIVE SOLUTE CLEARANCE
Blood
Membrane
Dialysate/Ultrafitrate
ADSORPTION
ADSORPTION: molecular adherence to the surface
or interior of the membrane.
ULTRAFILTRATION
ULTRAFILTRATION: The movement of fluid through a membrane
caused by a pressure gradient.
Clearance
SOLUTE CLEARANCE : CONVECTION VS
DIFFUSION
Convective
Clearance
Diffusive
Clearance
10
100
1,000
10,000
Molecular Weight
MECHANISM
 Filtration
(diffusion)
(convection) versus dialysis
HEMOFILTRATION

Replacement fluid composition
An isotonic replacement fluid is added to the blood to
replace fluid volume and electrolytes
 Fluid must be of high purity



Infused directly into the blood line of extracorporeal circuit.
Contains either lactate or acetate to generate the
electrolyte bicarbonate, or bicarbonate on its own

Use of Lactate may be occasionally be problematic in
patients with lactate acidosis or with severe liver
disease

Because in such cases the conversion of lactate to
bicarbonate can be impaired
 Bicarbonate is commonly used for such patients
HAEMODIAFILTRATION (HDF)

The rate of filtration of both large and small
solutes can be even more balanced by the use of
hemofiltration and dialysis in combination

This procedure is known as hemodiafiltration

Combination is theoretically useful because it results
in good removal of both large and small molecular
weight solutes
INTERMITTENT/CONTINUOUS

Hemofiltration and hemodiafiltration may be
performed

Eeither continuously or intermittently
The on-line, intermittent method can be used for
outpatient treatment, while the
 Continuous method is normally used in intensive
care


The intermittent method prepares replacement fluid
on-line by filtering the dialysis fluid, while the
continuous method uses pre-packaged, sterile,
commercially prepared replacement fluid
Nomenclature
MECHANISM (CONTD)
The arrangement
of a
haemofiltration
and a
haemodiafiltrati
on circuit
NOCTURNAL HEMODIALYSIS
(NHD)


Nocturnal hemodialysis or nightly hemodialysis
is a form of hemodialysis which is done at home
by the patient or a family member when the
patient is sleeping at night
Most patients dialyze three or four nights a week,
anywhere from six to12 hours, on average for
eight hours
NHD

NHD





Long, slow, gentle and generally self-performed
dialysis
Undertaken, usually at home, after a quiet dialysis
machine has been installed in the bedroom
Can be provided in ‘sleep-over’ centres in some
countries and states – though this is not as ideal as
home-based care as, usually, centre-delivered NHD is
limited in its frequency if not in its hours
Can be performed in frequency anywhere from every
alternate night through to 6 or 7 nights per week –
again, especially in the home
Delivers up to 4 times the amount of dialysis (8-9
hrs/treatment, 6-7 nights/week = 50-60 hrs/week
compared to ~12 hrs/week for CHD)
NHD

NHD – benefits
 No more of the usual side-effects of
conventional HD
 No more ‘crashes’ from falling blood pressure
 Minimal (alternate nights) or no (5-6
nights/wk) fluid or dietary restriction
 No need for phosphate binding medicines if ~45 sessions or more are given per week
 No need for BP medication for most patients
 No need for a dialysis partner – solo, home,
overnight dialysis is not only possible but is
practical in un-partnered people
NHD

Further benefits
 Stress on the heart is diminished
 Calcium deposits in blood vessels regress
 Sleep patterns normalize to generally
refreshing rest
 Sleep apnoea improves or resolves
 Thinking clears and memory improves
 Sexual drive/function improves
NHD

Further benefits





Day-time and waking hours are given back
Day-time activities return to normal without dialysis
interference
Energy to work and work capacity is restored
Employment opportunity is again equal with people
not on dialysis
Independence and self-esteem is restored
NHD

Potential risks include, but are yet to
demonstrate:
1. ‘Over-dialysis’ – the inadvertent removal
of essential substances, vitamins and
minerals by prolonged filtration
2. Access disconnection or infection
3. Blood or fluid loss whilst asleep
4. Heparin-related osteoporosis
5. Technique ‘burn-out’

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