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DVANCES IN DIALYSIS TECHNOLOGY

Dr Dhanesh Vaidya Surat

I NTRODUCTION

 Hemodialysis machine has evolved over the history of dialysis;  Increasing significantly in safety and reliability aspects  Dialysis technology  Highly specialized field of nephrology

I NTRODUCTION

 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

N EWER T ECHNOLOGIES

  Dialysis as more physiological and safe treatment due to Newer technologies like    Membrane technology Water treatment Microprocessor technology  Computer and software engineering

N EWER T ECHNOLOGIES

 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

H EMOFILTRATION

 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

H EMOFILTRATION

 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

H EMOFILTRATION - P RINCIPLE

    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

H EMOFILTRATION - P RINCIPLE

 The convection method solves the problem inherent in diffusion alone, allowing solutes of all sizes to be filtered at a similar rate

M ECHANISMS 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.

T ERMINOLOGY

 Hemodialysis  transport process by which a solute passively diffuses down its concentration gradient from one fluid compartment (either blood or dialysate) into the other  Hemofiltration  use of a hydrostatic pressure gradient filtration (or convection) of plasma water across the membrane of the hemofilter. to induce the  Hemodiafiltration   dialysis + filtration. Solute loss primarily occurs by diffusion dialysis but 25 percent or more may occur by hemofiltration

HEMODIALYSIS

D IFFUSION

HEMOFILTRATION : Convection

S OLUTE C LEARANCE

Blood Membrane Dialysate/Ultrafitrate

D IFFUSIVE S OLUTE

Blood

C LEARANCE

Membrane Dialysate/Ultrafitrate

D IFFUSIVE S OLUTE C LEARANCE

Blood Membrane Dialysate/Ultrafitrate

A DSORPTION

ADSORPTION

: molecular adherence to the surface or interior of the membrane.

U LTRAFILTRATION

ULTRAFILTRATION : The movement of fluid through a membrane caused by a pressure gradient .

S

OLUTE CLEARANCE

D

IFFUSION

: C

ONVECTION VS

Convective Clearance Diffusive Clearance 10 100 1,000 10,000 Molecular Weight

M ECHANISM



Filtration (convection) versus dialysis (diffusion)

H EMOFILTRATION

  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

H AEMODIAFILTRATION (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

I NTERMITTENT / 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

M ECHANISM (C

ONTD )

The arrangement of a haemofiltration and a haemodiafiltrati on circuit

N OCTURNAL

(NHD)

H EMODIALYSIS

 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 ~4 5 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’