Advances in dialysis technology

1. Advances in dialysis technology Dr DhaneshVaidya Surat

2. Introduction • Hemodialysis machine has evolved over the history of dialysis; • Increasing significantly in safety and reliability aspects • Dialysis technology • Highly specialized field of nephrology

3. 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

4. Newer Technologies • Dialysis as more physiological and safe treatment due to • Newer technologies like • Membrane technology • Water treatment • Microprocessor technology • Computer and software engineering

5. 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

6. 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

7. 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

8. 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]

9. Comparison of pre- and post-dialysis urea concentration-based methods and on-line monitoring methods

10. 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

11. 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

12. 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

13. 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

14. Hemofiltration - Principle • The convection method solves the problem inherent in diffusion alone, allowing solutes of all sizes to be filtered at a similar rate

15. 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.

16. Terminology • 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 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

17. HEMODIALYSISDiffusion HEMOFILTRATION :Convection

19. Solute Clearance Blood Membrane Dialysate/Ultrafitrate

20. Diffusive Solute Clearance Blood Membrane Dialysate/Ultrafitrate

21. Diffusive Solute Clearance Blood Membrane Dialysate/Ultrafitrate

22. Adsorption ADSORPTION: molecular adherence to the surface or interior of the membrane.

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

24. Clearance Convective Clearance Diffusive Clearance Molecular Weight 100 1,000 10,000 10 Solute clearance : Convection vs Diffusion

27. Mechanism • Filtration (convection) versus dialysis (diffusion)

28. 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

29. 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

30. Intermittent/continuous • Hemofiltration and hemodiafiltration may be performed • Eeithercontinuously 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

31. Nomenclature

32. Mechanism (Contd) The arrangement of a haemofiltration and a haemodiafiltration circuit

34. 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

35. 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)

36. 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

37. 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

38. 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

39. 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’

40. Thank You!