basics of the technique and its practiceCRRT and technical aspects.pptx

basic principles of the crrt

1. CRRT- Technical aspects Dr Ramesh Subedi Specialist, Critical Care Swami Dayanand Hospital Delhi

2. 1950’s - CRRT concept originated 1960’s - Scribner proposed CAVHD in context of ARF 1977 - Kramer introduces CAVH 1980 - Paganini introduces SCUF 1984 - Geronemus and Schneider propose CAVHD 1987 - Uldall introduces CVVHD 1990’s - Transition to VV therapies from AV therapies 1996 - R. Mehta, UCSD, hosts the first international conference on CRRT in San Diego

3. Classification and principle

4. Classification

5. Molecular Transport Mechanisms Diffusion Ultra-filtration Convection Adsorption

6. Dialysate Out Dialysate In Blood In Blood Out to waste (from patient) (to patient) HIGH CONC LOW CONC Blood In Blood Out to waste (from patient) (to patient) HIGH PRESS LOW PRESS Repl. Solution Hemodialysis Hemofiltration Repl. Solution Dialysate Solution Blood In Blood Out to waste (from patient) (to patient) HIGH PRESS LOW PRESS HIGH CONC LOW CONC Hemodiafiltration

7. SCUF Slow Continuous Ultrafiltration CVVHD Continuous Veno -Venous Hemodialysis CVVH Continuous Veno -Venous Hemofiltration CVVHDF Continuous Veno -Venous Hemodiafiltration

8. Diffusion or convection? Human kidney works convectively-more physiological Convection may remove the middle and the higher molecules .Diffusion removes only the smaller molecules More hemodynamic stability with convection

9. Vascular access

10. CATHETER TYPE soft, high flow polyurethene uncuffed nontunneled dialysis catheter (2D) (KDIGO-2012) SITE Rt. int. jugular>femoral route (KDIGO-2012) METHOD use ultrasound guidance (1A) (KDIGO2012)

11. Catheter Diameter and blood flow 8.5 FR 150-200 ml/min 11FR 250-300 ml/min 14FR 450-500 ml/min Recirculation SPECIALLY WITH FEMORAL CATHETER< 20 cm Length of insertion Rt internal Jugular-15 cm Femoral-20-24 cm

12. ACCESS Most Important aspect of therapy adequacy Filter life Increased blood loss Staff satisfaction

13. Access Reason to replace catheter Clotted catheter exit site pressure leakage severe kinked catheter bad recirculation issues

14. Hemofilter (Dialyzer)

15. Anatomy of a Hemofilter blood in blood out dialysate in dialysate out Outside the Fiber (effluent) Inside the Fiber (blood) Cross Section hollow fiber membrane (semi-permeable) Canister Filter membrane

16. DIALYZER MEMBRANE TYPES unmodified cellulose modified cellulose synthetic membranes WHICH MEMBRANE ? bio compatibility (with blood) adsorption surface area permeability (pore size, number,thickness)

17. Bradykinin release syndrome Sudden hypotension and pulmonary congestion Uncoated AN 69 Membranes Patients with severe acidosis Priming circuit with banked blood Patients on ACE-I ST filters (Surface Treated) : Neutralizing the electronegativity of the AN-69 membrane by coating with polyethyleneimine (PEI) significantly reduces bradykinin generation .

18. Oxiris Adsorbs endotoxins & cytokines in bloodstream Used during CRRT in septic shock patients Heparin pre-coating

19. Toraymyxin Extracorporeal direct hemoperfusion adsorption column Composed of polymyxin B covalently immobilized polystyrene derived fibers Effective in removing endotoxin in bloodstream

20. Cytosorb blood filtration and purification technology modified, chemically inert, polystyrenic co-polymer biocompatible, highly porous polymer beads spherical beads contain millions of optimally-sized pores and channels massive surface area to bind and remove inflammatory and toxic substances via pore capture and surface adsorption blood cells cannot get into the pores and go around the bead unaffected electrolytes are too small to be captured and go through the beads unaffected

21. Pore size, Flux, and Dialyzer Efficiency All membranes actually have a distribution of pore radii and tortuous structures. More selective dialyzers have a narrow distribution Substituted cellulosic and synthetic membranes have larger sizes. Permeable to water, urea and creatinine. Little or no removal of solutes above 1000 daltons Assuming the cylindrical shape of pores UF = TMP/R and substituting R from Poiseulles equation R = 8l η / π r 4 No of pores = pore density = porosity = K X N X r 2 Diffusive permeability dependant on pore size by an area factor (r 2 ) and flux by r 4 factor. 2 properties are independent of each other. High efficiency dialyzers have high diffusive permeability for small solutes , but low water permeability High flux dialyzers have significantly lower small solute diffusive permeability. Water flux and middle molecule permeability are directly related to each other.

22. Replacement fluids

23. Buffer solutions for Replacement fluid Four types Acetate : hemodynamic instability, weight loss Lactate : Multi Organ Failure, Circulatory shock Bicarbonate : higher risk of bacterial contamination and formation of insoluble precipitates in the presence of calcium and magnesium. Citrate

24. Replacement Fluids Replacement Access Return Effluent P R I S M A Pre-Dilution Lowers HCT,  risk of clotting Compromises efficiency Replacement Access Return Effluent P R I S M A Post-Dilution Better convection may  anticoagulation needs PRE ? / POST ?

25. FILTRATION FRACTION The degree of blood dehydration estimated by determining the FF  fraction of plasma water removed by ultrafiltration : FF(%) = (UFR x 100) / Qp ( Qp is the filter plasma flow rate in ml/min) Qp = BFR* x (1-Hct) *BFR: blood flow rate To prevent clotting, FF<25% Higher BFR and 1/3 pre dilution and 2/3 rd post dilution RF

26. Pressure monitoring