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CRRT solutions

CRRT solutions. Benan Bayrakci , 2014. CRRT deliver y. CVVH is convective , use replasment fluid ( lood side of the filter ) CVVHD is diffusive , use dialysate fluid ( opposite side of the filter ) T here are no convincing clinical data to support either CVVH or CVVHD

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CRRT solutions

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  1. CRRT solutions Benan Bayrakci, 2014

  2. CRRT delivery • CVVH is convective, usereplasmentfluid ( loodside of thefilter) • CVVHD is diffusive, usedialysatefluid (oppositeside of thefilter) • Thereare no convincing clinical data to support eitherCVVH orCVVHD • Combinationtherapy; CVVHDF is alsonot supported by evidence • Howfluid is delivered has little impact on the compositionof the fluid • The replacement and dialysate fluids should have the samecomposition to reduce staff confusion and the risk for error

  3. Options forfluids in CRRT • Custom fluidscompounded by the pharmacy - Thecomplications of compounding include increased costand a shortershelf life (usually 30 days). • Commercially prepared fluidswith additives - K, P, Mg and even bicarbcan be addedas needed but, carriestherisqueforpharmacy errors and may increase costs. - Whether replacement fluid or dialysateis utilized, the fluid should be ultrapure and sterile. - Eachtime an additive is injected, this isassociated with a chance of human error; contamination; wrongdose; wrong syringe,wrong vialetc. • Commerciallypreparedpre-mixedfluids - The safest approach. Lessexpensive and have longer shelf life. - Availablefrom multiple manufacturers, generally 3 l and 5 l bagswith a discrete number of fluid compositions. - The most common concentrations of these solutes are equal to normal plasmalevels

  4. Evaluation of Errors in Preparation of CRRT Solutions • Survey of 3 Pediatric Listserves: • Pediatric Critical Care, Nephrology, CRRT • 16/31 programs reported solution compounding errors • Consequences of improper solutions • 2 deaths • 1 non lethal cardiac arrest • 6 seizures (hypo/hypernatremia) • 7 without complications Barletta et al, PediatrNephrol. 21(6):842-5, 2006 Jun

  5. PD solutions are not recommended! becauseof therisque of hyperglycemiaandmetabolicacidosis

  6. Replacement fluids: • Aredirectlygiven in tothebloodpre- or post filter • Theyare used to increase the amount of convective soluteremoval • Despite their name, replacementfluids do not replace fluid. • Fluid removal rates are calculated independently of replacement fluid rates

  7. Predilution: • Lowersolute clearance, • Higherultrafiltrationrate • Largerfilter surface area • Reducedsludgingandneed for anticoagulation • Useofpre-filter replacement fluids invalidate post-filter lab draws Postdilution: • Higher filtrationfraction

  8. FluidComposition Sodium • Shouldbe in thephysiologicrange(140 meq⁄l). • Customization neededifhypertonic citrate for anticoagulation is used • CVVHDF is more likely toachieve serum sodium concentrations within the normal range than CVVH • Supraphysiologicalsodium concentration in the dialysate or replacement solutions would improvethe hemodynamic stability or prevent the increase in intracranial pressure, butthere are no conclusive data concerning this issue.

  9. Potassium • K concentrations between 0 to4 meq⁄ l are acceptable and commercially available. • Mostpatientshave a degree of hyperkalemia at initiation of RRT therapy. • If K freefluidis used, carefulmonitoringis necessary. • In cases of severe hyperkalemia associatedwith arrhythmia and⁄or hemodynamic collapsehemodialysisshould be utilized.

  10. Calcium • About 60% of total plasma calcium is ultrafilterable, substitutionfluid in CVVH must contain about 3 mEq/l of calcium • Patientsundergoing an exchange of very large volumes of ultrafiltratecarrythe risk of hypercalcemia, therefore mayrequire a lower content of calcium in replacement fluids. • Calcium is always absent from solutions when phosphate is present • Duringcitrate anticoagulation,ifcalcium is present in the fluid it will neutralize the citratebefore it can do itsjob of keeping the filter free of clots

  11. Magnesium • Mg in CRRT fluidsranges between 1 and 1.5 meq ⁄ l. This level is not wellstudied but has been clinically successful • A bolus of2–4 g should be prescribed when Mg levels fallbelow normal range.

  12. Phosphorus • P playsa key role in cellular metabolism and is essential inseveralbiologicalprocesses • Phosphorus is not a standard component of replacementor dialysate fluids in CRRT. This is appropriate asCRRT is commonly employed in the setting of hyperphosphatemia • Majorityof patients on CRRT will require phosphatesupplementation shortly after CRRT initiation. • Criticallyill patientspresent several conditions predisposing hypophosphatemiasuch as sepsis,malnutrition, catecholamines, intravenousglucoseinfusion, hyperventilation, diuretics and rhabdomyolysis. • Management of hypophosphatemia: • -Ensure proper nutrition. • - Add P tothesolutions • - UsePhosphate-containingready solutions

  13. Theaddition of phosphate to the CRRT fluids at concentrationsof up to 7.7 mg/dL does not cause problems with precipitationor instability of the mixture.

  14. Glucose • Physiologicconcentrations of glucose in the dialysate and replacement fluids is advised to compensate extracorporeal losses • Glucose-free solutions might be used when an adequate nutritional regimen has beenestablished

  15. Lactate • Thesimplest, most economical solution; no mixing required. • Effectiveness is well-supported in clinical literature. • Many adults are successfully treated with CVVH usingLactated Ringer's solution as itis: • - convenient • - cheap • - eliminates risk of pharmacy error • Patientswith severe liver failure, and particularly those with reducedmuscle blood flow, may fail to metaboliselactate and develop a metabolicacidosis. • In ICU patients suffering from multiple organ dysfunction, the conversion oflactate to bicarbonate is frequently impaired • Lactic acidosiscausescardiac dysfunction and hypotension • Manyfluidscontain a small, clinically insignificant amount oflactatetoimprovestability

  16. Sodiumbicarbonate • Thesodiumbicarbonateconcentration in CRRT fluidscan be variable. With customized solutions bicarbonatetheoretically can vary from 0 to 150 meq ⁄ l. • With prescribedCRRT clearances of 20 ml⁄kg⁄hour, mostacid base disturbances can be managed with commerciallyavailablebicarbonatecompositions of 25 meq⁄ l to35 meq⁄ l. • Ifthereis difficulty improving pH with a commercially available solution, therapy can bechanged to accommodate the patient’s needs. • Options:Pharmacy customizedsolutions with higher bicarb • Supplementalbicarbonate drip • Increasethe clearancerate of the CRRT system. By increasing the clearancerate, acid removal is increased as is bicarbonateadministration. • The first two options have a risk ofhuman error, whereas it issimple to increase clearances to significantlygreater than 35 ml ⁄kg ⁄hour.

  17. Bicarb-buffered replacement fluids can improve acid-base status and reduce cardiovascularevents better than lactate fluids • The buffer concentration should exert a buffer load thatmay compensate for deficits, for losses in the buffer process, and for extracorporeal lossesand should therefore usually be supraphysiological. • Be avare of hypercapnia! • Citrateis metabolized to bicarbonate, each citrate ion producingthree bicarbonate ions, no additional anionic base is required duringcitrateanticoagulation • Bicarbonate-baseddialysate/replacement fluids are considered standard of caretoday

  18. Dialysate solutions containing bicarbonate have low compatibility with calcium. Ifcalcium is added to a bag containing bicarbonate, calcium carbonateproduces , which could precipitate out of solution and clog the filter. • Calcium can be added to bicarbonate-containing solutions in limited amounts; calciumconcentrations of less than 2.5 mEq/L usually do not result in precipitation. • The two-compartment bag withunique peel-seam interface simplifies preparation and mixing prior to use.

  19. A total of 62 patients • Bicarbonate-basedCRRT fluidscostsome 28% more than standard lactate fluids • Bicarbonate fluids led to a morerapid fall in lactate and greater improvement in base excessduring CRRT, but not overall control of acidosis • Thechoice of fluidfor CRRT did not affect blood pressure or vasopressorrequirements.

  20. Albumin Can be added in dialysateto remove proteinbound medications in the setting of intoxication as well as substancessuchbilirubin

  21. Fluidtemperature • The use of replacement fluids or dialysate solutions at room temperature aswell as continuous blood flow through the extracorporeal system cause an average2C reduction in body temperature, and an energy loss of about1,000 kcal/day • The energy loss during CVVHD is important in hemodynamic stability andprognosis • Heat lossand consequent hypothermia may also affect immune functions and increase therisk of clotting of circuit • Lowerbody temperature may bedesirable in patients with excessive oxygen consumption and low systemic vascularresistance • It is not clearly known in which patients the neteffect of CRRT-induced hypothermia is useful or harmful

  22. Formula of anIdeal CRRT Solution • Physiological • Reliable • Inexpensive • Easy to prepare • Simple to store • Quick to the bedside • Widely available • Fully compatible

  23. Solution?

  24. A successful CRRT programcan onlyrunon safefluids!

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