LOGISTICS OF RENAL REPLACEMENTTHERAPY: RELEVANT ISSUES FORCRITICAL CARE NURSES

Commentary

By Ladan Golestaneh, MD, MS, Barbara Richter, RN, MA, and Margaret Amato-Hayes, RN, MSN

The term continuous renal replacementtherapy (CRRT) refers to a group of clear-ance techniques that have been tailoredfor hemodynamically unstable patientswith renal failure. Although the indica-

tions for starting this type of therapy are similar tothe indication used to start patients on intermittenthemodialysis (IHD), the prescription, including theduration and the intensity of clearance and fluidremoval, is different.

The types of machines used for each therapyalso are different. Patients with unstable hemody-namics are unable to tolerate the flow rates used torender therapy in typical dialysis patients: thesepatients cannot tolerate large amounts of fluidremoval in a limited time, nor can they tolerate thehigh electrolyte and solute fluxes that accompanythe higher blood flow and dialysate flow rates inIHD. Thus, it comes as no surprise that the adventof CRRT was an exciting opportunity for intensivistsand nephrologists caring for critically ill patientswith acute renal failure.

Types of Renal Replacement TherapyCRRT

CRRT refers to 4 main types of therapy: continu-ous venovenous hemofiltration (CVVH), continuousvenovenous hemodialysis (CVVHD), slow continuousultrafiltration (SCUF), and continuous sustained low-efficiency dialysis (cSLED). Continuous venovenoushemodiafiltration falls into this category as well, how-ever this paper will not address this technologydirectly. All 4 of these techniques share: the ability(and in some cases, necessity) of continuous deliveryfor 24 hours, use of low blood flow and dialysate flowrates, slow continuous fluid removal, venovenousaccess via a Shiley hemodialysis catheter or another

large catheter, and need for continuous observation.These techniques differ in the way they clear toxins,their cost, who monitors the therapy (intensive careunit [ICU] nurse or dialysis nurse), use of continuousanticoagulation, and their ease of use. Hybrid tech-niques such as SLED fall between IHD and CRRT.Differences are outlined in the following paragraphs.

CVVHA typical CVVH machine (eg, NxStage [NxStage

Medical Inc, Lawrence, Massachusetts] or Prisma[Gambro AB, Lund, Sweden]) has a blood pumpthat drives blood from a catheter from the patientinto a dialyzer (typically polysynthetic hollow fiberdialyzers that are high flux and have smaller surfacearea). After passing through the dialyzer, the bloodis returned to the patient as part of the circuit drivenby the blood pump. Within the dialyzer, a transmem-brane pressure differential is created that allowsnegative pressure to remove fluid (ultrafiltrate) andany solutes dissolved within the fluid from theblood compartment.1-3

This is usually done by using another pumpthat is active on the ultrafiltrate side of the mem-brane. The ultrafiltrate fluid and its contents aredisposed of into a drain.1-3 In turn, via another inletinto the circuit, dialysate or replacement fluid isinfused to maintain fluid balance. This form ofclearance is referred to as “convection” or solventdrag.1-3 Movement of particles is dependent on thetransmembrane pressure that is created in the dia-lyzer membrane (Figure 1).

CVVHDCVVHD can be done with any machine that

has a blood pump, a dialysate pump and a trans-membrane (dialysis membranes) pressure differen-tial to create ultrafiltration. The dialyzer is similar,if not the same, as a CVVH dialyzer. CVVHD, unlikeCVVH, uses diffusive clearance to achieve solute

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control. By enabling blood, with its high concentra-tion of toxins, and dialysate (plasma fluid withoutany solute buildup) to interact against a semiper-meable membrane, CVVHD ensures the movementof toxins from blood to dialysate.1-3

Ultrafiltration is done only to achieve fluid bal-ance (not clearance) and can be done by havinganother pump on the dialysate side of the membranecreate transmembrane pressure.1-3 This pump enablesnegative pressure on that side to create a transmem-brane pressure (the same pump used for filtrationin CVVH). CVVHD is very similar to IHD except thatthe blood and dialysate flow rates are much slower.In order for such slow rates to render effective clear-ance, CVVHD must be given continuously (Figure 2).

SCUFSCUF is not a clearance technique: it provides

only slow removal of fluid. This therapy is forpatients who do not need uremic toxin removaland need only fluid removal. Because patients’hemodynamics are fragile, fluid removal is doneslowly for 24 hours. SCUF can be done on anymachine that has a blood pump and can createtransmembrane pressure for fluid removal. A bloodpump drives blood from the patient into the dia-lyzer and circulates it back to the patient. A trans-membrane pressure is created by using a pump onthe opposite side of the membrane.1-3

SLED and Other Hybrid TechniquesSLED and similar techniques use the dialysis

machine to deliver prolonged dialysis (6-24 hours)by using diffusive clearance much like IHD andCVVHD. Because of hemodynamic considerations,SLED has lower blood flow and dialysate flow rates

than IHD has. These lower rates deliver lower solutefluxes and require more time for achievement ofultrafiltration. SLED can be tailored to the patientand does not have to be delivered continuously foroptimal clearance because SLED delivers efficientsolute clearance and still is able to maintain hemo-dynamic control. Notwithstanding, SLED can bedone continuously in circumstances when continu-ous clearance or fluid removal is desired. Continu-ous SLED involves a number of hours of SLED(3-12 depending on the patient’s needs) after whichdialysate is turned off and SCUF is continued.

For all intents and purposes all of these thera-pies, plus slow or regular intermittent hemodialysis,are available for use in ICU patients with hemody-namic instability. Although all randomized controlledtrials thus far do not show mortality benefit of any

About the AuthorLadan Golestaneh is assistant professor of medicine.Albert Einstein College of Medicine, Bronx, New York.Barbara Richther, is director of nursing at MontefioreMedical Center, Bronx, New York. Margaret Amato-Hayes, RN, MSN, is director of patient care services atBeth Israel Medical Center, New York, New York.

Corresponding author: Ladan Golestaneh, MS, MD, RenalDivision Montefiore Medical Center, 111 East 210 St,Bronx, NY 0467. E-mail: (lgolesta@montefiore.org).

The challenges in instituting a CRRT program include division of labor, training and troubleshooting,

anticoagulation and filter half-life, cost, and the administrative support needed to ensure a good program.

“”

Figure 1 Continuous venovenous hemofiltration: convection.Adapted from Neligan,4 copyright 2002. Used with permission.

Blood frompatient

Blood topatient

Ultrafiltratepump

Replacementfluid

Ultrafiltratebag

Dialyzer

Blood pump

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apy, for emergency takedown, and for alerting thenephrologists or dialysis nurse when there is an alarmor problem with the therapy that cannot be addressedby simple algorithms. The maintenance and supply ofthe dialysis machines, quality assurance, and continu-ing education fall on the shoulders of the dialysis unitand staff. Furthermore, the drafting of the policy andprocedures is the responsibility of the dialysis unitmanagement in conjunction with the medical direc-tor of the unit and any expert nephrologists, inten-sivists, and managers.

For CRRT, the bulk of the responsibility fallson the ICU nurse. The ICU nurse initiates therapy,monitors it, troubleshoots using very sophisticated/automated support (which most CRRT companiesprovide), and takes down therapy. The maintenance,continuing education, competency, and qualityassurance of the therapy are the responsibility ofthe ICU. Policies and procedures are the responsi-bility of ICU nurse management in conjunctionwith experts from nephrology and critical care.5,6

TrainingNo universal competencies exist for a CRRT

program. Each facility develops its own educationprogram and troubleshooting mechanisms. Policiesand procedures are developed by nurse managersinvolved with the therapy. A good resource is avail-able from the American Nephrology Nurses Associ-ation5: Continuous Renal Replacement NephrologyNursing Guidelines for Care.7 Furthermore the manu-facturers of the machines have education materialand competency evaluations specific to the therapiesthey offer (NxStage, Prisma, and Fresinius [FresiniusMedical Care, Waltham, Massachusetts]).

SLED. Because SLED is a collaborative nursingeffort, the training can be done by the dialysis staff.6

At our institution, the education of ICU nurses forSLED was done mainly by the dialysis managersand the dialysis nurses. A didactic session was givenby the champion nephrologists in the form of aPowerPoint presentation. This session was given inthe mornings such that the night shift leaving andthe day shift coming on duty (in the ICU) were allexposed to the session. This session was given dailyfor about 2 weeks, with occasional lectures given forthose nurses who were on vacation or leave. After thedidactic session, the ICU nurse was given a 4-hourhands-on session by the charge nurse in the dialysisunit or another dialysis nurse designee.

These sessions addressed the different compo-nents of the machine, how to set up and take downthe machine, and what each major alarm signifiesand how to address alarms. At the end of these ses-

of the techniques, major medical centers use themto enable fluid removal and dialysis in patients whereIHD is simply not possible. Furthermore, ongoingcontroversy centers on the design and endpointselection of major trials that have been done thus far.

Instituting a CRRT ProgramChallenges in instituting a CRRT program include

division of labor, training and troubleshooting, anti-coagulation and filter half-life, cost, and the admin-istrative support needed to ensure a good program.

Division of Labor: ICU Nurse vs Dialysis NurseIHD (slow or regular) requires that a dialysis

nurse start, monitor, and complete the therapy. TheICU nurse goes about the usual ICU care for thepatient. All maintenance, certification, quality assur-ance, policies, and procedures are the responsibility ofthe dialysis unit management. SLED requires the dial-ysis nurse to start the therapy, to change tubing whenthere is a problem with it (clotting, expiration of thefilter life), to troubleshoot when there is an alarmthat cannot be fixed by using a simple algorithm, andto complete therapy during dialysis unit duty hours.The ICU nurse is responsible for monitoring the ther-

Figure 2 Intermittent hemodialysis, continuous venovenoushemofiltration, sustained low-efficiency dialysis, continuous sustained low-efficiency dialysis: diffusion.Adapted from Neligan,4 copyright 2002. Used with permission.

Blood frompatient

Blood topatient

Ultrafiltratepump

Ultrafiltrate+ wasted

dialysate bag

Dialysate

Dialyzer

Blood pump

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sions, the educator would ask the ICU trainee toperform the simple tasks involved in troubleshootinga SLED treatment.6

Training in CVVH and CVVHD is done by thecompany staff. The CRRT company personnel comeon-site and conduct a training session (up to 8 hours).This session is set up by the nurse manager of theICU. The training session includes didactics, setup,takedown, and troubleshooting of the machine.Most CRRT machines have step by step instructionsavailable to users once the machine is turned on.Competencies are ensured initially by the companyand then yearly by nursing educators and managers.These competencies include operation of the machine,troubleshooting, skills such as verifying orders,technique chosen, treatment parameters, medica-tions, solutions, vascular access management, chang-ing dialysate/replacement fluid bags, adjusting flowrates, and standard/emergency disconnect.

Ongoing SLED/CRRT training is vital to a suc-cessful and effective program. Support after orienta-tion should be given by interdisciplinary presenceand via clinical mentorship provided by a designatedand experienced nurse.5 Furthermore, quality assur-ance and regular competency evaluations should beintegrated into each unit’s schedule of affairs. Men-torship, staff-led education committees, and stronginterdisciplinary cooperation are needed for a suc-cessful program.5 A formal performance improvementcommittee is strongly recommended for an institu-tion embarking on CRRT/SLED adoption. The per-formance improvement program can track andreport certain components of CRRT/SLED (fluidgoal compliance, filter changing, intensity of useof troubleshooting resources).5

TroubleshootingThe intensity of troubleshooting is higher dur-

ing the initial stages of a program’s institutionbecause the operators of the machine are inexperi-enced and the coordination of care system has notbeen fully established. Members of the multidisci-plinary team are still finding their exact role in theoverall operation. During this crucial period, it isimportant to have experienced designees who pro-vide practical and emotional support to the individ-ual staff members.5

SLED. As long as the dialysis unit in the hospi-tal is open and physically close to the ICU, dialysisstaff can troubleshoot any major issues that ariseduring SLED therapy. Troubleshooting at night isslightly more complicated because dialysis backupis not readily available. For overnight periods, ICUnursing champions are designated as backup for the

SLED nurse and they address major issues that comeup overnight. If effective troubleshooting does notresolve the matter at hand, then the therapy is stoppedby the ICU staff (they have learned emergent andnonemergent takedown during their training). Acall is made to the nephrologists or to whomeverordered the therapy. If the physician contacted feelsstrongly that the therapy should be continued, thenthe on-call dialysis nurse is contacted to arrive andset up a new system. A troubleshooting checklist

Table 1 Cost of a 4-hour session ofintermittent hemodialysis

Labor

Dialysis nurse

Total 231.78

3.44

13.74

6.96

7.44

20.20

51.78

Saline (2)

Dialyzer

Bloodlines

Dialysate

Catheter Pak

180.00

180.00

TotalCost, $Cost, $ Supplies

Table 2 Cost of a 12-hour session of sustained low-efficiency dialysis

Labor

ICU nurse

Dialysis nurse

Total 747.04

3.44

13.74

22.32

6.96

20.20

5.38

72.04

Saline (2)

Dialyzer

Dialysate (4)

Bloodlines

Catheter Pak

TEGO connectors

540.00

135.00

675.00

TotalCost, $Cost, $ Supplies

Table 3 Cost of a 12-hour session of continuousrenal replacement therapya

Labor

ICU nurse

Total 920.70

95.00

125.00

20.20

5.38

9.00

90.12

344.70

Bicarbonate/ Pure Flow (4)

Bloodlines/Cassette (1)

Catheter Care Pak

TEGO connectors

Dialyzer

Catheter set

576

576

TotalCost, $Cost, $ Supplies

a A 24-hour session would be twice as much.

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different regions, but focused on equipment andnursing intensity as primary drivers of cost for thedifferent techniques.8

ConclusionsICU dialysis is controversial in its practice and

the pressures it presents to a health care system. Aswith most complicated care services, issues relatedto cost, staffing, management, and quality assur-ance must be considered. Although no large trialshave shown a benefit of CRRT/SLED over carefullyprescribed IHD, conceptually, the therapy makesgood clinical sense. Until enough trials are availableto definitively disprove the utility of CRRT/SLED,ongoing efforts in institution and management ofthese therapies continue.

FINANCIAL DISCLOSURESNone reported.

REFERENCES1. Bellomo R, Baldwin I, Ronco C, Golper T. Atlas of Hemofil-

tration. London: W B Saunders; 2002.2. Zobel G, Rödl S, Urlesberger B, Kuttnig-Haim M, Ring E.

Continuous renal replacement therapy in critically illpatients. Kidney Int Suppl. 1998;66:S169-S173.

3. Dirkes S, Hodge K. Continuous renal replacement therapyin the adult intensive care unit. Crit Care Nurse.2007;27(2):61.

4. Nelligan P. Critical care medicine tutorials. Renal failure:what is continuous renal replacement therapy (CRRT)?2006. http://www.ccmtutorials.com/renal/rrt/index.htm.Accessed January16, 2012.

5. Graham P, Lischer E. Nursing issues in renal replacementtherapy: organization, manpower assessment, competencyevaluation and quality improvement processes. SeminDial. 2011;24(2):183-186.

6. Tolwani AJ, Wheeler TS, Wille KM. Sustained low-effi-ciency dialysis. Contrib Nephrol. 2007;156:320-324.

7. American Nephrology Nurses Association. ContinuousRenal Replacement Nephrology Nursing Guidelines forCare. Pitman, NJ: American Nephrology Nurses Associa-tion; 2005.

8. James MT, Tonelli M; Alberta Kidney Disease Network.Financial aspects of renal replacement therapy in acutekidney injury. Semin Dial. 2011;24(2):215-219.

9. Barbece AN, Richardson RMA. Sustained low-efficiencydialysis in the ICU: cost, anticoagulation, and soluteremoval. Kidney Int. 2006;70:963-968.

10. Srisawat N, Lawsin L, Uchino S, Bellomo R, Kellum JA;BEST Kidney Investigators. Cost of acute renal replace-ment therapy in the intensive care unit: results from TheBeginning and Ending Supportive Therapy for the Kidney(BEST Kidney) study. Crit Care. 2010;14(2):R46.

was developed by the nephrology staff for simplealarms and was attached to each SLED machine.

CRRT. For CRRT, there is no dialysis backup.The staff relies on troubleshooting that is availablefrom the manufacturer of the equipment. There isusually a nursing champion for the therapy in oneof the ICUs for each shift who can answer questionsand help troubleshoot as well.

The institution and management of an anticoag-ulation protocol needs to be built into training andcompetencies for the nursing staff. Furthermore, aspart of training, attention must be paid to recognitionof impending filter clot and ways of avoiding this.Both ICU nurses and dialysis nurses have the auton-omy to change a system after 72 hours or if impend-ing clotting is suspected.

CostStudies from several different centers suggest

that CRRT is more expensive than SLED, and bothCRRT and SLED are more expensive than IHD.These costs must be considered in the context oflong-term outcomes of acute kidney injury. Forexample, if the more expensive technique (CRRT)has benefit in terms of recovery from renal failure,length of stay in the ICU and hospital, and totalpatient morbidity, the cost of CRRT is offset bycosts associated with long-term care.8

Costs are determined by labor (provider staffingpatterns) and materials (fluids, anticoagulation,dialyzer filters, and sets). In our center, the high costof CRRT is driven by the high cost of disposables(therapy fluid and dialyzer/tubing sets).8 In thera-pies such as IHD and SLED, these components areless expensive because of online dialysate produc-tion and cheaper dialyzer sets. CRRT requires thatan ICU nurse with a 1 to 1 patient assignment man-age the therapy from startup to takedown. SLEDrequires that a dialysis nurse set up the therapy andassist in troubleshooting, and IHD requires that adialysis nurse stay with the therapy for the durationbut takes away the requirement for a 1 to 1 ICU nurseto patient ratio. In our center, the cost of CRRT washigher than the cost for SLED and IHD (Tables 1-3).

Several publications have focused on the costsof CRRT and SLED.9,10 These studies show consistentlyhigher costs for CRRT than IHD, with SLED fallingsomewhere in between. Variations in prescription,frequency and duration of treatment (as they per-tain to IHD and SLED), and which nurse is prima-rily managing the therapy can yield very differentcosts.8 In fact, a recent prospective analysis showedextremely wide variation in cost differences between

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Ladan Golestaneh, Barbara Richter and Margaret Amato-HayesLogistics of Renal Replacement Therapy: Relevant Issues for Critical Care Nurses

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