2 Continuous Renal Replacement Therapy (CRRT) Is an extracorporeal blood purification therapy intended to substitute for impaired renal function over an extended period of time and applied for or aimed at being applied for 24 hours a day.* Bellomo R., Ronco C., Mehta R, Nomenclature for Continuous Renal Replacement Therapies, AJKD, Vol 28, No. 5, Suppl 3, November 1996CRRT is the blanket term which encompasses all continuous therapies. It has been defined as…. Read the slide. Make sure to note the proof source.
3 CRRT Goals Mimic the functions and physiology of the native organ Qualitative and quantitative blood purificationRestore and maintain of homeostasisAvoid complications and good clinical toleranceProvide conditions favoring recovery of renal functionBefore I describe each unique therapy, it’s important to understand the goals of CRRT.The main goals are to:Mimic the functions and physiology of the native kidneyRestore and maintain hemodynamic stabilityAvoid complications while achieving good clinical toleranceProvide conditions that favor renal recovery
4 Requirements for CRRT CRRT requires: A central double-lumen veno-venous hemodialysis catheterAn extracorporeal circuit and a hemofilterA blood pump and a effluent pump.With specific CRRT therapies dialysate and/or replacement pumps are required.In order, to initiate CRRT there are some essential items you will need. CRRT requires a functioning vascular access, which is usually a central double-lumen catheter, and extracorporeal circuit, a hemofilter, a blood pump, and a effluent pump. In some CRRT therapies dialysate and/or replacement pumps are required.
5 CRRT Modalities SCUF- Slow Continuous Ultrafiltration CVVH- Continuous Veno-Venous HemofiltrationConvectionCVVHD- Continuous Veno-Venous HemodialysisDiffusionCVVHDF- Continuous Veno-Venous HemodiafiltrationDiffusion and ConvectionCRRT modalities contains four therapies, and we will begin by talking specifically about each therapy. CRRT is well-known by all the acronyms. Each acronym describes the therapy being performed in treating the patient. History has shown us that there are many ways to perform each therapy. However, each therapy does carry is own basic concept.SCUF- modality is only removing patient plasma water. Does not require replacement or dialysate solution.CVVH- modality requires replacement solution. This replacement solution drives convection.CVVHD- is continuous form of hemodialysis and requires dialysate solution to create a concentration gradient for diffusion.CVVHDF- hemodiafiltration requires the use of dialysate and replacement solution and uses both transport mechanisms of convection and diffusion.Let’s take a look at the transport mechanisms related to each individual therapy.
6 SCUF-Ultrafiltration Slow continuous ultrafiltration:Requires a blood and an effluent pump.No dialysate or replacement solution.Fluid removal up to 2 liters/hr can be achieved.Primary GoalSafe management of fluid removalLarge fluid removal via ultrafiltrationSCUF (slow continuous ultrafiltration) when using this therapy, significant amounts of fluid are removed from the patient. No dialysate or replacement fluid is used because solute control is not a goal of this therapy. Ultrafiltration can be adjusted to cause dramatic fluid shifts. SCUF treatment utilize UFR’s of up to 2L/hr in some cases. The only pumps needed for this therapy is a blood pump and an effluent pump.
7 Transport mechanism: Ultrafiltration The movement of fluid through a semi-permeable membrane driven by a pressure gradient (hydrostatic pressure). The effluent pump forces plasma water and solutes across the membrane in the filter.This transport mechanism is used in SCUF, CVVH, CVVHD, and CVVHDF.Ultrafiltration is defined as…. Read the slide. The pressure gradient in the extracorporeal circuit is created by positive, negative, or oncotic pressure from non-permeable solutes. For our purposes, ultrafiltration results in removal of fluid (plasma water) from the patient’s blood. The fluid that is removed is sometimes referred to as “Ultrafiltrate or UF”.
8 Here is a visual example of how ultrafiltration works Here is a visual example of how ultrafiltration works. On the blood side of the hemofilter you have a positive pressure gradient. on the fluid side of the hemofilter you have a negative pressure gradient. The effluent pump applies pressure on the membrane causing the fluid to move from the positive pressure gradient to the lower pressure gradient.
9 SCUF Return Pressure Air Detector Return Clamp Syringe pump Blood Pump PatientHemofilterFilter PressureAccess PressureEffluent PressureBLDEffluent PumpPre Blood PumpThis slide depicts the SCUF (slow continuous ultrafiltration) is a therapy that uses no dialysate or replacement solution.On the right hand side of the screen you see a Pre-blood pump that could deliver anticoagulation solution at the patient access. The there is really only 2 pumps that are required for this therapy: Blood pump, Effluent pump, and if desired the Pre-blood pump. Plasma water is removed by ultrafiltration.
10 CVVH-Convection Continuous veno-venous hemofiltration Requires blood, effluent and replacement pumps.Dialysate is not required.Plasma water and solutes are removed by convection and ultrafiltration.CVVH (continuous veno-venous hemofiltration) aims for maximizing convective removal of middle to large molecules. Replacement solutions are used to drive convective transport. When performing CVVH the following pumps are used: The blood pump, replacement pump and the effluent pump.
11 Transport Mechanism: Convection Removal of solutes, especially middle and large molecules, by convection of relatively large volumes of fluid and simultaneous.This transport mechanism is used:CVVHCVVHDFConvection is a transport mechanism that we see only in CVVH and CVVHDF. The replacement solution is infused into the blood. Whether it is infused pre-filter or post-filter the solution mixes with the blood. The premise is to move solutes with fluid, referred to as a “solvent drag”. Plasma water and certain solutes depending on the molecular weight are forced across the membrane.
12 Replacement FluidsPhysician Rx and adjusted based on pt. clinical need.Sterile replacement solutions may be:Bicarbonate-based or Lactate-based solutionsElectrolyte solutionsMust be sterile and labeled for IV UseHigher rates increase convective clearancesYou are what you replacePhysicians will always prescribe replacement solution according to patients clinical needs. Along with the replacement solution prescription the physician will indicate the route of administration whether it is to be delivered pre blood pump, pre-filter or post-filter. Replacement solutions are sterile and labeled for IV use. Replacement solutions usually contain electrolytes and a buffer similar to plasma values.
13 This visual will provide you with a better understanding of how convection works. From the picture you can see a faucet which represents replacement solution. The top faucet is an example of pre-filter dilution, which means that the replacement solution mixes with the blood as it enters the filter. The bottom faucet is an example of post-filter dilution and is delivered as the blood is returning to the patient.Now the effluent pump is removing ultrafiltration (just like SCUF), or patient plasma water and replacement solution.
14 CVVH Return Pressure Air Detector Syringe Pump Return Clamp Patient HemofilterFilter PressureAccess PressurePostEffluent PressurePrePostReplacement PumpPre Blood PumpEffluent PumpReplacement PumpThis slide depicts the CVVH flowpath for both blood and fluid. As you, can see there are several points that replacement solution can enter the circuit. On the right hand side of the slide the replacement solution is entering pre-blood pump. Delivering the replacement solution Pre-blood pump will allow for greater hemodilution of the access line, and better solute clearance before the blood comes in contact with the filter. The first purple bag from the right hand side delivers the replacement solution Pre-filter, which means that as the blood enters the filter it is mixed with replacement solution. Pre-filter offer greater hemodilution of the filter, which increases filter life. Unfortunately, about 15% of the replacement solution is lost over the filter, thus decreasing solute clearance. The purple bag on the left hand side of the slide is delivering replacement Post-filter, which means as the blood is returning to the patient replacement solution is added. Delivering replacement post-filter allows better solute clearance, but may decrease filter life due to the hemoconcentration of the blood in the filter.
15 CVVHD-Diffusion Continuous veno-venous hemodialysis Requires the use of blood, effluent and dialysis pumps.Replacement solution is not required.Plasma water and solutes are removed by diffusion and ultrafiltration.CVVHD (continuous veno-venous hemodialysis) is a therapy that uses dialysate solution on the fluid side of the filter to increase solute exchange by diffusion. Replacement solution is not required for this therapy. The pumps required for this therapy are as follows: Blood, dialysate and effluent pump. Plasma water and solutes are removed by diffusion and ultrafiltration.
16 Transport Mechanisms: Diffusion Removal of small molecules by diffusion through the addition of dialysate to the fluid side of the filter.Dialysate is used to create a concentration gradient across a semi permeable membraneDialysis uses a semi permeable membrane for selected diffusionThis transport mechanism is used in:CVVHDCVVHDFDiffusion is another transport mechanism and is defined as…. Read first bullet on slide. Dialytic therapies use a semi permeable membrane (the filter) through which solutes diffuse selectively, based on particle size, as blood passes through the filter. Solutes are defined as any substance that dissolves in a liquid to form a solution. Solutes removed by diffusion during CRRT might be waste products, electrolytes, buffers, etc.
17 Dialysate SolutionsThrough diffusion, dialysate corrects underlying metabolic problemsDialysate is dependent on buffering agent, electrolytes, and glucoseDialysate formulas should reflect normal plasma values to achieve homeostasisThe physician will also prescribe the dialysate composition as well as the delivery flowrates. Dialysate solution usually reflect normal plasma values. Through diffusion dialysate solution corrects underlying metabolic problems.
18 The patients blood contains a high concentration of unwanted solutes that can be effectively removed by diffusion. Diffusions key mechanism is to move a solute from a higher concentration gradient to a lower concentration gradient.For example, let us assume the blood in the filter has a high concentration of potassium molecules and on the fluid/dialysate compartment has a low concentration of potassium. The potassium gradually diffuses through the membrane from the area of a higher potassium concentration to the area of a lower potassium concentration until it is evenly distributed.
19 CVVHD Return Pressure Air Detector Return Clamp Syringe Pump Blood PumpPatientHemofilterFilter PressureAccess PressureEffluent PressureBLDDialysate PumpPre Blood PumpEffluent PumpThis schematic depicts a CVVHD flowpath. Describe the blood flowpath through the hemofilter and back to the patient. Then show green dialysate entry into the hemofilter (counter-current flow) and effluent removal through the yellow line/bag. Prismaflex allows use of the Pre blood pump fluid/anticoagulant infusion.The white bag on the right-hand side of the slide can deliver anticoagulation solution. We really want to focus on the green bag on the left hand side of the slide. This is the dialysate solution that is going to be delivered to the fluid side of the filter. The dialysate solution enters at the top of the filter and travels counter-current of the blood. The counter-current flow increases solute removal.
20 Bicarbonate Based Solution Bicarbonate based solutions are physiologic and replace lost bicarbonate immediately.Effective tool to correct acidosisConcentration of mEq/L corrects acidosis in 24 to 48 hours.As I prefaced, bicarbonate is fast becoming the buffer of choice, because of its physiologic nature and the immediate replacement of lost bicarbonate ions. This solution is a great tool to correct acidosis within a hours, and additionally improves hemodynamic stability, resulting in fewer cardiovascular events.
21 Bicarbonate Based Solution Preferred buffer for patients with compromised liver function.Mean arterial pressure remains stableSuperior buffer in normalizing acidosis without the risk of alkalosisImproved hemodynamic stability, and fewer cardiovascular events.Bicarbonate solution is the preferred buffer for patients with compromised liver function. Bicarbonate also offers stabilization in a variety of areas. The patient’s mean arterial pressure remains stable, and bicarbonate normalizes acidosis without the risk of alkalosis. It also allows the patient to remain hemodynamically stable and have fewer cardiovascular events.
22 PrismaSate Solution Plasma PrismaSate BK0/3.5 PrismaSate BGK2/0 Calcium Ca2+ (mEq/L)3.5Magnesium Mg2+ (mEq/L)1.0Sodium Na+ (mEq/L)140Potassium K+ (mEq/L)2.0Chloride Cl- (mEq/L)109.5108Lactate (mEq/L)3Bicarbonate HCO3- (mEq/L)32Glucose (mg/dL)110Osmolarity (mOsm/L)287292pH~ 7.40As you can see from the chart above, PrismaSate nearly matches normal plasma levels except where variations are needed to correct underlying problems through physician prescriptioncalciumPotassiumbicarbonateThe 3 Meq/L of lactate are required to maintain the physiologic pH of 7.40.
23 Lactate-based Solution Metabolized into bicarbonate providing it’s under normal conditions.Lactate is converted in the liver on a 1:1 basis to bicarbonate and can sufficiently correct acidemia.Today,there are two main buffers lactate and bicarbonate available in commercial solutions to administer during CRRT. At one time lactate-based solutions were predominately used with CRRT, because of its stability. The lactate in a dialysate or replacement solution must be metabolized into bicarbonate and this process takes place in the liver. The liver converts lactate on a 1:1 basis to bicarbonate. This can sufficiently correct acidemia, but there are clinical conditions that influence the use of this buffer.
24 Lactate Based Solution Non physiologic pH value of 5.4Is a powerful peripheral vasodilatorFurther acidemia for patients in:HypoxiaLiver impairmentPre-existing lactic acidemia can result in worsening of lactic acidemiaLactate based solution has a pH value of 5.4, which could worsen acidosis. Lactate is a powerful peripheral vasodilator, that affects myocardial contractility and inadvertently reduces blood pressure. Lactate administration can further compromise a patient who is already experiencing hypoxia, liver impairment, and can cause lactic acidemia.Now let’s take a look at a more physiologic buffer. Bicarbonate solution is quickly becoming the solution of choice….
25 CVVHDF Continuous veno-venous hemodiafiltration Requires the use of a blood, effluent, dialysate and replacement pumps.Both dialysate and replacement solutions are used.Plasma water and solutes are removed by diffusion, convection and ultrafiltration.CVVHDF (continuous veno-venous hemodiafiltration) combines the benefits of CVVH and CVVHD using both convective and diffusive transport mechanisms. Replacement and dialysate fluids are both employed. The pumps required for this therapy are as follows: A blood, dialysate, replacement and effluent pumps.
26 Transport Mechanisms: Diffusion and Convection Removal of small molecules by diffusion through the addition of dialysate solution.Removal of middle to large molecules by convection through the addition of replacement solution.This transport mechanism is used in:CVVHDFThe use of both diffusion and convection transport mechanism create a therapy called hemodiafiltration. This specific therapy combines dialysate solution to create diffusive clearance of small molecules, and replacement solution to create convective clearance of middle to large molecules.
27 CRRT Transport Mechanisms AdsorptionMolecular adherence to the surface or interior of the membraneThis mechanism is used in:SCUFCVVHCVVHD or CVVHD with ultrafiltrationCVVHDFAdsorption is the final transport mechanism that we will have to tackle. With adsorption, molecules are removed from the blood by adhering to either the surface of the membrane or become trapped inside of the membrane.
28 This picture gives you a great visual picture of how adsorption occurs during CRRT. some molecules will attach to the membrane surface. While other molecules may permeate the membrane, but become stuck within the fibers. It is believed that inflammatory mediators are effectively removed via adsorption.
29 Principles of CRRT clearance CRRT clearance of solute is dependent on the following:The molecule size of the soluteThe pore size of the semi-permeable membraneThe higher the ultrafiltration rate (UFR), the greater the solute clearance.CRRT solute clearance is dependent on the following: The size of the molecule and the pore size of the semi-permeable membrane. The best way to drive solute clearance is to increase the ultrafiltration removal rate ( combination of replacement solution and patient plasma water).
30 Intermediate or middle molecules 500-5000 Daltons e.g. B12 Remember the transport of a molecule through a membrane is governed largely by its molecular weight. Generally, the more a molecule weighs, the larger it is in size and the more resistant it is to transport. The chart gives an indication of relative molecular weights for some of the common molecules that we are concerned with in CRRT. Molecular weights are measured in units called Daltons.Small molecules <300 Daltons, e.g. urea, creatinine, Na+, electrolytesIntermediate or middle molecules Daltons e.g. B12Large molecules Daltons e.g. LMW proteins, beta 2 micro globulins, cytokines, myoglobin
31 Molecular size: Both molecule size and pore size determine the solute flow through the semi-permeable membrane. As you can see from this picture we have a membrane with small pores. The pink molecule represent Urea molecules, which are considered small size molecules. The green molecules represents cytokine molecules, which are considered a middle size molecules. The (pink molecule) Urea easily passes through the small pores, but the (green molecule) Cytokines are to large to move across the membrane therefore they remain in the blood.
32 This picture depicts a membrane that has large pore size This picture depicts a membrane that has large pore size. As you can see from this picture we have a membrane with large pores. Again, we will say the pink molecule represent Urea molecules, and the green molecules represent a cytokine molecules. The Urea easily passes through the large pores, and the Cytokines also move across the membrane therefore they are removed from the blood.
33 Principles of CRRT clearance Small molecules easily pass through a membrane driven by diffusion and convection.Middle and large size molecules are cleared primarily by convection.Semi-permeable membrane remove solutes with a molecular weight of up to 50,000 Daltons.Plasma proteins or substances highly protein—bound will not be cleared.Back to the basic CRRT transport principles: the combination of diffusion and convection allow small molecules to easily pass through the membrane, and middle and large molecules to be driven across the filter by convection. The semi-permeable membrane allows removal of solutes with a molecular weight of up to 50,000 Daltons. Keep in mind that anything that is protein-bound will not be cleared.
34 Principles of CRRT clearance Sieving CoefficientThe ability of a substance to pass through a membrane from the blood compartment of the hemofilter to the fluid compartment.A sieving coefficient of 1 will allow free passage of a substance; but at a coefficient of 0, the substance is unable to pass..94 Na+1.0 K+1.0 Cr0 albumin will not passNow that you have an understanding of molecular size and membrane porosity let me introduce to you sieving co-efficient. Sieving coefficient is defined as the ability of a substance to pass through a membrane from the blood compartment of the hemofilter to the filter side of the hemofilter. Solutes with a sieving coefficient of 1 means 100% movement of that solute moves across the membrane, but a coefficient of 0 the solute is unable to pass through the membrane at all. For example, the sieving coefficient of potassium is 1, meaning that 100% of it will cross the membrane. The sieving coefficient of Albumin is 0, meaning it is unable to move across the membrane because of its large size..
35 Vascular AccessA veno-venous double lumen hemodialysis catheter or two single lumen venous hemodialysis catheters may be used.A patient will need a veno-venous double lumen catheter or two single lumen venous hemodialysis catheter. One side of the lumen will deliver blood from the patient to the filter, and the other lumen will return the blood back from the filter to the patient.
36 Access Location Internal Jugular Vein Primary site of choice due to lower associated risk of complication and simplicity of catheter insertion.Femoral VeinPatient immobilized, the femoral vein is optimal and constitutes the easiest site for insertion.Subclavin VeinThe least preferred site given its higher risk of pneumo/hemothorax and its association with central venous stenosis.There are three access locations that are used some may be preferred over others. Internal jugular vein is the primary choice due to the simplicity of catheter insertion. Femoral vein is a great access when a patient is immobilized, and is also considered an easy site for insertion. Subclavin is the least preferred and often used if no other sites are available. A Subclavin has a high risk of pnemo/hemothorax and is associated with central stenosis.
37 Choosing the right catheter The length of the catheter chosen will depend upon the site usedSize of the catheter is important in the pediatric population.The following are suggested guidelines for the different sites:RIJ= 15 cm FrenchLIJ= 20 cm FrenchFemoral= 25 cm FrenchChoosing the right catheter is another important aspect to be considered.. The catheter length will depend on the site used. Pediatric of course will need to be assessed for an appropriate size catheter.
38 Membrane types and characteristics Hemofilter membrane are composed of:High flux materialSynthetic/biocompatible materialStructural design is characterized by:High fluid removalMolecular cut-off weight of 30,000-50,000 Daltons.Membrane types and characteristics are other important technical considerations. Hemofilters are composed of a membrane that consists of high flux material (porous). The membrane material is usually synthetic, but very biocompatible to the patient.Here are a few examples of high-flux membrane material:Polysulfone (PS)Polyamide (PA)Polyacrylonitrile ( PAN)AN69The structural design of a high flux membrane is characterized by high fluid removal and typically has a molecular cut-off weight of 55,000 Daltons.
39 Semi-permeable Membrane The semi-permeable membrane provides:An interface between the blood and dialysate compartment.Biocompatibility minimizes:Severe patient reactionsDecreases the complement activationThe hemofilter contains a semi-permeable membrane that provides an interface between the blood and dialysate compartment. This interface creates a barrier so that the blood and dialysate never come in contact with each. Biocompatibility is an important feature, because the membrane’s chemical properties minimize blood’s reaction I.e. thrombocytes and/or complement activation and immune system response (allergic reaction).
40 Complications Vascular access Vascular spasm(initial BFR too high) Movement of catheter against vessel wallImproper length of hemodialysis catheter insertedFluid volume deficitExcessive fluid removal without appropriate fluid replenishmentA common complication encountered during CRRT is vascular access. There are many reasons why a catheter may not be functioning properly during CRRT treatment. Here are only a few reasons a catheter may not be functioning:Vascular spasm caused by initial BFR being to high. The easiest way to remedy this complication is to decrease the blood flow rate.Catheter’s proximal or distal port opening move against the vessel wall impeding blood flow. This can sometimes be alleviated by repositioning the patient, or having the doctor reposition the catheter.Improper placement, or length of of the catheter.Fluid volume deficit may also occur during CRRT if the patient’s I/O status is not monitored closely and regularly. A fluid volume deficit may lead to hypotension and compromise patient safety.
41 Complications Hypotension Intravascular volume depletion Underlying cardiac dysfunctionElectrolyte imbalancesHigh ultrafiltration rates (high clearance)Inadequate replenishment of electrolytes by intravenous infusion,Inadequate replenishment of bicarbonate loss during CRRTIntravascular volume depletion (fluid volume deficit) can lead to hypotension. It is important to monitor I/O data to make sure the patient is hemodynamically stable. If hypotension occurs during treatment, the patient fluid removal should be decreased and sometimes placed at zero. A full assessment of the reasons for the hypotension should be addressed: loss of blood, increased urinary output, or fluid status has normalized.Patient electrolytes can become imbalanced for many reasons. A goal of CRRT is to balance electrolytes, however sometimes high ultrafiltration rates can disturb the delicate balance of electrolytes, therefore it is important to monitor and replenish electrolytes and bicarbonate. It is recommended the nurse and MD monitor lab values closely and regularly, with the MD making adjustments to dialysate or replacement solution accordingly.
42 Complications Acid/base imbalance Renal dysfunction Respiratory compromiseBlood lossIneffective anticoagulation therapyClotting of hemofilterInadvertent disconnection in the CRRT systemHemorrhage due to over-anticoagulationBlood filter leaksJust as with electrolyte imbalance, acid/base balance is another aspect to monitor closely. The physician and the nurse must identify whether acid/base imbalance is due to renal dysfunction or due to respiratory compromise.Blood loss during CRRT can and will occur due to ineffective anticoagulation therapy causing the hemofilter to clot. Once the filter is clotted the blood is not returned to the patient. Keep in mind when a system clots the patient can loss anywhere from 93 cc to 189 cc depending on the hemofilter set. Other reasons for blood loss could be due to over-anticoagulation so clotting parameters should be monitored closely. Inadvertent disconnection in the CRRT system could potentially happen if the connection between the catheter and set is not tight.
43 Complications Air embolus Leaks or faulty connections in tubing Line separation.Cardiac arrestHypotension/hypertensionHemolysisAir embolismCirculatory overloadArrhythmiasAll CRRT monitors on the market have an air detector so if by chance air enter the circuit the air detector would detect the air causing the treatment to be suspended. Leaks/faulty connections, or line separation could potentially happen after the air detector allowing air to enter the patient. In this case the nurse would initiate interventions of positioning the patient on their left side or in Trendelenburg position.As we have discussed, CRRT treats a variety of conditions from fluid overload to electrolyte imbalance, which could inadvertently cause cardiac arrhythmias. Monitoring cardiac status is important at all times to avoid cardiac arrest. Other reasons for cardiac arrest maybe hemolysis, air embolism, circulatory overload and arrhythmias.
44 Clinical Conditions to Consider ARF and need for fluid management related to:SIRSUnstable on IHDOrgan transplantsCHF /volume overloadPost CV surgeryPost trauma patientsSevere BurnsThere are many clinical conditions we see every day in practice that perhaps could be considered for CRRT. Encourage audience to share past experiencesThe main point of patient consideration is: DON’T WAIT TOO LONG!! CRRT is indicated for the treatment of Acute Renal Failure and Fluid Management. Think of your body of patients that you work with on a daily basis and let’s discuss how those patients might be considered for CRRT. Examples: Post cardiovascular Surgery, Pulmonary Edema/CHF, Organ Transplants, SIRS, Trauma, Burns (Thanks to improved Emergency Management of fluids, a very small percentage of these patients actually develop acute renal failure), or generally, patients that need fluid/electrolyte/acid base control.
45 Fluid Management in CRRT Goal of Fluid Management“The patient will achieve and maintain fluid volume balance within planned or anticipated goals”(ANNA Standards of Clinical Practice for Continuous Renal Replacement Therapy”)ConsiderationsIntakes and outputs (I&O)Hourly patient fluid removal (UFR) will be determined by the physician. Dialysate and/or replacement fluids will be administered as prescribed.The nurse will assess hemodynamic parameters and the patient’s response to the prescribed fluid loss prescription. Fluid losses and gains from all sources must be considered (IV, N/G, etc).Integration of other support (i.e. ventilator) will be considered as the clinical course continues. For example, ventilator settings may be adjusted temporarily to compensate for metabolic disturbances.
46 - I & O Formula + = Net fluid removal hourly (physician order) Nonprisma intake (IV, TPN, etc.)-Nonprisma output (urine, etc.)=Patient Fluid Removal Rate (set in prisma)
47 Hypothermia in CRRT Causes Patient’s blood in extracorporeal circuit at room temperatureAdministration of large volumes of room temperature fluids (replacement and dialysate)Signs and SymptomsHemodynamic instabilityChilling, shiveringSkin pallor, coolness and cyanosisThe patient’s blood is exposed to room temperature as it circulates through the extracorporeal circuit. Additionally, fluids (replacement fluid and/or dialysate) infused at room temperature may be administered, often in volumes of 2-4 liters per hour.As a result, the patient may show signs and symptoms of decreased body temperature. As you know, this can be reflected in the patient by hemodynamic instability, chilling and shaking, as well as skin pallor, coolness, and cyanosis.
48 Hypothermia Treatment measures Warming blankets Prismatherm™ II Blood WarmerPrismaflo® Blood WarmerYou can choose to warm the patient either with the use of warming blankets or the Prismatherm™ II.The Prismatherm™ II Blood Warmer and Prismaflo have been designed to replace heat to return blood flow, which was lost to the atmosphere and effluent flow during a Prismaflex System treatment. The Prismatherm has been designed to be easy to use and to be integrated into the Prismaflex extracorporeal circuit.
49 Initiation of TherapyAssess and record the patient’s vital signs and hemodynamic parameters prior to initiation of therapy.Review physician orders and lab dataPrepare vascular access using unit protocol.Set fluid removal, dialysate and replacement solution flow rates as prescribed.Administer anticoagulant and initiate infusion if applicable.Document patient’s hemodynamic stability with initiation of therapy.Initiation of therapy is a good time to closely examine your patients status, and prepare for any situation that may arise. Just as you are use to preparing for any procedure CRRT also requires some preparation: Physician orders, lab results, functioning vascular access, dialysate/replacement solution, anticoagulation, and of course a CRRT device.
50 Intratherapy Monitoring The critical care nurse must continuously monitor the following parameters during CRRTBlood pressurePatency of circuitHemodynamic stabilityLevel of consciousnessAcid/base balanceElectrolyte balanceHematological statusInfectionNutritional statusAir embolusBlood flow rateUltrafiltration flow rateDialysate/replacement flow rateAlarms and responsesColor of ultrafiltrate/filter blood leakColor of CRRT circuitIt is imperative that CRRT is continuously monitor for the following parameters: Blood pressure, Patency of circuit,Hemodynamic stability,Level of consciousness, Acid/base balance, Electrolyte balance, Hematological status, Infection,Nutritional status, Air embolus, Blood flow rate, Ultrafiltration flow rate, Dialysate/replacement flow rate, Alarms and responses, Color of ultrafiltrate/filter blood leak, Color of CRRT circuit.
51 Termination of Therapy The decision to terminate CRRT is made by the nephrologist or an intensivist based on the patient’s renal recovery or the patient’s status-recovery or decision of the patient and family.Extracorporeal circuit will be discontinued as per established protocol.Vascular access care administered as per unit protocolThere are a variety of reasons as to why CRRT is terminated, but the decision is made by the nephrologist or the prescribing physician. Termination may occur, because patient have gained renal recovery, patient status-recovery, or the patient or family have decided to terminate therapy. Your unit will have designed a protocol for discontinuing the treatment as well as vascular access care.
53 How much replacement and dialysate do you use? Ronco’s research
54 Prospective study on 425 patients - 3 groups: Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00Prospective study on 425 patients - 3 groups:Study:survival after 15 days of HF stoprecovery of renal functionDr. Ronco set forth to study answer the question “What is the adequate dose for the ARF patient?” thus began the journey to find this dose. The origin of ARF was mostly post surgical with the other causes from medical and trauma related. Sepsis was also prevalent throughout the study participants. Dr. Ronco selected 492 patients for the study, but 67 of those patient were excluded. Some of the 425 patients were actually randomized into the study, and assigned to one of the three doses: 20ml/kg/hr, 35ml/kg/hr, and 45ml/kg/hr. The study was conducted using only convection therapy. All replacement solution was delivered post-filter, and UFR was used to measure dosing.Why did he use UFR to measure dosing. Well, it is known that solute movement across the membrane is proportional to UFR. For example, Urea has a sieving coefficient of 1 it is then assumed that it is equal to UFR. Therefore, ultrafiltration rate corresponds with clearance, and can be used as a surrogate treatment dose.
55 Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00 100908070605040302010Group 1(n=146)(Uf= 20 ml/h/Kg)Group 2 (n=139)= 35 ml/h/Kg)Group 3 (n=140)= 45 ml/h/Kg)41 %57 %58 %p < 0.001p n..s.Survival (%)This is a another way to visually see the outcome from Dr. Ronco’s study. Group 1 is what we consider conventional delivery with poor patient outcome. Group 2 and 3 prove that a higher dose improves patient survival. Group 2 and 3 showed very little difference in survival therefore, the new dosing standard was announced that a dose of 35 mL/hr/kg improved patient outcome.
56 Effect of BUN at CVVH Initiation on Survival Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00Effect of BUN at CVVH Initiation on SurvivalSurvivorsNon Survivors8070605040302010p < 0.01p < 0.01p < 0.01Blood Urea Nitrogen (mg/dl)At least three different studies have shown a benefit for early initiation of therapy. Ronco’s study also suggests that patient’s with significantly lower BUN at the time of CVVH initiation had better survival rates whereas the patient with high BUN’s at the time of CVVH initiation had poor survival rates. This demonstrates a powerful effect of timing of treatment initiation on outcome.Group 1Group 2Group 3
58 RIFLE Stratification in Patients Treated with CRRT Bell et al, Nephrol Dial Transplant 2005 This is the first study attempting to validate the RIFLE system with respect to its ability to predict mortality in critically ill ARF patients. In this retrospective study, mortality over a six month period in 223 CRRT-treated patients was assessed. Overall, acuity of illness in the patient population was quite high, with 85% of patients receiving mechanical ventilation and 78% receiving vasopressor support. The RIFLE classification effectively stratified patients according to mortality risk, with a significant survival difference observed between patients with an “R” or “I” designation and patients with a “F” and “L/E” designation. If the RIFLE approach is validated clinically in prospective studies, it will address a major shortcoming in the field of ARF and should allow for more timely and accurate diagnosis of ARF.
59 Conclusions:An increased treatment dose from 20 ml/h/kg to 35 ml/h/kg significantly improved survival.A delivery of 45ml/kg/hr did not result in further benefit in terms of survival, but in the septic patient an improvement was observed.Our data suggest an early initiation of treatment and a minimum dose delivery of 35 ml/h/kg (ex. 70 kg patient = 2450 ml/h) improve patient survival rate.So based on the previous slides we can conclude that a dose of 35ml/h/kg is very appropriate in a CRRT setting and in the meantime is widely accepted as a golden standard.Besides the dose this study also indicates that TIMING seems to be another important influencing factor from an outcome perspective.Again you should point out the quality of the study and that there is not ONE single study available at the same level. So if you want to prescribe therapy and you feel comfortable to use a widely accepted guideline… this is one!Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00
60 CRRT does affect resumption of function. Renal Recovery?CRRT does affect resumption of function.
61 By avoiding hypotensive episodes, the risk of further kidney damage is reduced and the chance for renal recovery is enhancedSo, in conclusion by making the right choices an important contribution can be made towards renal recovery
62 Recovery from Dialysis Dependence: BEST Kidney Data Manuscript under review1CRRTRecovery from dialysis dependence.8.6IRRT.4These results also come from the BEST (Beginning and Ending Supportive Therapy) Kidney Trial and have not been “officially” published yet, although they have been presented at scientific meetings. These data are consistent with results from at least three other recent study but are much more compelling because of the large number of patients in the study. (There were approximately 1200 patients who received renal replacement therapy in this trial.) Whereas approximately 15% of CRRT patients whose initial modality was CRRT did not recover renal function, 40% of patients whose initial modality was IHD were left dependent on chronic dialysis. Note that the likelihood of recovering renal function after approximately 50 days is very low, as the two curves are “flat” after this time point..220406080100daysLeading the way…
63 CRRT vs. IHD in Renal Recovery Recent studies suggest that CRRT is superior to IHD with respect to recovery of renal functionImplications go far beyond just “hard” endpoint of renal recoveryNeed for chronic dialysis impairs quality of lifeIf length of stay (LOS) in ICU can be reduced this will have a major impact on hospital budgetPatients dependent on chronic dialysis will consume significant health care resources and have an impact on the community health care budgetSurvival and renal recovery is the most important clinical outcome for patients with ARF.Previous studies have suggested somewhere between 10 and 30% of patients in the clinical setting will be dependent on chronic dialysis after leaving the hospital.Clearly, dependence on chronic dialysis impairs quality of life.Moreover, patient who survive ARF and become dependent on chronic dialysis in the end have a poor survival rate whereas, patients who enter a chronic dialysis program due to natural progression of the their chronic kidney disease have better survival rates(ie, no preceding ARF).Finally, failure to recover renal function after ARF has both short-term and long-term implications with respect to health care costs, as will be discussed.Leading the way…