Continuous renal replacement therapy crrt

Prof. SAMIA TELEB
TAIBA UNVERSTY
MEEQAT GENERAL HOSPITAL MADINAH

1. CONTINUOUS RENAL REPLACEMENT THERAPY CRRT Prof. SAMIA TELEB TAIBA UNVERSTY MEEQAT GENERAL HOSPITAL MADINAH

2. CRRT

3. Introduction CRRT is a newer mode of dialysis that has many similarities to traditional hemodialysis. CRRT is a continuous therapy, slower type of dialysis that puts less stress on the heart, that is monitored by the critical care nurse, and it may continue over many days. Instead of doing it over four hours, CRRT is done 24 hours a day to slowly and continuously clean out waste products and f luid from the patient . It requires special anticoagulation to keep the dialysis circuit from clotting.

4. Introduction The preferred choice of dialysis for these critically ill patie nts needing renal support and/or fluid management It allows doctors to give patients the fluids, nutrition, antibiotics and other medications they need without worrying about the accumulation of waste products and fluid from the failing kidneys. The venous blood is circulated through a highly porous hemofilter. As with traditional hemodialysis, access and return of blood are achieved through a large venous catheter ( veno -venous)

5. Hemofilters ST 60 Filter :   membrane surface area 0.6 M2, blood flow range 50-180 ml/min and priming volume of 44 ml, requires 1 L of priming solution ST 100 Filter : membrane surface area of 1.0 M2, blood flow range of 75-400 ml/min and priming volume of 69 ml, requires 1 L of priming solution ST 150 Filter (standard size for CRRT in adults): membrane surface area of 1.5 M2, blood flow range of 100-450 ml/min and priming volume of 105 ml, requires 2 litres of priming solution

6. Definition of CRRT Continuous renal replacement therapy (CRRT) is a therapy indicated for continuous solute removal and/or fluid removal in the critically ill patient. It allows for slow and fluid removal that results in better hemodynamic tolerance even in unstable patients with shock and severe fluid overload . This process can be applied to both adults and children . CRRT therapy indications may be renal , non-renal, or a combination of both .

7. Classical renal ’ indications for starting renal replacement therapy (RRT) are : Rapidly rising serum urea and creatinine or the development of uraemic complications Hemodynamic instability ( cardiovascular) Hyperkalaemia unresponsive to medical management Severe metabolic acidosis ( DKA , Severe dehydration. Poisoning by aspirin, ethylene glycol (found in antifreeze), or methanol. (reduction in bicarbonate ( HCO 3, -pH may be markedly low or slightly subnormal, paCO 2 ↓ ) Severe fluid overload unresponsive to diuretics Oliguria or anuria

8. Non renal indications for starting RRT are: For patients in whom continuous removal of volume or toxic substance is desirable ( as in septic shock , AMI , severe GI bleeding ,ARDS or condition with or at risk for cerebral edema ….) Pre- and post-cardiovascular surgery / coronary artery bypass graft (CABG ), Removal of inflammatory mediators in sepsis? Intoxication (methylene glycol): toxic alcohol that is found in various household and industrial agents

9. Non renal indications for starting RRT are: Rhabdomyolysis: serious syndrome due to a direct or indirect muscle injury → → death of muscle fibers and release of their contents into the bloodstream. → → renal failure . A crush injury ( auto accident, fall, or building collapse) Long-lasting muscle compression ( prolonged immobilization after a fall or lying unconscious on a hard surface during illness or while under the influence of alcohol or medication) Electrical shock injury, or third-degree burn Venom from a snake or insect bite Extreme  muscle strain , heroin,  cocaine  or  amphetamines A very high body temperature (hyperthermia ) or heat stroke A metabolic disorder such as diabetic ketoacidosis Sepsis

10. The main advantage of CRRT over other types of renal replacement therapies is which one of the following? Faster electrolyte normalization Superior fluid control Faster recovery from acute kidney injury Lower mortality rates

11. Principles of CRRT / solute management Diffusion : the movement of solutes through a semi-permeable membrane from an area of higher concentration to an area of lower concentration Good for smaller sized molecules

12. Solute clearance- depends on Blood flow Recirculation Membrane characteristics- type of filter Pre/post dilution The removal of potassium , correction of acidosis or the removal of fluid may have just as much of an impact on patient outcome as solute clearance.

13. Pre filter dilution Decrease blood viscosity, reducing clotting and → → aids in extending the filter life Increases urea clearance by up to 20 %

14. Post filter dilution Primarily replaces fluid and electrolyte losses No solute dilution P ost dilution concentrates the blood in the filter → → enhancing clearance.

15. Convection : movement of fluid across a semi permeable membrane creating a solute drag. Efficient for both larger and smaller molecules ( Plasma water moves along pressure gradients )

16. Convection

17. Principles of CRRT / fluid management Ultrafiltration-UF Plasma water with solutes is drawn from the patient‟s blood across the semipermeable membrane in the filter The effluent pump controls the ultrafiltration rate automatically according to the set flow rates.

18. Modes of CRRT

19. Continuous Renal Replacement Therapy (CRRT ) Modes SCUF - Slow Continuous Ultrafiltration Ultrafiltration CVVH - Continuous Veno -Venous Hemofiltration Convection CVVHD- Continuous Veno -Venous Hemodialysis Diffusion CVVHDF - Continuous Veno -Venous Hemodiafiltration Diffusion and Convection

20. Choice of mode CVVH 35mls/kg/hour CVVH 35mls/kg/hour First choice for most ICU admissions with multi organ failure Septic shock/severe sepsis Fluid removal only Recovering multi organ failure but ongoing need for RRT AKI with high urea (initi al s ettin g ) Critical Care Clinical Guideline S CUF CVVHDF 35mls/kg/hour CVVH 25mls/kg/hour Failure of CVVH Limited period of time for therapy

21. SCUF-Ultrafiltration Slow continuous ultrafiltration: Main indication is fluid overload without uremia. Requires a blood and an effluent pump . The effluent pump forces plasma water and solutes across the membrane in the filter No dialysate or replacement solution. Fluid removal up to 2 liters/ hr can be achieved. Treatment of choice in patients with heart failure, Maintains cardiovascular stability Best suited to severely hypervolemic patients (i.e. post open-heart surgery, post resuscitation) This transport mechanism is used in SCUF, CVVH, CVVHD, and CVVHDF.

22. Maximum Patient Fluid Removal Rate = 1000 ml/ hr

23. CVVHD 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 . Dialysate formulas should reflect normal plasma values to achieve homeostasis Maximum Patient Fluid Removal Rate 1000 ml/ hr

24. 306100135 CVVHD Return Pressure Air Detector Return Clamp Access Pressure Blood Pump Syringe Pump Filter Pressure Hemofilter Patient Effluent Pump Dialysate Pump Pre Blood Pump BLD Effluent Pressure

25. CVVHDF Continuous veno -venous hemodiafiltration Requires the use of a blood, effluent, dialysate and replacement pumps . Both dialysate and replacement solutions are used . 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 Plasma water and solutes are removed by diffusion, convection and ultrafiltration . Maximum Pt. fluid removal rate = 1000 ml/ hr

26. CVVH 35mls/kg/hour CVVHDF 35mls/kg/hour Consider break/termination of therapy if patient has good solute clearance , normal pH , normal potassium and is euvolaemic/ persistently passing good urine volumes. Filters should be electively taken down where possible rather allowed to clot (to minimise blood loss) All filters should be electively taken down after 72 hours and a fresh circuit built. If therapy is terminated for 3 hours or more and the vascath remains in situ it should be locked with Taurolock . The vascath should be removed as soon as it is no longer needed for ongoing therapy . S CUF Critical Care Clinical Guideline Termination of therapy

27. Termination of therapy In daily practice, CRRT is discontinued on an individual basis : When urinary output increases or when the CRRT session ends and the attending physician supposes that renal function will recover because other organ functions improve

28. Anticoagulation for CRRT No antic oagulation : Saline flushes ↓ filter life span trauma, surgery, liver failure, coagulopathy, head bleeding Active or recent bleeding) Systemic Anticoagulation : systemic heparin or others use CRRT syringe, DVT ,PE, mechanical heart valve Regional Anticoagulation : Regional heparinization safe and effective Heparin Regional citrate

29. Standard Heparin T ypical regimen in CRRT : Priming of the circuit ( 5000 IU / L ) Initial Heparin Bolus : 5 - 8 IU / kg Infuse Heparin at : 5 to 12 IU / kg / hr The activated clotting time ( ACT) on post filter : Adjust heparin rate to keep ACT between 1.5 & 2.0 times Advantages Easy to perform Inexpensive Disadvantages Occasional Thrombocytopenia Hemorrhagic Risk with Bleeding patient

30. low molecular weight (LMW) heparin Typical regimen in CRRT : Priming of the circuit : 20 mg in 1 L Maintenance dose : 10 to 40 mg q6 hrs Advantages Decreased Risk of Bleeding Disadvantages Expensive With low doses frequent filter clotting

31. Regional Citrate Anticoagulation Typical regimen : Citrate anticoagulation is always regional Citrate infusion (4%) at ml/ hr initially Special Dialysate at 1 liter 170 / hr ( Na+ 117 , K+ 4 , Mg++ 1.5 , Cl- 121.5 , dextrose 0.5- 2.5% , no Ca++ , no base ) CaCL2 ( 0.75%) by central I.V at 40-60 ml/ hr , Maintain ionized Ca++ at 0.96 - 1.20 mmol /L NB : Citrate is converted into sodium bicarbonate ( 1mmol of citrate is converted into 3mmol sodium bicarbonate)

32. Citrate Advantages : No Bleeding No Thrombocytopenia Improved Filter Life and Efficacy Disadvantages : Complex for the set up Ca++ monitoring needed Occasional Alkalosis

33. Record I/O ( To calculate hourly urine output, multiply the patient’s weight by 0.5 mL/kg and BP q1hr 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 ultra-filtrate/filter blood leak Color of CRRT circuit Warm dialysate to 37C Nursing Care of a Patient on CRRT The critical care nurse must continuously monitor the following parameters during CRRT

34. Nursing Care of a Patient on CRRT General observations : In order to maintain the systems patency , hourly checks of the vascath site (looking for redness, oozing/bleeding and pain ) Dialysis lines and filter pressures, should be carried out . These checks give early warning of unwanted side effects such as accidental disconnection, air in a line or premature clotting of the filter , as well as signs of infection . Weigh the patient daily to assess fluid removal.

35. Nursing Care of a Patient on CRRT Patency of circuit Clotting in the circuit is a common complication of CRRT . Heparin is infused on a continuous basis into the arterial side of the CRRT circuit (called the prefilter ) immediately before blood enters the hemofilter. Citrate anticoagulation: it’s infused either prefilter or as a replacement solution Monitor for signs and symp­toms of bleeding in the oral mucosa, gastric aspirate, stool, and injection sites. Check coagulation studies regularly

36. Nursing Care of a Patient on CRRT Patency of circuit Monitor serum calcium and give calcium infusion continuous citrate infusion puts the patient at risk for metabolic alkalosis. Be sure to monitor laboratory values regularly for alkalosis Routinely monitor the patient’s complete blood counts to check for unintended blood loss in case the CRRT circuit suddenly clots

37. How do you manage a patient with worsening acidosis on CRRT? Step 1: Increase bicarbonate in dialysate Standard is 22 mEq /L  can increase to 32 mEq /L Step 2: Can evaluate for citrate toxicity Discontinue citrate if needed Step 3: Replacement fluid default is NS @ 200 cc/ hr Consider changing to Free water with 150 meQ /L of NaHCO3

38. Nursing Care of a Patient on CRRT Temperature Body temperature should be monitored every two hours, at least . CRRT patients will drop their temperature by at least 2 C despite the fact dialysate fluid is run through a warmer prior to entering the filter . ( we heat the dialysate fluid to reduce the amount of heat lost). Heating lights or warmed blankets are an option, but care must be taken not to cover the lines as this increases the risk of disconnection. If a patient receiving CRRT is pyrexial , then it is likely they have a systemic infection, so WCC and Blood Cultures should be checked . The results of these checks will indicate the presence and type of infection ,

39. Nursing Care of a Patient on CRRT Cardiovascular Continual cardiac monitoring is necessary because CRRT effects cardiovascular function, as a rapid change in serum electrolytes, such as potassium or magnesium, can cause arrhythmias. Regular sampling of blood is required to monitor electrolyte and acid-base imbalances, so treatment can be adjusted accordingly and supplements administered if necessary. ( Check BUN, Crea , Na,K , Cl, aPPT q6hr for 1 day & then q8hr. Check Ca,P,Mg qd . to assess CRRT efficacy)

40. Nursing Care of a Patient on CRRT Cardiovascular Accurate recording of fluid levels is important, to ensure that the patient does not become hyper - or hypo- volaemic ; the patient relies on external forces to control their internal environment . A common problem when on CVVHDF is hypotension . To maintain adequate blood pressure, inotropes may be used. The fluid balance in a patient receiving CRRT can be adjusted in two ways. The first is by removing more or less fluid via CRRT; the second is by administering more or less fluid intravenously. This ensures there is an adequate central venous pressure to maintain dialysis

41. Nursing Care of a Patient on CRRT Respiratory Dialysis can cause changes in a patients fluid balance, therefore it is important to closely monitor: respiratory effort the use of accessory muscles, signs of tachyponea distress, fatigue and signs of infection (regular sputum samples sent for culture). Such monitoring is essential to discover or prevent the development of pulmonary oedema or pleural effusions .

42. Nursing Care of a Patient on CRRT Respiratory For patients that are requiring non invasive or invasive ventilation there may be the need for an increase in Positive End Expiratory Pressure (PEEP) or Pressure Support (PS) requirements, as the recent acidosis or metabolic derangement may have caused the patient to overuse respiratory muscles. Use of PEEP and PS is ensures there is an adequate central venous pressure to maintain dialysis

43. Nursing Care of a Patient on CRRT Position The vascath access sites commonly used via the subclavian or internal jugular veins . This may create a problem with positioning the patient as the line needs to remain patent at all times . Positioning the patient on the vascath side will often occlude the vascath as the increased pressure causes the vascath to be advanced slightly. Patients still need to be turned at least every 2 hrs to maintain good skin integrity . They are often at a higher risk of pressure ulcers due to their compromised state.

44. Nursing Care of a Patient on CRRT Neurological Reduced levels of consciousness, increased restlessness, agitation and aggression are indications of neurological status changes. These changes result from raised creatinine levels, slow excretion of sedatives and levels of pain . Treatment of pain needs to be very carefully titrated to ensure that the patient is pain-free but not over-sedated.

45. Nursing Care of a Patient on CRRT Nutrition Nutrition of the patient, especially if they are to be dialysed for a prolonged period of time . Due to the increased metabolic rate of ill patients, many are not able to absorb provided nutrients and this can lead to gut atrophy . The use of enteral feeding is beneficial, as the feed helps to line the gut, protecting it from gastric acids . If the patient is able to eat normally then a dietician should be involved to ensure that a correct balance of nutritious foods is supplied . If the patient is unable to tolerate enteral feeding , Total Parenteral Nutrition (TPN) may be considered.

46. Nursing Care of a Patient on CRRT Psychosocial A dialysed patient will be concerned, and possibly anxious , about the machine. The presence of uncontrolled pain will add to these fears, as will the lack of control over what is happening to their body. Regular education of the patient and family is of utmost importance. To achieve this, simple explanations of ARF and dialysis are required. The inclusion of a social worker can be beneficial, as are regular visits by family . An Occupational Therapist can assist in offering diversional therapy activities.

47. Nursing Care of a Patient on CRRT Indwelling Catheter The development of a urinary tract infection is a side effect of anuria, as the lack of urine output allows microbes to travel up the catheter. The removal of the urinary catheter is advisable until the patient recommences micturating.

48. One of the main complications of CRRT Hypotension , which can be related to several distinct mechanisms including Hypovolemia alteration of myocardial function cardiac arrhythmia

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