【持续性肾脏替代治疗crrt英文】renal-replacement-therapy(63p)课件

1、Renal Replacement Therapy John Mc DonaldConsultant AnaesthetistSGHRenal Replacement Therapy JohCriteria for diagnosis of acute renal failureFall in urine volume to less than 500 ml per dayRising plasma urea and creatinine concentrationsRising plasma potassium and phosphate plus falling calcium and v

2、enous bicarbonateCriteria for diagnosis of acutInvestigations that may help to differentiate renal hypoperfusion from acute renal failure in oliguric patients Measurement Renal hypoperfusionAcute renal failureUrinary sodium (mmol/l)40Urine:plasma urea ratio202 10 cm of water and a urine output of 40

3、 mL/minute.Mean arterial pressure 80 mmHg, achieved and maintained by adequate volume replacement with or without inotropic support.Strategies to reduce the incidence of nosocomial infections, such as, the conservative use and rapid removal of intravascular and intravesical catheters.Cautious use of

4、 antibiotics.Sepsis needs to be aggressively investigated and treated.Restricted use and where possible the total avoidance of potentially nephrotoxic agentsMeasures for minimizing surgicDrugs that may cause acute interstitial nephritis in intensive care Antibiotics lactams Rifampicin Sulphonamides

5、Vancomycin Diuretics Thiazides Frusemide Non-steroidal anti-inflammatory drugs DiclofenacRofecoxibOthers Ranitidine Cimetidine Phenytoin Drugs that may cause acute intDrugs that induce renal damage Decrease in renal perfusionDiuretics, angiotensin converting enzyme inhibitors, blockers, vasodilators

6、Impaired intra-renal haemodynamicsNon-steroidal anti-inflammatories, radiocontrast agentsTubular toxicityAminoglycosides, amphotericin, cisplatinAllergic interstitial nephritis lactams, non-steroidal anti-inflammatoriesDrugs that induce renal damageGuidelines for immediate management of patients wit

7、h oliguria or anuria Assess and correct any respiratory or circulatory impairment Manage any life threatening consequences of renal dysfunction (hyperkalaemia, salt and water overload, severe uraemia, extreme acidosis) Exclude obstruction of the urinary tract Establish underlying cause(s) and instit

8、ute prompt remedial action Get a drug history and alter prescriptions appropriately Get help from senior appropriately trained specialists Guidelines for immediate managThe cause of acidosis will determine the treatment Tissue hypoxia/lactic acidosisoptimise circulation and oxygenation Salt and wate

9、r depletion normal saline Established renal failure (acute or chronic) sodium bicarbonate, ?RRT Poisoning (methanol, ethylene glycol, salicylate) sodium bicarbonate, ?dialysis Diabetes mellitus insulin, saline The cause of acidosis will detIndications for starting RRTOliguria Urine output 30 mmol/l

10、and/or Creatinine 300 Hyperkalaemia K+ 6.5 mmols with renal impairment or failure to respond to resonium/ glucose insulinVolume overload Metabolic Acidosis Indications for starting RRTOlIndications IIClinically significant organ dysfunction (especially pulmonary oedema)Ureamic encephalopathyUreamic

11、pericarditisUreamic neuropathy/myopathySevere dysnatremia (Na 160 mEq/L)HyperthermiaDrug overdose with dialyzable toxinIndications IIClinically signIndications IIIHypothermia for extracorporial warmingMeningococcal Septicaemia (Based on a number of case reports)Severe HypertensionIndications IIIHypo

12、thermia forModes of RRTHaemodialysisHaemofiltrationPeritoneal dialysisModes of RRTHaemodialysisHaemodialysisFast efficient ideal for maintenance therapy in established CRFProne to cause Haemodynamic InstabilityMay cause Cerebral Oedema due to Fluid ShiftsNeed for AnticoagulationHaemodialysisFast eff

13、icient idHaemodialysisThe movement of solutes from a compartment in which they are in high concentration to one in which they are in lower concentration along an electrochemical gradient. An electrolyte solution runs countercurrent to blood flowing on the other side of a semipermeable (small pore) f

14、ilter. Small molecules such as urea move along the concentration gradient into the dialysate fluid. Larger molecules are poorly removed by this process. Solute removal is directly proportional to the dialysate flow rate HaemodialysisThe movement of sPeritoneal DialysisHas the advantage of being simp

15、le and cost effective.No Extracorporeal circuit is needed which avoids the need for anticoagulation. The major disadvantages of PD are :poor solute clearance, poor uraemic control, risk of peritoneal infection and mechanical obstruction of pulmonary and cardiovascular performance. It is also unsuita

16、ble for patients who have undergone abdominal surgeryPeritoneal DialysisHas the advHaemofiltrationIn the past Arterio-venous haemofiltration was used where the patients own heart pumped blood through the filter from an arterial cannula and returned to the patient via a venous canulae. The system wor

17、ked but could be unreliable Recently machines which used 2 venous (or a single double lumen ) canulae and a mechanical pump have replaced this and Veno-venous haemofiltration now the treatment of choice in Intensive care units. Modern machines are largely automatic and can accurately monitor removal

18、 of effluent and administration of replacement fluid and heparin HaemofiltrationIn the past ArtULTRAFILTRATION: The movement of fluid through a membrane caused by a pressure gradient.UltrafiltrationULTRAFILTRATION: The movementHaemofiltrationSolute is carried (in solution) a fluid across a semiperme

19、able membrane in response to a transmembrane pressure gradient The rate of ultrafiltration depends upon the porosity of the membrane and the hydrostatic pressure of the blood, which depends upon blood flow. This is very effective in removal of fluid and middle-sized molecules, which are thought to c

20、ause uremia. Moreover, most of the cytokines involved in sepsis are “middle molecules”. HaemofiltrationContinuous Veno-venous HaemofiltrationBlood is pumped through a semi-permiable membrane in the filter under pressure. Small and mid sized molecules such as water and urea are squeezed out and form

21、the effluent. The haematocrit of fluid coming out of the filter is higher due to fluid loss. Replacement fluid is then added and the blood is returned to the patient. Continuous Veno-venous HaemofiHaemodialysisProcess uses dialysis there is a concentration gradient between plasma and the dialysis fl

22、uid and Urea and Creatinine move across the membrane The process is more efficient than filtration if Urea and Creatinine levels are highHaemodialysisProcess uses dialSolute ClearanceMembraneBloodDialysate/UltrafitrateSolute ClearanceMembraneBloodDDiffusive Solute ClearanceMembraneBloodDialysate/Ult

23、rafitrateDiffusive Solute ClearanceMembDiffusive Solute ClearanceMembraneBloodDialysate/UltrafitrateDiffusive Solute ClearanceMembHEMODIALYSISDiffusionHEMOFILTRATION :ConvectionHEMODIALYSISDiffusionHEMOFILTHaemodiafiltrationA mixture of filtration and dialysisThe Prisma has to be set up for this mod

24、e when priming the filterHaemodiafiltrationA mixture ofPrisma HaemodiafiltrationPrisma HaemodiafiltrationAdvantages of using CRRTSuitable for use in hemodynamically unstable patients. Precise volume control, which is immediately adaptable to changing circumstances. Very effective control of uremia,

25、hypophosphatemia and hyperkalemia. Rapid control of metabolic acidosis Improved nutritional support (full protein diet). Available 24 hours a day with minimal training. Safer for patients with brain injuries and cardiovascular disorders (particularly diuretic resistant CCF). May have an effect as an

26、 adjuvant therapy in sepsis. Probable advantage in terms of renal recovery. Advantages of using CRRTSuitaDisadvantages of using CRRTExpense probably the same as IHD. Anticoagulation to prevent extracorporeal circuit from clotting. Complications of line insertion and sepsis. Risk of line disconnectio

27、n. Hypothermia. Severe depletion of electrolytes and particularly K+ and PO4, where care is not takenDisadvantages of using CRRTExpSetting up and using CRRTThe machine circuit is set up as follows:A double lumen catheter. A line leading to the filter where blood flow is controlled by a series of rol

28、ler pumps: blood flow is usually set at 120ml/min. Anticoagulant to prevent blood clotting on the filter. A bag to collect the ultrafiltrate. Replacement fluid, to replace the excess ultrafiltrate over and above the required fluid removal. Setting up and using CRRTThe Vascular AccessLarge bore Doubl

29、e lumen catheter 150-250mm lengthJugular, Femoral or Subclavian veinUse 150 RIJ, 200 LIJ,200-250 FemoralVascular AccessLarge bore Doub“Dose” of RRTClinical bottom line (level 1b)Critically-ill patients with acute renal failure who received continuous veno-venous haemofiltration at ultrafiltration ra

30、tes of 35 or 45 mg/kg/hr compared with 20 mg/kg/hr were less likely to die (NN T = 6 at days) . There was no clear difference in mortality between the 35 and 45 mg/kg/hr groups. There was no clear difference in complications between the three groups. Ronco C, Bellomo R, Homel P, et al: effects of di

31、fferent doses in continuous veno-venous haemofiltration in outcomes of acute renal failure: a prospective randomised trial. Lancet 2000; 355 : 26-30 “Dose” of RRTClinical bottom lAnticoagulation for RRTUnfractionated HeparinLow Molecular Weight HeparinProstacyclineCitrateXigrisNoneAnticoagulation fo

32、r RRTUnfractSite of Action of Anticoagulants Site of Action of AnticoagulanUnfractionated HeparinCheap easy to monitorUsually 5000 units flushed through circuit 3-5,000 units given as a bolus then 1,000 units/hr adjusted to give an INR of around 2Risk of bleeding and Thrombocytopoenia due to HIT and

33、 HATLittle if any relationship between INR and Filter LifeUnfractionated HeparinCheap eaLow Molecular Weight HeparinMore expensive difficult to monitor effectCorrect dosage to optimise filter life and reduce bleeding effects problematicOptimal dose varies depending on which LMW Heparin is usedLow Mo

34、lecular Weight HeparinMoHeparin Induced ThrombocytopoeniaHIT can be suspected when there is a decrease of at least 30% from the initial platelet count, usually commencing 4 to 14 days after institution of heparin. Thrombocytopenia may occur sooner if there has been previous exposure to the drug, inc

35、luding possible undocumented heparin flushes.The mean delay of HIT emergence is dramatically longer when LMWH are used compared with unfractionated heparin (mean delay of 28 vs 14 days). The platelet count declines below 100 109/L, often below 60 109/L, but bleeding is uncommon despite the severe th

36、rombocytopenia.After heparin withdrawal, the platelet count usually rises to normal levels in 5 to 7 days. Thrombocytopenia recurs promptly on rechallenge with heparin.Heparin Induced ThrombocytopoeProstacyclineExpensive Antiplatelet drug used when there is significant risk of bleedingCan cause Hypo

37、tensionCan be used with Heparin but problems with assessing doseFilter life may be shorter than that seen with Heparin ProstacyclineExpensive AntiplaCitrate Not widely used but may be more popular in futureCauses anticoagulation by binding CalciumCan be used for regional anticoagulation citrate is i

38、nfused before the filter and calcium after the filter to leave the patient with normal clottingCitrate Not widely used but ma【持续性肾脏替代治疗crrt英文】renal-replacement-therapy(63p)课件XigrisVery Expensive anti-inflamatory drug with anticoagulant actionsIf patient is receiving a Xigris infusion no other antico

39、agulants are usually used because of risk of bleedingStop Xigris for 2 hours before Surgery or Line PlacementXigrisVery Expensive anti-inflNo AnticoagulantUsed when serious clotting disturbances ie platelets 48 hours is very good24 hours is acceptable 12 hours is problematicBlood testing A baseline

40、clotting screen and FBC should be sent.You do not necessarily need to delay getting the filter started by waiting on the results in most cases. Use your clinical judgement and make a best guess at where to start the heparin.All patients on unfractionated IV heparin should be Grouped and Saved.Blood

41、testing A baseline clottBlood TestingAPTT should be checked 6 hours after starting the filter. Thereafter it should be checked 6 hours after any dose change.If a steady state is achieved interval of testing can be extended to 12 hourly. In rare cases of stability this can be extended to 24 hourlyIf

42、the APTT is unstable or clinical circumstances dictate increase frequency of testing as required.The patients nurse should document lactate, K+ and haemoglobin from blood gases whenever an ABG is taken.If your patient is stable and has a well working filter; if you understand how RRT works and can p

43、rescribe replacement fluids properly you should not need to check formal U & Es more frequently than daily. Patient or biochemical or doctor! factors may mean this needs done more often.Blood TestingAPTT should be chWho and by how much to anticoagulateThis is a balance between prolonging circuit lif

44、e and minimising the risk of bleeding.Doing this well is as much part of the art as the science of medicine. There is reasonable evidence that for every 10-second increase in APTT, the incidence of circuit clotting decreases by 25%, however, at the cost of a 50% increased risk of haemorrhage. With f

45、ull anticoagulation in high-risk groups the incidence of significant haemorrhage can be as high as 50%.Who and by how much to anticoaWho and by how much to anticoagulateThe relationship between heparin dose, APTT and filter life suggests that, in the typical critically ill patient, as a starting poi

46、nt, an APTT between 35 and 45 sec APTTr 1.3 1.7 gives the best mix between safety and heparin therapy efficacy.Consideration of alteration of this target based on the life of the first couple of filters vs. patients risk of bleeding can be made thereafter. If the filters are clotting quickly one mig

47、ht cautiously aim for a higher target. If the filters are lasting well despite a low APTTr then one does not need to blindly chase a higher APTTr. Always consider access issues if clotting occurs frequently e.g. 2 sequential filters with less than 6 hour run time each. Is the line working well? Is t

48、he blood pump speed high enough?Who and by how much to anticoaWho and by how much to anticoagulateIn patients with a high risk of bleeding there is good evidence that around 50% - 60% can receive anticoagulant free RRT with acceptable filter life 24hrs.If patients are on Drotrecogin alpha Xigris and

49、 are receiving RRT they rarely need additional heparin to achieve acceptable filter life. The default position is no heparin whilst on Xigris.Platelet counts inevitably fall when on RRT. They fall further on anticoagulant free RRT c.f. than with the use of heparin. In a patient with thrombocytopenia

50、 e.g. from sepsis where one chooses to avoid heparin consideration can be given to the use of epoprostenol in a bid to prolong filter life and attenuate the anticipated fall in platelets c.f. heparin free RRT.Who and by how much to anticoaGROUP 1 - Patient at moderate risk of bleedingRegard this as

51、the standard option - the typical ITU RRT patient e.g. 1 Average 2 or more organ failures 4. Surgery 48 hours ago2 No florid coagulopathy 5. No evidence of active bleeding3 Platelets 50 6. No ureamic complicationsHEPARIN BOLUS DOSEINITIAL HEPARIN INFUSION RATETARGET APTT and ratio20 - 25 units/kg ma

52、ximum 3000 units10 units/kg/hr35 45 1.3 1.7GROUP 1 - Patient at moderate GROUP 2 - Patients at low risk of bleeding or where standard approach results in poor filter lifeOne may require to gradually escalate to this approach where the standard approach has failed and the risk is judged worthwhile.Th

53、ere will be the rare patient who justifies this approach from the start e.g. primary renal problem, another requirement for formal anticoagulationHEPARIN BOLUS DOSE INITIAL HEPARIN INFUSION RATE TARGET APTT and ratio 50 units/kgmaximum 5000 units 15 units/kg/hr 50 - 65 1.9 2.4Aim for the lower end o

54、f this range at first if escalating from the standard approachGROUP 2 - Patients at low riskGROUP 3 - Patient at high risk of bleedingWith problems such as 1.Within 48 hours of surgery4. Platelets 25. Recent active bleeding3. APTT 506. Urea 45 or ureamic complicationGenerally it is worth trying anti

55、coagulant free RRT in the first instance GROUP 3 - Patient at high riskGROUP 3 - Patient at high risk of bleedingIf filter life is thereafter judged unacceptable and/or the risk considered worthwhile then starting heparin or epoprostenol as below is reasonable.If thrombocytopenia is a particular pro

56、blem then perhaps Flolan should be the initial choice greater platelet sparing.If filter life is poor on either of these strategies then the use of them in conjunction may be worthwhile, alternatively it may be judged necessary to escalate to the standard approach above.GROUP 3 - Patient at high ris

57、kEpoprostenol Flolan target infusion rate 5nanograms/kg/min Start infusion at 2 nanograms/kg/min, increase the rate by 1nanogram/kg/min every 5 10 minutes until the target infusion rate is achieved.The patient should be primed with Flolan for 15 30 minutes prior to connecting the circuit. It is most

58、 practical to infuse Flolan directly into the patient. Although the dose of Flolan reaching the patient is reduced if it is infused directly into the circuit pre filter.Many units use higher target rates but the evidence base is not excessive for this practiceEpoprostenol Flolan target iGuidelines for heparin dose alterationRemember the variable half-life of heparin and the exponential rise in APTT that can occur if excessive upward increments are emp