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DR. ARATI MOHAN BADGANDI
RENAL REPLACEMENT
THERAPY
AKI STRATIFICATION
AKI STRATIFICATION
MECHANISMS
 2 fundamental processes underlie continuous renal replacement
therapy – diffusion and convection
Diffusion / ...
MECHANISMS
Convection / ultrafiltration –
 solute is carried (in solution) fluid across a semipermeable membrane
in respo...
Ultrafiltration
Conventional hemodialysis blood flow 350-
450 ml/min, dialysate flow 500-800 ml/min. In
continuous hemodia...
Access Location
Internal Jugular Vein
 Primary site of choice due to lower associated risk of complication and
simplicit...
AV fistula
AV Graft
AV fistula AV graft
MAJOR RRT TECHNIQUES
Intermittent hemodialysis
most efficient & large amounts of fluid can be removed,
electrolyte abnormalities can be rapidl...
set up is double lumen catheter, pump which forces blood into
filter (semi permeable membrane), dialysate (usually deioni...
Dialysis Disequilibrium Syndrome
self-limited condition characterized by nausea, vomiting,
headache, altered consciousnes...
Peritoneal dialysis
advantage
simple, cost effective.
major disadvantages of PD are –
poor solute clearance,
poor uremi...
How PD Works
In PD, catheter used to fill abdomen with dialysis solution.
peritoneum allows waste products & extra fluid...
Types
 continuous ambulatory
peritoneal dialysis (CAPD),
doesn’t require machine.
 can walk around with dialysis
solutio...
Transfer Set
 tubing that connects bag of dialysis solution to catheter.
 When catheter is first placed, exposed end of ...
Cycler
 Solution storage. At beginning of session, pt connect bags of dialysis
solution to tubing that feeds cycler.
 Pu...
Continuous hemodiafiltration techniques
developed to overcome deficiencies of IHD.
In critical illness phenomenon of cap...
CRRT Goals
Mimic the functions and physiology of the native
organ
Qualitative and quantitative blood purification
Resto...
MACHINE CIRCUIT
set up as follows:
 A double lumen catheter.
 A line leading to the filter where blood flow is
controlle...
Dialysis membrane
surface through which dialysis or ultrafiltration occurs: core
component of hemofilter.
Different memb...
Principles of CRRT clearance
 CRRT clearance of solute is dependent on the following:
 The molecule size of the solute
...
CVVH
 continuous venovenous hemofiltration - form of convective dialysis.
 ultrafiltration rate is high, replacement ele...
SCUF
 hypothesized that removal of such mediators play role in improving
outcome in sepsis. simple version of this is SCU...
CVVHD
 continuous venous venous hemodialysis– continuous diffusive dialysis
 dialysate driven in direction countercurren...
CVVHDF
 continuous venous venous hemodiafiltration
most popular method of dialysis in ICU, combines convective and
diffus...
CVVHDF similar to IHD in slow motion:
blood flow 100 – 200ml/min
dialysate flow 1000ml/hour
filtration rate 10-20ml/ho...
Most of these modes can remove up to 1 l/hr of fluid.
rare that this volume of fluid removal is required in ICU
(critica...
many pts, particularly those with head injuries, cannot tolerate
osmotic changes associated with HD.
Pts who are otherwi...
Clinical Conditions to Consider
ARF and need for fluid management related to:
 SIRS
 Unstable on IHD
 Organ transplant...
Advantages of CRRT
Suitable for use in hemodynamically unstable patients.
Precise volume control, immediately adaptable ...
Disadvantages of CRRT
 Anticoagulation
 Blood loss - Hemorrhage due to
over-anticoagulation
 Ineffective anticoagulatio...
Hypothermia in CRRT
Causes
 Patient’s blood in extracorporeal circuit at room temperature
 Administration of large volu...
Anticoagulation & its problems
 necessary to prevent clotting
of filter.
 may be a problem in pts who
at risk for bleedi...
ELECTROLYTE IMBALANCE
dialysate & replacement solutions should mirror what one wishes
blood chemistry to be – closest sol...
 KPO4 supplementation often necessary.
Note also that there is no NaHCO3 in dialysate, leading to loss of
bicarbonate: c...
Therapeutic Plasma Exchange
process to remove plasma while replacing it with another
substance .
blood will be drawn dir...
High volume haemofiltration
High-volume haemofiltration (HVHF) is an extra-corporeal
blood purification therapy aiming at...
 HVHF - extracorporeal blood purification therapy aimed at non-
selectively reducing circulating levels & activity of pro...
Biological and Clinical Rationale for HVHF
clinical picture of sepsis - overwhelming, systemic overflow of
pro- and antii...
Continuous renal replacement therapies (CRRTs) allow
extracorporeal treatment in critically ill patients with
hypercatabo...
‘Pulse HVHF’ – A New Approach
Ultrafiltration rates >50–60ml/kg/h (60 l/day including net
ultrafiltration) in continuous ...
despite high exchange volume during ‘pulse therapy’, net UF
maintained as low as possible, or even at zero balance.
with...
Bicarbonate buffered HF fluid (35mmol/L) should be
administered both pre-dilution (33–50%) & postdilution (50–
66%); temp...
Key points
 CRRT ensures adequate creatinine clearance in hemodynamically stable
environment. CRRT superior to IHD for vo...
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
Renal replacement therapy
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Renal replacement therapy

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Renal replacement therapy,
Haemodialysis and anaesthetic implications,
Different haemodialysis modalities,
SLEDD,
Complications,
Vascular access for renal replacement therapy

Veröffentlicht in: Gesundheit & Medizin
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Renal replacement therapy

  1. 1. DR. ARATI MOHAN BADGANDI RENAL REPLACEMENT THERAPY
  2. 2. AKI STRATIFICATION
  3. 3. AKI STRATIFICATION
  4. 4. MECHANISMS  2 fundamental processes underlie continuous renal replacement therapy – diffusion and convection Diffusion / dialysis–  movement of solutes from compartment in which they are in high concentration to 1 in which they are in lower concentration – along an electrochemical gradient.  electrolyte solution runs countercurrent to blood flowing on other side of semipermeable (small pore) filter.  Small molecules such as urea move along concentration gradient into dialysate fluid.  Larger molecules are poorly removed by this process.  Solute removal is directly proportional to the dialysate flow rate.
  5. 5. MECHANISMS Convection / ultrafiltration –  solute is carried (in solution) fluid across a semipermeable membrane in response to a transmembrane pressure gradient (known as solvent drag).  This mimics what actually happens in normal human kidney.  rate of ultrafiltration depends upon porosity of membrane & hydrostatic pressure of blood, which depends upon blood flow.  very effective in removal of fluid, middle-sized molecules, thought to cause uremia. Moreover, most of the cytokines involved in sepsis are “middle molecules”.
  6. 6. Ultrafiltration Conventional hemodialysis blood flow 350- 450 ml/min, dialysate flow 500-800 ml/min. In continuous hemodialysis (CVVHD) blood flow is usually set at 100-200 ml/min, dialysate flows at 1000-2000 ml/hr.
  7. 7. Access Location Internal Jugular Vein  Primary site of choice due to lower associated risk of complication and simplicity of catheter insertion. Femoral Vein  Patient immobilized, the femoral vein is optimal and constitutes the easiest site for insertion. Subclavin Vein  The least preferred site given its higher risk of pneumo/hemothorax and its association with central venous stenosis. The length of the catheter chosen will depend upon the site used  Size of the catheter is important in the pediatric population. The following are suggested guidelines for the different sites:  RIJ= 15 cm French  LIJ= 20 cm French  Femoral= 25 cm French
  8. 8. AV fistula
  9. 9. AV Graft
  10. 10. AV fistula AV graft
  11. 11. MAJOR RRT TECHNIQUES
  12. 12. Intermittent hemodialysis most efficient & large amounts of fluid can be removed, electrolyte abnormalities can be rapidly corrected. However, not suitable in unstable patients: 20-30% of patients with ARF who are being hemodialysed become hypotensive, with huge associated osmotic shifts – disequilibrium syndrome. Many ICU patients are intolerant of such shifts. Moreover it appears that the hemodynamic changes that occur during hemodialysis (hypotension) may worsen the pre-existing renal injury by increasing the ischemic insult. major complications rapid shifts in plasma volume and solute composition, vascular access, necessity for anticoagulation and dialysis membrane incompatibility.
  13. 13. set up is double lumen catheter, pump which forces blood into filter (semi permeable membrane), dialysate (usually deionized water) which flows in and out, return line to patient. blood flow rate 200-400ml/minute, dialysate flow approx 500ml/minute, filtration rate btwn 300 & 2000ml/hour, urea clearance of 150-250 ml/min. With this high flow & clearance rate pts, depending on extent of catabolism, only require 3-4 hrs of dialysis, 2-3 times/wk. There are huge swings in fluid between intravascular & extravascular compartments, causing transient hypotension & disequilibrium. Vascular access for short-term hemodialysis or hemofiltration is usually achieved using double-lumen catheter inserted into IJV. Anticoagulation with heparin is std method for preventing thrombosis of extracorporeal circuit during acute intermittent dialysis
  14. 14. Dialysis Disequilibrium Syndrome self-limited condition characterized by nausea, vomiting, headache, altered consciousness, and rarely seizures or coma. It typically occurs after first dialysis in very uremic patients. triggered by rapid movement of water into brain cells following development of transient plasma hypo-osmolality as solutes rapidly cleared from bloodstream during dialysis. incidence has fallen in recent yrs with more gradual institution of dialysis, precise prescription of dialysis to include such variables as membrane size, blood flow rate, and sodium profile.
  15. 15. Peritoneal dialysis advantage simple, cost effective. major disadvantages of PD are – poor solute clearance, poor uremic control, risk of peritoneal infection mechanical obstruction of pulmonary & cardiovascular performance.
  16. 16. How PD Works In PD, catheter used to fill abdomen with dialysis solution. peritoneum allows waste products & extra fluid to pass from blood into dialysis solution. usually contains dextrose that will pull wastes & extra fluid into abdominal cavity. used solution, containing wastes and extra fluid thrown away. process of draining and filling is called an exchange, takes about 30- 40 minutes. period the dialysis solution is in abdomen - dwell time. typical schedule calls for 4 exchanges/day, each with dwell time of 4- 6 hrs. Different types of PD have different schedules of daily exchanges.
  17. 17. Types  continuous ambulatory peritoneal dialysis (CAPD), doesn’t require machine.  can walk around with dialysis solution in abdomen.  Another form of PD, continuous cycler-assisted peritoneal dialysis (CCPD), requires machine called a cycler to fill & drain your abdomen, usually while you sleep. Also called automated peritoneal dialysis (APD). CAPD catheter standard catheter for PD made of soft tubing for comfort. It has cuffs made of Dacron that merges with scar tissue to keep it in place. end of tubing that is inside abdomen has many holes to allow free flow of solution.
  18. 18. Transfer Set  tubing that connects bag of dialysis solution to catheter.  When catheter is first placed, exposed end of tube will be securely capped to prevent infection.  Under the cap is a universal connector.  requires sterile technique.  Pt & nurse wear surgical masks. nurse soaks transfer set & end of catheter in antiseptic solution for 5 minutes before making connection, wearing rubber gloves.  tubing that connects to transfer set includes piece that can be clamped at end of an exchange. Dialysis Solution  Dialysis solution comes in 1.5-, 2-, 2.5-, or 3-liter bags.  dialysis dose can be increased by using a larger bag, but within limit of amount abdomen can hold.
  19. 19. Cycler  Solution storage. At beginning of session, pt connect bags of dialysis solution to tubing that feeds cycler.  Pump. sends solution from storage bags to heater bag before it enters body, then to disposal container/drain line after use.  Heater bag. measured dose is warmed to body temperature. Once solution is right temperature & previous exchange has been drained, clamp is released to allow warmed solution to flow into abdomen.  Fluid meter. cycler’s timer releases clamp to let the used dialysis solution drain from abdomen into disposal container/drain line.  Disposal container or drain line.  Alarms. Sensors will trigger an alarm and shut off the machine if there’s a problem with inflow or outflow.
  20. 20. Continuous hemodiafiltration techniques developed to overcome deficiencies of IHD. In critical illness phenomenon of capillary leak increases interstitial volume and makes patients edematous. This makes the clearance of solute difficult to calculate and indeed to carry out. Continuous techniques lead to more effective urea clearance, controlled fluid removal. 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. ICU pts particularly suited to these techniques as they are, bed bound, intolerant of fluid swings associated with IHD.
  21. 21. CRRT Goals Mimic the functions and physiology of the native organ Qualitative and quantitative blood purification Restore and maintain of homeostasis Avoid complications and good clinical tolerance Provide conditions favoring recovery of renal function
  22. 22. MACHINE CIRCUIT set up as follows:  A double lumen catheter.  A line leading to the filter where blood flow is controlled by a series of roller pumps: blood flow is usually set at 120ml/min.  Anticoagulant – to prevent blood clotting on the filter.  Dialysis fluid, which runs in countercurrent to the blood, the standard rate is 1litre per hour. This can be increased to improve clearance.  A bag to collect the ultrafiltrate.  Replacement fluid, to replace the excess ultrafiltrate over and above the required fluid removal.
  23. 23. Dialysis membrane surface through which dialysis or ultrafiltration occurs: core component of hemofilter. Different membranes used in RRT: may be cellulose based/synthetic. cellulose membranes are "low-flux" - very thin, low permeability co-efficient, strongly hydrophilic: known to activate inflammatory cascades, particularly complement, thus unsuitable (bioincompatible) in critical illness. Synthetic membranes should be used in this setting for both intermittent & continuous hemodialysis. These membranes tend to be slightly thicker than cellulose, have very high sieving coefficients at wide range of molecular wts: effective at convective clearance. Thus regardless of the technique involved, RRT with synthetic filters will always include significant ultrafiltration.
  24. 24. Principles of CRRT clearance  CRRT clearance of solute is dependent on the following:  The molecule size of the solute  The pore size of the semi-permeable membrane  higher the ultrafiltration rate (UFR), greater solute clearance.  Small molecules pass through membrane driven by diffusion & convection.  Middle & large size molecules are cleared primarily by convection.  Semi-permeable membrane remove solutes with mol wt of upto 50 KDaltons.  Plasma proteins or substances highly protein—bound will not be cleared.  Sieving Coefficient - ability of substance to pass through membrane from blood compartment of the hemofilter to the fluid compartment.  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 Cr  0 albumin will not pass
  25. 25. CVVH  continuous venovenous hemofiltration - form of convective dialysis.  ultrafiltration rate is high, replacement electrolyte solution required to maintain haemodynamic stability.  effective for clearing mid sized molecules, eg. inflammatory cytokines.
  26. 26. SCUF  hypothesized that removal of such mediators play role in improving outcome in sepsis. simple version of this is SCUF - slow continuous ultrafiltration, used for volume control in overloaded patients.  SCUF does not require replacement fluid,  fluid removal is 300ml to 500ml per hour.
  27. 27. CVVHD  continuous venous venous hemodialysis– continuous diffusive dialysis  dialysate driven in direction countercurrent to blood.  provides reasonably effective solute clearance, although mostly small molecules are removed.
  28. 28. CVVHDF  continuous venous venous hemodiafiltration most popular method of dialysis in ICU, combines convective and diffusive dialysis.  Both small and middle molecules are cleared  dialysate & replacement fluids are required.
  29. 29. CVVHDF similar to IHD in slow motion: blood flow 100 – 200ml/min dialysate flow 1000ml/hour filtration rate 10-20ml/hour (very efficient) urea clearance is 10-20ml/hour. continuous hemofiltration is as efficient as IHD at fluid removal by ultrafiltration, but not as efficient at dialysis (diffusion), due to slow fluid flows. to increase urea/creatinine clearance - should increase dialysate flow /blood flow/ both.
  30. 30. Most of these modes can remove up to 1 l/hr of fluid. rare that this volume of fluid removal is required in ICU (critically ill patients rarely tolerate any significant fluid removal). HD clears fluid out of intravascular space at rapid rate, usually faster than it can be replaced from extravascular space. In healthy pts this often causes hypotension. In ICU pts, who often have intravascular hypovolemia (decreased oncotic pressure due to capillary leak), this hypotension may be disasterous. may precipitate ischemic injury to various organs, particularly recovering kidneys, which have temporarily lost pressure-flow autoregulation (new ischemic injuries have been demonstrated after HD sessions).
  31. 31. many pts, particularly those with head injuries, cannot tolerate osmotic changes associated with HD. Pts who are otherwise healthy (except for CRF) have tremendous venous capacitance, & can tolerate fluid accumulation between dialysis sessions. Critically ill patients with leaky capillaries may develop significant PE btwn sessions - daily IHD is often required. Feeding & nutrient delivery significant problem in critical illness. pts are severely catabolic; more metabolic byproducts to be cleared. To prevent further loss of protein, feeding is essential, fluid restriction is not an option. If IHD strategy is used, in early critical illness, daily therapy is probably required.
  32. 32. Clinical Conditions to Consider ARF and need for fluid management related to:  SIRS  Unstable on IHD  Organ transplants  CHF /volume overload  Post CV surgery  Post trauma patients  Severe Burns
  33. 33. Advantages of CRRT Suitable for use in hemodynamically unstable patients. Precise volume control, immediately adaptable to changing circumstances. Very effective control of uremia, 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 adjuvant therapy in sepsis. Probable advantage in terms of renal recovery.
  34. 34. Disadvantages of CRRT  Anticoagulation  Blood loss - Hemorrhage due to over-anticoagulation  Ineffective anticoagulation therapy - Clotting of hemofilter  sepsis.  Hypothermia.  Severe depletion of electrolytes – particularly K+ and PO4, where care is not taken.  Acid/base imbalance - Renal dysfunction, Respiratory compromise  Vascular access - Vascular spasm, Movement of catheter against vessel wall, Improper length of hemodialysis catheter inserted,  Hypotension - Intravascular volume depletion, Underlying cardiac dysfunction  High ultrafiltration rates (high clearance)  Inadvertent disconnection in the CRRT system  Blood filter leaks  Air embolus  Cardiac arrest  Hemolysis  Circulatory overload  Arrhythmias
  35. 35. Hypothermia in CRRT Causes  Patient’s blood in extracorporeal circuit at room temperature  Administration of large volumes of room temperature fluids (replacement and dialysate) Signs and Symptoms  Hemodynamic instability  Chilling, shivering  Skin pallor, coolness and cyanosis Treatment measures  Warming blankets  Blood Warmer
  36. 36. Anticoagulation & its problems  necessary to prevent clotting of filter.  may be a problem in pts who at risk for bleeding/had recent surgery. Classically heparin has been used. potential drawbacks:  1. risk of bleeding due to systemic anticoagulation.  2. Heparin requires presence of antithrombin III, often deficient in ICU population.  3. may cause thrombocytopenia (HIT syndrome). Agents used instead of heparin include: 1. PGE1 and PGI2, which have anti platelet effects. 2. Citrate, which binds calcium and inhibits the coagulation cascade – and is metabolized to bicarbonate in the liver. 3. Low molecular weight heparins. 4. Hirudin. 5. Aprotinin.
  37. 37. ELECTROLYTE IMBALANCE dialysate & replacement solutions should mirror what one wishes blood chemistry to be – closest solution is RL (Hartmann’s Solution). reason for this - as time passes, blood & dialysate levels of electrolytes will equilibrate, whereas in IHD, one rigorously cleans blood & ECF for few hrs & awaits reaccumulation. In CRRT any depletion of electrolytes during process will continue until dialysate prescription is changed.  potassium and phosphate loss: standard dialysate solutions contain neither – levels can drop very low.
  38. 38.  KPO4 supplementation often necessary. Note also that there is no NaHCO3 in dialysate, leading to loss of bicarbonate: compensated for by passage of lactate (anionic, a base) into bloodstream. Calcium may also be required, although Ca & HCO3 cannot be given together, because they precipitate. This is usually metabolized into bicarbonate in the liver. In liver failure, wiser to use a lactate free dialysate – such as normal saline, adding bicarbonate
  39. 39. Therapeutic Plasma Exchange process to remove plasma while replacing it with another substance . blood will be drawn directly from blood vessel in arm/through a small tube (catheter) placed in a vein. blood will be separated into plasma & blood cells (RBCs WBCs & platelets) by centrifuge. plasma will be removed while blood cells & plasma replacement returned to in opposite arm or catheter During the procedure, an anticoagulant solution is slowly added to the blood to prevent unwanted clotting plasma replacement – albumin/FFP.
  40. 40. High volume haemofiltration High-volume haemofiltration (HVHF) is an extra-corporeal blood purification therapy aiming at non-selectively reducing circulating levels & activity of both pro- & anti-inflammatory mediators. Haemofiltration membranes exhibit some adsorption properties allowing capturing of HMW molecules in membrane itself.  Therefore, during septic shock, more the adsorption properties, the more cytokines & inflammatory mediators removed from blood circulation. Thus, associating convection with adsorption for blood purification.
  41. 41.  HVHF - extracorporeal blood purification therapy aimed at non- selectively reducing circulating levels & activity of pro-& anti- inflammatory mediators in sepsis & MODS.  Numerous in vitro studies shown that HF capable of removing nearly every known substance involved in sepsis to a certain degree.  Recent human studies demonstrated that HVHF improves haemodyamics with decreased vasopressor requirements & improved survival of septic patients. technical requirements of HVHF – i.e. high blood flows, tight ultrafiltration control & large amounts of costly sterile fluids – are problematic.  therefore ‘pulse HVHF’ technique developed - applied for short periods of upto 6-8 hrs/day, providing intense plasma water exchange.
  42. 42. Biological and Clinical Rationale for HVHF clinical picture of sepsis - overwhelming, systemic overflow of pro- and antiinflammatory mediators, leading to generalised endothelial damage, multiple organ failure and altered cellular immunological responsiveness. includes mediators with autocrine & paracrine actions, cellular & intracellular components. TNF-α, IL-1, IL-6, platelet activating factor (PAF) & NO - role in cascade. pro- & anti-inflammatory factors become upregulated - interact with each other, leading to various rises in mediator levels that change over time.
  43. 43. Continuous renal replacement therapies (CRRTs) allow extracorporeal treatment in critically ill patients with hypercatabolism & fluid overload. 3 types of depurative mechanisms: convection, diffusion & adsorption by filtering membrane. In addition to removing excess fluid & waste products in septic patients, convective modalities have advantage of removing HMW substances, including many inflammatory mediators. Adsorption to filter membrane is saturable process with timeframe of few hrs. augmented by increasing membrane surface area & ultrafiltration rate
  44. 44. ‘Pulse HVHF’ – A New Approach Ultrafiltration rates >50–60ml/kg/h (60 l/day including net ultrafiltration) in continuous HF mode considered high & defined as HVHF. To reach UF rates 85ml/kg/hr, vascular access that can ahieve constant flow of atleast 300ml/min required (e.g. 14F catheters). Filtration fraction of 25% can be set. If catheter/cannulated vessel too small, resistance of arterial lumen of catheter creates -ve pressure before pump which may reach as high as -300mmHg, resulting –ve impact on dialyzer life. Return/venous pressure may be greater because of haemoconcentration that accompanies high rates of ‘netUF’. (net UF -volume of fluid removed from pt less volume of substitution fluid.)
  45. 45. despite high exchange volume during ‘pulse therapy’, net UF maintained as low as possible, or even at zero balance. with high filtration fraction of pulse HVHF, increased blood viscosity & hct within filter mandates adequate anticoagulation to avoid clot formation &filter clotting. PHVHF requires large haemofilter with surface area of 1.8–2m2 (in 70kg pt) to achieve such a high UF rate. biocompatible, synthetic membrane with permeability coefficient ranging 30–40ml/h/mmHg recommended, with sieving coefficients close to 1 for wide spectrum of molecular weights.
  46. 46. Bicarbonate buffered HF fluid (35mmol/L) should be administered both pre-dilution (33–50%) & postdilution (50– 66%); temperature of replacement fluid set around 38.5–39.5°C. Other important aspects of general patient care - temperature monitoring, antibiotic dose adjustments & nutritional adjustments (derived from amino acid, phosphate, vitamin losses). haemodynamic &oxygenation improvements reasonable objectives for adjuvant therapy of hypotensive septic/MODS pt resistant to volume resuscitation &pressors.
  47. 47. Key points  CRRT ensures adequate creatinine clearance in hemodynamically stable environment. CRRT superior to IHD for volume control.  Hemodynamic stability added advantage of preventing secondary ischemic injury to kidneys due to hypotensive episodes during hemodialysis.  biggest single problem with continuous hemodiafiltration - anticoagulation in pts who are, invariably, coagulopathic or bleeding.  Care must be taken to ensure electrolyte balance, ideally dialysate should mirror that of ideal blood electrolyte composition.  Due to tendency for bicarbonate to caused precipitation, usually replaced by lactate in dialysis solutions.  If pt in liver failure, lactate not metabolized – cause academia.  Hemofiltration - role in management of septic patients, as a plasma cytokine filter, modulating the inflammatory response, but there is no evidence that this alters outcomes in humans.

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