renal failure and processes of dialysis.pptx

Stages of dialysis for nursing students

1. Approach to hemodialysis prescription Presenter : Dr. Yared G (IMR-II ) Moderator:Dr. Getnet ( Internist & Nephrology Fellow)

2. OUTLINE Introduction Principles of renal replacement therapy Apparatus & vascular access Components of acute hemodialysis prescription Complications of acute hemodialysis Management during recovery References

3. Introduction Derived from two Greek words: ‘Dia’ means through and ‘lysis’ means splitting The first working dialyzer was constructed in 1943, first dialysis in 1945 Dialysis: is a process whereby the solute composition of a solution A, is altered by exposing solution A to a second solution, B, through a semipermeable membrane

4. Cont …

5. Essentials of acute kidney RRT Mechanisms of solute and water removal: Transport of molecules across the dialysis membrane is driven by the concentration gradient (diffusive transport) the hydrostatic pressure gradient across the membrane (convective transport) Ultrafiltration: A process by which water and solute are pushed through semipermeable membrane, driven by hydrostatic pressure Water permeability is defined by the ultrafiltration coefcient (Kuf) volume per hour per unit of hydrostatic transmembrane pressure in mmHg.

6. 2. Convection solute cross a semi-permeable membrane together with a solvent, solvent drag It allows transport of small and medium size solutes The convective flux depend on: Quf, ultra filtration rate Membrane surface area Solute concentration in the plasma Sieving coefficient: measure of how easily a substance passes from the blood to dialysate

7. 3. Diffusion Net movement of solutes from region of high concentration to one of lower concentration In KRT the gradient across filter membrane created by running dialysate in effluent compartment Efficient for fast moving small molecules

8. 4. Adsorption Refers to binding of blood components to the membrane Determining factors: Molecules character: dimension, charge and structure Membrane character: porosity, composition, hydrophobicity and surface potential Rapid saturation of membrane site limit its effectiveness

9. Dialyzer eficiency increases with surface area (usually between 0.8–2.1m2) The dialyzer mass transfer area coefcient (KoA) for urea is a measure of the theoretically maximal possible urea clearance (mL/min). Dialyzer eficiency can be categorized based on KoA for urea as low (<500 mL/min), moderate (500–700 mL/min), and high (>700 mL/min). High-flux and medium cut-off membranes have pores large enough to allow some passage of molecules such as β2-microglobulin (molecular weight 11,800 Da), tumor necrosis factor (TNF)-α (17 kDa), and beyond.

10. Initiating KRT There’s no specific lab reference (Cr/BUN/GFR) for initiation of dialysis in either AKI,CKD or Dialyzable drug/toxin intake Volume overload refractory to diuretics Hyperkalemia refractory to medical management Persistent or worsening acidosis, refractory to medical management Uremic complication Toxic overdose of a dialyzable drug

11. Early Vs late initiation of Dialysis in AKI? STARRT-AKI trial (NEJM,2020) : Multinational, RCT comparing critically ill patients with severe AKI who received accelerated (within 12 hours)Vs standard dialysis (based on indication) Result : Among critically ill patients with acute kidney injury, an accelerated renal-replacement strategy was not associated with a lower risk of death at 90 days than a standard strategy

12. No consensus for early initiation of KRT to prevent rather than treating complications of AKI Threshold for diabetic patients should be low As they tolerate uremia poorly Uremic symptoms vs eGFR A purely GFR based decision regarding dialysis initiation showed no difference in survival or QoL Early start group : GFR of 9ml/min/1.73m2 Late start group : GFR of 7.2 ml/min/1.73 m2 (6 months later)

13. Therapeutic Goals: Individualized Goals: Physiologic targets Dose of KRT delivered, incremental Volume status goals These goals should be achieved with out exacerbating hemodynamic instability, increasing end organ damage, or delaying kidney recovery

14. Modalities of RRT

15. Hemodialysis Vascular Access

16. Central v ascular Access

17. Components of acute hemodialysis prescription Hemodialyzer membrane Dialysate composition Blood flow rate Dialysis solution flow rate Dialysate composition Ultra filtration Anticoagulation Dialysis solution temperature Dose of dialysis

18. 1. Hemodialyzer membrane Synthetic noncellulose higher permeability More biocompatible Substituted cellulose Cellulose High efficiency vs low efficiency Cellulose and substituted cellulose membranes, are relatively bioincompatible; initiate an inflammatory cascade and activate complement, resulting in the generation of the anaphylatoxins C3a and C5a

19. Use a synthetic membrane b/c: High flux Greater permeability for larger molecules, which enhance removal of toxins and improve outcome Biocompatible Lesser risk of infectious complications

20. 2. Dialysis session length The European best practice guidelines recommend that dialysis should be delivered at least 3 times per week and the total duration should be at least 12 h/wk, unless supported by signicant residual kidney function with GFR greater than 3 mL/min. More frequent in-center dialysis and longer dialysis hours delivered by in-center or home HD are increasingly used alternatives to conventional thrice-weekly treatment. improved solute clearance and complete removal of interdialytic weight gain (IDWG) with fewer hypotension

21. 12 months of follow-up, daily in-center HD resulted in lower phosphate levels, a reduction in left ventricular mass, and an improvement in self-reported physical health Conventional thrice weekly dialysis remains the standard of care in most countries, where treatment time is typically governed by dialysis dose (Kt/V)

22. 3. Blood flow rate: 1 st session, BFR should be based on elevation of BUN Patients with severe azotemia and those with/at risk for ICP, CKRT may be used Delivered dialysis dose depends on dialyzer eficiency (Kd), effective treatment time (t), and distribution volume (V). Dialyzer clearance Kd depends on the flow rates within the blood and dialysate compartments (Qb and Qd), dialyzer KoA, effective membrane surface area, hematocrit, and anticoagulation

23. A standard dialysis prescription should consist of a high-flux dialyzer, a minimum treatment time of 4 hours, a blood flow rate of at least 250 mL/min and up to 500ml/min The prescription is then adjusted to meet the target spKt/V of 1.4 volumes, min 1.2 and std Kt/V of 2.1 In severe and long-standing uremia, the target dose is approached slowly over the course of several sessions to avoid the dialysis disequilibrium syndrome.

24. 4. Dialysate flow rate: For acute dialysis, the usual dialysis solution flow rate is 500-800mL/min. The optimum value for the dialysis solution flow rate is 1.5 to 2.0x the blood flow rate

25. 5. Dialysate composition Generation of near-sterile dialysate and prescription of dialysate temperature are essential In acute hemodialysis is routinely altered each treatment to correct the metabolic abnormalities Dialysis machines mix different components with water to produce the final solution of dialysate

26. Dialysate composition… Sodium A positive sodium balance is a typical feature of ESKD hypertension, fluid overload, nonosmotic tissue sodium storage and left ventricular hypertrophy 5 to 6 g salt (2300 mg or 100 mmol sodium) care should be taken that dialysate sodium does not exceed the patient’s average predialysis serum sodium by more than 2 to 3 mmol/L- IDWG The choice of dialysate sodium concentration for individual patients depends upon: predialysis serum sodium concentration and hemodynamic status of the patient

27. Dialysate composition… Normal serum sodium  136 – 145 mEq /L Chronic hyponatremia The goal is to correct the hyponatremia over the course of multiple hemodialysis sessions the are performed over a period of several days Severe chronic hyponatremia: <120 mEq /L Set the dialysate sodium to the lowest available setting (130  mEq /L) Reduce the blood flow rate to 2 mL/kg/min Reduce the dialysis time

28. Chronic hypernatremia Less common than hyponatremia in a hemodialysis setting but does occur The use of dialysate sodium concentrations more than 3 to 5 mEq/L  below the plasma sodium concentration is associated with Hypotension Muscle cramps and Disequilibrium syndrome First dialyze a patient with a dialysis solution sodium level close to that of plasma (within 2 meq /L)

29. Potassium The typical dialysate potassium concentration is set between 2.0 and 4.0 mmol/L. Prescription of potassium dialysate concentrations less than 2.0 mmol/L is associated with an increased risk for tachyarrhythmia and sudden cardiac death and should be avoided For patient with high risk for arrhythmia avoid using potassium < 3 mEq /L Avoid using shifting agents before dialysis Avoid using dialysate with higher glucose level if you want to remove more potassium

30. Potassium… based upon the predialysis serum potassium value

31. Calcium In light of accelerated vascular calcication in ESKD, intradialytic calcium delivery to the patient should be minimized, and in patients using calcium salts as phosphate binders negative intradialytic calcium mass balance is desirable. A dialysate calcium concentration of 1.25 to 1.50 mmol/L is recommended by KDIGO, but many patients will be in positive balance even at 1.25 mmol/L. A positive calcium balance may be associated with tissue calcium accumulation, whereas lower dialysate calcium will stimulate parathyroid hormone (PTH) secretion. In most patients a dialysate calcium concentration of 1.25 mmol/L is now used.

32. Calcium The plasma ionized calcium should be measured prior to starting dialysis

33. Magnesium : The usual dialysis solution magnesium level ranges from (0.5–1 mEq/L) Glucose : The standard dialysate glucose concentration is 100 – 200 mg/dl

34. 6 . Dialysate solution Buffer The main dialysate buffer used in intermittent hemodialysis is bicarbonate Bicarbonate precipitates as an insoluble salt when stored with the divalent cation with no acid-base disorder we use a standard dialysate bicarbonate concentration of approximately 30 to 35 mEq/L

35. Chronic metabolic acidosis is associated with decreased protein synthesis and increased protein catabolism and contributes to mineral and bone disorders. Dialysate bicarbonate concentration is typically set between 30 and 35 mmol/L to generate a transmembrane concentration gradient favoring bicarbonate delivery to the patient. Data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) indicate that both high (>27 mmol/L) and low (<17 mmol/L) predialysis serum bicarbonate levels are associated with increased risk for mortality and hospitalization range of 20 to 23 mmol/L are associated with improved survival

36. Dialysate solution Buffer… Metabolic acidosis: mild or moderate (serum Hco3 10 - 23 mEq/L ) Hco3 of 30 -35 mEq/L severe metabolic acidosis (serum Hco3 <10 mEq/L ) Hco3 of 35 - 40 mEq/L

37. 7. Ultrafiltration Determining optimal ultrafiltration (UF) requirements in critically ill acute kidney injury (AKI) patients is challenging Volume status and the desired UF requirement are determined in part by physical examination and hemodynamic indices In hemodynamically stable patients It can be made in the usual fashion utilized for CKD patients In hemodynamically unstable patients should be titrated to invasive or noninvasive monitoring Fluid removal needs may range from 0 to 5 kg per dialysis session

38. High-flux membranes offering high hydraulic permeability, as well as high middle-molecule clearance, are required for effective HDF. Hydraulic permeability is reflected by the membrane ultrafiltration coefcient , whereas membrane permeability is defined by the sieving coeficients for selected middle molecules. For high-volume online HDF a high-flux membrane with ultrafiltration coeficient greater than 20 mL/h/mm Hg/m2 sieving coeficient for β2-microglobulin of 0.6 is required The major determinants of achieving a prescribed target CV in postdilution HDF are blood fow rate (Qb), ultrafiltration rate (UFR), and treatment time (t)

39. 8. Anticoagulation Factors Favoring Clotting of the Extracorporeal Circuit Low blood flow, High hematocrit, High ultrafiltration rate Intradialytic blood and blood product transfusion, Intradialytic lipid infusion Use of drip chambers (air exposure, foam formation, turbulence)

40. Medium risk High risk Pericarditis Bleeding diathesis Recent bleeding <48 hours Clotting factor disorder Recent placement of tunneled catheter <24 hours Actively bleeding Minor surgery <72 hours Eye or major surgery <72 hours Eye or major surgery within 3 to 7 days Intracranial hemorrhage <7 days

41. Standard anticoagulation: Given as a bolus at the start of the dialysis treatment, with a mid-treatment dose to maintain suitable anticoagulation Alternatively, heparin modeling can be performed using an initial bolus followed by a constant fixed infusion of heparin to maintain an elevating clotting time (ACT)

42. Anticoagulation… Patients at risk of bleeding: Options of intervention Minimum-dose heparin  No-heparin hemodialysis Regional citrate anticoagulation Saline flushes Argatroban or lepirudin

43. M inimum-dose heparin regimen for anticoagulation during hemodialysis

44. P rotamine reversal regimen for regional anticoagulation during hemodialysis

45. Regional citrate regimen for anticoagulation during hemodialysis

46. anticoagulation in dialysis patients at high risk for bleeding

47. 9. Dialysis solution temperature Dialysis solution temperature is usually 35–37°C The lower range should be used in hypotension prone patients

48. 10. Dialysis Dose Urea removal from the body during dialysis is expressed either by urea reduction ratio (URR) or by the treatment index Kt/V Refers to delivery of a treatment dose that is considered sufficient to promote optimal outcome It is conventionally assessed by removal of urea and expressed by: =Kt/V- total plasma volume cleared (K × t, in liters) in relation to the individual volume of distribution (V, in liters) single-pool Kt/V (spK/V), equilibrated Kt/V (eKt/V), and weekly standard Kt/V (stdKt/V)

49. physiologic “equilibrated” double pool urea kinetic model (eKt/V) considers the urea redistribution kinetics between the two compartments

50. The concept of Kt/V may be applied to any substance but in clinical practice is almost exclusively used for urea, where K is the dialyzer blood water urea clearance (in liters/hour), t is dialysis session length (hours), and V is the distribution volume of urea (in liters), which equates closely to total body water. A delivered Kt/V of 1.0 implies that the volume of plasma cleared of urea (K × t) during a dialysis session is equal to urea distribution volume (V). However, because of the multicompartment kinetics of urea equilibration, and constantly ongoing urea generation, clearing a plasma volume equivalent to 1 unit of total body water (V) does not mean that all urea has been removed from body water.

51. Dialysis dose … Urea Reduction Ratio (URR): A simpler measurement of Ur clearance does not consider intradialytic urea generation and convective urea removal by ultrafiltration, and it is a single-pool measurement After a dialysis treatment, urea rebound occurs, which takes 30 to 60 minutes until full equilibration between all compartments is achieved. A minimum URR of 65% to 70% is considered an adequate dialysis dose

52. Among all potential uremic toxins, only urea, a 60-Da water-soluble compound, is established as a marker of uremic solute retention and removal urea removal does not closely parallel the removal of other small water-soluble compounds and correlates poorly with removal of middle molecules and protein-bound solutes Although urea removal alone is not a sensitive marker of dialysis adequacy, it is still the standard measure to quantify removal of low molecular weight solutes during dialysis treatment

53. Dialysis Dose… Dialysis can be considered adequate if It provides relief of uremic symptoms & controls acidosis, fluid balance, and K + It allows a feeling of physical and psychological well-being Target Kt/V >1.2 URR < 40% in initial dialysis and Increased to target of > 65%

54. SAFETY Safety monitors are integral parts of the dialysis machine. Pressure monitor A venous air detector and air trap A blood leak detector Dialysate temperature monitor

55. KDIGO recommendations: The dose of RRT to be delivered should be prescribed before starting each session of RRT (not graded) We recommend frequent assessment of actual delivered dose in order to adjust the prescription (1B) We recommend delivering a Kt/V of 3.9/week when using intermittent or extended RRT in AKI (1A) We recommend delivering an effluent volume of 20-25 ml/kg/h for CRRT in AKI (1A)

56. Discontinuation of therapy Recovery of kidney function Increase in urine out put in oliguric patient Progressive decline in serum creatinine Measurement of creatinine clearance Creatinine clearance <12 ml/min.. Inadequate to discontinue Creatinine clearance > 20 ml/min.. Discontinue therapy In between provider decision

57. Acute Complication of During Hemodialysis Hypotension 25- 55 % arrhythmia 5-60% Cramps 5-20 % Nausea and vomiting 5-15% Headache 5% Chest pain2-5% Bach pain 2-5% Itching 5% Fever and chills < 1%

58. Intra-dialysis Hypotension Definition: The presence of a decrease in systolic blood pressure ≥20 mmHg or decrease in mean arterial pressure by 10 mmHg Providing it associated with clinical events or nursing intervention

59. Intra-dialysis Hypotension… Acute management: Place the patient in the Trendelenburg position, Reduce or stopping ultrafiltration, and Intravascular fluid replacement O2 should be administered Should be evaluated for serious causes

60. Preventive strategies 1 st line approach: Reassessing target weight Avoid food during dialysis Avoidance of antihypertensive drugs before dialysis Ensuring minimal salt intake Review dialysate composition 2 nd line approach: Assess primary cardiac factors Use of cool dialysate Increase dialysis time

61. …. 3 rd – line approach: Midodrine: selective alpha-1 adrenergic agonist Change to other modes of dialysis Sodium and UF modeling

62. Intradialytic hypertension 8% to 30% of cases may develop paradoxical hypertension in the later stages of dialysis Mostly indicates significant volume overload BP may remains elevated despite fluid removal, a syndrome called dialysis-refractory hypertension Pathogenesis: ?

63. Intradialytic hypertension … Predisposing factors: The use of high sodium dialysate Dialytic removal of drugs, such as ACEIs & β-blockers. EPO & other ESAs have been associated with a 20% to 30% incidence

64. … Treatment : Centrally acting agent such as clonidine or a short-acting ACE inhibitor Reduce sodium intake Optimization of antihypertensive drug therapy Use of minimally dialyzable/nondialyzable medications ARBs, Calcium channel blockers, Clonidine, & Carvedilol Vasodilator should be avoided

65. Cardiac arrythmia Are common and are often multifactorial in origin. LVH, Congestive CMP, Uremic pericarditis, silent MI are frequently encountered Constant alterations in fluid, electrolyte & acid-base homeostasis may precipitate

66. Cardiac arrythmia … Preventive measures : Careful attention to dialysate potassium and calcium levels. Serum digoxin levels should be regularly monitored

67. Disequilibrium syndrome Neurologic symptoms of varying severity that affect dialysis patients, particularly when they are first started on hemodialysis Thought to be primarily cerebral edema Predisposing factors: First session dialysis Severe metabolic acidosis Age extremes & pre-existing neurologic conditions Conditions associated with cerebral edema (Hyponatremia, Hepatic encephalopathy, and malignant HTN) BUN is markedly elevated (>175 mg/dL)

68. Pathogenesis: A rapid reduction in urea by hemodialysis lowers the plasma osmolality, creating a transient osmotic gradient that promotes water movement into the cells…. Cerebral edema Clinical features: Early symptoms: Headache, nausea, disorientation, restlessness, blurred vision, mania & asterixis Some patients, however, may progress to confusion, seizures, coma, & even death. Dx by exclusion

69. … Treatment: Patients with mild, nonspecific symptoms, are treated symptomatically Stop the dialysis & supportive care: in the patient with seizures, coma, and/or obtundation Prevention: Limit the reduction in urea nitrogen per treatment Initiate with 02 hours of duration, at a low blood flow rate of 150-250 mL/min  Fluid overloaded patients can be treated with ultrafiltration then by a short period of hemodialysis.

70. Hemodialysis-Associated Seizures

71. … Treatment Cessation of dialysis Investigation for metabolic abnormalities and seizure management Maintainace antiepileptic medications: levetiracetam – preferred lacosamide – alternative phenytoin and valproate

72. Muscle cramp Occur in 5% to 20% of patients late during dialysis and frequently involve the legs Account for 15% of premature discontinuations of dialysis. More common during the first month Treatment Acute management is directed at increasing plasma osmolality

73. … Preventive strategies: Counseling about excessive interdialytic weight gain Sodium modeling and UF profiling Stretching exercises, Magnesium supplementation may be effective

74. Reactions to HD membrane Type A reactions: Begin in the first few minutes Symptoms: mild-severe Caused by: leachable substances from the dialyzer (such as ethylene oxide) or by contamination with bacterial peptides. Rx: Stop immediately Anaphylaxis management Type B reactions: Occur after 15-30 minutes Complement mediated reactions to new cellulose membrane Mild symptoms which resolve with continuing HD

75. Air Embolism Air embolism is a potential catastrophe that can lead to death unless detected and treated quickly The most vulnerable source of air entry into the extracorporeal circuit is the pre-pump tubing segment but can be infusion circuits Clinical presentation ---Depends on: Volume and speed of air introduced Patient’s position sitting (CNS) and supine (CRS)

76. Other Complications: Restless Leg Syndrome Headache Nausea & Vomiting Complement Activation and Dialysis-Associated Neutropenia Hemorrhage Thrombocytopenia…….HIT Dialysis related Hypoxemia….hypoventilation

77. Reference Comprehensive Clinical Nephrology 7 th edition UpToDate 2024 Harrison principle of internal medicine 21 st edition