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Dry Weight 2018

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Establishing and maintaining normal extracellular volume (ECV) is required to achieve normotension. The achievement of an optimal fluid status, as expressed by "dry weight" (DW), should allow for controlling blood pressure (BP) in the large majority of HD patients

Publicada em: Saúde e medicina
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Dry Weight 2018

  1. 1. Fluid Balance, DryWeight and Intradialytic Hypotension . Dr Rodriguez Jose Dr. Faroeuk Consultant Nephrologist CNN 1. Paramaribo. Suriname .
  2. 2. INTRODUCTION Cardiovascular(CV) disease is the primary cause of mortality in Maintenance hemodialysis (HD) patients.
  3. 3. INTRODUCTION • Poor control of hypertension is, in great part, responsible for this situation. • Several factors are involved in the pathogenesis of hypertension, but the main one is extracellular volume (ECV) overload.
  4. 4. INTRODUCTION Establishing and maintaining normal extracellular volume (ECV) is required to achieve normotension. The achievement of an optimal fluid status, as expressed by "dry weight" (DW), should allow for controlling blood pressure (BP) in the large majority of HD patients. WE MUST FOCUS ON THE DRY WEIGHT
  5. 5. BODY WATER INTRACELLULAR FLUID INTRA VASCULAR FLUID INTERSTITIAL FLUID EXTRACELLULAR FLUID
  6. 6. BODY WATER INTRACELLULAR FLUID 2/3 TBW 28 LINTRAVASCULAR FLUID 3.5 L 70kg man TOTAL BODY WATER:42 L INTERSTITIAL FLUID 10.5 L
  7. 7. WHAT IS DRY WEIGHT?
  8. 8. Dry weight Ideal postdialysis weight that allows a constantly normal blood pressure to be maintained without using antihypertensive medications. "that body weight at the end of dialysis at which the patient can remain normotensive until the next dialysis without antihypertensive medication" Dry weight is not the actual postdialysis weight. It is the ideal postdialysis weight allowing for a normal BP.
  9. 9. Evaluation of fluid status (extracellular volume)
  10. 10. DW : Clinical evaluation Overload symptoms: – Hypertension – Peripheral edema – Pulmonary edema (Dry cough, exercise dyspnea, orthopnea, crackling rattles) – Effusions (hypoventilation / pulmonary dullness, ascites)
  11. 11. DW : Clinical evaluation Hypovolaemia symptoms: – Hypotension, tachycardia, polypnoea. – Vasoconstriction with peripheral and / or central hypoxemia signs (dry, cold and white skin; cramps and angina; confusion, coma; …). – Skin dryness and xerostomia.  Applicable to each dialysis session
  12. 12. Dry weight Assessment: Clinical Blood pressure JVP Oedema/ascites Lungs examinations Weighing scale. Advantages – Cheap – Immediate – universally available at the patient's bedside. Disadvantages: – Unreliable – Insensitive
  13. 13. Dry weight Assessment: non-clinical inferior vena cava diameter, atrial natriuretic peptide (ANP) Bioimpedance blood volume monitoring
  14. 14. Pathophysiology of dry weight
  15. 15. Pathophysiology of dry weight Normal kidney functions 24 hrs/day HD is discontinuous, a few hours every 2 or 3 days: to a peak-and-valley situation. The patient gains one to several liters of ECV during the interdialytic period.
  16. 16. Daily weight and DW variations  24h physiological weight variations :  – Food time & rythm of the appetite.  – Physical activity.  – Bladder content.  – Constipation.  – …etc…  • Extracorporal weight variation factors : Clothes & shoes,  prostheses, diaper and urine bag, scales, weighing errors, …   DW is highly variable   “Moving dry weight” concept
  17. 17. Pathophysiology of dry weight At the initiation of each HD session: the patient is saline overloaded, or "wet.“?? He needs to lose the weight gained during the interdialytic period to return to the last postdialysis weight. Wt : 62 kg Wt 58 kg
  18. 18. Pathophysiology of dry weight If this weight has been found to be too high, the planned ultrafiltration (UF) must be increased.  IDWG = 3 kg  Set UF = 3.2 kg – allow about 200 ml extra for blood return + fluid & food taken during HD If it has been found to be too low, the planned UF must be decreased.  IDWG = 1kg  Set UF =1.2 kg
  19. 19. Pathophysiology of dry weight The water and salt subtraction from the plasma volume creates a disequilibrium situation between the plasma and interstitial spaces. Water & salt removal from plasma/ intravascular space
  20. 20. Pathophysiology of dry weight Refilling from interstitial (and intracellular) spaces has started but is not yet completed (it takes about 4 hours).
  21. 21. Pathophysiology of dry weight At the end of the HD session, plasma volume reaches a nadir(the lowest point ) At disconnection the patient is hypovolemic, or "dry," and may have a postural BP drop that will disappear within a few hours.
  22. 22. Pathophysiology of dry weight Plasma volume preservation during UF is linked to the initial interstitial volume status. – The higher it is, the faster the refilling – During the session, as the patient gets less and less volume overloaded, his refilling capacity decreases and the hazard of hypotension increases.
  23. 23. Pathophysiology of dry weight Blood pressure usually remains stable during the first two thirds of the session. In some patients, hypotension, rather than being compensated by an adequate hemodynamic response, may be complicated by a vasovagal syncope
  24. 24. Pathophysiology of dry weight  In fact, several factors modulate cardiovascular compensation: – extracorporeal temperature – dialysate buffer – calcium concentration.
  25. 25. Pathophysiology of dry weight The heart's ability to compensate for an acute volume change is: – most important. – impaired by reduced left ventricular compliance, which is very common in HD patients. Poor LV compliance or LV function leads to poor cardiac output thus causing hypotension
  26. 26. Assessment of Dry Weight
  27. 27. Assessment Setting of accurate dry weight Usually determined by trial and error. The only way to clinically know: Symptomatic development: Cramps, hypotension, nausea. Other measures, Blood Volume Monitoring, bioimpedance, inferior vena cava ultrasound of uncertain value. More studies are needed. If the patient’s weight is below the dry weight, need to inform the physicians to adjust the dry weight or assess for acute/unresolved illnesses. Any new reasons for volume depletion?
  28. 28. Assessing Dry Weight If BP is elevated even slightly, DW is reduced by a few hundred grams. If, on the other hand, the patient experiences an orthostatic hypotension that persists more than a few hours after disconnection, then post- dialysis weight is increased. The trial-and-error process can be alleviated by ambulatory BP measurement, which gives a more objective view of the real BP than intermittent measurements.
  29. 29. “Failure” of Dry Weight Clinical Scenario antihypertensive treatment is a major source of failure to achieve DW . low BP artificially maintained by the medication, even if the patient is not really "dry“.
  30. 30. “Failure” of Dry Weight Clinical Scenario One of the main potential problems in achieving DW is insufficient dialysis time: insufficient time allocated for UF. A shorter HD session leads to more hypertension, and at the same time hypotension When session time is shortened, UF rate is increased and hypotension occur.
  31. 31. “Failure” of Dry Weight Clinical Scenario This has several bad effects: The patient has a poor perception and acceptance of HD and asks for a shorter session. The nurse has to cut down the UF rate or give saline, so prescribed DW is not achieved. The physician wrongly re-evaluates DW. Often he prescribes a higher dialysate sodium (Na profiling). This, reduces the diffusive sodium drag from the patient and leads to increased osmolality, thirst, and interdialytic weight gain. Consequence: the patient does not achieve DW 
  32. 32. “Failure” of Dry Weight Clinical Scenario Another potential factor in achieving an adequate ECV is the existence of so- called hypotension-prone patients Risk factors: – left ventricular hypertrophy (LVH) and impaired diastolic relaxation – Poor LV function impaired cardiac output
  33. 33. Management of Dry Weight
  34. 34. Which is more important? restricting fluid Versus restricting sodium on weight gain between dialyses
  35. 35. Management of Dry Weight Sodium intake must be reduced to the lowest level . Hamburger Ikan masin/pekasam Belacan Cincaluk Budu Chicken nuggets Kwan Tai Restaurant
  36. 36. Management of Dry Weight A multidisciplinary approach is needed to educate the patient and caregivers A low sodium diet of 2-3 gm. , daily fluid restriction (30-40 oz/day or 1000 to 1200 cc/day) is needed for the average 60 Kg patient
  37. 37. Intradialytic Hypotension
  38. 38. Intradialytic Hypotension Standard Definition (NKF K-DOQI) – Decrease in SBP by ≥20mmHg or decrease in MAP by 10mmHg • Associated with symptoms or clinical events to require intervention. – Potential symptoms: Abdominal discomfort, yawning, sighing, nausea, vomiting, cramps, restlessness, dizziness, anxiety.
  39. 39. Subclinical Negative Impact Brain Ischemia: MRI have shown pathologic changes with dialysis, worse with intradialytic hypotension (IDH) – Brain white matter ischemic injury from loss of axons and myelin (McIntyre, Seminars in Dialysis, 2010) Cardiac Stunning: Echo during dialysis confirms the presence of LV regional wall motion abnormality (Chesterton, Hemodialysis International, 2010) – Episodic IDH is thought to exacerbate evolving myocardial injury. – Cardiac muscles receive coronary flow during diastole and most HD patients have a widened pulse pressure.
  40. 40. Predicting Intradialytic Hypotension The first line of defense against IDH: – Pausing of ultrafiltration – Placing the patient in a reclined position – Possible administration of Saline IV Patients have individual MAP values which remain constant when well. – MAP=SBPx0.33+DBPx0.66 – BP1: 110/70=MAP 82; BP2:110/45=MAP 66
  41. 41. Predicting Intradialytic Hypotension Decreasing MAP can precede IDH – MAP <70mmHg or decrease by 30mmHg from pre-dialysis value – Preventive pause in Uf for 10 minutes; Uf resumed if MAP improved to 70mmHg or if MAP returned “close to starting MAP.” – This preventive maneuver reduced the risk of IDH by 61%.
  42. 42. Prevention of Recurrent Episodes Reassessing Dry Weight – Trial and error – Blood volume monitoring – Bioimpedance spectroscopy – Avoiding Food: Peripheral vascular resistance drops, up to 2 hrs following the ingestion – BP medication adjustments
  43. 43. Acute Management Decrease or stop the Uf rate Patient position: Trendelenburg with leg raised by 15-30° Saline Bolus IV: 200-500ml usually adequate Oxygen to maintain end-organ perfusion
  44. 44. As the immediate measures are taken, evaluate for other acute problems. Sepsis? Fever, chills, new coughs, wounds Hemolysis? Acute back/chest/abdominal pain, Pericardial effusion? Distant heart sounds, pericardial rubs , Worsened cardiac function? Recent MI, chest pains, Severe AS Bleeding? Melena, CGE, BRBPR , Air Emboli? Dialyzer reaction? , Medication overdose? Acute Management
  45. 45. Summary Safe Uf rate is <13 ml/kg/hr. – Remind patients to drink less liquids. – Discuss with the patient/physician to increase dialysis time. Low dialysate temperature in place? Monitor for changes in MAP. – Pre-emptive holding of Uf for 10 minutes until MAP better? – Saline, hypertonic saline, 20% dextrose, albumin as per local procedures and physician orders.
  46. 46. Summary Na profiling: Pros vs. Cons Uf profile review Holding BP medications pre- dialysis Discuss with physicians re: midodrine, caffeine, Zoloft Role of Blood Volume Monitoring? Always think of acute issues Is Peritoneal Dialysis an option?
  47. 47. Thank you

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