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Sodium

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Sodium

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  1. Sodium • Disorders of sodium concentration reflect abnormalities in water homeostasis • Serum sodium concentration does not provide any information about sodium content i.e. volume status It is only the ratio of sodium to extracellular fluid in which it is contained

  2. Hyponatremia • Hx: duration of hyponatremia, presence of symptoms,( change in mental status, lethargy, seizure, coma ) potential causes • PE: asses volume status, skin turgor, BP/orthostasis, pulmonary edema, peripheral edema

  3. Lab Evaluation

  4. Dilutional Hyponatremia

  5. Low volume

  6. Dilutional Hyponatremia

  7. SIADH • Inappropriate ADH response in a patient with hyponatremia. Urine is less than maximally dilute in the presence of relative euvolemia • Tx: free water restriction, loop diuretics, high protein and salt intake. Occasionally demeclocycline

  8. Symptomatic Hyponatremia • CNS symptoms often respond to modest increases in sodium (<5%) • Initial rate 1-2 mmol/L until symptoms resolve • Then 8 mmol total in first 24 hrs. • Then 10 mmol in next 24 hrs.

  9. Severity of Symptoms Moderately severe: nausea without vomiting, confusion, headache, Severe: nausea with vomiting, cardio- respiratory distress, abnormal and deep somnolence, seizures, coma Glasgow < 8

  10. Severe Symptoms – 1st hour 150 ml of 3% saline over 20 min Check serum sodium after 20 min while starting second 150 ml bolus of 3% Repeat up to 2 more times until a rise of 5 mmol/l is acheived

  11. Severe Symptoms – f/u care f/u care if improvement in symptoms after 5 mmol/L increase is achieved Stop hypertonic saline Start a diagnosis specific treatment Limit rise in sodium to no more than 10 mmol/L in first 24 hrs, and no more than 8 mmol/L in subsequent days till reach 130 Check Na every 6 and 12 hrs and then daily

  12. Severs symtoms – f/u care f/u care if no improvement in symptoms after 5 mmol/L rise in first hour of treatment Continue 3% saline IV aiming for an increase in 1 mmol/h rise in sodium Stop IV if symptoms improve, a rise in sodium of 10 mmol/L occurs, or sodium reaches 130 check sodium q4hrs during hypertonic drip

  13. Rate of 3%– Adrogue-Madias To achieve 1 mmol/L per hr increase Change Na = infusate Na – serum Na/TBW + 1 Include any potassium if in the infusate, i.e. infusate Na + infusate K TBW = .6 X body weight in men = .5 X body weight in women

  14. Correction Example • Chg in Na/L of fluid=IV Na – Pna/TBW+1 • 3%saline = 513 mmol/L • Vol IV = desired change/expected chg 1L • Rate infusion = Vol/time

  15. Correction Example • 70 kg man obtunded Na = 110 • Goal inc Na by 4 mmol/L • 513 – 110 / 42+1 = 9.37 with 1L of 3% • Vol of 3% = 4/9.37 = 400cc • Rate = 400cc / 2hrs = 200 cc/hr of 3%

  16. Moderate Symptoms 150 cc of 3% saline over 20 min Aim for a 5 mmol/L increase in Na over 24 hours Limit rise in sodium to no more than 10 mmol/L in first 24 hrs, and no more than 8 mmol/L in subsequent days till reach 130 Check Na after 1, 6 and 12 hrs and then daily

  17. Acute hyponatraemia w/o symptoms Cause specific treatment A single dose of 150 ml of 3% saline over 20 min, only if the acute decease in serrum sodium exceeds 10 mmol/L

  18. Chronic Hyponatremia w/o symptoms Mild hyponatremia 130 – 135 no treatment soley to increase sodium Moderate (125 – 129) and severe (< 125) avoid an increase of more than 10 mmol/L in first 24 hrs and no more than 8 mmol/L each subsequent 24 hrs till reach 130 Check sodium every 6 hrs till sodium has stabalized

  19. Expanded extracellular volume No treatment with sole aim of increasing sodium in mild and moderate cases Fluid restriction to prevent further fluid overload

  20. SIADH In moderate and profound cases – fluid restriction is first line tx 2 choices for second line therapy a) Combination of low dose loop diuretic and oral salt tablets b) increase solute load with 0.25 – 0.5 g/d of urea

  21. Reduced circulating volume 0.9 % saline infusion at 0.5 – 1.0 ml/kg per H In case of hemodynamic instability the need for rapid fluid resuscitation overrides the risk of an overly rapid increase in serum sodium concentration

  22. Overcorrection Prompt intervention for sodium rise > 10 mmol/L for the first day and 8 mmol/L for following days Start an infusion of 10 ml/kg of free water over 1 hour Consider IV desmporessin 2 micrograms, not more frequently than every 8 hours

  23. Correction • There is no substitute for frequent monitoring of the sodium response

  24. Hypernatremia • All forms of hypernatremia are associated with hyperosmolarity • Volume status cannot be inferred from the presence of hypernatremia

  25. Symptoms • CNS invovlement – lethargy, irritability, weakness, confusion – usually occur with sodium greater than 160

  26. Etiology

  27. Low ECF Volume

  28. Correction of Hypernatremia • Rate of correction .5 mmol/L/hr • Severe Vol depletion or hemodynamic instability merits tx with .9NS • Lesser degrees of volume depletion can be treated with ½ or ¼ normal saline • Once volume is corrected can use D5W

  29. Correction Example • 70 kg female Na 170 stable vitals • Goal 12 mmol/L over 24 hrs with D5W • 70kg X .4 = 28L of body water • Chg Na 1L D5W = 170-0/28+1 = 5.86 mmol/L • Vol of D5W = 12/5.86 = 2.04L • Rate = 2.04L/24hrs = 80 cc/hr • No accounting for ongoing losses

  30. Potassium • Hypo and hyper kalemia results from alterations in intake, cellular shifts or alterations in elimination

  31. Hyperkalemia Etiology • Transcellular Shift Exercise, hyperchloremic metabolic acidosis, Insulin deficiency, hypertonicity, alpha adrenergic stimulation, tissue breakdown/ischemia (rhabdo, brain, gi)

  32. etiology • Decreased renal excretion – CRF, Hypoaldo (meds i.e. ACE/ARB, NSAIDs, heparin. Type 4 RTA

  33. Etiology • Pseudohyperkalemia ischemic/traumatic blood draw,increased wbc/plts (100,000 400,000)

  34. Hyperkalemia • Sx: neuromuscular weakness and cardiac conduction problems • Level of K at which problems occur is very variable between patients

  35. Etiology • Increased Total Body K increased intake (rare as sole cause) decreased renal excretion Spurious – Thrombocytosis, Leukocytosis, ischemic blood draw

  36. Diagnosis • Normal to High 24 hr urinary K >40 meq/d relative increase in K intake Low 24 hr urinary K < 20 – 40 meq/d Decreased renal K excretion GFR < 20 ml/min endogenous K load drugs that impair K excertion

  37. Diagnosis • Low 24 hr urine K – GFR > 20 ml/min decrease mineralcorticoid production/action Action – pseudohypoaldo type 1 or 2 Acquired ARB, aldactone, amiloride, sickle cell, obstruction Production - Hypoaldo, ACE, Heparin,

  38. Diagnosis • Decreased distal nephron sodium delivery Heart failure, cirrhosis, volume depletion

  39. hypokalemia • Mild is asymptomatic (3.0 – 3.5) • Sever muscle weakness,pain can cause rhabdo prominent U waves diminished or inverted T waves ST depression leads to v-fib

  40. Hypokalemia - Etiology • Shift Alkalemia, insulin, refeeding, thyrotoxicosis, Hypokalemic perodic paralysis, Barium Decreased Total Body K Decreased intake Increased Loss GI or Renal Spurious – Extreme leukocytosis