Fluid and Electrolyte disturbances

1. Fluid and Electrolyte disturbances Ismail M. Siala

2. Fluid and electrolyte disturbances 65 Kg healthy man 40 L Water (60% of body wt) 70% ICF (28L) 30% ECF (12L) 75% Interstiatial fluid (9L) 25% Plasma (3L)

3. Fluid disturbances • Water passes freely from one compartment to another • In a healthy person water distribution remains constant despite variation in intake.

4. Factors determining water distribution: • Osmotic (oncotic pressure) draw water in • Hydrostatic pressure push water out

5. Fluid disturbances • Fluid disturbances could be in form of: • Volume depletion • Volume overload • Usually associated with electrolyte disturbances

6. Volume Depletion

7. 1-Volume depletionDehydration • Presentation: • Weight loss, thirst, concentrated urine • Tachycardia, low blood pressure, dry mucous membranes, skin turger • High Hct

8. Causes of volume depletion A- Loss of water: • GIT loss: • Vomiting • Aspiration of gastric contents • Diarrhoea • Sequestration of fluid in bowel • Loss in Urine: • Osmotic diuresis: DM • Diuretics • Adrenocortical insufficiency • Renal disease • DI • Profuse sweating: • Fever, hot environment • Third space loss: • Burns, extensive dermatitis • Ascites, peritonitis, acute pancreaitis B-Inadequate oral intake in a patient with impaired thirst mechanism

9. Management of volume depletion • Aim: • Restore plasma volume • What to give: • Crystalloids: NaCl 0.9% • Plasma expanders: plasma protein • Monitor: • Blood pressure • JVP/CVP (central venous pressure) specially in elderly patients and those with heart disease • Input-output charting

10. Volume Overload

11. 2-Volume overload • Clinical features: • Weight gain, • oedema, • high JVP, • +Ascites • Low Hct • Causes: • CCF • Chronic and end-stage Liver disease • Nephrotic syndrome • Advanced CRF, acute oliguric renal failure • Drugs: ACE, NSAID, mineralocorticoids, calcium channel blockers • Management of volume overload: • Dietary sodium restriction • Diuretics • Treat the underlying cause

12. Sodium Disturbances

13. Osmolality • Osmolality: • Represents solute concentration in ECF • More solutes  high osmolality  hypertonic state • Less solutes  low osmolality  hypotonic state • Osmolality =2(Na meq/l) + glucose mg/dl + BUN mg/dl • 18 2.8 N=285-295 mosm/kg

14. Hyponatremia • Hyponatremia : serum Na < 130 meq/l • Types of hyponatremia: • Isotonic ( Normal osmolality) • Hypertonic (  osmolality) • Hypotonic, (  osmolality)with; • Low ECF (hypovolumic) • Normal ECF (euvolumic) • High ECF hypervolumic)

15. Isotonic hyponatremia: Is a spurious hyponatremia • Total Serum sodium is normal • Osmolality is normal • It is due to; • hyperlipidemia or • hyperprotienemia(>10g/dl)  falsely low serum Na reading. plasma plasma Na Na

16. Hypertonic hyponatremia • Logically if Na is low osmolality should be low but, here there is low Na with High osmolality! • It is due to other solutes that will increase the osmolality • Causes: • Hyperglycaemia: osmotic diuresis • Manitol • Radio contrast agents • Treatment: that of the underlying cause

17. Hypotonic hyponatremia • Low serum Na • Low osmolality • Further classified according to ECF status into: • Hyponatremia with low ECF (Na + Water) • Hyponatremia with normal ECF (Na + N water) • Hyponatremia with high ECF (N/ Na +  water)

18. Hyponatremia with low ECF (Na + Water) • Due to loss of both Na and water • Na loss > water loss • Causes: • Renal: • Diuretics • Slat loosing nephropathy • Mineralocorticoid deficiency • Osmotic diuresis • Extra renal: • Vomiting • Diarrhoea • Third space loss: (ascites) • Skin, burns and sever dermatitis

19. Hyponatremia with low ECF • The urine Na • Measurement of urine Na helps differentiating renal from non-renal causes of hyponatremia with low ECF • In renal cause: urine Na > 20 meq/l • In non-renal cause: urine Na < 10 meq/l indicating Na retention by the kidney as a compensation for a loss of Na from outside the kidneys.

20. Hyponatremia with normal ECF (Na + N water) • Due to pure Na loss • Causes: • Nephrotic syndrome • NSAID • Hypothyroidism • Post operative pain and analgesia • Diuretics

21. Hyponatremia with high ECF (N/ Na +  water) • Low serum Na • Total body Na is increased • Total body water is increased • Total body water > total body Na • Causes: • Cardiac failure • Renal failure • Liver cirrhosis • SIADH

22. Appropriate or inappropriate ADH? • ADH is released in response to • Reduction of plasma volume • Increased osmolality • When there is reduction of plasma volume and low osmolality what will be the response of ADH? • It will respond preferentially to low plasma volume • So if plasma volume is normal or increased and ADH is high we call it inappropriate secretion.

23. Causes of SIADH • Neoplasms: • Carcinoma of bronchus (small cell), pancreas, lymphoma, mesothelioma, others • CNS disorders: • Meningitis, encephalitis, brain abscess, head injury,cerbral tumours, CVA, etc • Non-malignant pulmonary diseases: • TB, pneumonia • Drugs: • Narcotics, phenothiazines,TCA, vincristine, cyclophosmphamide, chlorpropamide, NSAID • Others: • Pain, nausea

24. Clinical features of hyponatremia • Mild confusional state gross confusion • Sleepiness • Myoclonic jerks generalized seizures • Features of the accompanying ECF status • Low ECF hypovolemia • High ECF fluid overload and oedema • Serious hyponatremia occurs if: [medical emergency] • Rapid reduction in serum Na • Serum Na < 110 meq/l

25. Investigations of hyponatremia • Serum Na: low • Osmolality: low • Urea and creatinine • Urinary Na • Urine osmolality • In volume depletion due to extra renal loss • Low Na • Low urinary Na • High urine osmolality (concentrated urine) • In SIADH • Low serum Na • Low serum osmolality • High urine osmolality • Normal or high ECF volume

26. Management of hyponatremia Water restriction if not hypovolumic + Diuretics Saline if hypovolumic Offending cause

27. Management of hyponatremia • Mild hyponatremia( >120meq/l) • with normal or high ECF: • Water restriction to 0.5 L/day • Demeclocycline could be used if water restriction is not tolerated or not effective, check Contraindications • Stop the offending drug • Correct the underlying cause • With low ECF: • 0.9% NaCl

28. Management of hyponatremia • Moderate hyponatremia (>110-120meq/l): • With normal or high ECF: • Water restriction <0.5l/day • 0.9%NaCl iv in normal ECF • Frusemide could be added orally if high ECF • With low ECF: • 0.9% NaCl iv

29. Management of hyponatremia • Severe hyponatremia: • Na <110 meq/l • Symptomatic • 1.8 or 3% NaCl slow iv infusion, aiming at • Raise plasma Na by 0.5 meq/l/hr • Do not exceed plasma Na of 130 meq/l in the first 48 hrs. • Frusemide 20 mg iv if overloaded or high CVP • Rapid correction to > 135 meq/l in the first 48 hrs or increase of plasma Na of > 25 meq/l in the firs 24 hrs  osmotically induced demylination of brain Osmotic Demylination Syndrome (central pontine myelinolysis) brain damage

30. Hypernatremia

31. Hypernatremia • Definition: serum Na > 145 meq/l due to pure water loss. • Causes: • Decreased water intake • Unavailable • Coma • Non-renal • Increased water loss in presence of impaired thirst mechanism • Dehydration, fever, hot climate,diarrhea • Urinary loss • Diabetes Insipidus • Cranial • nephrogenic • Osmotic diuresis • Increased salt intake

32. Hypernatremia • Clinical features: • Mild • Thirst • Concentrated urine • Moderate • Dizzinessconfusion • oliguria • Sever • Confusioncoma • Muscle weakness • Doughy skin • Tachycardia • Low BP

33. Hypernatremia • Investigations: • Raised Na • Raised osmolality • Raised Hct • Raised urea • Urine osmolality • If high>400 mosm/kgnon renal loss and kidney is concentrating urine • If< 200 mosm/kg  diabetes insipidus

34. Hypernatremia • Treatment: • Mild: • Water 2 litres over 6-12hrs orally or, • 5% dextrose iv over 6-12 hrs • Moderate: • 5% dextrose 2-4 litres over 24 hrs • Severe: usually associated with hypovolumia • 0.9%NaCl 1 litre iv over 1 hr • 5% dextrose 4L iv over 24 hrs • 5% dextrose 2-4L iv over 24-48 hrs • Aim: • Correct deficit over 48 hrs • Correction should not be > 1meq/l/hr • Correct K and phosphate as required

35. Idiogenic osmoles Rapid correction of Hypernatremia Water shift to brain cells Brain oedema Formation of Idiogenic Osmoles Hypernatremia Water shift out Brain cell dehydration Normal

36. Hypernatremia • High osmolalitybrain cells form idiogenic osmolesincrease the osmotic pressure in the brain cellsdraw water back to brain cell and thus prevent dehydrating brain cells, this usually begins 4-6 hrs after dehydration. • Rapid correction of Hypernatremia more water will go inside brain cells brain oedema severe neurological damage.

37. Potassium disturbances • K is filtered through the glomerular filtrate • 90% is reabsorbed in the proximal tubule • The urinary K is mainly derived from excretion through the distal nephron • 90% of the eliminated K is through the kidney and the rest is through faeces. • Factors affecting shift of K to inside the cell: • Insulin • B2 agonists • Aldosterone • alkalosis

38. Hypokalemia • Def: serum K < 3.5 meq/l, levels < 2.5 meq/l are considered as severe hypokalemia. • Causes of hypokalemia: • Shift to cell: • B2 agonists, alkalosis, insulin, mineral corticoids, theophyllines. • Decreased intake • GIT loss: • Vomiting/aspiration of gastric contents • Diarrhoea, villous adenoma • Sequestration of fluid in bowel, ilius • Renal loss: • Extra renal causes • Hyperaldosteronism, Cushing, • Diabetes mellitus • Metabolic alkalosis • Drugs: • Diuretics, corticosteroids, aminoglycosides, carbenoxolone • Renal: • Recovery phase of ATN • RTA

39. Hypokalemia Clinical features: • Mild to moderate • Muscular weakness • Muscular cramps • Fatigue • Constipation • Severe: ( <2.5 meq/l) • Ilius • Flaccid paralysis • Hyporeflexia • Tetany • Rhabdomyolysis • Hypercapnia

40. Hypokalemia • Investigations: • Serum K • ECG: • Low amplitude of T wave • Prominent U • Depression of ST segment • AV block • Cardiac arrest • Hypokalemia will increase the chance of digitalis toxicity • Urinary K • <20meq/l  extra renal cause • >30 meq/l  renal cause

41. Hypokalemia • Treatment: • Mild to moderate: • Oral K • Rapidly absorbed • May cause peptic ulcer • If not tolerated give parentral K • Severe: • Parentral K • 10meq/l/hr in a peripheral iv infusion • Concentration should not exceed 40meq/l • Rate should not exceed 40meq/l/h (60meq/l/hr) • Monitor by ECG • Check K every 3-6 hrs • If K deficiency is refractory to treatment then concomitant magnesium deficiency could be present • Treat underlying cause

42. Hypokalemia • Prevention: • Diuretics: • Additional KCl • (Do not give with K sparing diuretics, ACE) • Corticosteroids: • Monitor K level on prolonged use • Parentral therapy: • Add K to parentral therapy protocol

43. Hyperkalemia • A serum K of >5 meq/l • Causes: • Spurious: • Lysis of RBCs in tube • Thrombocytosis • Repeated fist clenching during phlebotomy • Increased intake: • Iv fluids containing K salts • Impaired excretion: • Renal failure • Adrenocortical insufficiency • Hyporeninemic hypoaldosteronism • Drugs: spironolactone, ACE, NSAID, amiloride, • Tissue breakdown: • Bleeding into soft tissues • Haemolysis • Rhabdomyolysis • Sever burns • Vigorous exercise • Shift of K out of cell: • Acidosis • Insulin deficiency • Aldosterone deficiency • B-receptor antagonists

44. Hyperkalemia • Clinical features: • Symptoms are rare • Weakness, flaccid paralysis, ilius, lost tendon jerks, abdominal distension, diarrhoea • Cardiac arrest is expected when K level is >7meq/l • Patients usually present with collapse due to bradyarrythmia

45. Hyperkalemia • Investigations: • Serum K >5 meq/l • ECG: Changes occur with high levels >6.5meq/l • Peaked T • Prolonged PR interval • Wide QRS • Atrial arrest • Biphasic QRS-T • Slowing of HR • VF • Cardiac arrest

46. Hyperkalemia • Management: • Exclude spurious hyperkalemia • Stop any K source • Cation exchange resin • Sodium polystyrene sulphonate • Calcium resonium • Correct underlying cause • Urgent treatment: • Indications: • Cardiac toxicity • Muscular paralysis • Severe hyperkalemia>6.5meq/l

47. Hyperkalemia • Urgent treatment: • 50 ml of 50% dextrose iv with insulin 1 unit for each 5 grams of dextrose , monitor serum K after half an hour. • Calcium gluconate 10%, give 10 ml over 10 min iv, to antagonise cardiac effect • Salbutamol iv in 5%dextrose over 15 min. • Na Bicarbonate 1.26%, give 500 ml over 6-8 hrs only if there is metabolic acidosis. • Hemodialysis or hemofiltraion or peritoneal dialysis if above fails or in patient with renal failure.