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Fluid and electrolyte therapy

Fluid and electrolyte therapy. Dr Ashoka Acharya Consultant Paediatrics Warwick hospital. Dehydration. Abnormal fluid losses overcoming renal compensating mechanisms Main aim of compensation is maintaining plasma volume and BP at all cost Loss of homeostasis –hypovolaemic shock

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Fluid and electrolyte therapy

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  1. Fluid and electrolyte therapy Dr Ashoka Acharya Consultant Paediatrics Warwick hospital

  2. Dehydration • Abnormal fluid losses overcoming renal compensating mechanisms • Main aim of compensation is maintaining plasma volume and BP at all cost • Loss of homeostasis –hypovolaemic shock • Principal causes: diarrhoea and DKA

  3. Definition • Parenteral or oral fluid therapy • Maintain/restore volume/composition of body fluids • Takes account of corrective physiological mechanisms

  4. Fluid therapy: Goal • Achieve normal intracellular and extracellular chemical environment • Thereby optimise cell and organ function

  5. Factors determining requirements • Maintenance fluid: replaces usual losses of fluid and electrolytes • Deficit replacement fluid: designed to replace abnormal losses due to disease • Supplemental fluid: replaces measured or estimated continuing abnormal losses

  6. Factors determining requirements • Each component is calculated separately • Fluid therapy often based on gross estimates. Deficit often overestimated. • Repeated clinical reassessment and adjustment needed

  7. Maintenance fluid • Directly related to metabolic rate • endogenous water production • urinary solute excretion, • heat production- 25% lost through insensible water loss)

  8. Maintenance therapy • Generally 100ml per 100 calories used • Urine: obligatory loss = 65 ml • Insensible water loss = 35 ml • Sweating =23 ml • pulmonary =12 ml

  9. Maintenance therapy: increased requirements • Increased activity (30%) • Fever (1°C increases by 12%) • Dry environment • Hyperventilation • ELBW- transcutaneous losses 100-200ml/kg/day • Overhead heaters, phototherapy units

  10. Maintenance fluid-decreased requirements • Comatose • Hypothermia • Highly humidified atmospheres • Humidified ventilator circuits

  11. Maintenance fluid: increased renal losses • High solute load (DM, Mannitol, high protein diets) • ADH insufficiency • Central • Nephrogenic • Primary • Secondary: sickle cell, obstructive uropathy, chronic PN, reflux nehropathy, hypokalemia, hypercalcemia, drugs, psychogenic polydipsia

  12. Maintenance fluid: decreased urinary losses • SIADH • Renal failure • Replace insensible water loss +urine output ml/ml with free water

  13. Maintenance sodium needs • Increased: CF, salt losing nephropathy, chronic PN, obstructive uropathy, diuretics, fistulas, diversions, NG drainage • Decreased: Hepatic failure, cardiac failure, renal failure, nephrotic syndrome

  14. Maintenance potassium needs • Increased: Chronic renal disease, gastric and intestinal drainage, chronic diuretics, laxative abuse • Decreased or nil: Acute renal failure, adrenal insufficiency, severe metabolic acidosis

  15. Normal maintenance requirements (holiday and segar

  16. Maintenance fluids: route • Oral or parenteral • Calories: usually as 5% dextrose • TPN

  17. Deficit Therapy: factors affecting • Oral or parenteral intake • Pathologic body losses • Physiologic body losses • compensatory attempts to modify volume and composition • Net effect- Deficits from different causes often similar in magnitude and composition

  18. Infant: moderately severe dehydration

  19. Deficit therapy • Severity: Magnitude and rapidity • Estimated from recent weight or clinical features • Type: Relative loss of water and electrolytes mainly sodium • pathophysiology • therapy • prognosis

  20. Deficit therapy: Types • Isotonic: sodium 130-150 mmol/l, no fluid shifts, 80% of cases • Hypotonic: sodium <130mmol/l, ECF to ICF, 10% cases • hypertonic:sodium>150 mmol/l, ICF to ECF, 10% cases

  21. Deficit Therapy:types and history • D and V for days, good intake, low salt • Cholera, bacillary dysentery • High fever, poor intake • Infant with NDI, poor water intake • Intake of dilute milk formula • Intake of boiled semiskimmed milk • wrongly prepared ORS

  22. Assessment of deficit severity

  23. Assessment of severity: contd

  24. Calculation of deficit fluid • Percentage dehydration x wt in kg x 10= ml of fluid • eg: 7% dehydration of infant weighing 10 kgs = 7x10x10=700 ml

  25. Clinical features • Signs represent depletion of ECF • Plasma: tachycardia, fall of BP, postural hypotension, cool extremities, increased CRT, decreased urine • Interstitial fluid: Tenting of skin • Transcellular fluid: dry mouth, sunken eyes, decreased tears, sunken fontanel

  26. Signs of dehydration • Mild dehydration: no signs • Severe dehydration: Prolonged capillary refill time,dry mucosa, decreased skin turgor, general appearance are the most sensitive and specific • Acidosis: Kussmaul’s breathing • Hypokalemia: weakness, abd dist, ileus,cardiac arrhythmias • hypocalcemia and magnesemia: tetany, muscle twitching

  27. Signs V's type of deficit • Hyponatremic: increased severity of signs for amount of fluid loss • Hypernatremic: Less signs, irritable, hypertonic, hyperreflexic, warm extremities, doughy skin

  28. Lab tests • FBC: Increased Hb, PCV • Serum Na: type of dehydration • serum K: gut loss, acidosis; needs ECG monitoring • Serum HCO3: acidosis- D&V, DKA: alkalosis-Pyloric stenosis, NG drainage • Serum chloride: changes with Na, chloride diarrhea • Urea/creatinine: elevated with decrease in GFR, may be normal! • Urine: infection screen, specific gravity, electrolytes • stool: culture, electrolytes

  29. Treatment • Oral therapy: mild to moderate dehydration • Parenteral therapy: • severe dehydration • Persistent vomiting • Refusal of oral intake • Abdominal distension • No caregiver to give close attention

  30. Stages of treatment • Initial therapy: expand ECF volume • Subsequent therapy: replace deficit/maintenance/ongoing losses • Final therapy: Return to normal composition/establish oral feeds/correct potassium deficit

  31. Commonly available crystalloids: isotonic

  32. Isotonic crystalloid fluids

  33. Hypertonic crystalloids

  34. Colloid fluids

  35. Initial therapy • Normal saline or Hartmans solution regardless of type of deficit • 20 ml/kg rapid bolus, repeat if needed • IV, intraosseous line • Never use hyponatremic fluids • Adequate crystalloid dose better than colloid • No potassium till urine output established

  36. Subsequent therapy • Calculate over 8 hour intervals • Deficit replaced over 24 hours but can be done over 8 to 12 hours except HYPERNATREMIA • Early K+ replacement after urine output • Maximum K+, 40 mmol/l (ITU 80 mmol/l)

  37. Isonatremic dehydration • Deficit plus maintenance plus ongoing losses calculated • Use 0.45%saline with 2.5% or 5% dextrose for subsequent therapy • Give 50% in first 8 hours and remaining over 16 hours • Subtract boluses from total fluid • Assess clinical state regularly and modify if needed

  38. Hyponatremic dehydration • Extra Na deficit (mmol/l)=desired Na-actual Na x 0.6 x Wt kgs • Manage as for isonatremic dehydration but replace deficit Na over 12-24 hours • Raise serum Na by 10 mmol/l/day • If Na <120mmol/l and seizures give 3% Nacl 1ml/min max 12ml/Kg

  39. Hypernatremic dehydration: complications • Cerebral haemorrhage, thrombosis, subdural effusion- permanent handicap, renal vein thrombosis • During treatment- cerebral oedema, seizures, hypocalcemia • High mortality if Serum Na >160mmol/l

  40. Hypernatremic dehydration • Always use isonatremic boluses • Slow correction of deficit over 48 to 72 hours • Aim to decrease serum Na by 10 mmol/l/day • Use 0.18saline or 0.45% saline with dextrose for subsequent therapy • Seizures: 3% saline, mannitol, hyperventilation, calcium gluconate

  41. Supplemental fluids • Consider composition of fluid lost • D&V: 0.45% saline • Cholera:0.9% saline • NG tube aspiration: 0.45 to 0.9% saline plus potassium • Gut losses: same

  42. Composition of external losses

  43. Appearance, activity Skin turgor BP Intake/output chart U&E, glucose blood gas CVP monitoring Eyeballs, tears CRT Weight Urine Specific gravity Urine output ECG monitoring Assessment of response

  44. Oral rehydration therapy • Mild to moderate dehydration • Types of ORS: high sodium- 90mmol/l, low Na- 50 mmol/l • Glucose facilitated sodium absorption, sucrose less effective, rice based effective

  45. ORS • Use 50ml/kg in mild and 100ml/kg in moderate dehydration. • Give over 4 hours. Allow breast feeds and formula after rehydration. Reassess regularly. Small frequent feeds decrease vomiting. Consider NG tube. • Maintenance with 100ml/kg/day till diarrhoea stops • For on going losses add 10-15ml/kg/hr

  46. Hyponatremia: sodium depletion • Renal losses: Preterm, ATN, Diuretics, mineralocorticoid deficiency, RTA • Extra renal loss: D&V, Burns, ascites, pleural effusion,csf drainage, NG drainage, CF • Nutritional deficits: Inadequate Na in TPN, oral intake

  47. Hyponatremia: water excess • SIADH • Glucocotricoid deficiency • Hypothyroidism • Excess parenteral fluid • Psychogenic polydipsia • Tap water enema

  48. Hyponatremia: excess Na and water • Nephrotic syndrome • Cirrhosis • Cardiac failure • Acute and chronic renal failure

  49. Hyponatremia: asymptomatic • Water Excess: (urinary Na usually >20 mmol/l) fluid restriction, may be needed for days • Salt deficiency: (urinary Na <10 mmol/l, except in renal salt loss) Add salt to diet

  50. Hypernatremia: sodium excess • Improperly mixed ORS or formula • Accidental or deliberate swap of salt for sugar in feeds • Excess Bicarb during resus • Hypernatremic enemas • Drugs: penicillin, gaviscon

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