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 ml/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 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
Fluids
Na (mmol/l)
K (mmol/l)
Cl (mmol/l)
Energy(kcal/l)
other
saline0.9%
150
saline0.45%dextrose 2.5% 75
100
Saline 0.18% dextrose 4%,KCl 20mmol/lit 30 20
160
Dextrose 5%
200

32. Isotonic crystalloid fluidsNa K Cl
Energy
Other
Saline 0.18% dextrose 4% 30
160
Hartmann’s solution
131 5
111
lactate

33. Hypertonic crystalloids
Fluid Na K Cl
Energy
Other
Saline 0.45% dextrose 5% 75
200
Dextrose 10%
400
Saline 0.18% dextrose 10% 30
Dextrose 20%
800

34. Colloid fluids Fluids Na K Ca Duration of action comments Albumin 4.5%
150 1 6
Protein buffers
Gelofusine
154
<1 3
Gelatine
Haemaccel
145 5
12.5
Pentastarch 7
Hydroxyethyl starch

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 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
Fluid
Na (mmol/l)
K (mmol/l)
Cl (mmol/l)
Protein (g/dl)
Gastric
20-80
5-20
Small bowel
5-15
90-130
Ileostomy
45-135
3-15
20-115
Diarrhoea
10-90
10-80
10-110
Burns
140 5
110
3-5
Sweat
10-30
3-10
10-35

43. Assessment of response
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

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

51. Hypernatremia: water deficit
Diabetes insipidus
Solute diuresis
D&V
Inadequate breast feeds
Intentional water with holding
Insensible loss in prematures

52. Hypernatremia: treatment
Salt poisoning: peritoneal dialysis
Phenobarbitone for seizures
Inotropes for heart failure

53. Hypokalemia: causes Diarrhoea Alkalosis Volume depletion
Primary hyperaldosteronism,cushing syn, thyrotoxicosis
Diuretic abuse
DKA
Bartters syndrome

54. Hypokalemia: consequences
Cardiac: flat T wave and prolonged QT interval
Orthostatic hypotension, tetany, hypotonia, muscle weakness, death from resp failure
Paralytic ileus, gastric distension
Failure to thrive
Rhabdomyolysis
Nephrosclerosis and interstitial fibrosis: polyuria
alkalosis

55. Hypokalemia: treatment
Replacement potassium orally or parenterally
3 mmol/kg/day in Bartter syn/indomethacin
Up to 10 mmol/kg/day in RTA/hyperaldosteronism

56. Hyperkalemia: causes Renal failure Acidosis Adrenal insufficiency
Cell lysis (trauma, surgery, tumour lysis)
Excessive intake
Sampling error!

57. Hyperkalemia: consequences
Paresthesias, flaccid paralysis
Tall T waves, increased P-R interval, wide QRS complex, VF

58. Hyperkalemia:management
If cardiac rhythm affected give calcium 1 mmol/kg iv/specific anti arrhythmic drug
If normal rhythm, give nebulised salbutamol 2.5 to 5 mg. Check K and pH.
If falling K- give calcium resonium 1g/kg po or pr- plan dialysis if needed
If still high (6.5 or more) give dextrose infusion 0.5g/kg/hr and iv insulin infusion, 0.05units/kg/hr if pH <7.34
If pH >7.35 give sodium bicarbonate 2.5 mmol/kg iv

59. Hypocalcemia
Septicemia, rickets,hypoparathyroidsm, pancreatitis, massive blood transfusion, renal failure
Weakness, tetany, convulsions, hypotension and arrhythmias
Calcium infusion, phosphate binders/dialysis, treatment of cause

60. Hypercalcemia
Hyperparathyroidism, Hypervitaminosis D&A, Idiopathic hypercalcemia, malignancy thiazide diuretic abuse,skeletal disorders,immobilisation
Polyuria, polydypsia
Volume expansion with saline, treatment of cause

61. Hypomagnesemia
Chronic diarrhoea, sprue, celiac d, prolonged TPN low in Mg, hyperaldosteronism, Gitelman’s syndrome, cisplatin and aminoglycosides
Convulsions, tetany athetoid movements, hyperaccusis
Im or iv magnesium replacement as magnesium sulphate

62. Hypermagnesemia
Usually in renal failure, Addison disease, toxemia of pregnancy, enemas in megacolon
Drowsiness, coma if levels exceed 10 meq/l. Intra ventricular and atrioventricular conduction defects at 5 meq/l
IV calcium gluconate rapidly reverses effects on heart and CNS

63. Case 1 8 week old infant Weight 4 kgs, poor wt gain in last 4 weeks,
Vomiting from 3 weeks of age, now after most feeds, forceful, not passing urine well last 24 hours
Moderate dehydration on examination
Na 130, Cl 94, K 2.6, HCo3 29.8

64. Case 1 Maintenance: 100 x 4= 400 ml
On going losses: Ng aspirate volume for volume with normal saline
Start 0.45% saline dextrose 5% to give 400 ml over 8 hours and remaining 400 ml over 16 hours
Add Kcl 4 mmol/100ml once urine output noted
Monitor weight, urine output, Nasogastric aspirate, blood gas and electrolytes,ECG.
Once serum K rises to 3.5 decrease Kcl to 2 mmol/100ml
Deficit fluid: 10 x10 x4= 400 ml
Once stable, send for surgery

65. Case 2
One year old, 10 Kgs with 2 days of D&V. Given clear fluids at home. No urine in last 6 hours. Some fever. Not drinking ,lethargic last 2 hours.
Severe dehydration on examination
Blood: Na 136, K 2.2, Hco3 8, pH7.35

66. Case 2 Bolus 20 ml/kg- 0.9%saline, repeat if still shocked
Deficit fluid: 15 x10 x10=1500 ml – 400ml bolus = 1100ml
Maintenance fluid: 100 x10= 1000 ml
Give 1050ml in 8 hours and 1050 remaining in 16 hours as 0.45% saline 5% dextrose
Add Kcl 40 mmol/l after urine output
Monitor ECG, weight, urine output, electrolytes, continuing losses for replacement
Once rehydrated offer ORS, milk and review fluids

67. Case 3
Four year old weighing 14 Kgs, lethargic, vomiting, rapid breathing since 12 hours. Producing urine. Normal stools. Over 2 weeks, since a cold has been drinking a lot, eating a lot and bed wetting again.
Moderate dehydration
Glucose 30 mmol/l, Na 128 mmol/l, K 4.8 mmol/l, HCO3 8 mmol/l, pH 7.28

68. Case 3 Start normal saline infusion, 20 ml/kg over 1 hour
Start insulin infusion 0.05u/kg/hr
0.45 saline+Kcl 20mmol/500 ml, 20 ml/kg over 2nd hour
0.45 saline+KCL or Pot phos 30mmol/l over 10 hours
Maintenance fluid for 36 hours: x4= =1800ml
Deficit fluid: 10x10x14= 1400 ml
Correct 50% deficit in first 12 hours
Monitor ECG, glucose, U&E, blood gas, weight, urine output, GCS hourly to 2 hourly
Change fluid to 0.18 saline 5% dextrose when blood glucose reaches 16 to 17 mmol/l. Adjust K and insulin infusion rates as needed. Consider an Antibiotic.
When blood gas normal, blood glucose stable, patient drinking, give subcutaneous insulin 0.2 to 0.4 units/kg qds and stop iv infusions.
Start regular insulin dose after another 24 hours

69. DKA: complication
Cerebral edema: headache, change in consciousness,unequal dilated pupil, vomiting,incontinence,delirium,bradycardia
Reduce iv rate, mannitol 1gm/kg iv, repeat in 2-4 hours