1. Fluids and Electrolytes
David A. Listman, MD
St. Barnabas Hospital
Pediatric Emergency Medicine

2. Goals and Objectives Understand where fluid and salts are in body
Understand and be able to order
maintenance fluids
Deficit fluids
Be familiar with causes and treatment of hypo/ hyper- natremia
Provide fluids to patients in special circumstances

3. Body Fluid Composition
Total body water (TBW)
75-80% of body weight at birth
60% of body weight after 1 year
Intracellular fluid
2/3 of TBW or about 40% body weight
Extracellular fluid
1/3 of TBW or about 20% body weight
¾ Interstitial fluid
¼ Plasma

4. Need for Fluid Therapy
Maintenance of fluids in patients with insufficient intake (i.e.. NPO)
Replacement of already diminished fluid volume (i.e.. dehydration, trauma)
Replace ongoing losses (i.e.. GI, renal)

5. Maintenance Fluids
Replacement of insensible losses due to heat dissipation
Replacement of Urinary Losses
Maintenance water needs are related to caloric requirement

6. Maintenance Fluids Caloric requirement 100 kcal/kg/24hr up to 10 kg
50 kcal/kg/24hr per kg over 10 up to 20
1500 kcal +
20 kcal/kg/24 hr per kg over 20

7. Maintenance Fluids Fluid requirement SO:
40 ml/100 kcal/ 24 hr to replace insensible losses
60 ml/100 kcal/ 24 hr to replace urine losses
100 ml/ 100 kcal/ 24 hours total
SO:

8. Maintenance Fluids Caloric requirement 100 kcal/kg/24hr up to 10 kg
50 kcal/kg/24hr per kg over 10 up to 20
1500 kcal +
20 kcal/kg/24 hr per kg over 20

9. Maintenance Fluids Fluid requirement 100 ml/kg/24hr up to 10 kg
50 ml/kg/24hr per kg over 10 up to 20
1500 ml +
20 ml/kg/24 hr per kg over 20

10. Maintenance Fluids Fluid requirement 100/ 50/ 20
Divided by 24 hours (or 25)
4 / 2/ 1 (cc’s per hour)

11. Maintenance Fluids Few examples: 8 kg 8 x 100 = 800 cc’s/ day
800 / 24 = 33.3 cc’s/ hr or
8 x 4 = 32 cc’s/ hr

12. Maintenance Fluids Few examples: 18 kg 10 x 100 = 1000 8 x 50 = 400
= 1,400 cc’s/ day
1,400 / 24 = 58.3 cc’s/ hr or
10 x 4 = x 2 = 16
= 56 cc’s/ hr

13. Maintenance Fluids Few examples: 28 kg
10 x 100 = x 50 = x 20 = 160
= 1,660 cc’s/ day
1,660 / 24 = 69.2 cc’s/ hr or
10 x 4 = x 2 = 20 8 x 1 = 8
= 68 cc’s/ hr

14. Maintenance fluids We’ve got the water, do we need anything else?
Is it necessary to replace electrolytes?
Recent data shows significant risk of hyponatremia in hospitalized patients
Hyponatremia can lead to fluid shift into cells causing cellular (and cerebral) edema

15. Maintenance fluids Daily sodium requirement
2-4 meq / kg / day
Daily Potassium requirement
1-2 meq / kg / day
This is a flat need per kilo and does not decrease as water needs do

16. Maintenance fluids- sodium
This is a flat need per kilo and does not decrease as water needs do So
As volume required goes down, sodium needed per liter goes up

17. Maintenance fluids- sodium
Some examples-
10 kg child needs meq Na+ per day
10 kg child needs 1000 cc’s per day
20-40 meq/ liter
20 kg child needs meq Na+ per day
20 kg child needs 1500 cc’s per day
26-53 meq/ liter
50 kg child needs meq Na+ per day
50 kg child needs 1800 cc’s per day
meq/liter

18. Sodium concentrations
Normal saline (0.9% NaCl/L) mEq Na+/L
1/2 normal saline (0.45% NaCl/L) 77 mEq Na+/L
1/3 normal saline (0.33% NaCl/L) 57 mEq Na+/L
1/4normal saline (0.2% NaCl/L) 34 mEq Na+/L
Ringer’s lactate mEq Na+/L
(Contains 4 mEq K+, 109 mEq Cl-, 28 mEq bicarb equivalent all/Liter, and 3 mg/dl of Ca++)

19. What else goes in it? Dextrose
5% dextrose is insufficient to nourish a patient
To spare catabolism of glycogen and protein

20. What else goes in it?
Potassium
Daily requirement 1-2 meq/kg/day

21. Need for Fluid Therapy
Maintenance of fluids in patients with insufficient intake (i.e.. NPO)
Replacement of already diminished fluid volume or deficit (i.e.. dehydration, trauma)
Replace ongoing losses (i.e.. GI, renal)

22. Treatment of volume loss
Decrease in extracellular fluid
Initial treatment- rapid expansion of ECF
Bolus of isotonic fluid (i.e.. NS or LR)
Should not include dextrose
Repeat bolus as necessary to improve perfusion
Replacement of deficit
Continue maintenance
Frequent reevaluation of
Vital sign
Electrolytes
Urine output and urine specific gravity

23. Treatment of volume loss
Decrease in extracellular fluid
Initial treatment- rapid expansion of ECF
Bolus of isotonic fluid (i.e.. NS or LR)
Repeat bolus as necessary to improve perfusion
Replacement of deficit
Continue maintenance
Frequent reevaluation of
Vital sign
Electrolytes
Urine output and urine specific gravity

24. Estimate of Fluid Deficit
Subtract
pre-illness weight - current weight
Calculate using current weight and % dehydration
Pre-illness wt (kg) = 100
Current wt (kg) % estimated dehydration
Current Weight x % dehydration
(slightly underestimates)

25. Estimate of Dehydration
Mild Moderate Severe
Skin Turgor Normal/Elastic ↓ Very ↓,Tenting
Oral Mucosa Sl Dry Very Dry Parched
Tears Sl ↓ Absent Absent
Fontanelle Normal/ Flat Depressed Sunken
Heart Rate Normal/ Sl ↑ ↑ Marked Tachycardia
Blood Pressure Normal Normal/ Sl ↓ ↓
Urine OP Mild Oliguria Oliguria Oliguria/ Anuria
CNS/ LOC Alert/ Responsive Irritable/Listless Minimal/Nonresponsive
Pulse Quality Full Rapid Rapid/ weak
Skin Warm/ Pink Cool/ Pale Cool

26. Estimate of Dehydration
Mild Moderate Severe
<1yr 5% 10% 15%
Older 3% 6% 9%

27. Replacement of Deficit
Deficit volume
Replace ½ over 1st 8 hours
Replace ½ over next 16 hours
Don’t forget maintenance fluid

28. Replacement of Deficit
Example-
16 kg child 10% dehydrated
Bolus(es) normal saline 20 ml/kg rapidly
Maintenance 1, = 1,300 / 24 = 54cc/hr
Deficit 1,600 ml
800 over 1st 8 hours=100ml /hr
800 over next 16 hours = 50ml /hr
Total 154 ml /hr x 8 hours then 104 ml/hr x16 hours
Not well approximated by 1 ½ maintenance

29. Need for Fluid Therapy
Maintenance of fluids in patients with insufficient intake (i.e.. NPO)
Replacement of already diminished fluid volume or deficit (i.e.. dehydration, trauma)
Replace ongoing losses (i.e.. GI, renal)

30. Ongoing losses Continued loss in excess of normal maintenance
GI loss- vomit/ diarrhea
Surgical drains/ NG tube
Increased insensible losses- fever
Increased urine output

31. Ongoing losses Continued loss in excess of normal maintenance
Volume can often be measured
NG output
Stool
Urine
Type of fluid needed for replacement
Can be measured
Can be estimated

32. Oral Rehydration Better than IV if tolerated
What makes a good oral rehydration fluid?
Proper balance of Na+ and glucose
Na+/glucose co-transporter in intestine non ATP dependant
Water follows passively

33. Oral Rehydration What makes a good oral rehydration fluid?
Proper balance of Na+ and glucose
Na+/glucose co-transporter in intestine non ATP dependant
1 : 1 osmolar ratio
Na+ 90 meq/l, glucose 111meq/l (2% solution)
Some K+ to prevent Hypokalemia

34. Oral Rehydration What makes a good oral rehydration fluid?
MMWR November 21, 2003 / 52(RR16);1-16

35. Oral Rehydration Mild to moderate dehydration
Deficit ml of ORS/kg body weight during 2-4 hours
Maintenance100 ml ORS/kg per day
limited volumes of fluid (e.g., 5 mL or 1 teaspoon) should be offered at first, with the amount gradually increased as tolerated.

36. Hypo/ Hypernatremia More to do with water than salt status (usually)
Hyponatremia
free water excess
Hypernatremia
Free water deficit

37. Hyponatremia Serum Na+ < 135 Common in hospitalized children
Kidneys unable to dilute urine and excrete free water

38. Hyponatremia
Measure serum Osm to confirm low serum Osm before aggressive treatment
Normal or high serum Osm with pseudohyponatremia
Hyperglycemia
Hyperlipidemia
Hyperproteinemia

39. Hyponatremia True hyponatremia causes influx of water into cells
Cellular swelling
Cerebral edema
Exacerbated by hypoxia

40. Hyponatremia Symptoms Headache, nausea, vomit, behavioral changes
Seizures, resp arrest, dilated pupils, decorticate posturing

41. Hyponatremia Causes of SIADH CNS Pulmonary Drugs Meningitis
CNS neoplasm
Hydrocephalus
Pulmonary
Pneumonia
Asthma TB
Positive Pressure Ventilation
Pneumothorax
Drugs
Vincristine, cyclophosphamide
Carbamazepine

42. Hyponatremia Post-operative Multi-factorial Volume depletion Stress
ADH
Hypotonic fluids

43. Hyponatremia Water intoxication Newborns
Fed dilute formula or water supplement
Decreased ability to maximally concentrate urine

44. Hyponatremia- treatment
If neurologic signs/ seizure
Hypertonic 3% saline (514 meq/l)
1 ml/kg/hr should raise Na+ by 1 meq/l
Goals
Raise Na+ by 1 meq/hr until
Symptoms resolve or
Serum Na+ has risen meq/l or
Serum Na meq/l

45. Hyponatremia- treatment
Asymptomatic
Restrict free water intake
Avoid hypotonic fluids

46. Hyponatremia
Recent evidence suggests use of isotonic rather than hypotonic fluids in post-op, gastroenteritis prevents hyponatremia.

47. Hypernatremia Serum Na+ >145 meq/l Debilitated patients
Neurologically impaired patients
Ineffective breastfeeding
Inability to access sufficient free water
Inability to maximally concentrate urine

48. Hypernatremia Clinical manifestations
Water moves from intracellular to extracellular space
Maintenance of ECF volume so classic signs of volume depletion are absent
Agitation, irritability, coma

49. Hypernatremia Clinical manifestations Cell shrinkage
Water moves from intracellular to extracellular space
Cell shrinkage
Brain cell volume decreases
If acute and rapid can lead to
Intracranial hemorrhage
Venous sinus thrombosis
Over short time brain cells increase intracellular
Na+, K+, amino acids, unmeasured organic substances
Not easily decreased so rapid rehydration will cause cerebral edema

50. Hypernatremia Treatment Correct serum Na+ and water deficit
Free water deficit =
4ml x lean body weight (kg) x (serum Na+ – desired Na+ )
Add maintenance fluid and correct slowly
At least hours if serum Na+ > 170

51. Various Causes of Volume Loss
Trauma- when is it time for blood
20 ml’s/kg NS or LR x 2
Then whole blood or PRBC’s

52. Diabetes IDDM what is the cause and presentation
Not enough insulin produced
Break down of fats and protein in response to low insulin levels
How does it present?
What are the fluid and electrolyte abnormalities?
Glucose
Sodium
Potassium
Phos pH

53. Diabetes Very hyperosmolar Pseudohyponatremia
Initial Boluses to restore intravascular volume
Slow deficit replacement to prevent cerebral edema
Constant infusion of insulin regardless of blood glucose
Add IV glucose if necessary

54. Diabetes Usual fluids Once sugar falls
Initial bolus(es) of Normal Saline
After 1st hour
Insulin infusion usually 0.1 units / kg/ hour
½ NS with 20KCL and 20 K Phos at maintenance plus slow deficit replacemement
Once sugar falls
2 bags
½ NS with 20KCL and 20 K Phos
D10 ½ NS with 20KCL and 20 K Phos
Total of these 2 infusions to equal maintenance plus slow deficit replacement
Can titrate to provide anywhere from no dextrose to D10 without changing electrolytes depending on the CBG’s

55. Burns Tremendous fluid losses Parkland formula
4 ml/ kg/ % BSA burns (2nd and 3rd degree)/ 24 hours
half over first 8 hours ½ over next 16 hours
in addition to maintenance

56. Summary
Provide water, sodium, glucose and potassium to patients who have a variety of disturbances of fluid and sodium balance