Fluids and Electrolytes

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
• 1000 kcal
• 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
• 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
• 1000 kcal
• 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
• 1000 ml
• 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 (ccs per hour)

11
Maintenance Fluids

• Few examples
• 8 kg
• 8 x 100 800 ccs/ day
• 800 / 24 33.3 ccs/ hr
• or
• 8 x 4 32 ccs/ hr

12
Maintenance Fluids

• Few examples
• 18 kg
• 10 x 100 1000 8 x 50 400
• 1000 400 1,400 ccs/ day
• 1,400 / 24 58.3 ccs/ hr
• or
• 10 x 4 40 8 x 2 16
• 40 16 56 ccs/ hr

13
Maintenance Fluids

• Few examples
• 28 kg
• 10 x 100 1000 10 x 50 500 8 x 20 160
• 1000 500 160 1,660 ccs/ day
• 1,660 / 24 69.2 ccs/ hr
• or
• 10 x 4 40 10 x 2 20 8 x 1 8
• 40 20 8 68 ccs/ hr

14
Maintenance fluids

• Weve 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 20-40 meq Na per day
• 10 kg child needs 1000 ccs per day
• 20-40 meq/ liter
• 20 kg child needs 40-80 meq Na per day
• 20 kg child needs 1500 ccs per day
• 26-53 meq/ liter
• 50 kg child needs 100-200 meq Na per day
• 50 kg child needs 1800 ccs per day
• 55-110 meq/liter

18
Sodium concentrations

• Normal saline (0.9 NaCl/L) 154 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
• Ringers lactate 130 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) 100 - 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 Min
  imal/Nonresponsive
• Pulse Quality Full Rapid Rapid/ weak
• Skin Warm/ Pink Cool/ Pale Cool

26
Estimate of Dehydration

• Mild Moderate Severe
• lt1yr 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
• Dont forget maintenance fluid

28
Replacement of Deficit

• Example-
• 16 kg child 10 dehydrated
• Bolus(es) normal saline 20 ml/kg rapidly
• Maintenance 1,000 300 1,300 / 24 54cc/hr
• Deficit 1,600 ml
• 800 over 1st 8 hours100ml /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 50-100 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 lt 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
• 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 20-25 meq/l or
• Serum Na 125-130 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 gt145 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
• 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 48-72 hours if serum Na gt 170

51
Various Causes of Volume Loss

• Trauma- when is it time for blood
• 20 mls/kg NS or LR x 2
• Then whole blood or PRBCs

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
• 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 CBGs

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