FLUIDS AND ELECTROLYTES

D E L P R A D O M. D.

FLUID COMPOSITION

• Total Body Water: • 60% Body Weight

• Intracellular • 40% Body Weight

• Extracellular• 20% Body Weight• Interstitial: 15% Body Weight• Intravascular: 5 % Body Weight

INTRACELLULAR AND EXTRACELLULAR FLUID COMPOSITION

Intracellular (mEq/L)

Extracellular (mEq/L)

Na+ 20 133-145

K+ 150 3-5

Cl- - 98-110

HCO3- 10 20-25

PO4 3- 110-115 5

Protein 75 10

Maintenance Requirements

• Holiday-Segar Method– Estimates caloric expenditure in fixed

weight categories; it assumes that for each 100 calories metabolized, 100ml of water will be required.

HOLIDAY-SEGAR METHOD

Water

Body Weight mL/kg/day ml/kg/hr

First 10kg 100 24 hr/day 4

Second 10kg 50 24 hr/day 2

Each additional kg.

20 24 hr/day 1

BODY SURFACE AREA METHOD

Mosteller’s Formula

• Surface area (m2): – Square root (Height (cm) x Weight (kg)/ 3600)

STANDARD VALUES FOR USE IN BODY SURFACE AREA METHOD

H20 1500 mL/m2/24 hr

Na+ 30-50 mEq/m2/24 hr

K+ 20-40 mEq/m2/24 hr

BSA

• TFR: Insensible water loss + urine output

• IWL: 400-600 ml/m2/day x BSA

• Urine: 600-1000 ml/m2/day x BSA

CONDITIONS THAT ALTER MAINTENANCE FLUID

• Fever: 12% for each C >37.5 C or 7ml/kg for each 0.5C > 37.5C

• Room temp: >31 C 30% per degree rise

• Hypermetabolism

– Major surgery

– Burns• 20-30%• 20% increase per 1% area burn

CONDITIONS THAT ALTER MAINTENANCE FLUID

Less required• Hypothermia

• High Humidity• Oliguria/Edema• Sedated/Paralyzed

• 12% for each C <37.5

• 30%• Case to case/ 30%• 40%

DEFICIT THERAPY

• Fluid Deficit (L) – pre-illness weight (kg) - illness weight (kg)

• % Dehydration– (pre-illness weight - illness weight)/pre-illness

weight x 100%

PERCENTAGE OF DEFICIT FROM EXTRACELLULAR AND INTRACELLULAR

COMPARTMENTS

Duration of Illness

Deficit from ECF (%)

Deficit from ICF (%)

<3 days 80 20

>3days 60 40

CLINICAL OBSERVATION IN DEHYRATION

OLDER CHILD

3% (30mL/kg) 6% (60mL/kg) 9% (90mL/kg)

INFANT

Examination 5% (50mL/kg) 10%(100mL/kg)

15%(150mL/kg)

Dehydration Mild Moderate Severe

Skin Turgor Normal Tenting None

Skin (Touch) Normal Dry Clammy

Buccal Mucosa

Moist Dry Parched/Cracked

CLINICAL OBSERVATION IN DEHYDRATION

Eyes Normal Deep Set Sunken

Tears Present Reduced None

Fontanelle Flat Soft Sunken

CNS Consolable Irritable Lethargic/ Obtunded

Pulse rate Normal Slightly increased

Increased

Pulse quality Normal weak Feeble/ Impalpable

Capullary refil Normal 2 sec > 3sec

Urine Output Normal Decreased Anuric

LUDANS METHODMild Moderate Severe

<15kg

< 2y/o

50cc/kg 100 150

> 15kg

> 2 y/o

30 60 90

D5 0.3NaCl

6-8 hrs

1st hr 1/4 PLRS Next 5-7 hr 3/4

D5LRS

1st hr PLRS

Next 5-7 hr 2/3 D5 0.3 NSS

COMPOSITION OF FREQUENTLY USED PARENTERAL FLUIDS

LIQUID CHOg/100mL

Proteing/100mL

Cal/L

Na+mEq/L

K+ mEq/L

Cl-mEq/L

HCO3mEq/L

Ca+2mEq/L

mOsm/L

D5W 5 - 170 - - - - - 252

NS (0.9% NaCl)

- - - 154 - 154 - - 308

D5 0.3 5 - 170 51 - 51 - - -

LRS 0-10 - 0-340

147 4 155.5 - 4

D5 IMB 5 - 170 25 20 22 - - -

D5 NM 5 - 170 40 13 40 - - -

D5 NR 5 - 170 140 5 98 - - -

ELECTROLYTE COMPOSITION OF VARIOUS BODY FLUIDS

Fluid Na+ (mEq/L) K+ (mEq/L) Cl- (mEq/L)

Gastric 20-80 5-20 100-150

Pancreatic 120-140 5-15 90-120

Small Bowel 100-140 5-15 90-130

Bile 120-140 5-15 80-120

Ileostomy 45-135 3-15 20-115

Diarrhea 10-90 10-80 10-110

Burns 140 5 110

Sweat 10-30 3-10 10-35

ANION GAP

(Na + K) - (Cl + HCO3)

N.V. : 8-16 mg/dL

SODIUM DEFICIT

• mEq Na deficit :– (desired - actual) x TBW– TBW = 0.6 x BW (kg)

• Initial goal : 120 mEq/L subsequent 130mEq/L in 24 hrs

• Correct up to 12 mEq/L/day

HYPERNATREMIA

(Plasma Na - 140) / 140 x TBWCorrect up to 10-15 mmol/L/day

HYPOKALEMIA

• mmol K deficit : – (desired-actual) x 0.3 x wt.kg.

• Deficit : Wt. (kg) x 50 x Estimated % deficit