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I. Overall Principles
A. Listen for the history.
B. Examine the Patient.
C. Don’t forget the ABCs: A –Airway
B – Breathing
C – Circulation – Requires Volume
D. The faster you are treating abnormalities (volume or electrolyte), the more
often you need to check the patient’s progress to reassess the accuracy of your
1. All the calculations made are estimates.
2. Accuracy of all estimates must be checked by clinical observation of the patient.
E. Use fluids which are pre-mixed commercially whenever possible.
1. less expensive
2. less opportunity for error
3. quicker
F. Becoming more facile with fluid management will lead to better outcomes.
1. This does not have to be difficult.

II. Maintenance Fluids

A. H2 O is generated in the process of metabolism.
1. Metabolism produces: Heat – regulation requires H2O
Solute – excretion requires H2O
2. Metabolic Rate is related to Surface Area and to Weight
3. Metabolic Rate (kcals/day) approximates Fluid Need (cc/day)

B. Holliday-Segar Method to calculate metabolic rate for “normal” patients at

1. weight caloric expenditure/24 hours
0-10 kg 100 kcals/kg
>10-20 kg 1000 kcals+ 50 kcals/kg for the increment>10kgs
>20 kgs 1500 kcals+ 20 kcals/kg for the increment> 20kgs

2. H2 O need = 1 cc H 2O per kcal energy expended.

C. Maintenance calculation by Holliday-Segar assumes:

1. fluid losses are “normal” and equal 1 cc/ estimated 1 kcal
a. insensible losses: respiratory =15% of total
skin =30%
b. urinary losses =55%
D. Alterations in “maintenance” requirement:
1. fever – 12% increase for each degree (Celsius) above 38.
2. activity – 0-30% increase
3. tachypnea, hyperpnea
4. anuria
fixed inability to make urine

5. obligate polyuria
requires more urine to clear each mOsm of solute
6. VLBW infants
Decreased skin integrity
Increased S.A./weight ratio

E. Maintenance Electrolyte Requirements

1. Na 2-4 mEq/ 100cc H2O (start with 3 mEq/100cc)
2. K 2-3 mEq/ 100cc H2O (start with 2 mEq/100cc)
3. Cl 5-6 mEq/ 100cc H2 O

EXAMPLE: Maintenance Requirements for 24 hours

Weight H2 O Na K IV fluid used
5kg 500cc 15mEq 10mEq D5/1/4 NS +20 KC1/L
10kg 1000cc 30mEq 20mEq “
20kg 1500cc 45mEq 30mEq “
70kg 2500cc 75mEq 50mEq “


A. History
Guess the content of the fluid losses
e.g. Na K
diarrheal losses 8mEq/100cc 6mEq/100cc
vomiting 8mEq/100cc 12mEq/100cc
NB these are estimates! The ranges are wide.

B. Physical Exam including BP

Goals: 1. Assess for signs of Shock
Definition: failure to deliver oxygen and nutrients to tissues
Sx: decreased alertness – poor brain perfusion
decreased urine flow – poor renal perfusion
decreased bowel sounds – poor gut perfusion
capillary refill time> 2 seconds
poor peripheral pulses
2. Estimate degree of dehydration
See chart next page

NB, BP may not decrease, and may actually increase as volume depletion progresses

Estimating Volume Depletion

“mild” “mod” “severe”
% decrease in body weight 3-5% 6-10% >10%
(infant and older children)
affect/mental status alert, normal irritable obtunded
skin turgor normal decreased very decreased
eyes subtle change sunken sunken
fontanelle normal sunken sunken/pt supine

urine high s.g. very high s.g. dark, muddy

decreased volume scant volume little or none

BP/HR nml/sl increasednml/very high v. low/very high

Peripheral pulses nml weak not palpable

Estimated deficit (volume) 30-50cc/kg 60-100cc/kg >100cc/kg

NOTE: These sx will overestimate dehydration if the pt is hyponatremic
These sx will underestimate dehydration if the pt is hypernatremic

IV. To Prescribe Fluids – calculate and give:

A. Maintenance fluids – adjusted for individual differences
B. Deficit Replacement fluids – estimated from PE and history type of
C. Replacement for any ongoing losses
1. e.g. continued diarrhea or NG tube drainage
D. Readjustment after lab values are known, and after follow-up
confirms or alters your estimates
When the pt is >3-5% dehydrated, always check electrolytes stat

V. Choosing a rate of fluid administration:

A. If the pt is poorly perfused, i.e. there are sx of shock:
1. give 20cc/kg of isotonic fluid as rapidly as possible
2. repeat as necessary to establish perfusion

B. Next choose a rate and composition which will:

1. replace the deficit early in the 24 hour period (4-8 hours)
2. use available fluids (see chart)
3. e.g. –
• ½ the deficit plus ½ the maintenance over 8 hours, then the
remaining ½ deficit and ½ maintenance over the next 16 hours,
• the whole deficit over 8 hours, then the whole day’s maintenance
over 16 hours
4. NB – plans may need to be changed after the electrolyte values are

C. Replacement of K+ and HCO3 may take longer than the replacement of

D. Do not start K+ replacement until urine flow is established

Available IV Fluids
Glucose g/L Na mEq/L Cl mEq/L K mEq/L mOm/L

Isotonic Fluids:

Normal Saline 0 154 154 0 308

Ringer’s Lactate 0 130 109 4 272
5% Albumin 0 100-160 <120 0

Other Fluids:

D5 W 50 0 0 0 278
D5 W/ ¼ NS 50 34 34 0 355
¼ NS 0 38.5 38.5 0 77

D5 W/ ½ NS 50 77 77 0 432
½ NS 0 77 77 0 154

25% Albumin 0 100-160 <120 0

5% NaHCO 3 0 595 0 0 1190
8.4% NaHCO 3 0 1000 0 0 2000

Hypertonic Saline:
3% NaCl 0 513 513 0 1026
5% NaCl 0 855 855 0 1710

EXAMPLE: A 10kg boy with diarrhea, has 2.5 sec cap refill, decreased skin turgor, sunken
fontanel, thready peripheral pulses, scant concentrated urine in the diaper will need:

Maintenance Deficit Replacement (for 10% dehydration

H2 O


IV orders:

D. Whenever IV fluids or oral rehydration fluids are administered for dehydration,

1. reassess PE, UV and VS to check the accuracy of your predictions
2. The faster the rehydration, or the more severe the fluid/electrolyte abnormality,
the more often the patient needs to be reassessed.

VI. Oral Rehydration -
A. Best used in the absence of shock
When poor perfusion is present, isotonic fluid bolus can restore perfusion, then oral
rehydration can proceed.

B. Glucose is actively absorbed and Na is co-transported across gut mucosa

1. works even in most forms of diarrhea
2. optimal glucose transport at concentrations: glucose 2-2.5gm/L
Na 45-90 mEq/L
3. higher glucose concentration will exacerbate diarrhea and Na loss

Content of Available Rehydration Solutions

Na K base glucose Osmolality
mEq/L mEq/L mEq/L gms/dl mOm/L
WHO-ORS 90 20 30 2.0 310
Pedialyte 45 20 30 2.5 270
Ricelyte 50 25 34 3.0 290
Lytren 50 25 30 2.0

Ginger ale 3 1 4 5-15 540

Apple juice 3 28 0 10-15 700
Gatorade 20 3 3 4.6 330
Tea 0 5 0 0 5

C. Instructions for Oral Rehydration

1. Use WHO-ORS or a commercial preparatio n for rehydration
i.e. to replace the deficit over 4-6 hours
2. Then use breast milk or other lower sodium maintenance fluids for the rest of the day.
3. Use more ORS to continue to replace ongoing losses.
4. Restart feedings as soon as possible (?lactose- free)

D. Cautions about Oral Rehydration

1. Should not start until shock has been treated and reversed.
2. Some patients (<10%) will need some IV rx due to vomiting or high volume stool.
3. All patients require monitoring (PE, serial wts) just as with IV rehydration.
4. Improper mixing of fluids can lead to iatrogenic fluid imbalance.
5. Some ORS doesn’t taste great.

VII. Hyponatremic Dehydration

A. Hyponatremia is seldom symptomatic unless the serum Na is <120 and occurred
1. very rapid correction of very low Na has been associated with CPM in adults
-central pontine myelinolysis
-usually seenin malnourished alcoholics, although reported elsewhere.
2. Hyponatremia can cause seizures when it is severe and sudden.
-some recommend correction – active discussion persists.

3. Consensus –Correct low S Na quickly only when it is compromising the pt.
-then, correct it only to 120 mEq/L
B. When there is clear dehydration with low SNa the sx may over-predict the degree of
1. i.e. more severe sx at 5% loss than if normonatremic

C. Calculating the Na deficit

Na deficit = (135 – measured Na) in mEq/L X TBW in L
TBW= total body water
Varies from 0.75 x weight in newborns to 0.5 in adults
Safe bet is to use 0.5 in all children to avoid overload

D. Note: Na deficit does not always exist when there is hyponatremia

Assess total body volume status first
If low-there is Na and H2O deficit, with Na> H20
If high-there is H2 O excess, and probably Na excess as well

EXAMPLE: A 10 kg infant with a serum Na of 120 and 10% dehydration due to diarrhea
24 hour fluid/electrolyte needs:
H20 Na K


Diarrhea deficit

Extra Na deficit

VIII. Hypernatremic Dehydration – Management when Serum Na is >150 mEq/L

A. First establish perfusion (reverse shock if it is present)
1. Initial treatment of poor perfusion/shock is done as always
-rapid bolus normal saline or colloid 10-20 cc/kg, repeated if necessary
-usually in progress before electrolytes are known

B. Subsequent replacement of the deficit is done slowly

1. Goal – decrease the SNA no faster than 0.5-1.0 mEq/L every hour.

A. Check to make sure there are no other factors elevating Serum somolality
-can measure serum osm directly
-or estimate: serum osmolality = 2 (NA) + glucose/18 +BUN/2.8
-if other factors are elevating SOSM they must be treated slowly as well.

2. Even though the deficit is predominantly H2 O, it is safer to use fluids no more dilute
than 34 mEq/L Na (1/4 NS) to replace the deficit

3. Rationale:
-H2 O moves freely across all cell membranes, including blood-brain barrier.
-when SNA is elevated for more than a few hours, the brain cells generate
“idiogenic osmoles” (AA) to maintain intracellular tonicity and size
-“idiogenic osomoles” are not diffuseable or transportable out of the cells

-sudden decrease of extracellular Na concentration will cause H2 O to enter the
CNS cells suddenly, causing cerebral edema.

C. Calculating the Water deficit

3. assume that the deficit is all free water (i.e. there is no Na deficit)
4. assume that Total Body Water (TBW) is approximately 0.5 x weight (kg)
5. the H2O deficit (in Liters) = TBW x [(measured SNA / 140) – 1]

EXAMPLE: A 10k child who has a serum Na measured at 180, and has a hx of diarrhea,
vomiting and rehydration with a home brew containing table salt and water, of unknown
composition, boiled.

TBW=0.5 x 10 kg = 5 kg = 5L

H2 O deficit = 5 L x (180/ 140 – 1)

= 5 L x (1.3 – 1)
= 5 L x 0.3
= 1.5 L

D. Planning the fluid resuscitation:

1. Re-establish perfusion
2. Give maintenance fluids
3. Spread the H2 O deficit replacement out over 48-72 hours, given as ¼ NS.
4. Check electrolytes frequently at first, then regularly until SNA is back to <150.

IX. Abnormalities of Potassium

A. K+ is mainly intracellular – 90% of total body K+ is intracellular
- intracellular fluid K+ concentration is 150mEq/L
-intravascular K+ accounts for only about 5% of total body K+
B. K+ Balance
1. Intake – nutritional or IV
2. Internal shifts
a. anabolism: K+ taken up into cells
1) cellular uptake regulated by insulin, aldosterone,
2) 3 mEq/L K+ required for each 1 gm N(protein)
b. catabolism: K+ released into extracellular space
c. cell injury: Na- K ATPase is slowed – K+ is released into extracellular space
d. pH shifts: K+ for H+ balance changes
1) acidosis à K+ leaves cells
2) alkalosis à K+ enters cells
3. Excretion
a. Renal – depends on GFR, but is mainly a secretory
b. Extrarenal – GI and sweat
4. Total Body K+ and Serum K+ are not closely correlated
It is impossible to predict accurately the size of a K+ deficit.
1 mEq/L decrease may reflect 10-30% loss of total body K+

C. Relationship of Serum K+ to ECG changes
1. depends on total body K+ deficit or overload
2. Serum K+ ECG changes
<3.0 Flat T waves, prominent U waves, Stdepression
7.0 Peaked T waves
7.0-8.0 Prolonged P-R interval
8.0-9.0 Widened QRS, absent P wave
> 9.0 Wider QRS, V Fib, arrest
NOTE: these changes can occur at lower Sk+ if intracellular K+ is low.
D. Hypokalemia
1. Causes
a. Decreased intake
b. Renal losses
1) intrinsic defects – e.g. Bartter’s syndrome
2) Diuretics – thiazides and loop diuretics
3) Renal response to GI Cl-losses and volume depletion
4) Hyperaldosteronism
2. Consequences
a. muscular weakness/ paralysis/ respiratory failure
b. loss of renal concentrating abillity
1) vacuolization of tubular cells
c. myocardial conduction abnormalities
1) exacerbation of digoxin toxicity
3. Treatment
a. Replacement of K+ may take longer than volume replacement
-care should be taken not to allow worsening of hypoK during volume
resuscitation and during correction of academia
b. Total amount of K+ deficit will not be known until:
1) acid-base abnormalities are fixed
-N.B. correction of acidosis may/usually will worsen
2) results of attempts at replacement are known

EXAMPLE: A 7 y.o. boy with Type I diabetes presents with vomiting and diarrhea for several
days. His laboratory values are as follows: Gluc-450, Na 134, K 3.2, CO2 8, Cl 89, BUN 75. WT
on arrival 20 kg. Weight in your office 3 weeks ago was 22 kg.

How would you calculate a:

1. Water deficit?
2. Na, K+ maintenance and CO 2 deficit?

H2 O/Vol Na K Base



IV Fluid Treatment Plan

E. Hyperkalemia
1. Causes
a. increased load: 1) catabolism
2) dietary or iatrogenic

b. decreased excretion 1) renal failure

2) adrenal insufficiency
3) “K-sparing” diuretics
4) other renal abnormalities without adrenal abn
s/p transplantation
obstructive uropathy
sickle cell disease

c. internal shifts 1) acidosis/ acidemia

2) rhabdomyolysis, very vigorous exercise
3) familial hyperkalemic paralysis
4) drugs: succinylcholine, digoxin overdose

2. Consequences- cardiac and neuromuscular

-severity depends on extracellular K+ level and intra-/ extra-cellular K ratio
-more severe at lower serum levels if the intracellular K+ level is lower

3. Treatment – a 3 phase approach

a. Stabilize the membrane effects
1) Ca gluconate 10% 0.5-1.0 ml/kg IV slow push or
2) Ca Cl 100mg/ml 0.2cc/ kg/ dose IV into a central or large vein
(has been reported to burn skin on contact)

3) effect – immediate, duration – 10 – 15 minutes

4) may need to be repeated during the episode

b. Shift K+ into the cells

1) NaHCO3 1-2 mEq/kg (may need more if there is a big deficit)
effect within 5-15 min, duration up to 2 hours
do not mix with Ca-containing solutions/ flush the line
if the pt is hypocalcemic, may cause tetany
contributes to Na overload

2) Glucose (to induce an endogenous insulin surge) .5-1.0 gm/kg IV over 15 min
effect in 15-30 min, duration 4-6 hours
if insulin is needed, use .3 units regular per gram glucose given over 2hrs

3) Beta agonists – Albuterol inhaler by nebulizer or MDI

effect with 1-5 min, duration 1-2 hours
doesn’t require access, but may increase HR

c. Remove K+ from the body

1) increase the GFR and tubular flow rate- volume expansion

2) diuretics – furosemide 1 mg/kg IV

-useful only if renal function is demonstrable
-onset varies from minutes to never, duration permanent

3) Kayexelate enema – 1 gm/kg mixed in sorbitol 5%

-onset over 2 hours, duration permanent
-if used PO, the effect takes much longer – up to 6-12 hours
-exchanges 1 mEq K for 1 mEq Na
-has caused bowel perforations in some immediately post-operative pts

4) Dialysis