5 Fluids and Electrolytes, part 1

Question 1

The most common cause of fluid and electrolyte abnormalities in children is

Answer 1

dehydration

Question 2

Basal metabolic rates are highest in young children, peaking at ________ of age and gradually decreasing starting at _______ of age.

Answer 2

12 months
3 years

Question 3

These predispose infants to dehydration

Answer 3

1. high percentage of total body water (70%)
2. coupled with a decresaed ability to control water loss (e.g., insensible losses from larger surface area-to-body ratio and faster respiratory rate)
3. decreased ability to concentrate the urine

Question 4

Fever incresaes the basal metabolic rate by _______ for each degree above _______

Answer 4

13%
37.8

Question 5

the most common form of dehydration.

Answer 5

isonatremic dehydration

Question 6

the gold standard for assessment of volume status.

Answer 6

weight loss

Question 7

compensated shock

Answer 7

tachycardia can present with normal BP with or without signs of shock

Question 8

IV rehydration for moderate to severe dehydration without signs of shock

Answer 8

20 mL/kg PNSS over 1 hour,
followed by D5NSS at 1-2x maintenance rate for 1 hour

Question 9

IV rehydration for severe dehydration with uncompensated shock

Answer 9

20 mL/kg PNSS bolus over 5 mins,
repeated until hemodynamically stable
up to 60 mL/kg or more may be required in the first hour, unless contraindicated based on underlying disease

Question 10

Replacement of ongoing losses after initial rehydration

Answer 10

5-10 mL/kg PNSS or D5NSS for each watery diarrheal stool
and
2 mL/kg PNSS or D5NSS for each emesis

Question 11

The primary formula for daily fluid requirements is calculated as

Answer 11

For the first 10 kg: 100 mL/kg/day (4 mL/kg/hour)
For the second 10 kg: 50 mL/kg/day (2 mL/kg/hour)
For each kg >20 kg: 20 mL/kg/day (1/mL/kg/hour)

Question 12

daily fluid requirement for 10-kg baby

Answer 12

1,000 mL/day

Question 13

daily fluid requirement for 18 kg child

Answer 13

1,400 mL/day

Question 14

daily fluid requirement for 40 kg child

Answer 14

1,900 mL/day

Question 15

NIHCE guidlines recommend using _______ for all neonates from birth onward

Answer 15

5% or 10% dextrose in normal saline

unless respiratory distress syndrome, MAS, or HIE is present
- if any of these are present, give no sodium (e.g., D10W), until the postnatal diuresis with weight loss occurs, typically before day 5 of life

others recommend using salt-free fluids in all neonates until after the postnatal diuresis occurs

Question 16

Treatmet of hyponatremia if hypovolemic and hemodynamically unstable

Answer 16

Correct instability with NS boluses
(20 mL/kg over 5 min followed by reassessment after each bolus)

Question 17

Treatment of hyponatremia if asymptomatic

Answer 17

Correct deficit to normal over 48 hours
mEq Na required = [(Na+ desired) - measured Na+)] x (0.6 x weight in kg)

Question 18

Treatment of hyponatremia if neurologic symptoms (altered mental status, seizures) are present

Answer 18

1-2 mL/kg/hour of 3% NaCl until asymptomatic or Na level >120 mEq/mL,
then increase Na level 0.5 mEq/L/hour (not to exceed increase of 12 mEq/mL in first 24 hours or 18 mEq/mL in first 48 hours)

Question 19

if hyponatremia occurs in the presence of normal osmolarity (________), this is likely due to ____________

Answer 19

normal osmoloarity is 275 to 290 mOsm/kg
hyperlipidemia or hyperproteinemia
in such cases, correct the underlying disorder rather than the serum sodium level

Question 20

When hyponatremia occurs in a hypoosmolar state (<275 mOsm/kg), this is likely due to

Answer 20

an excess of free water or loss of sodium

Question 21

The most common causes of hyponatremia in the ED are

Answer 21

GI losses and water intoxication caused by ingestion of hypotonic replacement fluids, especially during infancy

Question 22

Signs and symptoms of hyponatremia depend on the

Answer 22

serum sodium level and the speed at which the sodium level falls

Although patients may be only mildly symptomatic with sodium levels as low as 120 mEq/L if the low level is chronic (>48 hours), symptoms usually occur with an acute drop in serum sodium level below 120 mEq/L

without appropriate treatment, complications include respratory failure, seizures, and death

Question 23

Treatment of euvolemic hyponatremia

Answer 23

after correction of serum sodium level, begin water restriction and treat the underlying disorder.

Question 24

the most common cause of hypernatremia in children.

Answer 24

diarrhea

Question 25

Serum sodium levels of greater than _______ require immediate attention

Answer 25

> 160 mEq/L
due to the potential for serious complications and permanent neurologic sequelae, including intellectual deficits, seizure disorder, or other neurologic impairments.

conversely, patients who have a sodium level of <160 mEq/L and receive treatment typically have symptoms that are relatively mild and self-limited

Question 26

Treatment of hypernatremia if hypovolemic and hemodynamically unstable

Answer 26

Correct instability with NS boluses
(20 mL/kg boluses followed by reassessment after each bolus)

Question 27

Treatment of hypernatremia once hemodynamically stable [and hypovolemic or euvolemic hypernatremia]

Answer 27

Correct deficit to normal over 24 hours
Free water deficit (mL) = 4 mL x body weight (kg) x [desired change in serum sodium mEq/L (mmol/L)]

Subtract bolus fluids given from deficit; correct remaining deficit giving half of deficit over first 8 hours and remainder over the next 16 hours

Question 28

remarks on correction of hypernatremia

Answer 28

Correct serum sodium grually to avoid cerebral edema and associated central pontine mylinolysis

Closely monitor serum sodium levels every hours initially to ensure that the level is reduced no faster than 1 mEq/L/hour and no more than 15 mEq/L in the first 24 hours

Question 29

Dialysis in hypernatremia may be required when

Answer 29

there is hypervolemic hypernatremia, if sodium levels cannot be decreased without volume overload

or for hypernatremia of any type if the initial serum sodium is 180 mmol/L