5 Fluids and Electrolytes, part 1 Flashcards
The most common cause of fluid and electrolyte abnormalities in children is
dehydration
Basal metabolic rates are highest in young children, peaking at ________ of age and gradually decreasing starting at _______ of age.
12 months
3 years
These predispose infants to dehydration
- high percentage of total body water (70%)
- coupled with a decresaed ability to control water loss (e.g., insensible losses from larger surface area-to-body ratio and faster respiratory rate)
- decreased ability to concentrate the urine
Fever incresaes the basal metabolic rate by _______ for each degree above _______
13%
37.8
the most common form of dehydration.
isonatremic dehydration
the gold standard for assessment of volume status.
weight loss
compensated shock
tachycardia can present with normal BP with or without signs of shock
IV rehydration for moderate to severe dehydration without signs of shock
20 mL/kg PNSS over 1 hour,
followed by D5NSS at 1-2x maintenance rate for 1 hour
IV rehydration for severe dehydration with uncompensated shock
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
Replacement of ongoing losses after initial rehydration
5-10 mL/kg PNSS or D5NSS for each watery diarrheal stool
and
2 mL/kg PNSS or D5NSS for each emesis
The primary formula for daily fluid requirements is calculated as
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)
daily fluid requirement for 10-kg baby
1,000 mL/day
daily fluid requirement for 18 kg child
1,400 mL/day
daily fluid requirement for 40 kg child
1,900 mL/day
NIHCE guidlines recommend using _______ for all neonates from birth onward
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
Treatmet of hyponatremia if hypovolemic and hemodynamically unstable
Correct instability with NS boluses
(20 mL/kg over 5 min followed by reassessment after each bolus)
Treatment of hyponatremia if asymptomatic
Correct deficit to normal over 48 hours
mEq Na required = [(Na+ desired) - measured Na+)] x (0.6 x weight in kg)
Treatment of hyponatremia if neurologic symptoms (altered mental status, seizures) are present
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)
if hyponatremia occurs in the presence of normal osmolarity (________), this is likely due to ____________
normal osmoloarity is 275 to 290 mOsm/kg
hyperlipidemia or hyperproteinemia
in such cases, correct the underlying disorder rather than the serum sodium level
When hyponatremia occurs in a hypoosmolar state (<275 mOsm/kg), this is likely due to
an excess of free water or loss of sodium
The most common causes of hyponatremia in the ED are
GI losses and water intoxication caused by ingestion of hypotonic replacement fluids, especially during infancy
Signs and symptoms of hyponatremia depend on the
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
Treatment of euvolemic hyponatremia
after correction of serum sodium level, begin water restriction and treat the underlying disorder.
the most common cause of hypernatremia in children.
diarrhea
Serum sodium levels of greater than _______ require immediate attention
> 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
Treatment of hypernatremia if hypovolemic and hemodynamically unstable
Correct instability with NS boluses
(20 mL/kg boluses followed by reassessment after each bolus)
Treatment of hypernatremia once hemodynamically stable [and hypovolemic or euvolemic hypernatremia]
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
remarks on correction of hypernatremia
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
Dialysis in hypernatremia may be required when
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
