Fluid, Electrolyte, and Acid/Base Alterations in Pediatrics
ALTERATIONS IN FLUID ELECTROLYTE AND ACID/BASE
FLUID BALANCE
Definitions
Total Body Water (TBW): The total amount of water contained in the body, which is divided into two main compartments:
Extracellular Fluid (ECF): Fluid outside the cells, comprising of:
Intravascular Fluid: Fluid within blood vessels. 1/3 of body water
Interstitial Fluid: Fluid surrounding tissue cells.
Intracellular Fluid (ICF): Fluid within the cells. 2/3 body water
PEDIATRIC DIFFERENCES
Key Points
The percentage of body weight composed of water varies with age.
Infants have a high daily fluid requirement yet possess little fluid volume reserve, making them vulnerable to dehydration.
Stomach size limits the ability to rehydrate effectively in infants and children under 2 years
Infants and young children lose a greater proportion of fluid each day, and that is why they are more dependent on adequate fluid intake.
Fluid Composition by Age Group
Newborns:
75% Total body water
ECF: 45%
ICF: 30%
Infants:
65% Total body water
ECF: 25%
ICF: 30-40%
Children/Adolescents:
50% Total body water
ECF: 10-15%
ICF: 40%
Physiology Insights
The brain and skin occupy greater proportions of body weight in children and are high in interstitial fluid.
High Body Surface Area (BSA) promotes fluid loss.
Infants have little fluid reserve in intracellular fluid.
Infants undergo 5–6 times greater fluid exchange daily due to
High metabolic rates require a greater fluid intake.
Kidneys in children younger than 2 years are immature, impacting their ability to conserve water and electrolytes or assist in acid-base balance.
Pediatric Differences
Infants and children under 2 years have a greater body surface area (BSA)
Can not be measured directly
water loss is measured through the respiratory and the skin
respiratory and metabolic rates are high during early childhood
greater water loss from the lungs
greater water demand to fuel the body’s metabolic processes
Infants will lose my fluids through respirations because of the high respiratory rates
then putting them at increased dehydration risks
Kidneys
glomeruli, tubules, and nephrons are immature
unable to conserve or excrete water and solutes effectively
more water excreted
have difficulty regulating electrolytes
will become dehydrated more quickly
DEHYDRATION
Extracellular Fluid Volume Deficit
A condition characterized by insufficient fluid in the extracellular compartment (both intravascular and interstitial).
Commonly caused by the loss of sodium-containing fluid from the body
Serum sodium levels may be normal, low, or high depending on the cause.
Other causes include nasogastric suction, hemorrhage, and burns.
prolonged vomiting and diarrhea frequently lead to dehydration
Symptoms of Dehydration
Mild Dehydration
Symptoms:
Hard to detect.
Infants may be alert, restless, or irritable.
Moist mucous membranes.
Urine output is normal to mildly decreased. normal = 1mL per HR per KG
Vital signs within normal limits for age.
Anterior fontanel shows no change. meaning it is soft and flat
Capillary refill < 2-3 seconds; extremities warm and pink.
Turgor is brisk.
Up to 5% weight loss
may express thirst.
Moderate Dehydration
Symptoms:
irritability or lethargy in infants and young children.
Older children appear alert, thirsty, and restless.
Blood Pressure normal or low; check for postural hypotension.
tachycardic; respiratory rate may be normal or tachypneic.
Dry mucous membranes.
Urine output < 1 ml/kg/hour, dark in color.
Anterior fontanel may be sunken.
Capillary refill > 2 seconds.
Turgor is poor.
Eyes slightly sunken with decreased tears.
6–9% weight loss.
Severe Dehydration
Symptoms:
The child with severe dehydration is in hypovolemic shock.
lethargic to comatose for infants and young children
often conscious and apprehensive for older child and adolescent
low BP to almost undetectable
pulse rapid and weak to palpate
skin turgor is very poor
mucous membranes are parched
urine will be very low or absent
thirst is greatly increased unless they are lethargic
extremities will be cool, discolored, and cap refill is more than 3-4 secs
respiratory rate and regularity are changing
eyes will be deeply sunken and absent of tears
Case Scenario (Chloe)
Background:
2-month-old infant with a 2-day history of diarrhea and vomiting, weighing 4.5 kg.
Temperature: 38.9 °C; Heart Rate: 188 beats/min; Respiratory Rate: 62 breaths/min.
Urine output: 20 ml since 0800.
Notable symptoms: sunken anterior fontanel, dry mucous membranes, lethargy.
Symptoms of Dehydration: High heart rate, high respiratory rate, decreased urine output, anterior sunken fontanelle (posterior is closed by now), decreased tears, dry mucous membranes, lethargy.
Contributing Factors: Vomiting and diarrhea for 2 days; fever of 38.9 °C.
She has moderate dehydration
Diagnosis
Clinical observations are essential for identifying dehydration and its severity.
Required assessments include:
History of illness.
Serum electrolyte panel with high electrolytes
Bicarbonate levels (often low).
Clinical Therapy
Rehydration Needs:
intravenous (IV) rehydration is necessary due to:
High heart rate (188 bpm). tachycardia
High respiratory rate (62 bpm). tachypneic
Low urine output.
Lethargy
sunken fontanel.
She does not cry tears
history of diarrhea for 2 days
age
Therapy Details:
Administer an IV fluid bolus of isotonic solutions (e.g. Normal Saline or Lactated Ringer's) at a rate of 20 ml/kg over 20 minutes.
We will fluid bolus with moderate to severe dehydration
Establish maintenance IV fluids following the bolus.
Do not use D5W for a fluid bolus
isotonic fluids only for fluid bolus to help prevent fluid shifts
Careful calculation of IV fluid needs is crucial
identify cause
The patient will not get potassium until they void
patient will not get D5 until they void
ORAL REHYDRATION THERAPY
Recommended as an Intervention for Mild Dehydration:
Administer fluids in frequent small amounts, especially if they are vomiting or have been
(1-3 teaspoons every 10-15 minutes).
1 teaspoon= 5mL
Educate guardians on signs and symptoms of worsening dehydration, avoiding cola or full-strength juice.
can also educate parents on how to rehydrate at home
Jello and sports drinks should be given half-strength if that is the only thing available at home
DEHYDRATION NURSING MANAGEMENT
Key Tasks Include:
Daily weights at the same time each day to monitor for rapid weight gain; a gain of .5 kg suddenly is indicative of fluid accumulation.
Medications to control vomiting.
Strict intake & output (I&O) monitoring; urine may be assessed for color and amount.
darker in color = dehydrated
The amount of urine will be the first indicator of dehydration
1-12= 1ml/hr/kg
12+ = 0.5ml/hr/kg
Vital signs
assessments.
Monitoring and managing IV therapy
safety
Provide education on prevention to families.
tachycardia is because the heart is compensating d/t the hypovolemia
Tachypnea is compensating d/t the increased HR
mild hypertension d/t vasoconstriction, we won’t see this right away
As the dehydration continues, the BP will become hypotensive
EXTRACELLULAR FLUID VOLUME EXCESS (OVERHYDRATION)
Definition: A condition where there is an excessive amount of fluid in the extracellular compartment.
Possible Causes:
Conditions that cause retention of sodium or water, such as:
Adrenal tumors that lead to excessive aldosterone secretion, resulting in kidney retention of saline.
Congestive heart failure.
Chronic renal failure.
Overloaded sodium-containing isotonic IV fluid in infants or children.
Clinical Manifestations
Weight Gain: A sudden gain of .5 kg in one day signifies fluid accumulation.
1 kg = 1 liter of fluid
normal weight gains:
1-6 months = 5 to 7 oz per week
6-12 months = 3 to 5 oz per week
When weight seems to be increased, always reweigh the pt (first intervention for weight gain)
Edema:
Generalized edema across the body in infants.
Dependent areas of the body in children, their clothes, and shoes will be tight
Periorbital edema will be in all ages
Bounding pulse, distended neck veins
respiratory difficulties (dyspnea, tachypnea, crackles). d/t pulmonary edema
Clinical Therapy: Determine the cause and treat accordingly.
Nursing Management:
daily weights bc rapid weight gain is the most sensitive indicator
0.5kg suddenly gained in one day is due to fluid accumulation
strict I+O successful treatment causes output to be greater than intake
assess pulse
respiratory assessment
Assess neck veins while the child is sitting, and you will see neck veins in older children
assess edema, elevate the affected extremity
skin care- turns frequently
education with the family
HYPERNATREMIA
Definition: Sodium levels for newborns 131-140 mEq/L; for infants and children, 132-141 mEq/L.
Condition characterized by body fluids being too concentrated.
Potential Causes:
Poor feeding in breastfed infants, limited water intake in older children, excessively concentrated formula (not mixing formula correctly), diarrhea, vomiting, and diabetes insipidus.
Clinical Manifestations: Increased thirst, decreased urine output (exception: diabetes insipidus), confusion, seizures, lethargy, coma.
lethargy and coma are due to the shrinking of RBCs
Treatment: Monitor serum sodium level, administer hypotonic fluid such as 0.45 NS or D5W (once dextrose is absorbed, it acts on the body as hypotonic, so only plain water is left).
Nursing Management: Include assessments, monitoring lab values, IV infusion, I&O, and educational prevention strategies (4-6 wet diapers per day, proper formula preparation).
HYPONATREMIA
Definition: A condition where the osmolality of blood decreases, leading to dilute body fluids (more water than sodium).
Causes: Water intoxication, dilute formula, and exercise.
Clinical Manifestations: decreased level of consciousness due to swelling of brain cells. Also, can have a headache, anorexia, muscle weakness, seizures, lethargy, confusion, coma.
Clinical Therapy: Assess serum sodium levels, correct causes, administer hypertonic IV solutions (D5 0.45 NS, D5 0.9 NS).
Nursing Management: Continuous monitoring of serum sodium, correcting the cause, I&O assessments, and IV infusion assessments
HYPERKALEMIA
Definition: Elevated potassium levels in blood; normal levels for infants 4.1-5.3 mEq/L; for children 3.4-4.7 mEq/L (per AAP Pediatric Review 7/2023).
Causes: Can result from renal insufficiency, excessive potassium in IV fluids, blood transfusions, crush injuries, or sickle cell crises. Taking too long to get a blood draw can give a false elevation
Clinical Manifestations: Includes hyperactivity of gastrointestinal smooth muscles, resulting in cramping and diarrhea, skeletal muscle weakness, lethargy, and arrhythmias.
Clinical Therapy: Monitor serum potassium levels and perform a 12-lead EKG. Address and treat the underlying cause.
Nursing Management: Regular monitoring of potassium levels and assessments; vigilance in monitoring heart rate and arrhythmias.
Any child receiving IV therapy is at risk
Check urine output before implementing potassium in the IV fluid
if the patient has not voided, we don’t give potassium
HYPOKALEMIA
Definition: Decreased potassium in the blood.
Causes: Primarily caused by diarrhea and vomiting, but can also result from self-induced vomiting and NG suction.
Clinical Manifestations: Symptoms may include slowed GI smooth muscle activity resulting in abdominal distension, constipation, and ileus; weakness of skeletal muscles and unresponsiveness, cardiac arrhythmias, and respiratory muscles may be affected, and polyuria due to renal changes.
Clinical Therapy: Requires monitoring serum potassium levels, performing a 12-lead EKG, along with identifying and treating the underlying cause, and potassium replacement
Nursing Management: Monitor potassium levels and assess the patient; dietary potassium replacement may be required (high-potassium diet or IV fluids).
ACID-BASE IMBALANCES
Types of Imbalances:
Respiratory Acidosis: An accumulation of carbon dioxide in the blood; carbon dioxide and water are combined into carbonic acid
Respiratory Alkalosis: Characterized by insufficient carbon dioxide in the blood, and carbon dioxide and water are combined into carbonic acid
Metabolic Acidosis: Presence of an excess of any acid other than carbonic acid.
Metabolic Alkalosis: Arises from the loss of metabolic acid or excess bicarbonate; pyloric stenosis may induce metabolic alkalosis.
Nursing Management: Includes assessment and interventions tailored to correct the cause
PARENTERAL FLUID THERAPY
A healthcare provider must order IV fluids.
Caution: DO NOT add KCl until the child has voided.
IV sites should be assessed hourly and documented as per hospital policy; watch for infiltration or phlebitis.
infiltration- edema, cooling, discomfort, pale skin
phlebitis- redness, warmth, irritation, pain with meds, red streak up the arm
In pediatrics, substantial taping is common; assess the areas above and below the tape for warmth and pulse, but avoid removing tape or arm boards unnecessarily.
CASE SCENARIO (Johnnie)
Background: A 4-month-old was admitted with a 2-day history of diarrhea and a fever of 39 °C. Exhibiting sleepiness and difficulty being awakened.
Questions to Address:
Describe the appearance of diarrhea.
When was the last feeding?
How many wet diapers today?
Any tears when crying?
When did sleepiness begin?
Next Steps: Conduct an assessment including vital signs and a head-to-toe evaluation focusing on neurological and cardiovascular systems, respiratory and GI function, as well as integumentary assessments.
Lab Work: Conduct necessary blood tests such as electrolyte panel, CBC; plan for IV fluid bolus and maintenance fluid. Monitor intake and output (weigh the diapers), assessment, and vitals every 4 hrs, stool culture, ova and parasite, reg diet, contact plus precautions, and weigh the patient daily
Significance of Lab Work Results (example of Johnnie):
Sodium: 145 mEq/L high, Potassium: 6.5 mEq/L high, Chloride: 109 mEq/L, CO2: 15.7 mEq/L low,
CO2 low: metabolic acidosis
Sodium and potassium are elevated due to hypovolemia
Plan of Care:
Initiate IV fluid bolus (109 ml over 20 min).
Administer maintenance IV fluid consisting of D5NS or NS with added KCl; monitor vital signs and reassess regularly.
reassess when the bolus is done
I+O
reweigh the next morning
stool culture: shows a virus, a common cause of diarrhea
contact precautions and hand hygiene: gown and gloves
safety: side rails
educate fam