AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Volume depletion is a common complication of illness observed in pediatric patients presenting to the ED. At times, it is the presenting complaint. Early recognition and early intervention are important to prevent progression to shock and cardiovascular collapse.

Pathophysiology

The term dehydration commonly is used to denote intravascular fluid depletion. However, it is important for clinicians to understand that volume depletion is distinct from dehydration.

Volume depletion denotes contraction of the total intravascular plasma pool, while dehydration denotes loss of plasma-free water disproportionate to loss of sodium, the main intravascular solute. The distinction is important because volume depletion can exist with or without dehydration, and dehydration can exist with or without volume depletion.

Isonatremic volume depletion

In children with dehydration, the most common underlying problem actually is volume depletion, not dehydration. Intravascular sodium levels are within the reference range, indicating that excess free water is not being lost from plasma. Rather, the entire plasma pool is contracted with solutes (mostly sodium) and solvents (mostly water) lost in proportionate quantities. This is volume depletion without dehydration. The most common cause is excessive extrinsic loss of fluids.

Pediatric patients, especially those younger than 4 years, tend to be more susceptible to volume depletion as a result of vomiting, diarrhea, or increases in insensible water losses. Significant fluid losses may occur rapidly. The turnover of fluids and solute in infants and young children can be as much as 3 times that of adults. This is because of the following:

• Higher metabolic rates
• Increased body surface area to mass index
• Higher body water contents (water comprises approximately 70% of body weight in infants, 65% in children, 60% in adults)

Hyponatremic volume depletion

Volume depletion can be concurrent with hyponatremia. This is characterized by plasma volume contraction with free water excess. An example is a child with diarrhea who has been given tap water to replete diarrheal losses. Free water is replenished, but sodium and other solutes are not.

In hyponatremic volume depletion, the patient may appear more ill clinically than fluid losses indicate. The degree of volume depletion may be clinically overestimated. Serum sodium levels less than 120 mEq/L may result in seizures. If intravascular free water excess is not corrected during volume replenishment, the shift of free water to the intracellular fluid compartment may cause cerebral edema.

Hypernatremic volume depletion

Volume depletion exists concurrently with true dehydration. This is characterized by plasma volume contraction with disproportionate further free water loss. Dehydration, or excess free water loss, is present when plasma osmolarity increases. Osmolarity is the measure of solute concentration in a fixed solvent volume.

In plasma, water is the solvent volume and sodium is the primary solute measured. Thus, finding serum hypernatremia can make an objective qualification of dehydration. (Alternatively, serum osmolarity can be measured but is more time intensive and costly.) An example is the child with diarrhea whose fluid losses have been replenished with hypertonic soup, boiled milk, baking soda, or improperly diluted infant formula. Volume has been restored, but free water has not.

In hypernatremic volume depletion, the patient may appear less ill clinically than fluid losses indicate. The degree of volume depletion may be underestimated. Usually, at least a 10% volume deficit exists with hypernatremic volume depletion.

As in hyponatremia, hypernatremic volume depletion may result in serious central nervous system (CNS) effects as a result of structural changes in central neurons. However, cerebral shrinkage occurs instead of cerebral edema. This may result in intracerebral hemorrhage, seizures, coma, and death. For this reason, volume restoration must be performed gradually over 24 hours or more. Gradual restoration prevents a rapid shift of fluid across the blood brain barrier and into the intracellular fluid compartment.

Potassium considerations

Potassium shifts between intracellular and extracellular fluid compartments occur more slowly than free water shifts. Serum potassium may not reflect intracellular potassium levels. Although a potassium deficit is present in all patients with volume depletion, it is not usually clinically significant. However, failure to correct for a potassium deficit during volume repletion may result in clinically significant hypokalemia. Potassium should not be added to replacement fluids until adequate urine output is obtained.

Acid and base problems

Clinicians may observe derangements of acid-base balance with volume depletion. Some degree of metabolic acidosis is common, especially in infants.

Mechanisms include bicarbonate loss in stool and ketone production. Hypovolemia causes decreased tissue perfusion and increased lactic acid production. Decreased renal perfusion causes decreased glomerular filtration rate, which in turn leads to decreased hydrogen (H+) ion excretion. These factors combine to produce a metabolic acidosis.

In most patients, acidosis is mild and easily corrected with volume restoration (as increased renal perfusion permits excretion of excess H+ ions in the urine). Administration of glucose-containing fluids further decreases ketone production.

Frequency

United States

Pediatric volume depletion is a common ED complaint. Approximately 5% of outpatient visits result from gastroenteritis, which is frequently accompanied by some degree of volume depletion. An estimated 5% of pediatric hospital admissions result from volume depletion.

International

The annual incidence of diarrheal illness is 2.8 billion. Diarrheal illness remains the third leading cause of death in all age groups in the developing world. Some 4.3 million deaths occur annually, which exceeds the combined death rate from trauma and neoplasms. (The first and second leading causes of death are respiratory and cardiac disease.)

Mortality/Morbidity

In the US, approximately 400 children aged 1 month to 4 years die annually as a result of volume depletion. Infant and young children deaths from acute volume depletion are a worldwide health problem. Volume depletion from diarrhea is a significant cause of mortality in developing nations. An estimated 5 million children younger than 5 years die each year from this cause.

• Morbidity varies with the degree of volume depletion and the underlying cause.
• The severely volume-depleted infant or child is at risk for death from cardiovascular collapse.
• Hyponatremia resulting from replacement of free water alone may cause seizures.
• Improper management of volume repletion may cause iatrogenic morbidity or mortality.

Age

Infants and younger children are more susceptible to volume depletion than older children.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Obtaining a complete history from the parent or caregiver is important as it provides clues to the type of dehydration present.

• The emergency physician should be diligent in obtaining the following information:
• • Feeding pattern and fluids given
  • Fluid loss (eg, vomiting, oliguria or anuria, diarrhea)
  • Possible ingestions
• Activity
• Medications
• Heat and sunlight exposures

Physical

• Vital signs
• • Fever hastens fluid losses and resultant tachycardia and tachypnea.
  • Generally, the pulse increases 10-20 beats per degree Celsius of temperature elevation above reference range.
  • Tachycardia is an early sign of significant volume depletion.
  • Blood pressure usually is preserved until severe depletion is present.
  • Tachypnea usually is present.
• Weight loss is important as a measure of the degree of volume depletion. The first clinically apparent signs of volume depletion have been shown to correlate with volume deficits of up to 5% of body weight.
• Changes in activity level (eg, listlessness, poor interaction) may reflect decreased cerebral perfusion or significant electrolyte abnormalities (primarily sodium).
• In infants, inspection of the anterior fontanel and the eyes is important. In volume depletion, the anterior fontanel is depressed when sitting upright, and the eyes are sunken and dry, even when crying.
• Inspection of the skin may show decreased turgor, tenting, and mottling.
• Capillary refill may be prolonged (>2 s).
• Stool and urine may change character with volume depletion.
• Mild volume depletion
• • Mild volume depletion is defined as less than 5% intravascular contraction.
  • This corresponds to less than approximately 50 mL/kg loss of body weight and usually is determined from history because physical signs are minimal or absent.
  • The pulse may be slightly increased, urine output may be normal or slightly decreased, mucous membranes may be moist, and tears may be present.
  • Normal skin turgor and capillary refill are present.
• Moderate volume depletion
• • Moderate volume depletion corresponds to 100 mL/kg loss of body weight.
  • Patients usually have a resting tachycardia, normal blood pressure, prolonged capillary refill time, weak peripheral pulses, irritability, lethargy, dry mucous membranes, depressed anterior fontanel, sunken eyes, and dry skin.
• Severe volume depletion
• • Severe volume depletion corresponds to more than 100 mL/kg loss of body weight.
  • Patients usually have a resting tachycardia or bradycardia, hypotension, greatly prolonged capillary refill time, weak central pulses, and cold mottled skin.
  • They also exhibit altered sensorium with poor response to painful stimuli.
  • The infant or child may be listless or lethargic.

Causes

In most cases, volume depletion in children is from fluid losses from vomiting or diarrhea.

• Vomiting may be caused by any of the following systems or processes:
• • CNS (eg, infections, space-occupying lesions)
  • GI (eg, gastroenteritis, obstruction, hepatitis, liver failure, appendicitis, peritonitis, intussusception, volvulus, pyloric stenosis, toxicity [ingestion, overdose, drug effects])
  • Endocrine (eg, diabetic ketoacidosis [DKA], congenital adrenal hypoplasia, Addisonian crisis)
  • Renal (eg, infection, pyelonephritis, renal failure, renal tubular acidosis)
  • Cardiac (eg, congestive heart failure [CHF], infections [pneumonia, otitis, sinusitis, sepsis])
  • Pulmonary (eg, respiratory failure)
  • Psychiatric (eg, psychogenic vomiting) - This is not seen in infants and is rare in children compared with adults.
• Diarrhea may be caused by any of the following systems or processes:
• • GI (eg, gastroenteritis, malabsorption, intussusception, irritable bowel, inflammatory bowel disease, short gut syndrome)
  • Endocrine (eg, thyrotoxicosis, congenital adrenal hypoplasia, Addisonian crisis, diabetic enteropathy)
  • Renal (eg, infection, pyelonephritis)
  • Infection (eg, pneumonia, otitis, sinusitis, sepsis)
  • Psychiatric (eg, anxiety)
• Volume depletion not caused by vomiting or diarrhea may be divided into renal or extrarenal causes.
• • Renal causes include use of diuretics, renal tubular acidosis, renal failure (eg, trauma, obstruction, salt-wasting nephritis). The effects of diabetes insipidus, hypothyroidism, and adrenal insufficiency also fall into this category.
  • Extrarenal causes include third space extravasation of intravascular fluid (eg, pancreatitis, peritonitis, sepsis), skin losses (burns), lung losses, CHF, liver failure, and hemorrhage.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Serum electrolytes are important to determine sodium concentration, which can guide replenishment therapy.
• Bicarbonate and potassium levels also are important to assess the degree of metabolic acidosis and to screen for coexisting hypokalemia.
• Blood urea nitrogen and creatinine measure renal function and intravascular volume.
• Glucose may reveal hyperglycemia or hypoglycemia.
• Determination of serum osmolarity is optional.
• Arterial blood gases are indicated in patients with severe volume depletion. Serum arterial pH provides a more direct measure of acidosis than the calculated bicarbonate level.
• Urine specific gravity indicates the degree of volume depletion and may reveal an underlying infectious etiology.
• Urine electrolytes and osmolarity are useful in severe instances or where extrinsic fluid loss is poorly understood.
• Because dehydration or volume depletion may accompany many other illnesses, further workup should be tailored to the patient's presentation.

Procedures

• Prior to vascular access attempts, consider oral rehydration in mild and moderate dehydration.
• Intravenous access: Typical sites include superficial veins in the dorsum of the hand, antecubital fossa (median cephalic or basilic veins), dorsum of the foot, and scalp veins.
• Intraosseous access
• • Use intraosseous access if attempts to start percutaneous IV are unsuccessful.
  • Typical sites are proximal tibia and distal femur.
• Central venous access
• • Typical sites are femoral, external jugular (may be difficult because of short neck in infants and young children), subclavian, and antecubital.
  • Umbilical vein catheterization may be difficult and usually is not recommended for neonates who have been discharged from the hospital and are returning to the ED.
• Venous cutdown
• • Use venous cutdown for emergent access and resuscitation only. Safe performance depends on the skill of the provider.
  • The typical site is the distal saphenous vein, which is anterior and superior to the medial ankle malleolus.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Prehospital Care

• Address emergent airway, breathing, and circulatory problems first.
• Obtain IV access, and give an isotonic fluid bolus (Ringer lactate or isotonic sodium chloride solution) to children with severe volume depletion. This should not delay transport to the appropriate facility.

Emergency Department Care

• Patients in shock require isotonic fluids in 20 mL/kg fluid boluses.
• In children with difficult peripheral access, perform interosseus or central access promptly.
• Once vital sign abnormalities are corrected, initiate maintenance fluid therapy.
• Daily requirements for maintenance fluids can be approximated as follows:
• • If the patient weighs less than 10 kg, give 100 mL/kg/d.
  • If the patient weighs less than 20 kg, give 1000 mL/d plus 50 mL/kg/d for each kilogram between 10-20 kg.
  • If the patient weighs more than 20 kg, give 1500 mL/d, plus 20 mL/kg/d for each kilogram over 20 kg.
• Divide the total by 24 to obtain the hourly rate.
• The emergency physician also should consider daily sodium and potassium requirements as follows:
• • Sodium 2-3 mEq/kg/d
  • Potassium 2-3 mEq/kg/d
• Daily fluid requirements may be met using dextrose 5% in 0.25 isotonic sodium chloride solution with 20 mEq/L added potassium.
• It is important to observe adequate urine output prior to adding potassium to the IV fluids.
• Oral rehydration therapy
• • Several solutions are available commercially.
  • It is important to include glucose as well as electrolyte replacement because of the physiologic transport mechanisms. Glucose mediates transmembrane fluid absorption.
  • As volume replenishment generally occurs over 8 hours, oral replacement therapy is recommended only for select patients.
  • Children must be cooperative and have caregivers available to instruct and administer the oral fluids.
  • Oral rehydration therapy is not used routinely in Western EDs because of time constraints, but it is a major treatment modality in the non-Western world.
  • It is effective for severe states of volume depletion. It was originally (and still is) used to treat volume depletion from cholera.
• For readers in the developing world or in areas without access to IV therapy, an easy recipe for oral rehydration solution is as follows:
• In 1 liter of water, add 2 level tablespoons of sugar or honey, one-fourth teaspoon of table salt (NaCl) and one-fourth teaspoon of baking soda (bicarbonate of soda).
• If baking soda is not available, use another quarter teaspoon of salt instead.
• If available, add one half cup of orange juice, coconut water, or a mashed ripe banana to the drink.
• The water is safer if boiled, but do not lose time doing this if the child is very ill.
• Before giving the drink, taste it to be sure it is no saltier than tears.
• Give this drink in sips every 5 minutes around the clock until normal urination returns.
• A small child needs at least 1 glass of replacement for every watery stool.
• IV access
• • All critically ill children should have 2 IV lines started. Bloodwork can be drawn from the IV to save the child the pain of multiple needle sticks.
  • Parental presence generally is helpful during blood drawing and placement of IV catheters.
  • • Beware of the parent with a strong aversion to needles or blood.
    • Parental syncope is not uncommon.
    • Children take their cues from their parents, and in some instances a caregiver's presence may not be helpful.
• IV fluids
• • For children in shock, isotonic sodium chloride solution, lactated Ringer solution or, in the developing world, Hartmann solution, should be rapidly bolused at 20 mL/kg.
  • • Rapid administration requires an IV catheter of sufficient size.
    • Repeated boluses may be necessary.
  • The actual speed of bolused therapy depends on urgency of the clinical scenario.
  • • Clinicians may need to push fluids with syringes or use an infusion pump.
    • An infusion pump allows precise control of fluid rate and is encouraged in pediatric fluid resuscitation.
  • Reassess children after every bolus.
  • • If a patient reaches 60-80 mL/kg in crystalloid boluses and is not significantly improved, consider other causes of shock (eg, sepsis, hemorrhage, cardiac disease).
    • Once a patient is stabilized, volume replacement rate can be slowed and further therapy planned based upon a reevaluation of the patient's clinical state.
    • Children who are unable to tolerate oral fluids at this point should be admitted for further therapy.
• Isonatremic and hyponatremic volume depletion states may be treated with saline or other isotonic solutions.
• • Hypernatremic volume depletion should be corrected more slowly because of the possibility of CNS complications resulting from rapid correction of the osmolar gradients.
  • Full correction of severe sodium abnormalities usually should be staged over 24 hours or longer.
  • In all patients, oral hydration should be a part of therapy if possible.
  • Potassium shifts between the intracellular and extracellular fluid compartments occur more slowly than free water shifts. For this reason, the serum potassium may not immediately reflect intracellular potassium levels.
  • Although a potassium deficit is present in all cases of volume depletion, it is not usually clinically significant; however, failure to correct for hypokalemia during volume repletion may result in clinically significant hypokalemia.

Consultations

Infants and children who present to the ED with mild-to-moderate dehydration may respond to fluid boluses and be discharged home with close follow-up with their primary care provider.

Patients who are severely volume depleted or who are unable to tolerate oral fluids must be admitted, often with a pediatric consultation.

• If the child is in shock, unable to drink fluids, or does not respond to IV bolused therapy, significant abnormalities requiring correction may exist. In such patients, obtain pediatric consultation for admission and further therapy.
• If renal tubular acidosis (RTA) or other primary renal or endocrine disorder is suspected, specialty consultation may be indicated.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The consensus of the American Academy of Pediatrics subcommittee on acute gastroenteritis is that pharmacologic agents are not recommended to treat either acute diarrhea or vomiting. Fluid replacement (via oral rehydration or IV fluids) is the mainstay of treatment. Antiemetics should be considered for those patients with protracted vomiting; the efficacy of antiemetics for preventing admission of patients with gastroenteritis is not proven.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• Inpatient therapy generally is not indicated for mild volume depletion. However, it is prudent to arrange outpatient follow-up evaluation within 48 hours, with instructions to return sooner if needed.
• Children with moderate volume depletion may require further inpatient IV rehydration or treatment of the underlying etiology of the fluid deficit.
• Children with severe volume depletion, especially patients with hypernatremia or hyponatremia, require inpatient therapy.
• Children with severe hyperosmolar states, severe electrolyte derangements, or associated renal failure may require admission to a critical care unit.

Prognosis

• Generally, prognosis is excellent if appropriately treated.

Patient Education

• For excellent patient education resources, visit eMedicine's Children's Health Center. Also, see eMedicine's patient education article Dehydration in Children.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Iatrogenic electrolyte imbalance
• Overly aggressive replacement of volume deficits leading to serious CNS sequelae
• Failure to diagnose sepsis or another more serious underlying condition
• Failure to admit to recognize and treat shock

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• American Academy of Pediatrics. Practice parameter: the management of acute gastroenteritis in young children. American Academy of Pediatrics, Provisional Committee on Quality Improvement, Subcommittee on Acute Gastroenteritis. Pediatrics. Mar 1996;97(3):424-35. [Medline].
• American Heart Association. Guidelines for cardiopulmonary resuscitation and emergency cardiac care. Emergency Cardiac Care Committee and Subcommittees, American Heart Association. Part VI. Pediatric advanced life support. JAMA. Oct 28 1992;268(16):2262-75. [Medline].
• Bezerra JA, Stathos TH, Duncan B, et al. Treatment of infants with acute diarrhea: what''s recommended and what''s practiced. Pediatrics. Jul 1992;90(1 Pt 1):1-4. [Medline].
• Carcillo JA, Davis AL, Zaritsky A. Role of early fluid resuscitation in pediatric septic shock. JAMA. 1991;266(9):1242-5. [Medline].
• Cunningham FJ, Engle WA, Rescola FJ. Pediatric vascular access and blood sampling techniques. In: Roberts and Hedges, eds. Clinical Procedures in Emergency Medicine. 3rd ed. 1998:281-308. [Medline].
• De Bruin WJ, Greenwald BM, Notterman DA. Fluid resuscitation in pediatrics. Crit Care Clin. Apr 1992;8(2):423-38. [Medline].
• Duggan C, Refat M, Hashem M, et al. How valid are clinical signs of dehydration in infants?. J Pediatr Gastroenterol Nutr. Jan 1996;22(1):56-61. [Medline].
• Holliday M. The evolution of therapy for dehydration: should deficit therapy still be taught?. Pediatrics. Aug 1996;98(2 Pt 1):171-7. [Medline].
• Idris AH, Melker RJ. High-flow sheaths for pediatric fluid resuscitation: a comparison of flow rates with standard pediatric catheters. Pediatr Emerg Care. Jun 1992;8(3):119-22. [Medline].
• Kallen RJ, Lonergan JM. Fluid resuscitation of acute hypovolemic hypoperfusion states in pediatrics. Pediatr Clin North Am. Apr 1990;37(2):287-94. [Medline].
• King CK, Glass R, Bresee JS, et al. Managing acute gastroenteritis among children: oral rehydration, maintenance, and nutritional therapy. MMWR Recomm Rep. Nov 21 2003;52(RR-16):1-16. [Medline].
• Mange K, Matsuura D, Cizman B, et al. Language guiding therapy: the case of dehydration versus volume depletion. Ann Intern Med. Nov 1 1997;127(9):848-53. [Medline].
• McGee S, Abernethy WB 3rd, Simel DL. The rational clinical examination. Is this patient hypovolemic?. JAMA. Mar 17 1999;281(11):1022-9. [Medline].
• Reid SR, Bonadio WA. Outpatient rapid intravenous rehydration to correct dehydration and resolve vomiting in children with acute gastroenteritis. Ann Emerg Med. Sep 1996;28(3):318-23. [Medline].
• Sowa B. Fluid and electrolyte therapy. In: Emergency Medicine: A Comprehensive Study Guide. 4th ed. 1996:242-6. [Medline].
• Steiner MJ, DeWalt DA, Byerley JS. Is this child dehydrated?. JAMA. Jun 9 2004;291(22):2746-54. [Medline].
• Teach SJ, Yates EW, Feld LG. Laboratory predictors of fluid deficit in acutely dehydrated children. Clin Pediatr (Phila). Jul 1997;36(7):395-400. [Medline].
• Ward DG. Acute infectious diarrhea disease and dehydration. In: Rosen, Berkin, eds. Emergency Medicine: Concepts and Clinical Practice. Vol 2. 4th ed. 1998:1200-12. [Medline].
• Wright JL, Patterson MD. Resuscitating the pediatric patient. Emerg Med Clin North Am. Feb 1996;14(1):219-31. [Medline].

Article Last Updated: Mar 23, 2006