WORKUP	Section 5 of 9
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Bibliography

Lab Studies:

• Laboratory data are generally not required if the etiology is apparent and mild-to-moderate dehydration is present.

• With severe dehydration, the following laboratory studies are suggested:

• Serum sodium should be determined because hyponatremia (Na <130 mEq/L) and hypernatremia (Na >150 mEq/L) require specific treatment regimens.

• Potassium may be elevated (eg, congenital adrenal hyperplasia, renal failure) or low (eg, pyloric stenosis, alkalosis).

• Chloride may be low in pyloric stenosis (eg, hypochloremic, hypokalemic, or metabolic alkalosis).

• Poor tissue perfusion in dehydration results in production of lactic acid. Bicarbonate is consumed as lactic acid levels increase. In DKA, ketoacids also consume bicarbonate. Bicarbonate levels can also be reduced because of loss of bicarbonate in diarrheal stools.

• Glucose may be dangerously low because of poor intake or extremely elevated in DKA.

• Blood urea nitrogen and creatinine may be elevated because of renal hypoperfusion.

• Urine specific gravity may be elevated; diabetes insipidus causes the urine to be dilute.

• Urinalysis may show findings of DKA (eg, ketones, glucose).

• Electrolyte analysis of any fluid that is lost (eg, urine, stool, gastric fluid) can be performed to further refine the composition of replacement fluids.

Procedures:

• Intravenous line

• If severe dehydration is present, peripheral intravenous line insertion may be difficult. The preferred sites for initial insertion attempts include the basilic and cephalic veins in the antecubital fossa and the saphenous veins near the ankle. Transillumination of the insertion site with a fiberoptic light source may be used to facilitate locating the desired vein.

• If peripheral intravenous access cannot be rapidly achieved (<90 s) in a child with severe dehydration and shock, intraosseous cannulation should be attempted. If the child is not in extremis, more time may be taken to establish central venous access percutaneously (eg, femoral, subclavian, internal, external jugular).

• Intraosseous line: Intraosseous cannulation can easily and rapidly be achieved in children younger than 6 years. Specially designed intraosseous infusion needles or Jamshidi-type bone marrow aspiration needles may be used. Short large-bore spinal needles may also be used but often bend during placement. The ideal site of insertion is the anteromedial surface of the tibia, 1-3 cm below the anterior tibial tuberosity.

	TREATMENT	Section 6 of 9
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Bibliography

Medical Care: Medications such as loperamide, opiates, anticholinergics, bismuth subsalicylate, and adsorbents are not recommended because of questionable efficacy and potential adverse effects.

Oral rehydration solutions

During gastroenteritis, the intestinal mucosa retains absorptive capacity. Sodium and glucose in the correct proportions can be passively cotransported with fluid from the gut lumen into the circulation. Rapid oral rehydration with the appropriate solution has been shown to be as effective as intravenous fluid therapy in restoring intravascular volume and correcting acidosis.

Table 3. Composition of Appropriate Oral Rehydration Solutions

Solution	CHO*, g/dL	Na, mEq/L	K, mEq/L	Base, mEq/L	Osmolality
Pedialyte	2.5	45	20	30	250
Infalyte	3	50	25	30	200
Rehydralyte	2.5	75	20	30	310
WHO/UNICEF†	2	90	20	30	310

*Carbohydrate
^†World Health Organization/United Nations Children's Fund

All of the commercially available rehydration fluids are acceptable for oral rehydration therapy (ORT). They contain 2-3 g/dL of glucose, 45-90 mEq/L of sodium, 30 mEq/L of base, and 20-25 mEq/L of potassium. Osmolality is 200-310 mOsm/L.

Table 4. Composition of Inappropriate Oral Rehydration Solutions

Solution	CHO, g/dL	Na, mEq/L	K, mEq/L	Base, mEq/L	Osmolality
Apple juice	12	0.4	26	0	700
Ginger ale	9	3.5	0.1	3.6	565
Milk	4.9	22	36	30	260
Chicken broth	0	2	3	3	330

Traditional clear fluids are not appropriate for ORT. Many contain excessive concentrations of CHO and low concentrations of sodium. The inappropriate glucose-to-sodium ratio impairs water absorption, and the large osmotic load creates an osmotic diarrhea, further worsening the degree of dehydration.

• Oral rehydration therapy for mild or moderate dehydration

• Mild or moderate dehydration can usually be treated very effectively with ORT.

• Vomiting is generally not a contraindication to ORT. If evidence of bowel obstruction, ileus, or acute abdomen exists, then intravenous rehydration is indicated.

• Calculate fluid deficit. Physical findings consistent with mild dehydration suggest a fluid deficit of 5% of body weight in infants and 3% in children. Moderate dehydration occurs with a fluid deficit of 5-10% in infants and 3-6% in children (see Table 1 and Table 2). The fluid deficit should be replaced over 4 hours.

• The oral rehydration solution should be administered in small volumes very frequently to minimize gastric distention and reflex vomiting. Generally, 5 mL of oral rehydration solution every minute is well tolerated. Hourly intake and output should be recorded by the caregiver. As the child becomes rehydrated, vomiting often decreases and larger fluid volumes may be used.

• If vomiting persists, infusion of oral rehydration solution via a nasogastric tube may be temporarily used to achieve rehydration. Intravenous fluid administration (20-30 mL/kg of isotonic sodium chloride solution over 1-2 h) may also be used until oral rehydration is tolerated.

• Replace ongoing losses from stools and emesis (estimate volume and replace) in addition to replacing the calculated fluid deficit.

• Once the child is rehydrated, start an age-appropriate diet (see below).

• Severe dehydration

• Laboratory evaluation and intravenous rehydration are required. The underlying cause of the dehydration must be determined and treated appropriately.

• Phase 1 focuses on emergency management. Severe dehydration is characterized by a state of hypovolemic shock requiring rapid treatment. Initial management includes placement of an intravenous or intraosseous line and rapid administration of 20 mL/kg of lactated Ringer solution or isotonic sodium chloride solution. Additional fluid boluses may be required depending on the severity of the dehydration. The child should be frequently reassessed to determine the response to treatment. As intravascular volume is replenished, tachycardia, capillary refill, urine output, and mental status all should improve. If improvement is not observed after 60 mL/kg of fluid administration, other etiologies of shock (eg, cardiac, anaphylactic, septic) should be considered. Hemodynamic monitoring and inotropic support may be indicated.

• Phase 2 focuses on deficit replacement, provision of maintenance fluids, and replacement of ongoing losses. Daily maintenance fluid requirements may calculated as follows:
  • Less than 10 kg = 100 mL/kg

  • 10-20 kg = 1000 + 50 mL/kg for each kg over 10 kg

  • Greater than 20 kg = 1500 + 20 mL/kg for each kg over 20 kg

• Severe dehydration by clinical examination suggests a fluid deficit of 10-15% of body weight in infants and 6-9% of body weight in older children. The daily maintenance fluid is added to the fluid deficit. In general, the recommended administration is one half of this volume administered over 8 hours and administration of the remainder over the following 16 hours. Continued losses (eg, emesis, diarrhea) must be replaced promptly.

• If the child is isonatremic (130-150 mEq/L), the sodium deficit incurred can generally be corrected by administering the fluid deficit plus maintenance as 5% dextrose in 0.45% NaCl. Potassium (20 mEq/L KCl) may be added once urine output is established.

• An alternative approach to the deficit therapy approach is rapid replacement therapy. With this approach, a child with severe isonatremic dehydration is administered 20-40 mL/kg of isotonic sodium chloride solution or lactated Ringer solution over 15-60 minutes. As perfusion is restored, the child improves and is able to tolerate an oral rehydration solution for the remainder of his rehydration. This approach is not appropriate for hypernatremic or hyponatremic dehydration.

• Hyponatremic dehydration
  • Phase 1 management of hyponatremic dehydration is identical to that of isonatremic dehydration. Rapid volume expansion with 20 mL/kg of isotonic sodium chloride solution or lactated Ringer solution should be administered and repeated until perfusion is restored.

  • Severe hyponatremia (<130 mEq/L) indicates additional sodium loss. In phase 2 management, rehydration is calculated as for isonatremic dehydration. The additional sodium deficit must be calculated and added to the rehydration fluids. The deficit may be calculated to restore the sodium to 130 mEq/L and administered over 24 hours.
    • Sodium deficit = (sodium desired - sodium actual) X volume of distribution X weight (kg)

    • Example: Na = 123, weight = 10 kg, assumed volume of distribution of 0.6; Na deficit = (130-123) X 0.6 X 10 kg = 42 mEq Na

  • A simplified approach is to use 5% dextrose in 0.9% NaCl or 0.45% NaCl as the replacement fluid. The sodium is monitored closely, and the amount of sodium in the fluid is adjusted to maintain a slow correction (<0.5 mEq/L/h).

  • Frequently reassessing the serum sodium level during correction is imperative. Rapid correction of chronic hyponatremia (>2 mEq/L/h) has been associated with central pontine myelinolysis. Rapid partial correction of symptomatic hyponatremia has not been associated with adverse effects. Therefore, if the child is symptomatic (seizures), a more rapid partial correction is indicated. Hypertonic (3%) isotonic sodium chloride solution (0.5 mEq/mL) may be used for rapid partial correction of symptomatic hyponatremia. A dose of 4 mL/kg raises the serum sodium by 3-4 mEq/L.

• Hypernatremic dehydration
  • Phase 1 management of hypernatremic dehydration is identical to that of isonatremic dehydration. Rapid volume expansion with 20 mL/kg of isotonic sodium chloride solution or lactated Ringer solution should be administered and repeated until perfusion is restored.

  • Varied regimens may be successfully followed to achieve correction of severe hypernatremia (>150 mEq/L). In phase 2 management, the most important goal is to reestablish intravascular volume and return serum sodium levels toward the reference range by not more than 10 mEq/L/24 h. Rapid correction of hypernatremic dehydration can have disastrous neurologic consequences, including cerebral edema and death.

  • The most cautious approach is to plan a slow correction of the fluid deficit over 48 hours. Following adequate intravascular volume expansion, rehydration fluids should be initiated with 5% dextrose in 0.9% NaCl. Serum sodium levels should be assessed every 4 hours. If the sodium has decreased by less than 0.5 mEq/L/h, then the sodium content of the rehydration fluid is decreased. This allows for a slow controlled correction of the hypernatremic state.

  • Hyperglycemia and hypocalcemia are sometimes associated with hypernatremic dehydration. Serum glucose and calcium levels should be monitored closely.

Diet:

• Once the child is rehydrated, an age-appropriate diet should be started. Children with dehydration from gastroenteritis have decreased duration of diarrhea when feedings are rapidly restarted.

• Diluting milk or formula is not indicated. Breast-feeding should be resumed as soon as possible.

• Foods containing complex carbohydrates (eg, rice, wheat, potatoes, bread, cereals), lean meats, fruits, and vegetables are encouraged. Fatty foods and simple carbohydrates should be avoided.

	FOLLOW-UP	Section 7 of 9
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Bibliography

Further Inpatient Care:

• Severe dehydration warrants hospital admission for rehydration, as do hypernatremic or hyponatremic states.

• Inability to tolerate oral rehydration therapy may necessitate hospital admission for nasogastric or intravenous fluid therapy.

Further Outpatient Care:

• ORT may be continued at home if clear instructions are provided for the family and if the family members can be relied upon to carry out the hydration regimen. Close follow-up by the primary physician is recommended.

Complications:

• Complications may include irreversible shock, sagittal or other venous sinus thrombosis, intractable seizures, and renal failure.

Prognosis:

• Prognosis is excellent if the child is promptly and effectively treated. However, the child with severe dehydration and hypovolemic shock can have significant morbidity and mortality if treatment is delayed.

Patient Education:

• An excellent Web site containing patient education materials regarding dehydration, gastroenteritis, and oral rehydration therapy can be found at AAFP Family Health Facts. Additional patient education resources can be found by visiting eMedicine's Children's Health Center. Also, see eMedicine's patient education article Dehydration in Children.

	MISCELLANEOUS	Section 8 of 9
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Bibliography

Medical/Legal Pitfalls:

• Failure to recognize and appropriately treat DKA

• Failure to recognize hypoglycemia

• Failure to recognize severe hyponatremia or hypernatremia

• Failure to recognize an acute abdomen

• Inadequate volume administration (too slow, not enough) for the child with severe dehydration

• Failure to recognize cardiogenic shock (gallop rhythm, hepatomegaly): Rapid fluid resuscitation may further impair cardiac output.

	BIBLIOGRAPHY	Section 9 of 9
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Bibliography

• AdroguĂ© HJ, Madias NE: Hypernatremia. N Engl J Med 2000 May 18; 342(20): 1493-9[Medline].
• Atherly-John YC, Cunningham SJ, Crain EF: A randomized trial of oral vs intravenous rehydration in a pediatric emergency department. Arch Pediatr Adolesc Med 2002 Dec; 156(12): 1240-3[Medline].
• Bellemare S, Hartling L, Wiebe N, et al: Oral rehydration versus intravenous therapy for treating dehydration due to gastroenteritis in children: a meta-analysis of randomised controlled trials. BMC Med 2004 Apr 15; 2: 11[Medline].
• Bhatnagar S, Bahl R, Sharma PK, et al: Zinc with oral rehydration therapy reduces stool output and duration of diarrhea in hospitalized children: a randomized controlled trial. J Pediatr Gastroenterol Nutr 2004 Jan; 38(1): 34-40[Medline].
• Choice Study Group: Multicenter, randomized, double-blind clinical trial to evaluate the efficacy and safety of a reduced osmolarity oral rehydration salts solution in children with acute watery diarrhea. Pediatrics 2001 Apr; 107(4): 613-8[Medline].
• Dale J: Oral rehydration solutions in the management of acute gastroenteritis among children. J Pediatr Health Care 2004 Jul-Aug; 18(4): 211-2[Medline].
• Duggan C, Refat M, Hashem M, et al: How valid are clinical signs of dehydration in infants? J Pediatr Gastroenterol Nutr 1996 Jan; 22(1): 56-61[Medline].
• Duggan C, Fontaine O, Pierce NF, et al: Scientific rationale for a change in the composition of oral rehydration solution. JAMA 2004 Jun 2; 291(21): 2628-31[Medline].
• Duke T, Molyneux EM: Intravenous fluids for seriously ill children: time to reconsider. Lancet 2003 Oct 18; 362(9392): 1320-3[Medline].
• Fonseca BK, Holdgate A, Craig JC: Enteral vs intravenous rehydration therapy for children with gastroenteritis: a meta-analysis of randomized controlled trials. Arch Pediatr Adolesc Med 2004 May; 158(5): 483-90[Medline].
• Gorelick MH, Shaw, KN, Murphy, KO: Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics. 1997; May;(5):99: E6[Medline].
• Holliday M: The evolution of therapy for dehydration: should deficit therapy still be taught? Pediatrics 1996 Aug; 98(2 Pt 1): 171-7[Medline].
• Holliday MA, Friedman AL, Wassner SJ: Extracellular fluid restoration in dehydration: a critique of rapid versus slow. Pediatr Nephrol 1999 May; (4): 292-7[Medline].
• Holliday MA, Friedman AL, Segar WE, et al: Acute hospital-induced hyponatremia in children: a physiologic approach. J Pediatr 2004 Nov; 145(5): 584-7[Medline].
• Hoorn EJ, Geary D, Robb M, et al: Acute hyponatremia related to intravenous fluid administration in hospitalized children: an observational study. Pediatrics 2004 May; 113(5): 1279-84[Medline].
• King CK, Glass R, Bresee JS, et al: Managing acute gastroenteritis among children: oral rehydration, maintenance, and nutritional therapy. MMWR Recomm Rep 2003 Nov 21; 52(RR-16): 1-16[Medline].
• Miyasaka K, Shimizu N, Kojima J: Recent trends in pediatric fluid therapy. Methods Find Exp Clin Pharmacol 2004 May; 26(4): 287-94[Medline].
• Moritz ML, Ayus JC: Prevention of hospital-acquired hyponatremia: a case for using isotonic saline. Pediatrics 2003 Feb; 111(2): 227-30[Medline].
• Moritz ML, Ayus JC: Preventing neurological complications from dysnatremias in children. Pediatr Nephrol 2005 Aug 4;[Medline].
• Moritz ML, Manole MD, Bogen DL, Ayus JC: Breastfeeding-associated hypernatremia: are we missing the diagnosis?. Pediatrics 2005 Sep; 116(3): e343-7[Medline].
• Murphy C, Hahn S, Volmink J: Reduced osmolarity oral rehydration solution for treating cholera. Cochrane Database Syst Rev 2004; CD003754[Medline].
• Nager AL, Wang VJ: Comparison of nasogastric and intravenous methods of rehydration in pediatric patients with acute dehydration. Pediatrics 2002 Apr; 109(4): 566-72[Medline].
• Nalin DR, Hirschhorn N, Greenough W, et al: Clinical concerns about reduced-osmolarity oral rehydration solution. JAMA 2004 Jun 2; 291(21): 2632-5[Medline].
• Ozuah PO, Avner JR, Stein RE: Oral rehydration, emergency physicians, and practice parameters: a national survey. Pediatrics 2002 Feb; 109(2): 259-61[Medline].
• Phin SJ, McCaskill ME, Browne GJ, Lam LT: Clinical pathway using rapid rehydration for children with gastroenteritis. J Paediatr Child Health 2003 Jul; 39(5): 343-8[Medline].
• Playfor SD: Hypotonic intravenous solutions in children. Expert Opin Drug Saf 2004 Jan; 3(1): 67-73[Medline].
• Reid SR, Bonadio WA: Outpatient rapid intravenous rehydration to correct dehydration and resolve vomiting in children with acute gastroenteritis. Ann Emerg Med 1996 Sep; 28(3): 318-23[Medline].
• Santosham M, Keenan EM, Tulloch J, et al: Oral rehydration therapy for diarrhea: an example of reverse transfer of technology. Pediatrics 1997 Nov; 100(5): E10[Medline].
• Sarnaik AP, Meert K, Hackbarth R, Fleischmann L: Management of hyponatremic seizures in children with hypertonic saline: a safe and effective strategy. Crit Care Med. 1991; Jun;19(6): 758-62[Medline].
• Spandorfer PR, Alessandrini EA, Joffe MD, et al: Oral versus intravenous rehydration of moderately dehydrated children: a randomized, controlled trial. Pediatrics 2005 Feb; 115(2): 295-301[Medline].
• Steiner MJ, DeWalt DA, Byerley JS: Is this child dehydrated?. JAMA 2004 Jun 9; 291(22): 2746-54[Medline].
• Wathen JE, MacKenzie T, Bothner JP: Usefulness of the serum electrolyte panel in the management of pediatric dehydration treated with intravenously administered fluids. Pediatrics 2004 Nov; 114(5): 1227-34[Medline].

Dehydration excerpt