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Pediatric Dehydration: What You Need to Know
Dehydration is a common clinical presentation in pediatrics, and it can lead to significant morbidity and mortality. It is important to recognize the signs and symptoms of dehydration in order to prevent complications such as hypovolemic shock, end-organ failure and death.
Case #1
A 4-month-old boy presents with copious vomiting and diarrhea for the last 24 hours. His parents say it started shortly after he woke up yesterday. He has not tolerated formula since the previous evening and has not urinated all day. The parents describe the diarrhea as non-bloody and liquid brown. The emesis is non-bloody and non-bilious. The parents mention that their son attends daycare. His first set of vitals is temperature 37ºC, pulse 170, respiratory rate 34, blood pressure 80/42. On exam the baby is difficult to arouse, his eyes are sunken, his mucous membranes are dry, and his anterior fontanel is depressed. On skin examination, his capillary refill time is 4 seconds, and he has abnormal skin turgor. Upon stimulation he begins to cry, but does not produce any tears.
Case #2
A 4-year-old girl, previously healthy, presents with fever, headache and vomiting for two days. Her parents say she started feeling weak last night prior to calling EMS. She refused her dinner and skipped breakfast today. She has vomited three times and is complaining of a headache and neck pain. Her vitals on presentation are temperature 39.4ºC, pulse 110, respiratory rate 16, blood pressure 100/60. She appears ill and mildly lethargic, and has tacky mucous membranes, normal capillary refill and normal skin turgor. On pulmonary exam, her lungs are clear to auscultation, and she has no accessory muscle use.
Epidemiology & Pathophysiology
Dehydration is a frequent reason for emergency room visits and affects at least 2 million children annually.1 Frequently caused by gastroenteritis, dehydration may result in serious morbidity and mortality. Gastroenteritis and dehydration account for 30% of all infant and toddler deaths worldwide, and approximately 300 deaths annually in the U.S.2 Gastroenteritis alone results in 1.9 million pediatric deaths annually, or 19% of all deaths under the age of 5.3
Clinically significant dehydration, as used in this review, refers to extracellular fluid volume depletion. The body contains two major volume compartments, the extracellular fluid (ECF) and intracellular fluid (ICF). The ICF represents two-thirds of the body’s fluid, while the ECF accounts for the remaining third. The ECF can further be divided into the interstitial fluid (75%) and plasma (25%). When symptoms of dehydration occur, the intravascular volume, the plasma component of the ECF, is depleted.
In infants (children under 1 year), the ECF and ICF comprise 70% of their total weight, while in adults they account for only 60%.4 An average 70-kg adult excretes 40 ml/kg of water per day, while a 5-kg infant excretes 100 ml/kg, and is therefore more susceptible to dehydration. 4 Infants and young children require greater volumes of water than adults to maintain a homeostatic fluid environment.
Clinical dehydration can be classified as mild (less than 3% change in body weight), moderate (3%–9% change in body weight) or severe (greater than 9% change in body weight).5 These are rough percentages and do not always correlate with clinical presentation.
Although the majority of children presenting with dehydration have associated acute gastroenteritis, it is important to consider the multiple other etiologies. Most pediatric dehydration is secondary to fluid losses from vomiting and diarrhea, but it can also be from severe bacterial infection such as pneumonia, meningitis or urinary tract problems. Other etiologies of dehydration include diabetic ketoacidosis, pyloric stenosis or anything causing increased intracranial pressure. Volume depletion can also occur secondary to trauma with associated hemorrhage.
Presentation
The presentation of dehydration may vary but can include the symptoms of vomiting, diarrhea, headache, abdominal pain and myalgias. Signs may include pallor, depressed anterior fontanel in newborns and infants, delayed capillary refill, abnormal skin turgor, abnormal respiratory pattern, absent tear production and tachycardia.
There are three clinical scales designed to asses the degree of dehydration in children (see Figure 1): a World Health Organization scale (used for children 1 month–5 years); the Gorelick scale (1 month–5 years); and the Clinical Dehydration Scale, or CDS (1 month–3 years).3 The WHO scale is composed of four clinical signs that are assessed based on severity. Demonstrating fewer than two signs from columns B and C correlates to less than 5% (or zero to mild) dehydration; demonstrating two signs from column B corresponds to 5%–10% dehydration; and showing two from column C corresponds to greater than 10% (or severe) dehydration. The Gorelick scale consists of multiple signs, each assigned one point. A total of 3 points or more corresponds to 5% change in body weight, and 7 points corresponds to a 10% change.3 The CDS is also composed of four clinical signs that are each scored from 0–2. A total score of 0 represents no dehydration, 1–4 is some dehydration, and 5–8 is moderate/severe dehydration.3
A group led by Dr. Kimberly Pringle of Brown University performed a study in Rwanda of children presenting with diarrhea and/or emesis and compared all three clinical scales against the gold standard for determining dehydration, body weight percentage change. All scales showed poor sensitivities and specificities and were found to be ineffective at predicting the actual degree of dehydration.3 Another study, led by Canadian pediatrician Benoit Bailey, MD, found the CDS scale was a good predictor of length of hospital stay (p<0.001).6
Although there is overlap among the three scales and they do not effectively predict true degree of dehydration, they all illustrate clinical signs that can be assessed within a matter of seconds, which can guide clinical decision making. A review of 26 dehydration studies found the most useful (i.e., highest likelihood ratios) signs for recognizing 5% dehydration are abnormal capillary refill, abnormal skin turgor and abnormal respiratory pattern.2 These three clinical parameters can be used effectively while assessing pediatric patients.
Management
After clinically evaluating the severity of dehydration, a practitioner can decide whether IV therapy is necessary. The WHO, CDC, American Academy of Pediatrics and European Society for Paediatric Gastroenterology and Nutrition all support the use of oral rehydration therapy (ORT) for mild or moderate dehydration.3,7 IV therapy is usually reserved for severe dehydration. In terms of prehospital management, ORT is typically not found on ambulances. Ideally, a patient should be transported to a hospital for a more thorough evaluation. If in the hospital it is determined that ORT is appropriate, 50 ml/kg should be given over four hours. For moderate dehydration, 100 ml/kg can be given over that period.7
In terms of IV therapy, the clinical standard is to administer an initial 20 ml/kg bolus of isotonic crystalloid fluid, such as 0.9% normal saline or lactated Ringer’s.7 If the patient does not respond to one bolus, it is appropriate to try a total of 3–4 20 ml/kg boluses before considering other etiologies of hypovolemia and prior to using pressors.5 Isotonic crystalloid is used to effectively restore intravascular volume without causing free water retention. Administering hypotonic fluid, such as 0.45% or 0.22% saline, can lead to hyponatremia.8
This is because dehydration causes a state of antidiuretic hormone (ADH) excess due to volume depletion. Administering hypotonic fluid with an elevated ADH would cause excess amounts of free water to be retained, leading to hyponatremia.9 One retrospective review of children found that 18.5% of those admitted with gastroenteritis who had normal blood sodium levels and were treated with hypotonic fluid developed mild hyponatremia.10 Hyponatremia can lead to serious neurologic sequelae, and thus hypotonic fluids should initially be avoided. Hyponatremia also frequently occurs when parents or other caregivers attempt to rehydrate children with fluids with inadequate amounts of sodium, such as water, juice, soda and Gatorade.7 Caretakers should be advised against giving inappropriate oral rehydration solutions on scene or en route to the hospital.
A Cochrane Library database review found no significant clinical differences between ORT and IV therapy for treating dehydration secondary to gastroenteritis in children. ORT did have a higher rate of paralytic ileus; however, the IV group has all the risks related to IV placement and therapy. For every 25 children who received ORT, one failed and needed IV hydration.11
Other rehydration methods include nasogastric, intraperitoneal, subcutaneous, intraosseous and rectal rehydration. Unfortunately, there are few clinical trials that evaluate the efficacy and long-term safety of some of these techniques. Nasogastric rehydration has been adequately studied. It is a safe technique with minimal adverse effects and has been found in four different clinical trials to have efficacy similar to IV therapy.1 NG rehydration can be performed using nonsterile oral rehydration solution.
Intraosseous rehydration is also as effective as IV therapy.1 Furthermore, IO access is sometimes faster and more reliable than IV access; however, it should only be reserved for crisis situations.
Hospital Management
Depending on the etiology and severity of the dehydration, further studies may be performed in the hospital. If the dehydration is so severe that the patient has an altered mental status, an appropriate laboratory workup may be conducted. A basic metabolic panel will typically be drawn which analyzes certain electrolyte levels in the blood, such as sodium, potassium and bicarbonate. Disturbances in these electrolytes are associated with dehydration.
Case Reviews
1) According to all scales for the evaluation of dehydration, this baby classifies as severely dehydrated. His mental status is poor, and he has multiple signs on exam indicating the severity of his dehydration. Additionally, his vital signs show mild tachycardia, corresponding with low intravascular volume. His respiratory rate and blood pressure are appropriate for his age. This baby should receive a 20 ml/kg bolus of isotonic crystalloid fluid either IV or IO (if IV access fails) and be transported to the hospital immediately. As for the etiology of his dehydration, he likely suffered from acute viral gastroenteritis. He may have been infected with a virus at daycare and subsequently developed symptoms. The organism is unlikely bacterial given the baby’s lack of fever, lack of blood in the stool and relatively short duration of symptoms.
2) This child is dehydrated, though clinically less dehydrated than the infant in case #1. She is mildly lethargic and has dry and sticky mucous membranes; however, her capillary refill and skin turgor are normal. Additionally, she has a normal respiratory pattern. With the exception of a fever, the rest of her vital signs are appropriate for her age. According to the WHO and Gorelick scales (the appropriate scales for the age of 4 years), she can be categorized as mildly dehydrated given her mental status and dry mucous membranes. She does not require IV therapy unless she does not tolerate ORT. As for the etiology of her mild dehydration, her presentation is suspicious for meningitis. Transport her promptly to the hospital for further evaluation.
Conclusion
Dehydration occurs frequently, and young children are at increased risk. Recognize key clinical signs such as abnormal capillary refill, abnormal skin turgor and irregular respiratory pattern. If in doubt about the severity of dehydration, give a 20 ml/kg bolus of normal saline and transport the child to the hospital.
References
1. Rouhani S, Meloney L, Ahn R, Nelson BD, Burke TF. Alternative rehydration methods: a systemic review and lessons for resource-limited care. Pediatrics 2011; 127: e748.
2. Steiner MJ, DeWalt DA, Byerley JS. Is this child dehydrated? JAMA 2004; 291: 2,746–54.
3. Pringle K, Shah SP, Umulisa I, et al. Comparing the accuracy of the three popular clinical dehydration scales in children with diarrhea. Int J Emerg Med 2011; 4: 58.
4. Reid SR, Losek JS. Rehydration role for early use of intravenous dextrose. Pedi Emerg Care 2009; 25: 49–55.
5. Takayesu JK, Bachur RG. Pediatric dehydration. Medscape, https://emedicine.medscape.com/article/801012-overview.
6. Bailey B, Gravel J, Goldman RD, Friedman JN, Parkin PC. External validation of the clinical dehydration scale for children with acute gastroenteritis. Acad Emerg Med 2010; 17(6): 583–8.
7. Canavan A, Arant BS. Diagnosis and management of dehydration in children. Am Fam Phys 2009; 80(7): 692–96.
8. Holliday MA, Ray PE, Friedman AL. Fluid therapy for children: facts, fashions, and questions. Arch Dis Child 2007; 92: 546–50.
9. Moritz ML, Ayus JC. Improving intravenous fluid therapy in children with gastroenteritis. Pediatr Nephrol 2010; 25: 1,383–4.
10. Hanna M, Saberi MS. Incidence of hyponatremia in children with gastroenteritis treated with hypotonic intravenous fluid. Pediatr Nephrol 2010; 25: 1,471–75.
11. Hartling L, Bellemare S, Wiebe N, Russell K, Klassen TP, Craig W. Oral versus intravenous rehydration for treating dehydration due to gastroenteritis in children. Cochrane Database Syst Rev 2006; 19(3): CD004390.
Jonathan Ludmir, MD, is a resident in Internal Medicine and Pediatrics at the Hospital of the University of Pennsylvania, Children’s Hospital of Philadelphia.
