JAMA RCE Rundown

This month’s RCE Rundown asks the question:  Is this child dehydrated?

The background:
  • Non-hemorrhagic hypovolemia is commonly classified as mild (3-5%), moderate (6-9%) and severe (>10%)
  • The level of dehydration in children is important, since you can attempt to orally rehydrate those with mild dehydration
  • The assessment of dehydration can be separated into signs of tissue desiccation (dry mucous membranes, skin turgor) and compensatory reactions to maintain vital perfusion (capillary refill time, low urine output)

So what can I rely on to help me recognize dehydration and distinguish between mild and severe?

The quick answer:

1.  No individual sign is reliable, but the best 3 individual examination signs for assessing dehydration are:

  • prolonged capillary refill time
  • abnormal skin turgor
  • abnormal respiratory pattern

2.  Groups of signs or use of clinical scales improves diagnostic characteristics
3.  A normal bicarbonate concentration helps somewhat to reduce the likelihood of dehydration

Will a decision tool help me?

The most evidence-based scale that has been created to form a prediction tool was put out by Gorelick et al many years ago, but it still demonstrates the most enduring data. They use 10 physical exam findings weighted equally (see table; of note, a, sunken anterior fontanelle is not a criterion).

Having 3 or more signs present yields an LR of 4.9 that the child is at least 5% dehydrated. The presence of 7 or more of the 10 signs in your patient gives an LR of 8.4 that the child is severely (at least 10%) dehydrated.

Is there a scale that I would actually use in the ED?
A simplified version of this scale takes 4 of the most predictive elements and weighs them equally:

  • capillary refill time
  • dry mucous membranes
  • absence of tears
  • abnormal overall appearance

If a child demonstrates 2 of these 4 elements there is a LR of 6.1 to predict at least 5% dehydration. The presence of 3 findings offers an LR of 4.7 for severe dehydration (>10%).

If only one or none of these findings are present, there is an LR(-) of 0.24 for 5% dehydration, making it a useful quick assessment tool.

4pt scale

Steiner, DeWalt, Byerley. Is This Child Dehydrated? Ch. 25 in JAMA Rational Clinical Exam. 2009
Gorelick MH1, Shaw KN, Murphy KO. Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics. 1997 May;99(5):E6.

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