Fontanel depression
Depression of the anterior fontanel below the surrounding bony ridges of the skull is a sign of dehydration. A common disorder of infancy and early childhood, dehydration can result from insufficient fluid intake, but it typically reflects excessive fluid loss from severe vomiting or diarrhea. It may also reflect insensible water loss, pyloric stenosis, or tracheoesophageal fistula. Assess the fontanel when the infant is in an upright position and isn’t crying.
Emergency interventions
If you detect a markedly depressed fontanel, take vital signs, weigh the infant, and check for signs of shock—tachycardia, tachypnea, and cool, clammy skin. If these signs are present, insert an I.V. line and administer fluids. Have size-appropriate emergency equipment on hand. Anticipate oxygen administration. Monitor urine output by weighing the wet diapers.
History and physical examination
Obtain a thorough patient history from a parent or caregiver, focusing on recent fever, vomiting, diarrhea, and behavioral changes. Monitor the infant’s fluid intake and urine output over the last 24 hours, including the number of wet diapers during that time. Ask about the child’s pre-illness weight, and compare it with his current weight; weight loss in an infant reflects water loss.
Medical causes
Dehydration
In mild dehydration (5% weight loss), the anterior fontanel appears slightly depressed. Other findings include pale, dry skin and mucous membranes; decreased urine output; a normal or slightly elevated pulse rate; and possibly irritability.
Moderate dehydration (10% weight loss) causes slightly more pronounced fontanel depression along with gray skin with poor turgor, dry mucous membranes, decreased tears, and decreased urine output. The infant has normal or decreased blood pressure and an increased pulse rate; he may also be lethargic.
Severe dehydration (15% or greater weight loss) may result in a markedly sunken fontanel along with extremely poor skin turgor, parched mucous membranes, marked oliguria or anuria, lethargy, and signs of shock, such as rapid, thready pulse, very low blood pressure, and obtundation.
Special considerations
Continue to monitor the infant’s vital signs and intake and output, and watch for signs of worsening dehydration. Obtain serum electrolyte values to check for an increased or decreased sodium, chloride, or potassium level. If the patient has mild dehydration, provide small amounts of clear fluids frequently or provide an oral rehydration solution. If the infant can’t ingest sufficient fluid, begin I.V. parenteral nutrition.
If the patient has moderate to severe dehydration, your first priority is rapid restoration of extracellular fluid volume to treat or prevent shock. Continue to administer the I.V. solution with sodium bicarbonate added to combat acidosis. As renal function improves, administer I.V. potassium replacements. Once the infant’s fluid status has stabilized, begin to replace depleted fat and protein stores through diet.
Tests to evaluate dehydration include urinalysis for specific gravity and possibly blood tests to determine blood urea nitrogen and serum creatinine levels, osmolality, and acid-base status.
Book Source Details
- Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.
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Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2008 Williams & Wilkins.
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