Parents bring an infant seeking treatment for vomiting and diarrhea for two days. On assessment, the student finds dry mucous membranes and lethargy. What other finding suggests a fluid volume deficit?

1. A

   A sunken fontanelle

2. B

   Decreased pulse rate

3. C

   Increased BP

4. D

   Decreased urine specific gravity

Appeared in: DSSSB Public Health Nurse - 2015

Explanation

• A sunken or depressed anterior fontanelle is a classic and specific sign of moderate to severe dehydration in an infant whose fontanelles are still open.
• This occurs because the loss of body fluid, particularly from the extracellular fluid (ECF) compartment, reduces the volume of the cerebrospinal fluid and brain tissue, causing the soft spot on the skull to sink inward.
• Along with sunken eyes and dry mucous membranes, a depressed fontanelle is a key indicator of worsening dehydration in a child.

Why Other Options Were Wrong

• Option B: Fluid volume deficit causes tachycardia (an increased pulse rate) as a compensatory mechanism to maintain cardiac output and blood pressure, not a decreased pulse rate (bradycardia).
• Option C: Dehydration leads to hypovolemia (low blood volume), which results in hypotension (decreased blood pressure), particularly in moderate to severe cases.
• Option D: In dehydration, the kidneys work to conserve as much water as possible. This leads to the production of highly concentrated urine, which has an increased or high specific gravity (typically greater than 1.025).

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Assessment of fluid volume deficit (dehydration) in infants to guide bedside assessment, documentation, and the next nursing action.
• Accurate and rapid assessment of dehydration in infants is a critical nursing skill, as they can deteriorate much faster than adults due to their higher percentage of body water and metabolic rate.
• Nurses should teach parents to monitor for early signs of dehydration, such as fewer wet diapers, no tears when crying, and unusual sleepiness or fussiness.
• A key nursing intervention is to accurately monitor intake and output. For infants, this involves weighing diapers to quantify urine output (1 gram of weight equals approximately 1 mL of urine).

How to Approach the Question

• First, identify the patient population from the stem: an infant. This is a crucial clue that age-specific signs, like the fontanelle status, will be important.
• Next, identify the core clinical problem: a two-day history of vomiting and diarrhea, with existing signs of dehydration (dry mucous membranes, lethargy). The question asks for another sign.
• Systematically evaluate each option based on the pathophysiology of fluid volume deficit.
• Recall that fluid loss leads to decreased volume in all body compartments. This would cause a sunken fontanelle, not a bulging one.
• Remember the body's compensatory mechanisms: the heart rate increases (tachycardia) to compensate for low volume, and blood pressure eventually drops (hypotension).
• Consider the renal response: the kidneys conserve water, leading to concentrated urine with a high specific gravity.

Concept Tested & Keywords

• Concept Tested: Assessment of fluid volume deficit (dehydration) in infants.
• Stem keywords: infant, vomiting, diarrhea, dry mucous membranes, lethargy, fluid volume deficit
• Lead-in keywords: What other finding
• Clinical cues: The patient is an infant, making fontanelle assessment a key diagnostic sign.
• Clinical cues: A two-day history of vomiting and diarrhea points to a significant loss of body fluids.

Question ID

QeG548s3YVLjFJhyQ4RNnr

Copy ID

Reference Book

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 310-312

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 1 p. 140-142