A 4-week-old infant is admitted with a diagnosis of hypertrophic pyloric stenosis. The infant has been vomiting for the past week and shows signs of dehydration. Which nursing intervention should be the priority immediately after admission?

The priority nursing intervention is to establish IV access and monitor electrolyte balance to correct fluid and electrolyte imbalances before surgery. Other options are contraindicated or less immediate.

Core Nursing Explanation This question assesses the priority nursing intervention for an infant with Hypertrophic pyloric stenosis (HPS) who is dehydrated. The core concept is preoperative stabilization. HPS causes a mechanical obstruction at the pylorus, leading to persistent, projectile, non-bilious vomiting. This results in significant losses of gastric fluids (hydrochloric acid and potassium), leading to a Key Point! hypochloremic, hypokalemic metabolic alkalosis. The infant's condition is a surgical emergency, but the patient must be stabilized *before* going to the operating room. Answer Rationale Key Point! The correct answer is Establish intravenous access and monitor electrolyte balance. This is the priority because: 1. Correcting Fluid and Electrolyte Imbalance is Life-Saving: The dehydration and metabolic alkalosis are the immediate threats to the infant's life. IV access allows for rapid correction of volume depletion with isotonic fluids (e.g., Normal Saline). 2. Essential for Safe Anesthesia and Surgery: Operating on a patient with uncorrected electrolyte imbalances and dehydration is extremely dangerous, increasing risks of arrhythmias and poor response to anesthesia. 3. Monitoring (e.g., serum electrolytes like chloride, potassium, sodium, and blood gases) guides the rate and composition of IV fluid replacement. Distractor Analysis Watch out for confusion!

• Option 1 (Oral rehydration): Is contraindicated. The pylorus is obstructed, so any oral intake will likely be vomited, worsening dehydration and the risk of aspiration. The infant is made NPO (Nothing by mouth) until after surgery.
• Option 2 (Prone positioning): While placing the infant on the right side or upright may help reduce vomiting, and careful positioning is important for aspiration prevention, it is a supportive measure, not the priority intervention for correcting the life-threatening physiological derangement.
• Option 3 (Prepare for immediate surgery): This is the definitive treatment (a Pyloromyotomy), but it is not the immediate nursing priority upon admission. The nursing role is to recognize that stabilization precedes intervention. The nurse prepares the infant *for* surgery by first achieving physiological stability.

Related Concepts The classic presentation of HPS includes: non-bilious, projectile vomiting; visible peristaltic waves; and a palpable "olive-shaped" mass in the right upper quadrant. Diagnosis is often confirmed by ultrasound. Postoperatively, feeding is gradually resumed, starting with small amounts of clear liquids or formula. Concept Summary
Pathophysiology: Hypertrophy of pyloric muscle → Gastric outlet obstruction → Projectile vomiting → Loss of H+ and Cl- → Hypochloremic, hypokalemic metabolic alkalosis & dehydration.
Priority Nursing Diagnosis: Deficient Fluid Volume / Imbalanced Nutrition: Less Than Body Requirements / Risk for Aspiration.
Pre-op Priority: IV access, fluid resuscitation, electrolyte correction (focus on Chloride < 98 mEq/L and Potassium).
Definitive Treatment: Pyloromyotomy (surgery). Side-by-Side Comparison!

Condition	Type of Vomiting	Key Feature	Immediate Nursing Priority
Hypertrophic Pyloric Stenosis (HPS)	Projectile, non-bilious	Palpable "olive" mass, metabolic alkalosis	IV fluids & correct electrolytes (pre-op stabilization)
Gastroesophageal Reflux (GER)	Regurgitation/spitting up	Worsens with lying flat, often improves with age	Positioning, feeding adjustments, parental education
Intestinal Malrotation with Volvulus	Bilious (green) vomiting	Surgical emergency, abdominal distension, pain	Immediate notification of provider, prepare for emergency surgery

Anatomy, Physiology & Pharmacology Points
Anatomy: The pylorus is the muscular valve between the stomach and duodenum. Hypertrophy blocks this passage.
Physiology: Vomiting gastric acid (HCl) loses H+ (causing alkalosis) and Cl- (causing hypochloremia). The kidneys excrete K+ and H+ to retain Na+, worsening hypokalemia and alkalosis.
Pharmacology: IV fluids are the "drug." Normal Saline (0.9% NaCl) is often first-line to replace chloride. Potassium chloride (KCl) is added to the IV fluids once urine output is confirmed. Memory Tips
HPS = "Hard Pylorus, Stabilize First": Remember the hard "olive" mass and that stabilization (IV fluids/electrolytes) comes before surgery.
Vomiting Formula: Think of the lost gastric contents as H+, Cl-, and K+ (You can remember "HCK" for the losses). High-Frequency NCLEX Topics NCLEX loves to test prioritization and delegation. For pediatric surgical conditions, the pattern is often: 1) Recognize life-threatening symptoms (e.g., dehydration, bilious vomiting), 2) Know that stabilization (ABCs, fluids) is almost always the nurse's first action, 3) Then prepare for the definitive procedure. Watch Out for Question Variations!

• Instead of asking for the priority intervention, it might ask: "The nurse should monitor for which laboratory finding?" → Answer: Metabolic alkalosis (elevated pH and HCO3-, low Cl- and K+).
• Or: "Which finding requires immediate notification to the provider postoperatively?" → Answer: Bilious vomiting (suggests a complication, whereas non-bilious vomiting is common initially).
• Or: "The parent asks why the baby can't eat before surgery. What is the nurse's best response?" → Explain the obstruction and risk of aspiration.

Nursing Clinical Practice Guide Clinical Scenario: You are the nurse in the Pediatric Emergency Department. A young mother brings in her 4-week-old son. She reports he has been vomiting forcefully after every feed for 5 days, and now he seems listless, has a sunken fontanelle, and has had only one wet diaper in 12 hours. The pediatrician suspects hypertrophic pyloric stenosis. Nursing Intervention Strategy: 1. Assessment: Perform a focused assessment: Vital signs (tachycardia, hypotension?), weight (compare to birth weight), hydration status (skin turgor, mucous membranes, fontanelle), abdominal exam (visible peristaltic waves? attempt to palpate for an olive-shaped mass in the right upper quadrant during a feed or after vomiting). 2. Immediate Action (Priority): Obtain IV access (often challenging in a dehydrated infant; may require an experienced nurse or use of a vein finder). Send STAT labs: Electrolytes (Na, K, Cl, CO2), BUN/Creatinine, and possibly a blood gas. 3. Care Implementation: * Initiate IV fluid resuscitation per protocol (e.g., 20 mL/kg bolus of Normal Saline). * Place the infant NPO. Place a sign above the crib. * Maintain accurate I&O (Intake and Output) and daily weights. * Position the infant on the right side or upright to minimize gastric contents in the esophagus. * Provide emotional support and clear explanations to the anxious parents. 4. Monitoring & Evaluation: Closely monitor electrolyte results. The goal is to correct the chloride deficit (aim for Cl > 100 mEq/L) and ensure adequate urine output (>1-2 mL/kg/hr) before surgery. Assess for resolution of dehydration signs. Patient Safety and Precautions: * Key Point! Never attempt oral feeds once HPS is suspected until cleared by the surgeon postoperatively. * Handle the abdomen gently during assessment to avoid causing discomfort. * During IV therapy, use an infusion pump and carefully monitor the site for infiltration, as the infant's veins are fragile. Nursing Procedure & Medication Flow
Procedure: Managing IV Fluids for a Dehydrated Infant 1. Verify provider's order for IV fluid type and rate (e.g., D5 1/2 NS + 20 mEq KCl/L at maintenance rate). 2. Calculate the rate based on weight (e.g., using the 4-2-1 rule or hospital pediatric protocol). 3. Prime IV tubing, ensuring no air bubbles. 4. Start IV in an appropriate site (e.g., hand, foot, scalp vein). 5. Secure the site well with a transparent dressing and an arm board if needed. 6. Label the tubing with date/time and rate. 7. Program the infusion pump with the correct rate (mL/hr) and set appropriate pressure alarms. 8. Critical: Do not add potassium (KCl) to the IV fluids until you have confirmed the infant is voiding (has adequate renal function). A Word from Your Senior Nurse "In pediatrics, your assessment skills are everything. That sunken fontanelle and those few wet diapers tell you this baby is in trouble before the lab results even come back. Remember the mantra: 'Fix the plumbing before you call the plumber.' In this case, the surgeon is the plumber, but your job is to get the patient's fluid and electrolyte 'pipes' in working order first. This prioritization saves lives and is exactly what the NCLEX wants you to know. Always think: What is the immediate threat to life? Here, it's not the obstructed pylorus itself—it's the dehydration and alkalosis it caused."