Understanding the Clinical Picture
A
2-month-old infant with
hypertrophic pyloric stenosis (HPS) presents with a history of projectile, non-bilious vomiting over the past week. The pathophysiology involves hypertrophy of the pyloric muscle, leading to gastric outlet obstruction. Persistent vomiting results in the loss of hydrochloric acid from the stomach. This sequence causes a specific set of metabolic derangements:
hypochloremic, hypokalemic metabolic alkalosis. The accompanying dehydration can range from mild to severe, and the infant is at risk for electrolyte imbalances that may predispose them to cardiac arrhythmias. However, the immediate preoperative priority targets the root cause of ongoing fluid and electrolyte loss: the gastric distention and obstruction.
Prioritizing Preoperative Nursing Interventions
The question asks for the
priority nursing intervention before surgery. Using clinical reasoning, the nurse must first address the physiological problem that is actively causing deterioration and could lead to immediate life-threatening complications, such as aspiration.
Analysis of the Correct Answer
Option 3: Insert nasogastric tube for gastric decompression.
This is the correct priority action. In hypertrophic pyloric stenosis, the stomach is obstructed and often remains full of gastric contents and secretions that cannot pass into the duodenum. This poses a high risk of aspiration, especially in a dehydrated and weak infant. Decompressing the stomach with a
nasogastric (NG) tube immediately reduces this risk and allows for accurate measurement of ongoing gastric losses. This step is a fundamental component of preoperative stabilization, as highlighted in case reports discussing anesthetic preparation for pyloromyotomy, where ensuring an empty stomach is critical before induction
[3]. The consensus statement on pediatric anesthesia also underscores the importance of managing the unique physiological vulnerabilities of infants, where aspiration risk is a primary safety concern .
Analysis of Incorrect Options
Option 1: Administer oral electrolyte solution to correct fluid deficit.
This is contraindicated. The infant has a gastric outlet obstruction, meaning any oral intake will not pass into the small intestine for absorption and will instead accumulate in the stomach, worsening distention and dramatically increasing the risk of vomiting and aspiration. Fluid and electrolyte correction in HPS is achieved exclusively through intravenous (IV) fluid therapy, not oral routes.
Option 2: Position the infant prone to prevent aspiration.
This is an unsafe practice. Current safe-sleep and aspiration-prevention guidelines for infants recommend the
supine position for sleep. For an infant with active vomiting and a full stomach, the prone position does not reliably protect the airway and is associated with an increased risk of sudden infant death syndrome (SIDS). The correct nursing action to prevent aspiration is to place the infant in a semi-upright or side-lying position if vomiting occurs, but the definitive intervention is gastric decompression via an NG tube.
Option 4: Begin continuous cardiac monitoring for arrhythmias.
While this is an important intervention, it is not the
priority. The severe electrolyte imbalances (hypokalemia) that result from prolonged vomiting can indeed lead to cardiac arrhythmias, making monitoring necessary. However, cardiac monitoring is a diagnostic and surveillance measure. It does not treat the underlying cause of the electrolyte loss. The priority is to stop the ongoing loss of gastric acid by decompressing the stomach, which is the source of the problem. The emergency medicine curriculum for pediatric gastrointestinal emergencies reinforces that stabilization begins with addressing the immediate anatomical and physiological insult . Once the NG tube is placed and IV fluid replacement is started, continuous cardiac monitoring is then established as part of comprehensive care.
References (research sources)