Infants with hypertrophic pyloric stenosis (IHPS) require meticulous preoperative stabilization due to the predictable metabolic derangement caused by persistent vomiting of gastric contents. The priority is always to correct the hypochloremic, hypokalemic metabolic alkalosis and dehydration before proceeding to pyloromyotomy.
Key Preoperative Priorities
- Fluid Resuscitation: Initiate intravenous (IV) isotonic fluids, typically 0.9% NaCl with 5% dextrose, to restore intravascular volume. Potassium is added only after adequate urine output is established to prevent hyperkalemia.
- Electrolyte Monitoring: Serial serum electrolyte panels are essential. Surgical correction is generally delayed until the serum chloride is above 100 mEq/L and bicarbonate is below 30 mEq/L, indicating resolution of the metabolic alkalosis.
- Gastric Decompression: A nasogastric (NG) tube is placed to low intermittent suction to decompress the stomach and prevent further vomiting and aspiration.
- Strict Intake and Output: Monitor urine output closely as a primary indicator of renal perfusion and adequate fluid resuscitation. Document all emesis and NG tube output.
Critical Safety Alert
- Avoid Oral Intake: The infant must remain NPO (nothing by mouth). Oral rehydration is contraindicated due to the mechanical obstruction and high risk of vomiting and aspiration.
- Positioning: To reduce the risk of aspiration, position the infant with the head of the bed elevated, not prone. Supine positioning for sleep remains the standard for SIDS prevention, but vigilant monitoring is required.
- Anesthesia Risk: Uncorrected metabolic alkalosis significantly increases the risk of intraoperative and postoperative apnea, cardiac arrhythmias, and respiratory depression.
The surgical procedure, pyloromyotomy, is minimally invasive and curative, but its safety is entirely dependent on achieving a stable physiological state preoperatively. The nursing role is to continuously assess hydration status, ensure IV therapy is patent and accurate, and monitor for signs of electrolyte imbalance such as changes in muscle tone or cardiac rhythm.