What are the best preoperative medications for a 14-year-old patient, weighing 42 kilograms, undergoing Open Reduction Internal Fixation (ORIF) of the femur, with a 6-hour Nil Per Os (NPO) status, considering options like Ranitidine, Omeprazole, and Metoclopramide?

Preoperative Medication Recommendations for Pediatric Femur ORIF

For a 14-year-old, 42kg patient undergoing ORIF femur with 6-hour NPO status, ranitidine 150mg orally is the most effective single-agent premedication for aspiration prophylaxis, though combining ranitidine with metoclopramide 10mg provides optimal protection by addressing both gastric acidity and volume.

Primary Recommendation: Ranitidine-Based Regimen

The combination of ranitidine 150mg (given the evening before and morning of surgery) plus metoclopramide 10mg (morning of surgery) provides the most comprehensive aspiration prophylaxis, with studies showing 0% of patients meeting high-risk criteria (pH <2.5 and volume >0.4 mL/kg). 1

Dosing Algorithm for This Patient (42kg):

• Ranitidine: 150mg orally at bedtime (night before surgery) AND 150mg orally on morning of surgery with 20mL water 2, 1
• Metoclopramide: 10mg orally on morning of surgery 1
• Timing: Morning dose should be given approximately 2-3 hours before anticipated induction 2, 3

Why This Combination is Superior

Ranitidine Efficacy:

• Two-dose ranitidine regimen (bedtime + morning) achieved mean gastric pH of 6.1 and volume of 0.09 mL/kg, with 0% of patients at risk for aspiration 2, 1
• Single morning dose of ranitidine 150mg was significantly more effective than omeprazole in reducing both pH and volume 2
• H2-blockers like ranitidine work rapidly (within 2-3 hours) and are highly effective for elective surgery 3, 1

Metoclopramide Addition:

• Metoclopramide independently reduces gastric volume through prokinetic effects, clearing existing gastric contents 1, 4
• The combination addresses both acidity (ranitidine) and volume (metoclopramide), providing dual-mechanism protection 1
• Metoclopramide 10mg is appropriate for this patient's weight and is FDA-approved for pediatric use above 14 years at adult dosing 5

Why NOT Omeprazole as Primary Agent

Omeprazole is significantly less effective than ranitidine for acute preoperative prophylaxis and should be avoided in this setting:

• Omeprazole 40mg given 2-4 hours preoperatively left 15% of patients at high risk (pH <2.5 and volume >0.4 mL/kg) compared to 0% with ranitidine 3
• Proton pump inhibitors require longer onset time (ideally 12-24 hours) to achieve maximal effect, making them suboptimal for elective surgery with standard NPO times 2, 3
• When directly compared, omeprazole was "significantly less effective in increasing gastric pH" than ranitidine 3
• Even two doses of omeprazole (80mg total) were inferior to single-dose ranitidine for aspiration prophylaxis 2, 4

Additional Perioperative Considerations for Femur ORIF

Pain Management:

• Regular paracetamol should be administered throughout the perioperative period 6
• NSAIDs can be used in pediatric orthopedic surgery but should be dosed appropriately for age and weight 6
• Regional anesthesia (femoral nerve block or fascia iliaca block) should be strongly considered for superior postoperative analgesia 6

Fluid Management:

• Ensure adequate preoperative hydration, as many trauma patients are hypovolemic 6
• Optimized perioperative fluid management reduces morbidity and hospital stay 6

Antibiotic Prophylaxis:

• Antibiotics must be administered within one hour of skin incision per institutional protocols 6

Critical Pitfalls to Avoid

• Do not use omeprazole as primary aspiration prophylaxis in elective surgery with standard NPO times—it is demonstrably inferior to ranitidine 2, 3
• Do not rely on metoclopramide alone—it reduces volume but does not adequately address gastric acidity 1
• Do not give medications without adequate water (20mL minimum) to ensure gastric absorption 2
• Avoid excessive metoclopramide dosing—10mg is appropriate; higher doses increase dystonic reaction risk, particularly in young patients 5

Practical Implementation

For this 14-year-old, 42kg patient:

1. Night before surgery (approximately 9:00 PM): Ranitidine 150mg PO with 20mL water 2, 1
2. Morning of surgery (2-3 hours before anticipated induction): Ranitidine 150mg PO + Metoclopramide 10mg PO with 20mL water 2, 1
3. Maintain NPO status except for medication administration with minimal water 2

This regimen provides the highest level of aspiration prophylaxis based on comparative evidence, with 0% of patients meeting high-risk criteria in the best available studies 2, 1.