A 55-year-old man with a history of gastroesophageal reflux disease (GERD) is scheduled for emergency laparotomy for acute abdomen. He had a meal 2 hours ago. Which drug should be administered preoperatively to reduce the risk of acid aspiration pneumonitis?

Explanation

## Emergency Preoperative Acid Prophylaxis: Sodium Citrate **Key Point:** In emergency surgery with a full stomach (recent meal), **sodium citrate (non-particulate antacid)** is the drug of choice for *immediate* reduction of gastric acidity to prevent Mendelson's syndrome (acid aspiration pneumonitis). ### Why Sodium Citrate in This Emergency Setting? 1. **Immediate onset:** Acts within minutes of ingestion — critical when surgery cannot be delayed 2. **Directly neutralizes existing gastric acid:** Raises gastric pH above the critical threshold of 2.5 immediately 3. **Non-particulate:** Unlike magnesium trisilicate, sodium citrate does not cause granulomatous pneumonitis if aspirated 4. **Reliable in full-stomach emergencies:** The patient ate 2 hours ago — there is already acid present in the stomach that must be neutralized NOW **High-Yield:** Mendelson's syndrome risk is highest when gastric pH < 2.5 AND volume > 25 mL. Sodium citrate addresses the pH component immediately, which is the priority in an emergency with no time to wait for systemic agents. ### Drug Comparison in Preoperative Context | Agent | Onset | Mechanism | Emergency Suitability | |-------|-------|-----------|----------------------| | **Sodium citrate** | **Immediate** | Neutralizes existing acid | **Drug of choice for immediate use** | | Ranitidine | 30–60 min IV | H₂-blocker (reduces new secretion) | Useful adjunct if time permits; largely withdrawn globally | | Sucralfate | 1–2 hours | Mucosal protectant | Not for acute acid neutralization | | Lansoprazole | 1–2 hours | PPI (reduces new secretion) | Too slow for emergency | **Clinical Pearl (Morgan & Mikhail, Clinical Anesthesiology):** For emergency surgery with a full stomach, **0.3 M sodium citrate 30 mL orally** is given immediately before induction. It neutralizes gastric contents already present. H₂-blockers and PPIs reduce *future* acid secretion but cannot neutralize acid already in the stomach — making them inadequate as sole agents when surgery is imminent. **Why not Ranitidine?** Ranitidine (a) has a 30–60 minute onset even IV, (b) does not neutralize acid already present, and (c) has been widely withdrawn from global markets (including FDA withdrawal in 2020) due to NDMA contamination concerns. It cannot provide immediate protection in this scenario. **Mnemonic:** **"Citrate = Immediate; H₂ = Half-hour"** — In a true emergency with no time to spare, only sodium citrate acts fast enough.