Management of Sulphuric Acid (H₂SO₄) Ingestion

Pathophysiology

• Acids with pH < 2 cause coagulation necrosis: protein denaturation creates a protective eschar that partially limits penetration depth
• Despite this, sulphuric acid is highly concentrated and exothermic on contact with tissues, making it capable of full-thickness burns
• Gastric injury predominates over esophageal injury (opposite to alkali ingestions) because the esophageal squamous epithelium is more resistant, while gastric acid environment does not neutralize the ingested acid
• Systemic absorption can cause severe anion gap metabolic acidosis (specific to sulphuric acid), along with hemolysis, coagulopathy, and acute renal failure
• Risk of esophageal squamous cell carcinoma is 1000x higher after caustic esophageal injury, manifesting ~50 years later
• Tintinalli's Emergency Medicine, Chapter 200
• Yamada's Textbook of Gastroenterology, p. 990

Immediate Assessment

History

• Amount and concentration ingested, time of ingestion, intentional vs. accidental
• Suicidal intent = higher risk of large-volume ingestion
• Co-ingestants (screen for acetaminophen, salicylates in suicidal patients)

Physical Examination

• Oral/oropharyngeal burns - lip, buccal mucosa, tongue (may be absent even with significant esophageal injury)
• Dribble burns on chin and upper chest (Figure 200-2 in Tintinalli's) - suggest significant contact time
• Stridor, drooling, dysphagia, odynophagia - indicate pharyngeal/esophageal injury
• Respiratory distress - aspiration, airway edema, acute lung injury
• Peritoneal signs - hollow viscus perforation
• Chest wall/neck crepitus - subcutaneous emphysema from perforation (mediastinitis)
• Hemodynamic instability from GI bleeding, perforation, or systemic acid toxicity

Investigations

• Tintinalli's Emergency Medicine, p. 1338-1341

Contraindicated Interventions

1. Induced emesis / gastric lavage - reexposes mucosa to acid, risks aspiration
2. Activated charcoal - no benefit; may induce vomiting, obscure endoscopic visualization, worsen outcome if perforation present
3. Neutralization with alkali - exothermic reaction causes additional thermal injury
4. Nasogastric tube placement without endoscopic guidance - risk of perforation through injured mucosa

• Yamada's Textbook of Gastroenterology, p. 991
• Pfenninger and Fowler's Procedures for Primary Care, p. 4393

Emergency Management

1. Airway

• Early endotracheal intubation if there are signs of severe oral, pharyngeal, or supraglottic burns (stridor, dysphonia, edema)
• Airway edema can progress rapidly - secure airway before it is lost
• RSI preferred; have surgical airway backup ready

2. Resuscitation

• Large-bore IV access x2; resuscitate with crystalloids
• Central venous access for monitoring in severe cases
• Treat shock (GI hemorrhage, perforation, third-spacing, systemic acid toxicity)

3. Decontamination

• Dilution with water or milk (100-250 mL) may be considered within minutes of ingestion if patient is alert and able to swallow - limited evidence but low risk
• Do NOT attempt this in obtunded patients or if there is airway compromise

4. Endoscopy

• Timing: within 6-18 hours of ingestion
• Always perform in intentional/suicidal ingestions
• Perform in accidental ingestions when symptoms present (stridor, drooling, dysphagia, vomiting, oropharyngeal burns)
• Do not advance scope beyond first circumferential burn - greatly increases perforation risk (Rosen's Emergency Medicine)
• Grading guides all further management:

• Yamada's Gastroenterology, Table 48.1

Graded Management Based on Injury Severity

Grade 1 / Grade 2a

• Supportive care, diet as tolerated (grade 1) or NPO with gradual reintroduction
• Hospital admission recommended for grade 2a
• Oral feeding resumed when tolerated

Grade 2b / Grade 3 (No Perforation)

• ICU admission
• Esophageal rest (NPO for at least 1 week in severe burns)
• Early percutaneous feeding tube (gastrostomy/jejunostomy) or total parenteral nutrition (TPN)
• Dilation therapy within first 3 weeks (with or without stenting) to prevent stricture formation
• Monitor for evolving perforation, bleeding

Grade 4 / Perforation / Peritoneal Signs

• Emergency surgery (laparotomy preferred over laparoscopy for full posterior gastric visualization)
• Indications for surgery:
  • Esophageal or gastric perforation
  • Peritoneal signs / free intraperitoneal air
  • Large-volume ingestion (>150 mL)
  • Signs of shock unresponsive to resuscitation
  • Persistent lactic acidosis
  • Ascites or pleural fluid
  • Respiratory distress
• Procedures may include esophagectomy, total/partial gastrectomy
• Tintinalli's Emergency Medicine, p. 1341

Systemic Toxicity (Specific to Acid Ingestions)

• Severe anion gap metabolic acidosis (direct systemic effect - unique to sulphuric acid among common acids)
• Hemolysis
• Coagulopathy / DIC
• Acute kidney injury
• Non-cardiogenic pulmonary edema (acute lung injury)
• Hepatotoxicity

• Tintinalli's Emergency Medicine, p. 1341

Steroid Use (Controversial)

• Not routinely recommended
• Rationale was prevention of stricture formation by reducing inflammation
• One prospective trial showed benefit for grade 2b lesions; subsequent meta-analyses showed no benefit and potential harm (increased infection, perforation, hemorrhage)
• If used (e.g., dexamethasone 1 mg/kg/day or methylprednisolone), pair with antibiotics covering oral flora (penicillin or equivalent)
• Most current guidelines do not recommend routine steroid use
• Tintinalli's Emergency Medicine, p. 1340
• Yamada's Gastroenterology, p. 991

Long-term Complications and Follow-up

• Mulholland and Greenfield's Surgery, p. 2076
• Yamada's Gastroenterology, p. 991

Summary Algorithm

Sulphuric Acid Ingestion
         |
    AIRWAY FIRST
    (Intubate if oropharyngeal burns, stridor, dysphonia)
         |
  2x Large-bore IV, Bloods (ABG, FBC, CMP, LFTs, Lactate, Coag, T&S)
         |
  DO NOT: induce emesis, lavage, give charcoal, or neutralize
         |
  CT chest/abdomen (IV contrast) + CXR: rule out perforation
         |
       Perforation? ──YES──> Emergency Surgery (Laparotomy)
         |
        NO
         |
  Endoscopy within 6-18 hrs
    (Always in intentional ingestion)
         |
  Grade 1/2a ──> Supportive, diet resume, ward admission
         |
  Grade 2b/3 ──> ICU, NPO, early feeding tube/TPN,
                 dilation within 3 weeks
                 Monitor for delayed perforation
         |
  Systemic toxicity ──> Bicarbonate, RRT if needed
         |
  Long-term: surveillance endoscopy from year 15-20