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Management of Engine Oil (Hydrocarbon) Poisoning

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Pathophysiology

• Ingestion — GI irritant; systemic absorption is poor due to high viscosity
• Inhalation — vapor exposure in occupational settings
• Dermal — defatting dermatitis, irritant contact

• C — Camphor → seizures, neurotoxicity
• H — Halogenated hydrocarbons → dysrhythmias, hepatotoxicity
• A — Aromatic hydrocarbons → bone marrow suppression, leukemia
• M — Metals (lead, arsenic, mercury) → neurotoxicity (engine oil often contains zinc, lead, or other metals)
• P — Pesticides → cholinergic crisis, seizures

Engine oil additives (detergents, zinc dialkyldithiophosphate, antioxidants) may cause additional toxicity. Always attempt to identify the specific product.

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Initial Assessment

• Identify exact product and additives (bring the container if possible)
• Estimate quantity ingested/inhaled and time of exposure
• Route of exposure (ingestion vs. aspiration vs. dermal vs. inhalation)

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Investigations

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Management

1. Airway & Breathing

• Secure the airway if significant respiratory or CNS depression is present
• Swelling of lips/tongue from irritant effects may complicate intubation
• Supplemental oxygen to correct hypoxia
• Inhaled β₂-agonists for bronchospasm
• PEEP/CPAP if needed for adequate oxygenation
• Mechanical ventilation indications: hypercarbia, severe respiratory distress, hypoxia unresponsive to noninvasive measures, CNS depression
• Consider intrapulmonary surfactant for severe pneumonitis (elevated oxygenation index, poor lung compliance)

2. Circulation

• IV crystalloid for hypotension
• Avoid catecholamines (epinephrine, dopamine, norepinephrine) — they sensitize the myocardium to hydrocarbon-induced dysrhythmias
• For ventricular dysrhythmias: propranolol, esmolol, or lidocaine
  • Esmolol: 1 mg/kg IV bolus over 30 sec, then infusion at 50 mcg/kg/min (max 300 mcg/kg/min)
  • Avoid class IA (procainamide) and class III (amiodarone, sotalol) antiarrhythmics — risk of QT prolongation

3. Decontamination

• Gastric lavage — NOT indicated (risk of aspiration outweighs benefit)
• Activated charcoal — NOT indicated (does not adsorb hydrocarbons; increases aspiration risk)
• Exception: consider poison center consultation if a highly toxic additive (e.g., organophosphate, aromatic/halogenated hydrocarbon) was ingested very recently (<1 hour) — but even then, benefit is unproven

• Remove all hydrocarbon-soaked clothing
• Wash skin with soap and copious cold/lukewarm water
• Eye exposure: saline irrigation
• Staff must wear protective gloves and aprons (especially if organophosphate mixtures)

4. Antidotes (where applicable)

• Oxygen (high-flow/hyperbaric) for carboxyhemoglobinemia (methylene chloride metabolite)
• Methylene blue for methemoglobinemia

5. What NOT to do

• ❌ Corticosteroids — not beneficial in hydrocarbon pneumonitis
• ❌ Prophylactic antibiotics — not indicated unless superimposed bacterial pneumonia is clinically suspected
• ❌ Epinephrine or catecholamines for hemodynamic support
• ❌ Induced emesis

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Disposition

• Consult a medical toxicologist or regional poison control center for symptomatic exposures and for those involving toxic additives
• Hospitalization also warranted if delayed complications are expected (e.g., halogenated hydrocarbon hepatotoxicity)
• Psychiatric/behavioral health evaluation for intentional self-poisoning or solvent abuse

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Key Points Specific to Engine Oil

• Engine oil is high viscosity → lower aspiration risk than gasoline or kerosene, but not zero
• Engine oil contains metal additives (zinc, lead, phosphorus compounds) → check for systemic metal toxicity
• Used engine oil is a potential carcinogen (contains polycyclic aromatic hydrocarbons from combustion)
• Most acute ingestions of pure engine oil are managed supportively without GI decontamination

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Management of Abdominal Pain

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Step 1 — Initial Stabilisation (Any Acute Presentation)

• Vital signs: HR, BP, RR, SpO₂, temperature, GCS
• IV access and fluid resuscitation if haemodynamically compromised
• Nil by mouth if surgical pathology is suspected
• Analgesia early — do not withhold analgesia awaiting diagnosis; this is supported by evidence and does not impair diagnostic accuracy

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Step 2 — History (Characterise the Pain)

• Sudden severe "tearing" onset → AAA / aortic dissection
• Signs of shock (hypotension, tachycardia)
• Peritonism (rigid abdomen, guarding, rebound tenderness)
• Absence of bowel sounds → obstruction or ileus
• Pulsatile abdominal mass → AAA

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Step 3 — Physical Examination

• Inspect: distension, scars, hernias, jaundice
• Auscultate: bowel sounds (high-pitched = obstruction; absent = peritonitis/ileus)
• Percuss: tympany (gas, obstruction), dullness (fluid, mass)
• Palpate: tenderness, guarding, rigidity, masses, organomegaly
• Carnett's sign: pain worsens with tensed abdominal muscles → suggests abdominal wall origin rather than visceral
• Rectal exam if indicated (PR blood, pelvic mass)
• Pelvic exam in women with lower abdominal pain (consider PID, ectopic pregnancy)

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Step 4 — Investigations

Bedside

• Urine dipstick ± β-hCG (all women of childbearing age)
• ECG (exclude inferior MI presenting as epigastric pain)

Blood tests

Imaging

In older patients, laboratory values and vital signs are often falsely normal despite serious pathology. Maintain a low threshold for CT in the elderly.

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Step 5 — Analgesia

Mild Pain

• Paracetamol (acetaminophen): 1 g oral/IV every 6 hours
• NSAIDs (e.g., ibuprofen, diclofenac): effective for colicky pain; avoid in PUD, renal impairment, GI bleeding

Moderate to Severe Pain

• Opioids are the drugs of choice for moderate-to-severe visceral abdominal pain
  • Morphine: 0.1 mg/kg IV titrated; peak effect 60–90 min orally, faster IV
  • Hydromorphone: if morphine not tolerated
  • Fentanyl IV: faster onset, useful in procedural settings
• There is no evidence that early analgesia masks the diagnosis — withholding it is not justified

Antispasmodics

• Hyoscine butylbromide (Buscopan): for smooth muscle spasm (IBS, biliary/ureteric colic)

Specific situations

• Biliary/renal colic: NSAIDs (diclofenac IM/IV) are effective; opioids if inadequate
• Pancreatitis: IV opioids; early IV fluids (Ringer's lactate preferred); nil by mouth
• Functional/chronic abdominal pain:
  • Tricyclic antidepressants (TCAs) — most proven for chronic visceral pain (e.g., amitriptyline 10–25 mg nocte); effective at doses lower than those used for depression
  • SNRIs (duloxetine, venlafaxine): alternative; duloxetine approved for chronic pain syndromes
  • SSRIs: benefit for global wellbeing but less effective for pain than TCAs
  • Avoid long-term opioids for functional pain — risk of opioid-induced hyperalgesia

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Step 6 — Treat the Underlying Cause

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Step 7 — Disposition

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Special Populations

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