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Emergency and Acute Medicine – Isopropanol Poisoning
Basics Description
Isopropanol (isopropyl alcohol) is a potent central nervous system depressant, with effects that are two to three times stronger than ethanol. It is rapidly absorbed after oral ingestion and is metabolized by alcohol dehydrogenase to acetone, which itself is a CNS depressant. Unlike other toxic alcohols, isopropanol is ketogenic but does not usually cause significant metabolic acidosis. Concomitant ethanol ingestion prolongs the half-life of isopropanol but not acetone. Isopropanol has a half-life of approximately 3–16 hours, while acetone persists longer, with a half-life of 7.5–26 hours. Acetone is eliminated through the lungs and kidneys.
Etiology
Isopropanol is a clear, colorless, volatile liquid with a bitter taste and a faint odor of acetone. It is commonly available as a 70% rubbing alcohol solution, sometimes containing blue dye (“blue heaven”) to discourage abuse. It is found in many household and industrial products, including toiletries, disinfectants, window cleaners, paint removers, solvents, jewelry cleaners, detergents, antifreeze, and hand sanitizers. The typical adult patient is a chronic alcoholic who has depleted their ethanol supply and substitutes isopropanol. Systemic toxicity can also occur from dermal absorption or rectal administration.
Diagnosis: Signs and Symptoms
Symptoms usually develop within 30–60 minutes of ingestion. Neurologic manifestations include lethargy, weakness, headache, inebriation, vertigo, ataxia, apnea, and coma. Unlike ethanol, an initial excitation phase is typically absent. Gastrointestinal symptoms are common and include nausea, vomiting, abdominal pain, gastritis, and hematemesis. Cardiovascular findings may include hypotension, tachycardia, myocardial depression, and peripheral vasodilation. Pulmonary effects include respiratory depression and hemorrhagic tracheobronchitis. Dermatologic exposure can cause skin irritation or burns, and ocular exposure leads to irritation and lacrimation.
In children, accidental ingestions are common in those younger than 6 years, and rubbing alcohol sponge baths may cause inhalational toxicity. Pediatric patients are particularly prone to hypoglycemia.
Essential Workup
Diagnosis is supported by a history of ingestion and the presence of an acetone or isopropanol odor on the patient’s breath.
Diagnosis Tests and Interpretation
Laboratory evaluation should include electrolytes, BUN, creatinine, and glucose. Hypoglycemia may be present. Significant acidosis is uncommon unless there is associated hypoperfusion or a coingestant. Acetone can falsely elevate serum creatinine; when acetone levels exceed 40 mg/dL, creatinine may rise approximately 1 mg/dL for every 100 mg/dL of acetone, returning to baseline as acetone is cleared. CBC may show decreased hematocrit in cases of hemorrhagic gastritis. Arterial blood gas analysis typically shows little or no acidosis. Urinalysis and serum testing reveal ketosis.
Serum isopropanol levels correlate with severity, with coma often occurring at levels above 150 mg/dL. Serum osmolarity should be assessed, as an elevated osmolar gap (>10) is common. Each 5.9 mg/dL of isopropanol and 5.5 mg/dL of acetone increases the osmolar gap by approximately 1 mOsm/kg. Chest radiography is indicated if aspiration pneumonia is suspected, and head CT should be considered when altered mental status or head injury is possible.
Differential Diagnosis
The differential diagnosis for CNS depression with an elevated osmolar gap includes ethanol, ethylene glycol, methanol, glycerol, and mannitol.
Treatment Prehospital
All potentially ingested bottles and medications should be located and transported with the patient to the emergency department.
Initial Stabilization and Therapy
Management begins with airway, breathing, and circulation. Airway protection and ventilatory support may be required. Hypotension should initially be treated with IV 0.9% normal saline; vasopressors such as dopamine or norepinephrine may be required if hypotension persists. Patients with significant hemorrhagic gastritis may require packed red blood cell transfusion. Nasogastric tube placement and irrigation may be indicated for hematemesis. Naloxone, thiamine, and dextrose should be administered for altered mental status as indicated.
ED Treatment and Procedures
Treatment is primarily supportive, as there is no specific antidote. Skin and eye exposures should be treated with copious irrigation. Activated charcoal may be considered for coingestants and, in large doses, can adsorb some isopropanol. Ethanol infusion and fomepizole (4-methylpyrazole) are not indicated. Hemodialysis effectively removes both isopropanol and acetone but is rarely required. Indications for dialysis include persistent hemodynamic instability despite fluids and pressors or very high serum levels (>400 mg/dL), which are associated with severe hypotension and prolonged coma.
Medication
Supportive medications may include activated charcoal, IV dextrose for hypoglycemia, dopamine for refractory hypotension, naloxone if opioid exposure is suspected, and thiamine for patients at risk of deficiency.
Follow-Up Disposition
Patients with moderate to severe toxicity, including altered mental status or hypotension, should be admitted. Asymptomatic patients should be observed for 2–4 hours after ingestion before discharge. Mild intoxication that resolves within 4–6 hours may be safely discharged.
Follow-Up Recommendations
Patients with intentional ingestion should be referred for alcohol detoxification or psychiatric evaluation. Gastroenterology referral is recommended for those with recurrent hematemesis requiring endoscopic evaluation.
Pearls and Pitfalls
Supportive care is the cornerstone of treatment for isopropanol poisoning. Unlike other toxic alcohol ingestions, ethanol infusion and fomepizole should not be used.
Basics Description
Isopropanol (isopropyl alcohol) is a potent central nervous system depressant, with effects that are two to three times stronger than ethanol. It is rapidly absorbed after oral ingestion and is metabolized by alcohol dehydrogenase to acetone, which itself is a CNS depressant. Unlike other toxic alcohols, isopropanol is ketogenic but does not usually cause significant metabolic acidosis. Concomitant ethanol ingestion prolongs the half-life of isopropanol but not acetone. Isopropanol has a half-life of approximately 3–16 hours, while acetone persists longer, with a half-life of 7.5–26 hours. Acetone is eliminated through the lungs and kidneys.
Etiology
Isopropanol is a clear, colorless, volatile liquid with a bitter taste and a faint odor of acetone. It is commonly available as a 70% rubbing alcohol solution, sometimes containing blue dye (“blue heaven”) to discourage abuse. It is found in many household and industrial products, including toiletries, disinfectants, window cleaners, paint removers, solvents, jewelry cleaners, detergents, antifreeze, and hand sanitizers. The typical adult patient is a chronic alcoholic who has depleted their ethanol supply and substitutes isopropanol. Systemic toxicity can also occur from dermal absorption or rectal administration.
Diagnosis: Signs and Symptoms
Symptoms usually develop within 30–60 minutes of ingestion. Neurologic manifestations include lethargy, weakness, headache, inebriation, vertigo, ataxia, apnea, and coma. Unlike ethanol, an initial excitation phase is typically absent. Gastrointestinal symptoms are common and include nausea, vomiting, abdominal pain, gastritis, and hematemesis. Cardiovascular findings may include hypotension, tachycardia, myocardial depression, and peripheral vasodilation. Pulmonary effects include respiratory depression and hemorrhagic tracheobronchitis. Dermatologic exposure can cause skin irritation or burns, and ocular exposure leads to irritation and lacrimation.
In children, accidental ingestions are common in those younger than 6 years, and rubbing alcohol sponge baths may cause inhalational toxicity. Pediatric patients are particularly prone to hypoglycemia.
Essential Workup
Diagnosis is supported by a history of ingestion and the presence of an acetone or isopropanol odor on the patient’s breath.
Diagnosis Tests and Interpretation
Laboratory evaluation should include electrolytes, BUN, creatinine, and glucose. Hypoglycemia may be present. Significant acidosis is uncommon unless there is associated hypoperfusion or a coingestant. Acetone can falsely elevate serum creatinine; when acetone levels exceed 40 mg/dL, creatinine may rise approximately 1 mg/dL for every 100 mg/dL of acetone, returning to baseline as acetone is cleared. CBC may show decreased hematocrit in cases of hemorrhagic gastritis. Arterial blood gas analysis typically shows little or no acidosis. Urinalysis and serum testing reveal ketosis.
Serum isopropanol levels correlate with severity, with coma often occurring at levels above 150 mg/dL. Serum osmolarity should be assessed, as an elevated osmolar gap (>10) is common. Each 5.9 mg/dL of isopropanol and 5.5 mg/dL of acetone increases the osmolar gap by approximately 1 mOsm/kg. Chest radiography is indicated if aspiration pneumonia is suspected, and head CT should be considered when altered mental status or head injury is possible.
Differential Diagnosis
The differential diagnosis for CNS depression with an elevated osmolar gap includes ethanol, ethylene glycol, methanol, glycerol, and mannitol.
Treatment Prehospital
All potentially ingested bottles and medications should be located and transported with the patient to the emergency department.
Initial Stabilization and Therapy
Management begins with airway, breathing, and circulation. Airway protection and ventilatory support may be required. Hypotension should initially be treated with IV 0.9% normal saline; vasopressors such as dopamine or norepinephrine may be required if hypotension persists. Patients with significant hemorrhagic gastritis may require packed red blood cell transfusion. Nasogastric tube placement and irrigation may be indicated for hematemesis. Naloxone, thiamine, and dextrose should be administered for altered mental status as indicated.
ED Treatment and Procedures
Treatment is primarily supportive, as there is no specific antidote. Skin and eye exposures should be treated with copious irrigation. Activated charcoal may be considered for coingestants and, in large doses, can adsorb some isopropanol. Ethanol infusion and fomepizole (4-methylpyrazole) are not indicated. Hemodialysis effectively removes both isopropanol and acetone but is rarely required. Indications for dialysis include persistent hemodynamic instability despite fluids and pressors or very high serum levels (>400 mg/dL), which are associated with severe hypotension and prolonged coma.
Medication
Supportive medications may include activated charcoal, IV dextrose for hypoglycemia, dopamine for refractory hypotension, naloxone if opioid exposure is suspected, and thiamine for patients at risk of deficiency.
Follow-Up Disposition
Patients with moderate to severe toxicity, including altered mental status or hypotension, should be admitted. Asymptomatic patients should be observed for 2–4 hours after ingestion before discharge. Mild intoxication that resolves within 4–6 hours may be safely discharged.
Follow-Up Recommendations
Patients with intentional ingestion should be referred for alcohol detoxification or psychiatric evaluation. Gastroenterology referral is recommended for those with recurrent hematemesis requiring endoscopic evaluation.
Pearls and Pitfalls
Supportive care is the cornerstone of treatment for isopropanol poisoning. Unlike other toxic alcohol ingestions, ethanol infusion and fomepizole should not be used.
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