DESCRIPTION

Isopropyl alcohol (isopropanol, rubbing alcohol) is a short-chain alcohol with the formula CH₃CHOHCH₃.

FORMS AND USES

• Not all rubbing alcohol products contain isopropanol.
• Isopropyl alcohol is used as a rubefacient, solvent, cleaning agent, disinfectant, and preservative.
• Isopropyl alcohol is a component of some window cleaners, liquid soaps, cosmetics, pharmaceuticals, and antifreezes, and is used in chemical manufacturing.

TOXIC DOSE

• Ingestion of 2 to 3 ounces of 70% isopropanol (typical rubbing alcohol or some window de-icers) may produce profound CNS depression in adults.
• Toxicity may develop after ingestion, inhalation, or dermal application.
• In children, exposure to all alcohols predispose to hypoglycemia due to suppression of gluconeogenesis.

PATHOPHYSIOLOGY

• In children, any ingestion is potentially toxic.
• Intoxication has developed both in children sponged with isopropanol and following application of isopropyl alcohol to the umbilical cord.
• Children may be more susceptible to intoxication after dermal application of isopropanol because of their increased skin permeability and greater relative body surface area.
• Isopropanol is metabolized to acetone, and is metabolized much slower than ethanol; thus, isopropanol persists in the blood much longer than ethanol.

EPIDEMIOLOGY

• Exposure is common; poisoning is uncommon.
• Toxic effects following exposure are typically moderate, with death occurring rarely after large exposures in patients without adequate airway protection.

CAUSES

• Isopropyl alcohol poisoning usually results from accidental exposure in children or intentional ingestion as an ethanol substitute by alcoholic patients.
• Child neglect should be considered if the patient is under 1 year of age; attempted suicide if the patient is over 6 years of age.

WORKPLACE STANDARDS

• ACGIH. TLV TWA is 400 ppm; STEL is 500 ppm.
• NIOSH. IDLH is 2,000 ppm.
• OSHA. PEL TWA is 400 ppm.

Section Outline:

• DESCRIPTION
• FORMS AND USES
• TOXIC DOSE
• PATHOPHYSIOLOGY
• EPIDEMIOLOGY
• CAUSES
• WORKPLACE STANDARDS

DIFFERENTIAL DIAGNOSIS

• Other toxic agents that cause alcohol-like intoxication include ethanol, acetone, and sedative-hypnotic agents, among others.
• Nontoxic causes of alcohol-like intoxication include hypoxia, hypoglycemia, or CNS events (infection, thromboembolic disease, etc.).

SIGNS AND SYMPTOMS

• CNS depression, ataxia, dysarthria, and gastrointestinal irritation are the most common effects.
• Isopropanol causes inebriation, as do other alcohols; the depth of CNS depression in isopropyl alcohol intoxication, however, is considered to be more intense than that of other alcohols.

Vital Signs

• Tachycardia is common.
• Hypotension and hypothermia may develop with severe poisoning.

HEENT

Eye and upper airway irritation may develop.

Skin

Dermal irritation or 1st degree burns may develop with prolonged exposure.

Pulmonary

• Inhalation may cause respiratory irritation.
• Respiratory depression may develop with severe poisoning.
• Absorption may occur by inhalation.

Cardiovascular

• Tachycardia is common.
• Hypotension is rare but develops in severe poisoning.

Gastrointestinal

• Nausea and vomiting are common.
• Gastritis and hematemesis may develop.
• Abdominal pain may be substantial and mimic acute abdomen.

Hepatic

Mild elevation of hepatic enzymes may develop.

Renal

Renal failure occurs rarely, following rhabdomyolysis or hypotension.

Fluids and Electrolytes

• Unlike ethylene glycol or methanol toxicity, significant metabolic acidosis does not develop.
• Acetonemia and ketonuria are common.

Musculoskeletal

Rhabdomyolysis occurs rarely, and may develop with prolonged coma.

Neurologic

CNS depression, ataxia, nystagmus, dysarthria, hypotonia, hyporeflexia, and, in severe cases, coma may develop.

Endocrine

• Mild hyperglycemia has been reported in adults.
• Hypoglycemia may develop, especially in children.

PROCEDURES AND LABORATORY TESTS

Essential Tests

• Serum isopropanol level and glucose level should be obtained in symptomatic patients.
• Intoxication is generally evident at serum isopropanol levels of 50 to 100 mg/dl, and coma may develop at levels higher than 150 mg/dl.

Recommended Tests

• Serum electrolytes, BUN, and creatinine should be obtained to assess other causes of altered mental status.
  • If metabolic acidosis is present, other etiologies should be considered.
  • Serum creatinine may be falsely elevated in the presence of elevated serum acetone levels, if measured by colorimetric assays.
• Serum acetone level should be markedly elevated in symptomatic patients.
• Serum osmolar gap may be elevated early in the course of isopropyl alcohol toxicity.
• ECG, serum acetaminophen, and salicylate levels should be obtained in overdose setting to detect occult ingestion.

Section Outline:

• DIFFERENTIAL DIAGNOSIS
• SIGNS AND SYMPTOMS
  • Vital Signs
  • HEENT
  • Skin
  • Pulmonary
  • Cardiovascular
  • Gastrointestinal
  • Hepatic
  • Renal
  • Fluids and Electrolytes
  • Musculoskeletal
  • Neurologic
  • Endocrine
• PROCEDURES AND LABORATORY TESTS
  • Essential Tests
  • Recommended Tests

• Supportive care, including maintenance of hydration and support of cardiovascular function, with appropriate airway management is vital.
• The dose and time of exposure should be determined for all substances involved.

DIRECTING PATIENT COURSE

The health-care provider should call a poison control center when:

• Signs and symptoms are not consistent with isopropanol poisoning.
• Coingestant, drug interaction, or underlying disease precludes or complicates initial treatment measures.
• Any toxic effects, especially coma, hypotension or other severe effects, are present.

The patient should be referred to a health-care professional when:

• Attempted suicide or homicide is possible.
• The patient or caregiver seems unreliable.
• Any toxic effects, especially coma, hypotension, or other severe effects, are present.
• Coingestant, drug interaction or underlying disease presents an unusual problem.

Admission Considerations

Inpatient management in an ICU is warranted for patients with hypotension, respiratory compromise, or CNS effects that do not clear over 4 to 8 hours of observation.

DECONTAMINATION

Out of Hospital

• Induction of emesis with ipecac should be avoided because of the risk of CNS depression.
• Exposed skin should be washed with soap and water.

In Hospital

• Aspiration of gastric contents may reduce isopropanol ingestion. Gastric lavage with a large bore tube may be needed if a coingestant is possible.
• Activated charcoal is not routinely recommended because it does not absorb isopropanol well; one dose of activated charcoal (1-2 g/kg) may be administered, however, if a coingestant is suspected.
• Exposed skin areas should be washed with soap and water.

ANTIDOTES

There is no specific antidote for isopropanol poisoning.

ADJUNCTIVE TREATMENT

• Hypotension
  • The health-care provider should administer 10 to 20 ml/kg of 0.9% saline and place the patient in the Trendelenburg position.
  • Further fluid therapy is guided by central pressure monitoring to avoid volume overload.
  • Vasopressors should be added if needed.
• Ethanol infusion, which is used for methanol or ethylene glycol toxicity, is not indicated for isopropanol toxicity.
• Hemodialysis
  • Hemodialysis increases isopropanol clearance, but is rarely necessary; it should be considered in patients with hemodynamic instability or prolonged coma.

Section Outline:

• DIRECTING PATIENT COURSE
  • Admission Considerations
• DECONTAMINATION
  • Out of Hospital
  • In Hospital
• ANTIDOTES
• ADJUNCTIVE TREATMENT

PATIENT MONITORING

Glucose level and hemodynamic and respiratory parameters should be monitored in patients with mental status depression.

EXPECTED COURSE AND PROGNOSIS

• Aspiration occurs relatively commonly.
• Inadequate airway management may result in hypoxic injury.
• Most patients recover within 4 to 24 hours with supportive care, unless sequelae of hypoxia or hypotension supervene.

DISCHARGE CRITERIA/INSTRUCTIONS

• From the emergency department
  • Patients who have returned to baseline mental status after 4 to 8 hours of observation and continued normoglycemia may be discharged after decontamination.
  • Psychiatric or substance abuse referral should be considered.
• From the hospital
  • Patients may be discharged when toxic effects have resolved or stabilized.
  • Psychiatric or substance abuse referral should be considered.

Section Outline:

• PATIENT MONITORING
• EXPECTED COURSE AND PROGNOSIS
• DISCHARGE CRITERIA/INSTRUCTIONS

• Isopropyl alcohol intoxication may be difficult to diagnose because of its similarity to ethanol intoxication.
• If metabolic acidosis occurs, another cause such as hypotension (lactic acidosis) or methanol or ethylene glycol toxicity should be considered.
• Severe gastritis and substantial hematemesis may develop.

Toxic effect of alcohol: isopropyl alcohol.

See Also: SECTION II, Hypotension chapter; SECTION III, Ethylene Glycol and Methanol chapters.

RECOMMENDED READING

Goldfrank LR, Flomenbaum NE, Howland MA. Methanol, ethylene glycol, and isopropanol. In: Goldfrank LR, Flomenbaum NE, Lewin NA, et al., eds. Goldfrank's toxicologic emergencies, 6^th ed. Norwalk, CT: Appleton & Lange, 1998.

Pappas AA, Ackerman BH, Olsen KM, et al. Isopropanol ingestion: a report of six episodes with isopropanol and acetone serum concentration time data. J Toxicol Clin Toxicol 1991;29:11-21.

Author: Katherine M. Hurlbut

Reviewer: Richard C. Dart