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Gait Disturbance, Confusion, and Coma in a 93-Year-Old Blind Woman* FREE TO VIEW

Mark Fahlen, MD; Alexander G. Duarte, MD
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*From the Department of Internal Medicine (Dr. Fahlen) and the Division of Pulmonary and Critical Care Medicine (Dr. Duarte), University of Texas Medical Branch, Galveston, TX.

Correspondence to: Alexander G. Duarte, MD, Division of Pulmonary and Critical Care Medicine, University of Texas Medical Branch, John Sealy Annex, 301 University Blvd, Galveston, TX 77555-0561; e-mail: aduarte@utmb.edu

Chest. 2001;120(1):295-297. doi:10.1378/chest.120.1.295
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A 93 -year-old woman with a history of blindness and dementia was found unconscious following 2 days of gait disturbance and confusion.

Physical examination revealed the following: BP, 90/40 mm Hg; pulse, 45 beats/min; temperature, 31°C; and respiration, 14 breaths/min. The patient was obtunded and not able to be aroused. Her pupils were equal and reactive to light. The lungs were clear. A heart examination revealed a systolic ejection murmur. She did not follow commands but moved all extremities upon painful stimuli. Corneal and gag reflexes were present. Deep tendon reflexes were symmetric.

The results of laboratory testing were as follows: WBC count, 5,300/μL; serum sodium level, 149 mEq/L; potassium level, 4.3 mEq/L; chloride level, 123 mEq/L; bicarbonate level, 20 mEq/L; BUN level, 12 mg/dL; and glucose level, 98 mg/dL. Serum osmolality was 326 mEq/L. The results of a urinalysis were positive for ketones. Arterial blood gas measurements were as follows: pH, 7.36; Pco2, 36 mm Hg; and Po2, 85 mm Hg.

Diagnosis: Isopropyl alcohol intoxication

The symptoms of isopropyl alcohol intoxication occur within 30 min of ingestion and include dizziness, headache, confusion, stupor, and coma. Hypothermia and hypotension can occur with large doses and may mimic sepsis, environmental exposure, or hypothyroidism. The setting of this particular case, a subtropical climate, made environmental exposure extremely unlikely and alerted the clinician to alternative diagnoses. Dizziness, gait disturbance, and confusion are frequently observed in association with isopropyl alcohol intoxication. Following ingestion, GI symptoms are common and include abdominal pain, gastritis, vomiting, and occasionally hematemesis.

Isopropanol is a component of rubbing alcohol, solvents, deicers, and antifreeze. It is rapidly absorbed following ingestion and hepatically metabolized to acetone by alcohol dehydrogenase. Toxic exposure also has been reported in cases involving topical application. Approximately 80% is excreted through the kidneys as acetone, and the remainder is excreted as isopropyl alcohol. The half-life of isopropyl alcohol is 3 to 6 h, while the half-life of acetone is 20 to 30 h. Isopropyl alcohol is a CNS depressant, like ethanol and methanol, but it does not produce retinal damage or acidosis. Since isopropyl alcohol is oxidized more slowly than ethanol and its major metabolite, acetone, is also a CNS depressant, intoxication may last longer.

The management of acute ingestion includes emptying of the stomach through gastric lavage, primarily when ingestion is within 2 h of presentation. Activated charcoal is ineffective, because it does not adequately bind low-molecular-weight substances. Supportive therapy is all that is usually required and includes airway management, IV fluid administration, and, when necessary, body rewarming. Hemodialysis may be considered in those patients who have high serum isopropyl alcohol levels (ie, > 400 mg/dL), hypotension, prolonged coma, or hepatic or renal insufficiency. Ethanol infusion is not indicated.

A fundamental observation in establishing this diagnosis is the presence of an increased osmolar gap in the absence of an anion gap acidosis. An elevated serum osmolarity measurement indicates the presence of foreign low-molecular-weight substances or an increased quantity of normal serum constituents (ie, sodium, glucose, or urea). A normal or calculated serum osmolarity is provided by the equation 2 × [Na] + [BUN]/2.8 + [glucose]/18. By taking the difference between the measured osmolarity and the calculated osmolarity, one may estimate the osmolar gap or the quantity of unmeasured serum solute. An elevated serum osmolar gap (ie,> 10 mOsm/L) represents decreased serum water content or the presence of low-molecular-weight solutes. In this case, the osmolar gap was 18 mOsm/L, as can be observed with ketoacidosis, hyperglycemia, mannitol infusion, and the ingestion of ethanol, methanol, ethylene glycol, or isopropyl alcohol. Furthermore, a normal anion gap in the presence of urine ketones narrows the diagnosis to isopropyl alcohol ingestion. These findings occur because the principal metabolite of isopropyl alcohol is acetone, a volatile ketone that does not acidify the blood. In contrast, following methanol, ethanol, or ethylene glycol ingestion, the metabolic byproducts are acids, thus leading to an increase in the number of unmeasured anions and solutes. In this case, the serum acetone was 54 mg/dL, and further questioning of the family revealed that the patient was demented and had been living by herself for several weeks. Furthermore, they had found an empty 8-oz bottle of rubbing alcohol and stated that she frequently applied rubbing alcohol to her skin to ease arthritic pain. On asking the patient about the ingestion of the rubbing alcohol, she was unable to remember any events, and because of this it was unclear whether the observed toxicity occurred because of ingestion or topical application. However, the absence of GI symptoms suggested the latter.

The patient was treated conservatively with IV hydration and warming blankets. Within 72 h, the patient’s mentation returned to baseline as the serum acetone level became undetectable.

  1. Mental status changes, hypothermia, and GI symptoms are clinical features of isopropyl alcohol poisoning.

  2. The presence of serum or urine ketones in the absence of hyperglycemia should suggest isopropyl alcohol ingestion.

  3. A normal serum anion gap and elevated serum osmolality are characteristic of isopropyl alcohol poisoning.

  4. The treatment of isopropyl alcohol poisoning is supportive, with hemodialysis reserved for severe cases that are associated with high isopropyl alcohol levels (ie, > 400 mg/dL), hypotension, prolonged coma, or hepatic or renal failure

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Lacouture PG, Heldreth DD, Shannon M, et al. The generation of acetonemia/acetonuria following ingestion of a subtoxic dose of isopropyl alcohol. Am J Emerg Med 1989; 7:38–40

Lacouture PG, Wason S, Abrams A, et al. Acute isopropyl alcohol intoxication diagnosis and management. Am J Med 1983; 75:680–686

Leeper SC, Almatari AL, Ingram JD, et al. Topical absorption of isopropyl alcohol induced cardiac and neurologic deficits in an adult female with intact skin. Vet Hum Toxicol 2000; 42:15–17

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




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