A 15-year-old boy is brought to the emergency department by his father, who found him unconscious on his bedroom floor. It was unclear exactly how long the boy had been unconscious, but his father last saw him walking upstairs 5 minutes before finding him. The father was able to rouse him quickly, but the patient continued to feel drowsy and experienced dizziness and headache. The father found no drugs or related paraphernalia, although the boy has come home drunk on several occasions. At the time of evaluation an hour later, the patient's symptoms have resolved and he denies any knowledge of why he lost consciousness. He has no history of cardiac problems and takes no medications. Mental status appears normal. Temperature is 36.7 C (98 F), blood pressure is 100/60 mm Hg, and pulse is 70/min. Examination shows a mild rash around the patient's mouth. Sensation is decreased in bilateral lower extremities. Liver function tests are slightly elevated. ECG is normal. Abuse of which of the following substances is the most likely cause of this patient's condition?

Question

A 15-year-old boy is brought to the emergency department by his father, who found him unconscious on his bedroom floor.  It was unclear exactly how long the boy had been unconscious, but his father last saw him walking upstairs 5 minutes before finding him.  The father was able to rouse him quickly, but the patient continued to feel drowsy and experienced dizziness and headache.  The father found no drugs or related paraphernalia, although the boy has come home drunk on several occasions.  At the time of evaluation an hour later, the patient's symptoms have resolved and he denies any knowledge of why he lost consciousness.  He has no history of cardiac problems and takes no medications.  Mental status appears normal.  Temperature is 36.7 C (98 F), blood pressure is 100/60 mm Hg, and pulse is 70/min.  Examination shows a mild rash around the patient's mouth.  Sensation is decreased in bilateral lower extremities.  Liver function tests are slightly elevated.  ECG is normal.  Abuse of which of the following substances is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

This adolescent's initial symptoms and physical findings are consistent with inhalant abuse. Commonly abused inhalants include glue, toluene, nitrous oxide ("whip-its"), amyl nitrite ("poppers"), and spray paints. Inhalants may be abused by sniffing, huffing (inhaled from a saturated cloth), or bagging (bag over mouth or nose) to concentrate the inhaled substance. Signs of acute intoxication may include brief transient euphoria and loss of consciousness and vary depending on the specific chemicals inhaled. Inhalants are highly lipid soluble and produce immediate effects that typically last 15-45 minutes. They act as central nervous system depressants and may cause death. Dermatitis ("glue sniffer's rash") due to chemical exposure can be seen around the mouth or nostrils. Liver function tests may be elevated with repeated use. Chronic abuse of nitrous oxide is associated with vitamin B₁₂ deficiency and resultant polyneuropathy, as in this patient. Boys age 14-17 are at highest risk for inhalant abuse, which may go unnoticed as common household products are used and no drug paraphernalia is found. (Choices A and B) Although this patient may have a history of alcohol abuse, substantial amounts of alcohol or benzodiazepines would be needed to cause loss of consciousness and would have resulted in a longer period of intoxication. (Choice C) Cocaine is a central nervous system stimulant that typically produces increased arousal, psychomotor agitation, and increased heart rate and blood pressure. (Choice D) The patient did not report or manifest any signs of hallucinations. Hallucinogens do not usually cause loss of consciousness. (Choice E) Although heroin intoxication can cause loss of consciousness, it would likely last longer than a few minutes and would not be associated with such a rapid recovery. Educational objective: Inhalant abuse usually occurs in boys age 14-17 and may involve multiple common household chemicals. Users may display characteristic perioral skin changes ("glue sniffer's rash"). Inhalant intoxication is characterized by a rapid onset and relatively short duration. References: Adolescent inhalant use prevention, assessment, and treatment: a literature synthesis. (http://www.ncbi.nlm.nih.gov/pubmed/26969125)

A 15-Year-Old Boy Is Brought to the Emergency Department by His