Huffing Away – Toxicology Blog

Author: Jack Bates, PA-C, Emergency Medicine PA Resident
Fellow: Alexis Cates, DO, Medical Toxicology Fellow PGY6
Faculty: David Goldberger, MD, Medical Toxicology / Emergency Medicine Attending 

The Case

You are just starting your shift in a community Emergency Department (ED) when a 13 year old girl is brought in by her parents after they found her sleepier than they expected when they got home from work. They state she smelled “funny” earlier, but that has gone away after the car ride to the ED with the windows open.  The patient herself states that she is having a hard time catching her breath.  She is otherwise healthy, is up-to-date on vaccines, has no allergies and is on no daily medication.  

Vitals: HR 115, RR 22, BP 122/74, 94% on RA, 100.6 F

Physical exam is significant for a tired but generally well-appearing young female in no apparent distress, crackles in bilateral lung bases, and findings of mild erythema and dry skin surrounding the mouth.  

The parents are not sure that she has any prior exposure to illicit substances, but kids these days are always talking about experimenting and she had just been in shop class.  To be sure, you reach out to your local poison control center to speak to a toxicologist and run a differential diagnosis on this patient.  Given the recent exposures noted of similarly-aged children in the area, the toxicologist discusses the possibility of hydrocarbons.

Learning Point 1: Types of Hydrocarbons, Epidemiology, Diagnostics

  • Hydrocarbons are molecules made up of a carbon and hydrogen backbone, and are considered aliphatic (straight chain), aromatic (ring structure) or halogenated (containing brominated, chlorinated, or fluorinated sites).
  • Commonly found in household and industrial products, these products are easily purchased and readily accessible. Common hydrocarbons include gasoline, propane, paint and paint thinners, and keyboard dusting products.
  • The ease of accessibility, as well as ubiquitous presence in the modern home, make them ripe for abuse.
  • Routes of exposure include ingestion, inhalation, transdermal, and more rarely, subcutaneous injection.
  • Most common route of exposure varies by age group: age <5, most common route is ingestion as a result of exploratory behavior; for adolescents, it is intentional inhalation.
  • In general, there may be several thousand cases of hydrocarbon exposure reported per year with a dozen or more deaths.

Figure 1. Common inhalants and constituent xenobiotics. From Goldfranks Toxicology.

  • Diagnostics should be guided by your history and physical. 
    • Basics: EKG, chest x-ray, point-of-care glucose 
  • Other labs that can be considered:
    • Complete blood count with differential
    • Comprehensive metabolic panel with magnesium, phosphorous
    • Urinalysis 
    • Troponin , especially with signs of cardiovascular toxicity
    • Blood gas (arterial or venous)
    • Coagulation panel
    • Levels of common co-ingestants such as acetaminophen and salicylate
    • Other imaging, such as computed tomography (CT) of the head or elsewhere as dictated by history and physical exam

The case continued…

The patient’s chest x-ray is concerning and shows evidence of pulmonary edema.  Her EKG shows sinus tachycardia with normal intervals and no ischemic changes. Her blood work reveals a serum glucose of 149 mg/dL, mild leukocytosis to 14,000, a lactate of 0.8 mmol/L, potassium of 8.9 mmol/L  but the specimen is hemolyzed.  The remainder of her blood work is unrevealing and a repeat potassium is pending.

On your reassessment, she has increased crackles at the lung bases bilaterally and is now on 3L/min nasal cannula.  She had an oxygen desaturation to 88% while returning from the bathroom and was quite short of breath.  She is still sleepier than usual, according to her parents.

Learning Point 2: Clinical Effects of Hydrocarbon Toxicity

Hydrocarbon exposure affects three systems primarily: Nervous, cardiac, and pulmonary. Absorption is rapid, and clinical intoxication can occur in seconds. Duration of action is usually only minutes, but prolonged or concentrated exposure can produce longer effects.

  • Cardiovascular system
    • Sudden sniffing death is the most serious cardiac complication; hydrocarbons sensitize the myocardium to catecholamines, which can precipitate ventricular dysrhythmias. Classically, this is described as a sudden cardiac arrest following running from police after being caught huffing. 
      • The inhalant sensitizes the myocardium by blocking the potassium current and prolonging repolarization
    • Some electrolyte disturbances such as hypokalemia can occur with some hydrocarbon xenobiotics and can contribute to the development of dysrhythmias
    • Other cardiovascular effects can include palpitations, dizziness and dyspnea
    • EKG findings can include atrial fibrillation, ectopy, the presence of U waves, prolonged QTc intervals, and ventricular dysrhythmias
  • Nervous system
    • All hydrocarbons are CNS depressants, causing drowsiness, lightheadedness, euphoria
    • As intoxication progresses, patient will experience slurred speech, lethargy and weakness
      • Can eventually lead to coma, seizures and respiratory depression
    • Acts on NMDA and GABA receptors, causing hyperpolarization, manifesting as decreased excitability
    • Hydrocarbons also act to inhibit glutamate-mediated excitation
    • Chronic effects can include dementia, ataxia and peripheral neuropathy, but varies by the specific substance and duration/patterns of use
  • Pulmonary system
    • Hypoxia is the most common complication, especially with inhalation. This results from the hydrocarbon displacing oxygen directly, as well as the rebreathing of expired air (in the case of bagging).
    • Inhalation can lead to chemical pneumonitis and reactive airway disease.
      • Direct alveolar damage results in disrupted alveolar-capillary barrier, causing pulmonary edema and inflammation
      • Develops over 4-6 hours, so may not be clinically apparent on presentation.
  • Other Effects
    • Skeletal fluorosis (pictured) can be seen with chronic 1,1-difluoroethane use
    • Toluene in particular can cause distal renal tubular acidosis, resulting in potassium wasting (hypokalemia) and other electrolyte abnormalities
    • Halogenated hydrocarbons can cause increase in LFTs (which usually resolves in 1-2 weeks after discontinuation)
    • Hydrocarbons have also been associated with transient cardiomyopathies
    • Nausea, vomiting and abdominal pain are also seen, especially if the product is ingested.
    • Dry, eczema-like rash is often seen periorally if the patient bags or huffs
    • Thermal injury can result, especially with 1,1-difluoroethane (such as in products like “Dust-Off”); as the compressed gas expands, it cools and can result in frostbite (usually fingers, and around the mouth and nose)

Figure 2. Skeletal fluorosis seen in the hand, from Tucci et. al.  (2017)

Learning Point 3: Treatment

As most effects of hydrocarbons last only minutes, treatment is primarily supportive. There is little role for gastrointestinal (GI) decontamination when ingested, as these substances are rapidly absorbed.  There is risk of aspiration when considering GI decontamination with something such as activated charcoal, especially in a patient with potential for CNS compromise.  This decision should be made on a case-by-case basis. 

A systems-based approach to treatment is outlined below:

  • Cardiopulmonary:
    • Non-perfusing rhythms
      • Cardiac arrest secondary to hydrocarbon use is managed differently from standard ACLS. Remember, the myocardium has been sensitized to catecholamines, so doses of epinephrine should be avoided as it could further precipitate the arrhythmia. Consider lidocaine (1-1.5mg/kg first dose, 0.5-0.75mg/kg second dose) in place of epinephrine.
      • Consider esmolol infusion to blunt the endogenous catecholamines that likely precipitated the arrest (500mcg/kg bolus followed by 50mcg/kg/min, titrate by 50mcg/kg/min every 10 minutes).
      • Unstable ventricular tachycardia or ventricular fibrillation (non-perfusing) should be treated with defibrillation
    • Perfusing Rhythms
      • Unstable ventricular tachycardia (with a pulse) is treated with synchronized cardioversion. Consider Esmolol as above
      • For torsades de pointes, consider:
        • Magnesium infusion, 1-2mg/kg bolus (can repeat in 5-15 minutes), followed by 1-2g/hr
        •  Cardioversion, if the patient is unstable
        • Overdrive pacing, with goal HR of 90-110.
      • Stable ventricular tachycardia, consider amiodarone 150mg over 10 minutes
    • All patients with cardiac symptoms should have electrolyte derangements rapidly corrected. 
  • Neurologic:
    • Though most toxicologic-induced seizures self-resolve, benzodiazepines can be considered
    • Supportive care for CNS depression
      • Usually resolves within 12 hours
  • Pulmonary:
    • Supportive care with oxygen supplementation or positive pressure when indicated 
      • If the patient needs to be intubated, use lung-protective ventilator settings: tidal volume 6-8mg/kg, plateau pressures <30
    • Chest x-ray may be beneficial to assess for signs of aspiration, chemical pneumonitis or pulmonary injury.  However, this may be normal if too early in the presentation
    • Caution with beta-agonists such as albuterol for wheezing, as this may precipitate dysrhythmias 
    • For pediatric patients, endogenous surfactant, high frequency ventilation, and ECMO have been used but these are not not likely to be initiated in the ED
  • The Asymptomatic Patient
    • You may encounter a patient who states they are asymptomatic and your workup is unrevealing. These patients should be observed for 4-6 hours and have a repeat chest x-ray prior to discharge. If they remain asymptomatic, have unremarkable chest x-rays, and no concerning EKG abnormalities, they may be safely considered medically stable.

Case Resolution

Because your patient had a new oxygen requirement, as well as concerning findings of acute lung injury (likely chemical pneumonitis based on your suspicion of hydrocarbon exposure) on her physical exam, you consider admission.  Her repeat potassium level resulted as normal.

You send the patient to a close children’s hospital where she is taken care of by one of your co-residents. He later relays that the patient admitted to huffing kerosene after seeing some kids in shop class doing it and wanted to try for herself, confirming your suspicion of a hydrocarbon poisoning.  Despite a chest x-ray showing mild pulmonary edema on hospital day 1, the patient was discharged on hospital day 3 after resolution of her dyspnea and successful ambulation on room air.  She was counseled extensively by the inpatient pediatric medicine and psychiatry teams on the misuse of hydrocarbons.

References

Aleguas Jr., A. Acute Hydrocarbon Exposure: Clinical Toxicity, Evaluation, and Diagnosis. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2021.

Aleguas, Jr, A. Acute Hydrocarbon Exposure: Management. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2021.

Brown, K, Armstrong, T. (2020,*/26). Hydrocarbon Inhalation. National Center for Biotechnology Information. https://www.ncbi.nlm.nih.gov/books/NBK470289/

Carpenter, J., et al. (February 20, 2021). Torsades De Pointes. WikiEM. https://wikem.org/wiki/Torsades_de_pointes

Cates, A. L., Cook, M.D.. Severe Cardiomyopathy after Huffing Dust-Off™”, Case Reports in Emergency Medicine, vol. 2016, Article ID 9204790, 2 pages, 2016. https://doi.org/10.1155/2016/9204790

Long, N. (2020, November 3). Hydrocarbon Toxicity. Life In The Fast Lane. https://www.litfl.com/hydrocarbon-toxicity/

Marion, DW. Diaphragmatic pacing. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2014.

Nelson, L., Howland, M., Flomenbaum, N., Godlfrank, L., & Hoffman, R. (Eds.). (2019). Goldfrank’s Toxicologic Emergencies, Eleventh Edition. New York, NY: The McGraw-Hill Companies.

Perry, H. Inhalant Abuse in Children and Adolescents. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2021.

Tucci, J.R., Whitford, G.M., McAlister, W.H., Novack, D.V., Mumm, S., Keaveny, T.M. and Whyte, M.P. (2017), Skeletal Fluorosis Due To Inhalation Abuse of a Difluoroethane‐Containing Computer Cleaner. J Bone Miner Res, 32: 188-195. https://doi.org/10.1002/jbmr.2923

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