Hydrocarbon Poisoning
Hydrocarbons are a heterogeneous group of organic substances that are primarily composed of carbon and hydrogen molecules. They are quite abundant in modern society. Some of the most commonly ingested hydrocarbons include gasoline, lubricating oil, motor oil, mineral spirits, lighter fluid/naphtha, lamp oil, and kerosene. [1] Other common sources of hydrocarbons include dry cleaning solutions, paint, spot remover, rubber cement, and solvents. In addition, many volatile substances that contain hydrocarbons (eg, glue, propellants) are commonly abused for their euphoric effects.[1]
EPIDEMIOLOGY
Hydrocarbon ingestion accounts for one to two percent of non-pharmaceutical exposures in children younger than six years of age reported to United States poison control centers. Although rare, hydrocarbon aspiration may cause death secondary to respiratory failure. Hydrocarbons were implicated in almost 5% of all single substance fatalities in this pediatric population. Gasoline, chlorofluorocarbon propellants, motor oils, lighter fluid/naphtha, lamp oil, and mineral spirits, are the most commonly ingested substances. In young children, the ingestion typically occurs as a result of exploratory behavior. Frequently, the hydrocarbon is unsecured or improperly stored in a drinking container (e.g., soda bottle). Moderate or major toxic effects are associated most commonly with ingestion of lamp oil, kerosene, lighter fluid, and/or naphtha. Toxicity in adolescents often arises from inhalant abuse of hydrocarbons. [1]
PATHOPHYSIOLOGY & ETIOLOGY
A. Pulmonary Toxicity
1. Aspiration usually occurs during ingestion or subsequent vomiting.
2. Inhalation is less likely to cause pulmonary injury, but it can occur with high concentrations or prolonged exposure.
3. Inhibition of surfactant leads to alveolar collapse and ventilation perfusion mismatch. Chemical pneumonitis results from direct capillary damage.
4. Agents with a low viscosity and low surface tension spread easily to distal airways and cause pneumonitis, whereas highly viscous agents with high surface tension cause more localized (lipoid) pneumonia.
B. Central Nervous System Toxicity
1. Hydrocarbons are readily absorbed following inhalation but poorly absorbed by other routes.
2. They are highly lipophilic, rapidly enter the brain, and cause central nervous system (CNS) excitation followed by depression after systemic absorption.
C. Cardiac Toxicity.
Myocardial sensitization to catecholamines can occur after exposure to halogenated and aromatic hydrocarbons, leading to ventricular irritability and dysrhythmias.
D. Dermal, Gastrointestinal, and Ocular Toxicity
1. Hydrocarbons have mild corrosive effects.
2. Metabolism of ingested or inhaled carbon tetrachloride via CYP450 enzymes leads to free-radical formation and subsequent hepatic necrosis.[2]
RISK FACTORS
Children younger than 5 years of age, poor socioeconomic status, overcrowding with large family size, improper storage of dangerous household products and hot weather especially summer vacations were identified as leading cause of hydrocarbon ingestion in children. Lack of awareness on part of parents regarding the appropriate storage of hazardous substances also exits.[3]
CLINICAL FEATURES
Some common features of hydrocarbon toxicity include the following:
1. Skin. Dermatitis caused by defatting or removal of oils in the skin is common, especially with prolonged contact. Some hydrocarbon agents also can cause frank chemical burns.
2. Arrhythmias. Many hydrocarbons, most notably fluorinated, chlorinated, and aromatic compounds, can sensitize the heart to the arrhythmogenic effects of epinephrine, resulting in premature ventricular contractions (PVCs), ventricular tachycardia, or fibrillation. Even simple aliphatic compounds such as butane can have this effect.
a. Because arrhythmias may not occur immediately, cardiac monitoring for 24 hours is recommended for all victims who have had significant hydrocarbon exposure (e.g., associated with syncope or coma).
b. Ventricular arrhythmias.
3. Pulmonary aspiration of most hydrocarbons, especially those with relatively high volatility and low viscosity (e.g, gasoline, kerosene, and naphtha), can cause severe chemical pneumonitis.[2]
DIAGNOSIS & TREATMENT
1) X-Ray: Changes may be evident as early as 30 minutes after exposure and peak at about 72 hours, after which there is gradual resolution. Common radiologic findings include perihilar densities, bronchovascular markings, bibasilar infiltrates, and pneumonic consolidation. Early upright X-rays may reveal two liquid densities in the stomach (double bubble sign), which represents two interfaces: air-hydrocarbon, and hydrocarbon-fluid, since hydrocarbons are not miscible with water and are usually lighter. Two important points are to be noted in connection with radiographic changes in hydrocarbon ingestion:
a. They correlate poorly with clinical symptoms.
b. They lag behind clinical improvement.
2) Arterial blood gases: Hypoxemia.
3) Blood: Leucocytosis is common during the first 48 hours.[4]
TREATMENT
A. Advanced life support measures should be instituted as necessary.
B. All patients with altered mental status, respiratory symptoms, or hypoxia should be given supplemental oxygen.
1. Early intubation is indicated for significant respiratory distress.
2. Mechanical ventilatory support is indicated when appropriate.
3. Steroids have no proved benefit in the treatment of hydrocarbon aspiration.
4. Antibiotics are not routinely indicated. Their use should ideally be guided by cultures of sputum or bronchial lavage.
5. Asymptomatic patients who are suspected of aspirating hydrocarbons may be safely discharged if the chest radiograph is normal 6 hours after exposure.
C. Ventricular dysrhythmias should be treated with B-blockers, lidocaine, and benzodiazepines. Epinephrine may exacerbate myocardial irritability and should be avoided.
D. N-acetylcysteine may be useful for the treatment of hepatotoxicity from carbon tetrachloride.
E. Activated charcoal is of limited use in preventing the absorption of hydrocarbons and is not recommended. Emesis is contraindicated because of the risk of aspiration. Gastric aspiration with a small-caliber nasogastric (NG) tube may be useful for large-volume ingestions (>30 mL) or for inherently toxic hydrocarbons described by the pneumonic CHAMP (camphor, halogenated, aromatic, metal containing, or pesticides in a hydrocarbon vehicle).
F. Saturated clothing should be immediately removed and the patient’s skin washed with soap and water to limit dermal absorption.
G. The initial treatment of ocular exposures is eye irrigation with normal saline.[5]
COMPLICATIONS
Complications of aspiration include:
A. Bacterial infection, pleural effusion, pneumatoceles, pneumothorax, and persistent respiratory dysfunction.
B. Chronic inhalation can lead to leukoencephalopathy characterized by cerebellar ataxia and encephalopathy or dementia.
C. Chronic inhalation, particularly of n-hexane, can also cause peripheral neuropathy.
D. Chronic exposure to benzene may cause bone marrow suppression and aplastic anemia and is linked to acute myelogenous leukemia. [2]
DIFFERENTIAL DIAGNOSIS
– sleep disorders
– major depression,anxiety, substance abuse and the excessive use of CNS-affecting medications,
– neurodegenerative disorders
– neurovascular disorders
– neoplasms
– metabolic causes
– toxic encephalopathy (alcohol, drugs of abuse, lead, mercury)
– traumatic brain disorders.
References:
1) James B. Mowry, Daniel A. Spyker, Daniel E. Brooks, Ashlea Zimmerman & Jay L. Schauben (2016) 2015 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 33rd Annual Report, Clinical Toxicology, 54:10, 924-1109
2) Eric Brush (2006): Hydrocarbons. IN Christopher H. Linden, James M. Rippe, Richard S. Irwin, (Editors). Manual of Overdoses and Poisonings. 2nd Edition. USA: LIPPINCOTT WILLIAMS & WILKINS. Chapter (21): 126-129.
3) Emad Uddin Siddiqui, Junaid A. Razzak, Farah Naz and Sabeena Jalal Khan (2008): Factors associated with hydrocarbon ingestion in children. Journal of Pakistan Medical Association. 58, (11): 608-612.
4) V V Pillay (2013): Hydrocarbons. In V V Pillay (Editor) Modern Medical Toxicology. 4th Edition. Nepal: Jaypee Brothers Medical Publishers (P) Ltd. Chapter (27): 375-385.
5) Gary Ordog and Johanthan Wasserberger (2004): Hydrocarbons. In Kent Olson (Editor) poisoning and drug overdose. 8th Edition. USA: McGraw-Hill Companies, Inc. Chapter (Hydrocarbons): 183-185.
6) L. M. Tormoehlen, K. J. Tekulve and K. A. Nanagas (2014): Hydrocarbon toxicity: A review. Clinical Toxicology. 52 (5): 479-489.
AUTHOR: Heba Ammar MD, Assistant professor Forensic Medicine and clinical toxicology.
Faculty of Medicine Suez Canal University, Egypt
