The American Association of Poison Control Centers reported more than 37,000 exposures to gas, fumes, and vapors in 2019, and those were the most common exposures in pediatric deaths. Toxicity from gas, fume, and vapor exposures can be categorized by their mechanism: simple asphyxiants, pulmonary irritants, and systemic asphyxiants.
Simple asphyxiants work by displacing oxygen from ambient air. Patients may be exposed to these chemicals by huffing. A 2010 survey reported that more than two million adolescents in the United States ages 12-17 reported using inhalants at least once, including noble gases (helium), nitrogen gas (nitrous oxide), and aliphatic hydrocarbons (methane, ethane, propane).
Gas is inhaled by discharging nitrous gas cartridges, often called whippets, into an object like a balloon or directly into the mouth. Credit: evemilla/iStockphoto.com
Simple Asphyxiant Symptoms
Symptoms are consistent with hypoxia and include tachypnea, lethargy, nausea and vomiting, seizures, and death. Patients who have been huffing may present with burns on the oral mucosa.
This patient presented after huffing with swollen lips, bullae on the lateral margin of the mouth, and midline burns. (Courtesy Brandie LaSala, MD; Pediatr Dermatol. 2013;30:e57; https://bit.ly/3ujAWqm.)
Treatment for Simple Asphyxiants
Treatment is the immediate removal from the exposure and supplemental oxygen. Assisting with respirations may be needed until a patient is awake enough to maintain his own respirations.
Pulmonary irritants are water-soluble chemicals that combine with water in the mucosa to produce acid. This destroys the endothelial lining and causes an inflammatory response that leads to the destruction of the mucosal barrier of the respiratory tract. Examples include ammonia, chlorine, sulfur dioxide, phosgene, and chloramine, a combination of bleach and ammonia.
Illustration: Sam Teng; [email protected]
Pulmonary Irritant Symptoms
Patients generally develop mucosal injury in the upper respiratory tract. They have nasal and oropharyngeal pain, drooling, edema, cough, and stridor, and can develop conjunctival irritation and lacrimation. Patients can also go on to develop acute respiratory distress syndrome. This can be immediate or delayed up to six hours after exposure.
Treatment for Pulmonary Irritants
Remove the patient from the exposure, and provide supportive care and oxygenation. Signs of upper airway dysfunction (stridor) require direct visualization of the larynx. If a patient develops ARDS and requires intubation, treating this similar to other etiologies of ARDS is reasonable: lower tidal volume 6 mL/kg, elevated PEEP, early neuromuscular blockade, and sometimes proning.
Nebulized albuterol can benefit patients with bronchospasm. Nebulized bicarbonate has shown some efficacy in chlorine gas exposure but is inconclusive for chloramine exposure, though it offers little harm and may be recommended. Steroids are controversial and have shown no proven benefit on mortality.
Systemic asphyxiants cause cellular hypoxia by interfering with oxygen transport or mitochondrial respiration. Examples include carbon monoxide, hydrogen cyanide, and hydrogen sulfide.
Treatments for Systemic Pulmonary Asphyxiants
The treatment would depend on the gas to which the patient was exposed. Initial treatment for all would be immediate removal from the exposure and supportive care with supplemental oxygen. Carbon monoxide exposures should be treated with supplemental oxygen and followed by hyperbaric oxygen if indicated. Hydrogen cyanide toxicity patients should receive supportive care and hydroxocobalamin if the patient is unstable. Hydrogen sulfide is considered a knock-down gas, and death from inhalation is rapid. No definitive treatments or antidotes show improvement.
2019 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 37th Annual Report. Clin Toxicol (Phila). 2020;58(12):1360; https://bit.ly/3cRWgNC.
- Cutaneous and Mucosal Blistering Secondary to “Huffing." Pediatr Dermatol. 2013;30(4):e57; https://bit.ly/3ujAWqm.
- “Simple Asphyxiants and Pulmonary Irritants." Goldfrank's Toxicologic Emergencies, 11th Edition. 2019.