A 23-year-old man arrives by ambulance to the Emergency Department with severe shortness of breath, cough, nausea, and vomiting for several hours. Between rapid breaths and frequent coughing, he is able to state he has been healthy, has not traveled recently, and has had no recent ill contacts. He smoked one-half to one pack of cigarettes daily for a few years “on and off,” and began using electronic cigarettes (e-cigarettes) a few months ago on advice from a friend as a way to quit tobacco.
Exam – P 115, regular; R 28; BP 140/86; T 37.5⁰C; Pulse ox 86% saturation on 2L NC O2; Chest – tachypneic, with decreased breath sounds and scattered rhonchi bilaterally; Cardiac – tachycardic, without murmurs; Abdomen, Skin, Neuro – normal
Labs – WBC 15,000, neutrophil predominant, o/w normal CBC and normal chem panel; CXR – diffuse, bilateral, poorly-defined opacities
O2 saturation continued to drop, he became less responsive and required intubation and ICU admission.
Discussion
Although available for decades, e-cigarettes have recently been gaining in popularity. There are now over 500 brands and 10,000 flavors of e-cigarettes and growing. They are becoming more popular at a time when the United States has effectively banished tobacco from most public areas. Global sales exceed 25 billion dollars annually and are predicted to double over the next few years.
E-cigarettes are marketed as a safe alternative to tobacco, and many advertising campaigns promote their utility in smoking cessation. There are, however, very few high-quality and no long-term studies of e-cigarettes in smoking cessation. Also, many studies classify smokers who switch from tobacco to e-cigarettes as having quit smoking.
Unlike tobacco, e-cigarettes allow the user individualized control over variables such as temperature, wattage, amount of nicotine, the glycerin-to-propylene glycol ratio, and inhalational style (mouth-to-lung vs. deep-lung), providing a highly customizable experience. E-cigarette users have also been known to add tetrahydrocannabinol (THC), the high-inducing chemical found in marijuana, and cannabidiol (CBD) oil, a phytocannabinoid, to the e-cigarette liquid.
Especially attractive to younger people is an e-cigarette that looks like a USB flash drive, and a myriad of “kid-friendly” flavors, including mint, cherry, candy crush, cotton candy, strawberry-watermelon, and gummy bear.
The potential for harm from the components of e-cigarettes and the ingredients in the liquids is a growing concern. E-cigarettes contain a battery-operated element which heats a coil inside a wick saturated with liquid. The liquid is heated to approximately 200⁰C (up to 300⁰ C in temperature-control e-cigarettes). The main components of the liquid are propylene glycol and vegetable glycerin, both of which have been approved for oral ingestion but have not been studied as inhalational agents. Several studies have shown that a wide variety of chemicals are suspended in what is commonly referred to as a “vapor” (i.e. steam) but is actually an aerosol. These aerosols have been found to contain free radicals, heavy metals, formaldehyde, and many other volatile organic compounds.
Most e-cigarette liquids also contain nicotine, at levels set by the user. This allows for tapering doses, a common practice in nicotine replacement programs. Nicotine is widely known to be very addictive, and many studies have shown that adolescents are more vulnerable to this effect than adults. Chronic nicotine use in adolescents is also associated with a decreased ability to concentrate and increased stress levels.
The Centers for Disease Control and Prevention (CDC) reports from the 2015 National Youth Tobacco Survey that 27.1% of U.S. adolescents (approximately 7.3 million people) have ever tried e-cigarettes. This includes 37.7% of high school students and 13.5% of those in middle school. In 2018, the surgeon general deemed youth e-cigarette use to be an epidemic, and surveys show it continues to be on the rise. Many young people now start smoking with e-cigarettes. As with tobacco, nicotine dependence occurs rapidly and often becomes chronic. Surveys have shown many go on to smoke tobacco as well, some remaining dual users.
Recently, increasing numbers of e-cigarette-related lung injury have been observed throughout the United States. A CDC alert was published on August 23, 2019, reporting 193 cases of lung injury associated with e-cigarette use in 22 states between June 28th and August 20th of this year, including the first known death related to e-cigarettes on August 23rd. It is likely that these numbers are even greater and have been occurring over a longer period, as many cases were not linked to e-cigarette use at the time.
The mechanism(s) of lung damage in these cases is unknown. They involve a wide age-range and geographic distribution, and the pattern of lung injury is varied – including lipoid pneumonia, acute eosinophilic pneumonia, cryptogenic organizing pneumonia, and alveolar hemorrhage syndrome.
Studies of the effects of condensed e-cigarette aerosols on in-vitro human alveolar macrophages have shown dose-dependent toxicity. Below cytotoxic doses, increasing levels of reactive oxygen species (ROS) and inflammatory cytokines have been observed. These effects may be causing the inflammation and lung injury seen in these cases.
No link has been made to any specific product, ingredient, or infectious agent to date. One theory discussed on social media is that these cases are likely caused by CBD oil, given that the use of CBD is a more recent trend, and because it is an oil, unlike other e-cigarette liquids. Although there is no evidence to corroborate this theory, more research needs to be done. The CDC states it is continuing to work with state health departments in their investigations to find the source of this epidemic.
References
CDC, CDC, FDA, States Continue to Investigate Severe Pulmonary Disease Among People Who Use E-cigarettes, (2019), Retrieved from cdc.gov/media/releases/2019/s0821-cdc-fda-states-e-cigarettes.html (Accessed 26 August 2019).
CDC, Surgeon General’s Advisory on E-cigarette Use Among Youth, (2019), Retrieved from cdc.gov/tobacco/basic_information/e-cigarettes/surgeon-general-advisory/index.html (Accessed 26 August 2019).
Dinakar C, O’Connor GT. The health effects of electronic cigarettes. N Engl J Med 2016; 375: 1372-81. doi: 10.1056/NEJMra1502466
Scott A, Lugg ST, Aldredge K, et al. Pro-inflammatory effects of e-cigarette vapour condensate on human alveolar macrophages. Thorax 2018; 73:1161-69.