Vaping Associated Pulmonary Injury

Article Author:
Hassam Zulfiqar
Article Editor:
Omar Rahman
Updated:
9/8/2020 8:47:18 AM
For CME on this topic:
Vaping Associated Pulmonary Injury CME
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Vaping Associated Pulmonary Injury

Introduction

Vaping associated pulmonary injury (VAPI), also called e-cigarette or vaping product use associated lung injury (EVALI), is an acute or subacute respiratory illness characterized by a spectrum of clinicopathologic findings mimicking various pulmonary diseases. According to the CDC criteria, EVALI is a clinical diagnosis that requires the use of an e-cigarette in the 90 days preceding the appearance of initial symptoms, pulmonary infiltrates on plain chest radiograph or chest CT, and absence of any other possible etiology, such as infection.[1]

Etiology

Although the etiology remains unclear, several causes are under investigation. Of these, Vitamin E acetate is by far the most recognized agent associated with EVALI. Supporting this is the fact that a recent study identified Vitamin E acetate in bronchoalveolar lavage (BAL) fluid samples of 48 out of the 51 EVALI patients as opposed to none in the fluid samples obtained from the healthy control group.[2] Vitamin E acetate was illegally being used as a diluent in multiple counterfeit, low cost, tetrahydrocannabinol (THC) containing cartridges. Its use as a diluent in THC based cartridges became common in 2019, coinciding with the EVALI outbreak.[3] However, the possibility of other agents, including chemicals in either THC or non-THC products, implicated in the causation of disease cannot be ruled out.

Epidemiology

The outbreak started in March 2019 when a cluster of cases emerged in the USA of patients who had developed lung injury associated with the use of e-cigarettes. As of February 2020, more than 2800 patients had been admitted to various hospitals in the US due to EVALI, with a total of 68 deaths reported so far. Outside the US, Canada has reported a handful of cases. Europe reported its first fatal EVALI case in March 2020.[4] Moreover, sporadic cases have been reported in travelers from the US in other countries.[5] Owing to the banning of various vaping products, the number of new cases has significantly declined in the US.

Pathophysiology

The pathology of the disease is still poorly understood. A comprehensive pathophysiological basis for the lung injury seen in these patients is yet to be established. Butt et al., in a recent study, described a wide spectrum of histopathological findings seen in EVALI, including acute fibrinous pneumonitis, diffuse alveolar damage, or organizing pneumonia, usually bronchiolocentric and accompanied by bronchiolitis.[6] 

Previously, studies had suggested that EVALI may represent a form of exogenous lipoid pneumonia.[7] However, a recent literature review concluded that no histologic evidence of exogenous lipoid pneumonia was seen in the tissue samples. The histological findings are more likely suggestive of airway-centered chemical pneumonitis from one or more inhaled toxic substances found in the vapes. Testing for lipid-laden macrophages in bronchoalveolar lavage fluid samples using oil red O staining was previously thought to be a useful marker of the disease process. However, the current consensus is that although common, this is an essentially non-specific finding.[8]

History and Physical

Patients with EVALI can present with a wide variety of symptoms, ranging from respiratory such as cough, chest pain, shortness of breath, gastrointestinal such as abdominal pain, nausea, vomiting, diarrhea to general symptoms such as fever, chills, or weight loss. A thorough history is crucial to establishing the diagnosis focusing on the acuity of symptoms. The CDC recommends obtaining detailed information during the patient interview regarding the type of vaping device used, type of substance used, frequency of vaping, and where the e-cigarette, or vaping, products were obtained.[9] 

Most patients report using products from informal sources, including friends, family, online, or in-person dealers. Knowing the particular substance used is noteworthy as most EVALI patients report using THC-containing products before the onset of symptoms. Maintaining confidentiality and a non-judgmental attitude is of paramount importance in conducting a successful patient interview as some patients may not be comfortable talking about their vaping product use, especially those who use products that contain THC or CBD. Physical examination should focus on vital signs, pulse oximetry, and a detailed chest examination, including auscultation for any added breath sounds.

Evaluation

Evaluation of patients is guided by the clinical presentation and severity of the patient's symptoms. All patients with a history of vaping product use in the last 90 days should at least get a chest x-ray, even if the symptoms are mild. Those having significant respiratory distress and low oxygen saturation (<95%) should be evaluated with a chest computed tomography (CT) scan if the suspicion for EVALI is high. It is important to note that EVALI is a diagnosis of exclusion. Therefore it is necessary to rule out other possible causes of lung injury such as viral pneumonia, community-acquired pneumonia, and any ongoing chronic inflammatory process that might affect the lungs.

Locally appropriate and clinically indicated diagnostic evaluation should be performed, including respiratory viral panel, influenza polymerase chain reaction or rapid test, RT-PCR for SARS-COV2, urine antigens of Streptococcus pneumoniae, and Legionella spp., sputum culture, bronchoalveolar lavage, blood culture, and testing for HIV-related opportunistic infections.[1][9] 

Diagnostic imaging demonstrates a variety of radiographic presentations. Plain chest radiographs commonly show hazy bilateral opacities with central and peripheral sparing. Likewise, the most common CT finding is diffuse bilateral ground-glass opacities, with a basilar predominance and sometimes subpleural or lobular sparing.[10] 

Laboratory evaluation should include complete blood count with differential, liver transaminases, and inflammatory markers (e.g., erythrocyte sedimentation rate and C-reactive protein). Moreover, urine toxicology testing, with informed consent, including testing for THC, should be carried out in all patients. The primary role of bronchoscopy is to exclude alternative diagnoses, especially when the imaging findings are atypical and suggestive of an alternate etiology. Other potential candidates for bronchoscopy include patients with a high suspicion of infection, e.g., immunocompromised patients and those on invasive mechanical ventilation.

Treatment / Management

The mainstay of treatment in EVALI is supportive care. The severity of symptoms guide as to whether the patient needs a hospital admission or can be managed on an outpatient basis. Respiratory distress, comorbidities that compromise pulmonary reserve, or decreased oxygen saturation (<95% while breathing room air) are strong indications that the patient will require hospital admission. It is essential to rule out any infectious etiology by maintaining a high clinical suspicion for common respiratory pathogens. Early institution of therapy is key to the management of influenza and other infectious pathologies. Therefore, influenza testing should be strongly considered, particularly during the influenza season. Empiric antiviral or antimicrobial treatment should be considered in accordance with local antimicrobial resistance patterns. Patients with severe lung injury without any identifiable cause and a strong suspicion for EVALI have responded well to corticosteroids.[11] 

It is vital to strongly discourage further use of vaping products. There is limited evidence to support the use of corticosteroids in patients with milder symptoms being managed on an outpatient basis. Corticosteroids can potentially worsen an underlying respiratory infection; therefore, it is important to involve the pulmonologist when starting the patient on corticosteroids. These patients can deteriorate very rapidly and may end up requiring assisted mechanical ventilation.

When discharging patients with EVALI, it is crucial to ascertain the patient's clinical stability as dictated by stable oxygenation and exercise tolerance for 24 to 48 hours prior to planned discharge. These patients should follow-up with their primary care provider or pulmonologist within 48 hours. Furthermore, follow-up testing with spirometry and chest x-ray may be required for some patients as recommended by the pulmonology provider.

Differential Diagnosis

In the midst of a pandemic caused by the deadly respiratory pathogen SARS-COV2, COVID 19 remains the topmost differential for any patient presenting to the emergency department with respiratory distress having bilateral infiltrates on chest radiograph. Community-acquired pneumonia is another important consideration whenever dealing with a patient having significant respiratory symptoms as it is quite common. EVALI is a relatively new disease, and there is a lot of confusion surrounding the diagnosis since it mimics the clinicopathologic presentation of various other pulmonary ailments. Nevertheless, the following patterns of lung injury have been reported with EVALI:

  • Acute eosinophilic pneumonia
  • Lipoid pneumonia
  • Acute lung injury and acute respiratory distress syndrome
  • Acute and subacute hypersensitivity pneumonitis
  • Organizing pneumonia
  • Acute eosinophilic pneumonia
  • Diffuse alveolar hemorrhage
  • Respiratory bronchiolitis-associated pneumonitis

It is noteworthy to remember that the aforementioned pathologies can present without a history of e-cigarette use and hence should be considered as a possible differential in the appropriate clinical context.

Prognosis

EVALI is a potentially fatal disease, with 68 deaths reported so far. A significant number of patients may end up requiring non-invasive or invasive mechanical ventilation. A recent study of 98 patients showed that as many as 76% of the cases needed supplemental oxygen, 22% required non-invasive ventilation (NIV), and 26% required intubation and mechanical ventilation.[12] Poor prognostic indicators include age>35 years, comorbidities that compromise pulmonary reserve, and patients presenting with resting oxygen saturation <95%.[13] These patients can rapidly deteriorate and end up developing acute respiratory distress syndrome.

Complications

The main serious complications of EVALI are the need for intubation and mechanical ventilation and death.

Deterrence and Patient Education

All the patients presenting with signs and symptoms of EVALI should be counseled to discontinue vaping as the risk of rehospitalization with potentially severe symptoms exists. Adults without any previous history of smoking tobacco products should not start vaping. Those patients using e-cigarettes or vapes as an alternative to cigarettes should not go back to smoking cigarettes.

CDC strongly advises against the use of all THC containing vapes or e-cigarettes. Adults using vapes or e-cigarettes to help with tobacco smoking cessation should only buy vaping products from commercially authorized vendors. Potentially harmful ways of exposure, such as dabbing or dripping, must be avoided altogether as users who dab or drip vaping liquid directly onto the heating element are exposed to a much denser cloud of aerosol thereby increasing the risk of lung injury.

Enhancing Healthcare Team Outcomes

Treatment by an interprofessional team is beneficial for patients with EVALI. Consultations with pulmonary, critical care, medical toxicology, infectious disease, psychology, psychiatry, and addiction medicine specialists should be considered, especially in hospitalized patients, to optimize patient care. Involving the pulmonologist is essential in commencing the judicious use of corticosteroids and later tapering them off. Intensivists should be onboard for patients requiring assisted ventilation.

Psychiatrists, psychologists, and addiction medicine specialists should discuss quitting vaping, including devising a cessation strategy and offering evidence-based tobacco product cessation interventions, including behavioral counseling and medications. Healthcare providers need to ascertain whether these patients have strong social support and access to mental health and substance use disorder services. Patients requiring prolonged hospitalization, particularly those ending up in intensive care units, can benefit from physical therapy.


References

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