High clinical suspicion is necessary to make the diagnosis of VAPI. As of October 2019, VAPI was considered a diagnosis of exclusion because no specific tests or markers existed for its diagnosis. Healthcare providers were advised to evaluate for alternative diagnoses (e.g., cardiac, gastrointestinal, rheumatologic, neoplastic, environmental, or occupational exposures, or causes of acute respiratory distress syndrome) as suggested by clinical presentation and medical history, while also considering multiple etiologies, including the possibility of VAPI occurring with a concomitant infection. All healthcare providers evaluating patients for VAPI were urged to consider obtaining a thorough patient history, including symptoms and recent use of e-cigarette, or<unk> , products, along with substances used, duration and frequency of use, and method of use. Additionally a detailed physical examination was recommended, specifically including vital signs and pulse-oximetry. Laboratory testing guided by clinical findings, which might include a respiratory virus panel to rule out infectious diseases, complete blood count with differential, serum inflammatory markers (C-reactive protein CRP, erythrocyte sedimentation rate ESR), liver transaminases, and urine toxicology testing, including testing for THC were recommended. Imaging, typically a chest X-ray, with consideration for a chest CT if chest X-ray results did not correlate with the clinical picture or to evaluate severe or worsening disease were urged. It was pointed out that consulting with specialists (e.g. critical care, pulmonology, medical toxicology, or infectious disease) could help guide further evaluation. The diagnosis is commonly suspected when the person does not respond to antibiotic therapy, and testing does not reveal an alternative diagnosis. Many of the reported cases involved worsening respiratory failure within 48 hours of admission, following the administration of empiric antibiotic therapy. Lung biopsies are not necessary for the diagnosis but are performed as clinically indicated to rule out the likelihood of infection. Bronchoalveolar lavage sample from a patient with acute lung injury<unk>  with<unk> , showing alveolar macrophages laden with vacuoles (A) and extensive lipid deposits (B). There are non-specific laboratory abnormalities that have been reported in association with the disease, including elevations in white blood cell count (with neutrophilic predominance and absence of eosinophilia), transaminases, procalcitonin, and inflammatory markers. Infectious disease testing, including blood and sputum cultures and tests for influenza, Mycoplasma, and Legionella were all found to be negative in the majority of reported cases. Imaging abnormalities are typically bilateral and are usually described as "pulmonary infiltrates or opacities" on chest X-ray and "ground-glass opacities" on chest CT. Bronchoalveolar lavage specimens may exhibit an increased level of neutrophils in combination with lymphocytes and vacuole-laden macrophages. Lavage cytology with oil red O staining demonstrated extensive lipid-laden alveolar macrophages. In the few cases in which lung biopsies were performed, the results were consistent with acute lung injury and included a broad range of features, such as acute fibrinous pneumonitis, diffuse alveolar damage, lipid-laden macrophages, and organizing pneumonia. Lung biopsies often showed neutrophil predominance as well, with rare eosinophils. Case definitions Based on the clinical characteristics of VAPI cases from ongoing federal and state investigations, interim surveillance case definitions for confirmed and probable cases have been developed. The CDC surveillance case definition for confirmed cases of severe pulmonary disease<unk>  with e-cigarette use: * Using an e-cigarette <unk> ") or dabbing during the 90 days before symptom onset AND * Pulmonary infiltrate, such as opacities on plain film chest radiograph or ground-glass opacities on chest computed tomography AND * Absence of pulmonary infection on initial work-up. Minimum criteria include: * A negative respiratory viral panel * A negative influenza polymerase chain reaction or rapid test if local epidemiology supports testing. * All other clinically indicated respiratory infectious disease testing (e.g., urine antigen for Streptococcus pneumoniae and Legionella, sputum culture if productive cough, bronchoalveolar lavage culture if done, blood culture, human immunodeficiency virus–related opportunistic respiratory infections if appropriate) must be negative and * No evidence in medical record of alternative plausible diagnoses (e.g., cardiac, rheumatologic, or neoplastic process). The CDC surveillance case definition for probable cases of severe pulmonary disease<unk>  with e-cigarette use: * Using an e-cigarette <unk> ") or dabbing in 90 days before symptom onset AND * Pulmonary infiltrate, such as opacities on plain film chest radiograph or ground-glass opacities on chest computed tomography AND * Infection identified via culture or polymerase chain reaction, but clinical team believes this is not the sole cause of the underlying respiratory disease process OR minimum criteria to rule out pulmonary infection not met (testing not performed) and clinical team believes this is not the sole cause of the underlying respiratory disease process and * No evidence in medical record of alternative plausible diagnoses (e.g., cardiac, rheumatologic, or neoplastic process). These surveillance case definitions are meant for public health data collection purposes and are not intended to be used as a clinical diagnostic tool or to guide clinical care; they are subject to change and will be updated as additional information becomes available. Differential diagnosis As VAPI was, as of October 2019, a diagnosis of exclusion, a variety of respiratory diseases must be ruled out before a diagnosis of VAPI can be made. The differential diagnosis should include more common diagnostic possibilities, such as community-acquired pneumonia, as well as do-not-miss diagnoses, such as pulmonary embolism. Other commonly documented hospital diagnoses for cases of severe pulmonary disease<unk>  with e-cigarette use have included acute respiratory distress syndrome (ARDS), sepsis, acute hypoxic respiratory failure, and pneumonitis. As of September 2019, distinctions were still being made between processes occurring in association with<unk>  or the use of nicotine-containing liquids and those considered as alternative diagnoses to VAPI. These processes include the following: * Acute eosinophilic pneumonia * COVID-19 * Diffuse alveolar hemorrhage * Giant cell pneumonitis * Hypersensitivity pneumonitis * Lipoid pneumonia * Organizing pneumonia * Respiratory bronchiolitis interstitial lung disease The use of imaging and other diagnostic modalities, including chest CT, bronchoscopy with bronchoalveolar lavage, and lung biopsy, may provide additional information to determine the presence of these processes and potentially establish a definitive diagnosis, but are generally not performed unless clinically indicated.
Vaping-associated pulmonary injury
Ventilator-associated lung injury
Swimming-induced pulmonary edema
Occult pneumonia
Ventilator-associated pneumonia
Hospital-acquired pneumonia
Acute exacerbation of chronic obstructive pulmonary disease
Hantavirus pulmonary syndrome