Friday, November 22, 2019

Case of Popcorn Lung in Canada Due to E-Cigarettes? Not so Fast

It is being widely reported in the media that there was recently a case of "popcorn lung" in Canada that was due to the use of e-cigarettes. These reports are exaggerated and inaccurate representations of a medical journal article published in the Canadian Medical Association Journal.

The article reports the case of a 17-year-old patient who presented with severe respiratory failure requiring mechanical ventilation. A chest CT scan revealed a "bud-in-tree" pattern which is consistent with a diagnosis of bronchiolitis. Because the study authors had heard that some e-liquids contain a flavoring called diacetyl, which has linked to popcorn lung disease in popcorn factory workers who were exposed to very high doses of the pure chemical, they speculated that this could be a case of popcorn lung attributable to the use of e-cigarettes.

The Rest of the Story

It is very unlikely that this case represents popcorn lung attributable to electronic cigarette use, and there is certainly no documentation or hard evidence to draw such a conclusion. Importantly, the authors are merely speculating when they suggest that this could be popcorn lung and that it could be attributable to e-cigarettes. It also could be a different type of bronchiolitis, and it could be attributable to the use of THC vape carts, which the patient admitted using very heavily prior to becoming sick. These THC vape carts were apparently not purchased from a licensed cannabis dispensary.

Importantly, the authors themselves acknowledge that they were unable to confirm a diagnosis of popcorn lung.

First, they were unable to examine the patient's airway pathology. As they state: "the transbronchial biopsies did not include airway mucosa for evaluation." Thus, although they identified the presence of bronchiolitis, they are unable to assess any pathology taking place in the airway mucosa.

Second, they did not even conduct testing for lipoid pneumonia. The authors acknowledge that: "because of the preparation method, no staining for lipoid pneumonia could be done."

Third, the "bud-in-tree" pattern is a non-specific pattern seen in a wide variety of respiratory diseases and illnesses. It is not specific to popcorn lung. In fact, the differential diagnosis of a "bud-in-tree" pattern includes inhalation of chemical toxins.

Fourth, as the authors acknowledge, several of the confirmed case patients in the U.S. also had the "bud-in-tree" pattern. So the presentation of this patient is not entirely inconsistent with that of other case patients.

Fifth, there is a wide variety of ways in which patients' lungs have responded to the inhalation of vitamin E acetate oil and any contaminants in it. These presentations have ranged from lipoid pneumonia to chemical pneumonitis to crypotogenic organizing pneumonia to acute eosinophilic pneumonia. The point is that different people respond differently to whatever in vitamin E acetate oil is causing this outbreak. There are a variety of presentations and although this presentation does have some different features from many previous ones, it is not clear that this represents a completely different entity due to a completely different cause.

Sixth, the patient reported heavy use of what were apparently black market THC vape carts. It is entirely possible that his respiratory illness is due to cannabis vaping, not e-cigarettes.

Finally, the study authors were unable to provide one key piece of evidence that would absolutely be necessary to establish that the disease in question was caused by diacetyl: they failed to document that there was diacetyl in the e-liquids used by the patient and they were unable to verify that diacetyl was present at levels that are sufficient to cause popcorn lung.

Sadly, many e-cigarette opponents are already using this case as justification for banning e-cigarettes. This is a disservice to the millions of former smokers whose health and lives depend on the continued availability of e-cigarettes.

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