Pulmonary function in cannabis users: Support for a clinical trial of the vaporizer.

BACKGROUND Debates about cannabis policy often mention respiratory symptoms as a negative consequence of use. The cannabis vaporizer, a machine that heats the plant to release cannabinoids in a mist without smoke and other respiratory irritants, appears to have the potential to minimize respiratory complaints. METHODS Twenty frequent cannabis users (uninterested in treatment) reporting at least two respiratory symptoms completed subjective ratings of respiratory symptoms and spirometry measures prior to and following 1 month's use of a cannabis vaporizer in a pre/post-design. Outcome measures included self-reported severity of nine respiratory symptoms as well as spirometry measures, including the maximum amount of air exhaled in 1s (forced expiratory volume; FEV1) and maximum total lung volume (forced vital capacity; FVC). RESULTS The 12 participants who did not develop a respiratory illness during the trial significantly improved respiratory symptoms (t(11)=6.22, p=0.000065, d=3.75) and FVC, t(11)=2.90, p=0.007, d=1.75. FEV1 improved but not significantly t(11)=1.77, p=0.053, d=1.07. CONCLUSIONS These preliminary data reveal meaningful improvements in respiratory function, suggesting that a randomized clinical trial of the cannabis vaporizer is warranted. The vaporizer has potential for the administration of medical cannabis and as a harm reduction technique.