Ethiopathogenesis of spontaneous primary pneumothorax. Marijuana: cause or a blame?]

There are contradictory data on chronic lung injury caused by marijuana, which is partially due to insufficient basic research. Anecdotic reports draw attention to an increased rate of primary spontaneous pneumothorax (PSP) among young marijuana smokers, suggesting a causative link.A retrospective analysis of 20 patients treated for PSP in our department in the last two years was performed. Demographics, treatment modality and outcome data were analysed. Chi-square, Mann-Whitney and Fisher tests were applied for statistical evaluation. Gender distribution: 16 male, 4 female, age 23.95 ± 4,57 years: min: 18, max: 32. 13/20 patients admitted to be regular cannabis users (CU), among them 11 male, 2 female, age 24.54 ± 4.77 years. Altogether 7/20 patients had a history of previous pneumo-thorax, with a higher recurrence rate among CU (odds ratio 1.56).In the non-cannabis user group (NCU) 3/7 patients were managed with thoracic drainage alone. 4/7 NCH patients needed major surgery, VATS was performed on all 4 patients. 4/13 CU patients were managed with thoracic drainage, 9/13 patients needed thoracotomy (8 VATS, 1 open thoracotomy). We found a shorter drainage time among NCU patients (4.00 ± 1.00 days NCU vs 4.5 ± 1.73 days CU, p = 0.651). Operative treatment was needed more frequently among cannabis users (69.23% vs NCU 57.14%, p = 0.651) due to impaired lung expansion. Recurrence was detected in 2 patients after drainage, 1 CU, 1 NCU patients, respectively, both of them were managed with VATS. On histological examination there were no major differences between the two groups, 11/13 of operative cases had pulmonary emphysaema . Based on county demographical and clinical data, there's a higher risk for PSP among cannabis users (odds ratio 3.86).Despite the small sample size, there seems to be a connection between marijuana use and PSP prevalence. It's unclear if marijuana directly contributes to the development of pneumothorax, or just aggravates a fundamentally fragile lung parenchyma condition. In this group of young patients a more aggressive surgical approach is recommended, considering underlying parenchymal impairment and higher recurrence rate.