Atmospheric pressure influences the risk of pneumothorax: beware of the storm!

BACKGROUND: Idiopathic spontaneous pneumothorax (ISP) results from rupture of blebs, bullas, or diseased alveolar walls. Initiating mechanisms may relate to increased transpulmonary pressure. The possible impact of changes in atmospheric pressure (Patm) on the occurrence of ISP remains uncertain. METHODS: We studied the relationship between the occurrence of ISP and meteorological conditions during a 4-year period in the urban area of Bologna, Italy, in which all cases of pneumothorax can be exhaustively identified. For each day of the study period, Patm and ambient temperature were obtained from the local meteorological institute. A cluster was defined as the admission of at least two patients with pneumothorax within 3 days of each other. RESULTS: There were 294 episodes of ISP; 247 (84%) occurred in 76 clusters. Clusters were significantly associated with wider differences in Patm between the index day (ie, the first day of the cluster) and the previous day (ie, the difference in mean [+/- SEM] Patm, -1.23 +/- 0.45 vs + 0.04 +/- 0.12 mm Hg, respectively; p = 0.01[analysis of variance]). Similarly, pneumothorax and storms (but not temperature) were significantly associated (p < 0.0001 [chi(2) test]). CONCLUSIONS: This large-scale study shows that patients with ISP are hospitalized in clusters and suggests that important variations in Patm may be involved. The knowledge of this relationship may help to understand the pathophysiology of the disease.