Birt–Hogg–Dubé syndrome is caused by germline mutations in the FLCN gene and characterized by skin fibrofolliculomas, lung cysts, spontaneous pneumothorax (SP) and renal cancer. Because sudden changes in air pressure can increase the chances of developing a collapsed lung, a concern many BHD patients have is whether it is safe to air travel and scuba dive, or whether this increases the chances of a pneumothorax. In a new study, Johannesma et al. (2016) evaluate the incidence of SP in patients with BHD during or shortly after air travel and diving. The study was conducted by sending a survey to a cohort of BHD patients. The authors assessed SP episodes occurring within 1 month after air travel or diving and concluded that exposure to changes in air pressure associated with flying and diving may increase the risk of developing pneumothorax.
A survey was sent to 190 BHD patients, with diagnosis confirmed by FLCN mutations analysis, to collect information about history of spontaneous pneumothorax, flying and diving history within 1 month before the SP episode and adverse effects during flying and diving (including shortness of breath, chest pain, palpitations, anxiety, fatigue, nausea, dizziness, headache, chills and light-headedness). Medical records were collected and reviewed for radiological evidence of SP.
In total, 158 (83.2 %) patients completed the questionnaire. One or more adverse effects were experienced by 30/145 patients (20.7 %) during flight and in 10/54 patients (18.5 %) during diving. 13/145 BHD patients (9.0 %) developed a SP < 1 month after air traveling. The diagnosis of pneumothorax was confirmed in all patients with chest X-ray, additional thoracic CT was performed in some patients. The authors calculated a pneumothorax risk of 0.63 % per flight. 2/54 (3.7 %) developed a SP < 1 month after diving at depths between 3 and 10 m. A pneumothorax risk of 0.33 % per diving session was calculated. Although these patients did not undergo chest radiographic imaging before air travel or diving session, the authors assume that patients developed a pneumothorax during air travel or ascending in the diving session, as patients had no previous symptoms of pneumothorax.
Due to the lack of studies in this subject, recommendations regarding air travel and diving with pneumothorax are variable. The British Thoracic Society (BTS) guidelines on air travel emphasize that patients with a current closed pneumothorax should avoid air travel, patients may be able to fly 6 weeks after a surgical intervention and resolution but careful medical assessment is required. BTS also recommends that after a pneumothorax, diving should be discouraged permanently unless a prevention strategy has been performed (MacDuff et al., 2010). In-flight pneumothorax seems to be rare in the general population (Sand et al., 2009; Peterson et al., 2013). Between 1969 and 2012 a total of 38 episodes of pneumothorax during air travel are described (summarized in Hu et al., 2014), a number of these episodes had LAM as an underlying disease. So far, little data concerning BHD and air travel is available. The same group conducting this new study had previously found that 6.3 % of a BHD patient cohort suffered episodes of pneumothorax within one month of flying (Postmus et al., 2014). Interestingly, although the authors reported no link between air travel and risk of pneumothorax, another study found a similar proportion of BHD patients reported chest tightness following air travel but without being diagnosed with pneumothorax (Hoshika et al., 2012), however the length of the pneumothorax free period after flying was not specified.
The size of the connection between airway and pleural cavity in the lungs is likely to determine how fast a pneumothorax will increase, the location of the cysts in the periphery of the lungs and the lack of a direct connection with the airways supports this theory. Therefore, it may take weeks before a pneumothorax causes symptoms so to determine whether a pneumothorax occurred during or shortly after air travel or diving, imaging before and right after would be required. It would also be interesting to try to correlate specific FLCN mutations with increased risk of pneumothorax.
In summary, the data in this study suggests that patients with BHD might possibly have an increased risk for pneumothorax in flying and diving. Patients with BHD should be advised that the presence of any clinical symptoms during or shortly after air travel or diving might indicate a pneumothorax. Further research is required to draw more conclusive associations and to address the exact rate of pneumothorax during and directly after air travel and diving.
- Johannesma, P., van de Beek, I., van der Wel, J., Paul, M., Houweling, A., Jonker, M., van Waesberghe, J., Reinhard, R., Starink, T., van Moorselaar, R., Menko, F., & Postmus, P. (2016). Risk of spontaneous pneumothorax due to air travel and diving in patients with Birt–Hogg–Dubé syndrome SpringerPlus, 5 (1) DOI: 10.1186/s40064-016-3009-4