One concern many BHD patients have is whether it is safe to take commercial flights, or whether this would increase the chances of a pneumothorax. A recently published study, by Professor Pieter Postmus and his team at the VU Medical Center in the Netherlands, sheds some light on this issue.
Postmus et al. (2014) describe the case of a 38 year-old man with BHD who developed a pneumothorax after taking a speed lift to the top of one of the highest towers in the world. This episode was also two days following a trans-Atlantic flight. Upon his return home, the patient reviewed when his previous episodes of pneumothorax had occurred in relation to his flight pattern and found that both of his previous pneumothoraces had occurred within ten days of his return flights.
The authors also conducted a survey of 190 BHD patients and found that 12 patients (6.3%) suffered 13 episodes of pneumothorax within one month of flying. Of these, six cases occurred within 10 days; 4 cases between 10-20 days; and 3 cases between 20-30 days of their flight. Interestingly, although the authors concluded there was no link between air travel and increased risk of pneumothorax, a Japanese study found a similar proportion of BHD patients (3/48 or 6.3%) reported chest tightness following air travel although they were not diagnosed with pneumothorax (Hoshika et al., 2012).
It is thought that BHD-associated pneumothoraces are caused by lung cysts rupturing, which allows air to escape into the pleural cavity (Furuya and Nakatani, 2012). Thus, it is possible that the air pressure change experienced on the flight causes lung cysts to rupture. The long time lag – up to 30 days – between travel and symptoms developing suggests that pneumothorax does not occur instantaneously following cysts rupturing, but that it takes time for enough air to build up in the pleural space to collapse the lung.
Postmus et al. suggest that flying may cause a small pneumothorax to develop, which is then aggravated by further air pressure changes, most commonly the return flight. Thus, they recommend that patients are assessed for pneumothorax before making the return flight, although realistically this may not always be possible.
These results suggest that roughly 1 in 16 BHD patients are at risk of developing a pneumothorax within a month of flying, meaning that the risk is small but not insignificant. It is likely that a BHD patient’s precise risk will depend on the extent that BHD has affected their lungs, whether they have had previous episodes of pneumothorax, and how often they fly. It would also be of interest to determine whether the 12 BHD patients who reported having a pneumothorax within a month of flying had any shared characteristics such as gender, height, or FLCN mutation, to more accurately predict patient risk.
The most unexpected result of this study is the potentially large time lag between air travel and a collapsed lung becoming apparent. This may have confounded previous studies investigating the risks of air travel for BHD patients, as researchers may have only thought the two were linked if the pneumothorax occurred within a day or two of the flight. Thus, any future studies should take this into account to conclusively calculate the risk to BHD patients.
Additionally, patients should be aware of this risk and should be particularly alert to any symptoms of pneumothorax that develop up to 30 days after their flight. It may also be prudent for patients to avoid flying too frequently if possible; while British guidelines recommend that pneumothorax patients can fly 1 week after their pneumothorax has resolved, the BHD patient described in this study flew within a month of his first collapsed lung resolving, and subsequently suffered a second pneumothorax.
- Furuya M, & Nakatani Y (2013). Birt-Hogg-Dube syndrome: clinicopathological features of the lung. Journal of clinical pathology, 66 (3), 178-86 PMID: 23223565
- Hoshika Y, Kataoka H, Kurihara M, Anod K, Sato T, Seyama K, & Takahashi K. (2012). Features of pneumothorax and risk of air-travel in Birt-Hogg-Dube´ syndrome [abstract]. American Journal of Respiratory and Critical Care Medicine, 185 DOI: 10.1164/ajrccm-conference.2012.185.1_MeetingAbstracts.A4438
- Postmus PE, Johannesma PC, Menko FH, & Paul MA (2014). In-Flight Pneumothorax: Diagnosis May Be Missed because of Symptom Delay. American journal of respiratory and critical care medicine, 190 (6), 704-5 PMID: 25221882