Previous studies show that BHD syndrome causes spontaneous pneumothorax (SP) in 24-38% of patients, with a recurrence rate of up to 75% (Toro et al., 2007; Toro et al., 2008; Houweling et al., 2011). A common preventative strategy used following an initial SP in patients with BHD is pleurodesis, however, its efficacy in preventing recurrent episodes is not well known. Due to the pressure changes during air travel, cystic air spaces expand and compress in the thorax possibly leading to cyst rupture and pneumothorax. In their new study, Gupta et al. (2017) evaluate the risk of pneumothorax, the efficacy of pleurodesis, and the safety of air travel in patients with BHD.
104 BHD patients were recruited from the Rare Lung Diseases Clinic Network and the BHD Foundation, and surveyed about pneumothorax and air travel experiences. This study classified any pneumothorax occurring either during a flight or within 24 hours after as a flight related pneumothorax. Differently, considering symptom delay, a recent study discussed on a previous blog classified any pneumothorax that happened within one month of air travel as flight related pneumothorax (Johannesma et al., 2016). Here, the limit to 24 hours meant to distinguish between a flight related SP and an unrelated SP that happened to occur after a flight.
The survey results showed that the average age at diagnosis of BHD was 47 years, with an average delay from first symptoms of 13 years. Pulmonary cysts were the most frequent phenotypic manifestation of BHD, in 85% of patients. Spontaneous pneumothorax was the presenting manifestation that led to the diagnosis in 65% of patients, typically after the second episode. Mild symptomatic dyspnea was reported by 50% of the patients. 76% of patients had at least one spontaneous pneumothorax during their lifetime, and 82% had multiple. Of the patients with a sentinel pneumothorax, 73% had an ipsilateral recurrence. The mean age at first and second pneumothorax was 36.5 and 37 years, respectively and the average number of recurrent episodes was 3.6.
Spontaneous pneumothorax was mainly diagnosed by chest radiograph, with computed tomographic imaging used as a diagnostic modality for the first episode in only 8 patients. 62% of patients had at least one pleurodesis to prevent recurrent pneumothoraces. Pleurodesis was generally performed after the second pneumothorax and reduced the recurrence by half – 63% of recurrence rate of SP managed without pleurodesis compared to 33% following pleurodesis. Similar conclusions regarding efficacy of pleurodesis have been previously published (Johannesma et al., 2014).
Air travel
96% of the patients in the study had flown at least once in their lifetime and the average number of flights per patient was 25. There was no difference in the average number of flights taken by patients with a history of SP versus patients without a SP. Patients frequently experienced adverse effects during air travel, including chest pressure, anxiety, headache, shortness of breath and chest pain. 11 episodes of spontaneous pneumothorax occurred in 8 patients either during or within 24 hours of air travel. The authors calculated a flight related pneumothorax risk of 8% per patient, and 0.12% per flight. 8 of these 11 episodes represented recurrent SP and the majority had not undergone prior pleurodesis. Prior pleurodesis reduced the occurrence of a subsequent flight-related pneumothorax.
24% of patients changed their flight frequency after the diagnosis of BHD was established, either by avoiding or reducing air travel. The recommendations that patients were given by physicians regarding the safety of air travel after spontaneous pneumothorax were variable and more than half of the patients were given no specific recommendations. Clear recommendations are currently not available but studies emphasize that patients with a current closed pneumothorax should avoid air travel and recommend flight restrictions between 1 and 4 weeks after resolution of pneumothorax (Hu et al., 2014, Ahmedzai et al., 2011).
A significant proportion of the patients were recruited from pulmonary clinics, representing an ascertainment bias, perhaps causing the higher prevalence of spontaneous pneumothorax (76%) observed in this study compared with the 24-38% previously reported in the literature.
Similarly to Johannesma et al., 2016, the present study indicates that patients with BHD have a risk of spontaneous pneumothorax during flight that is most likely less than 1%, and even lower for patients with a history of pleurodesis. Patients with BHD should be advised about the risks of pneumothorax and benefits of pleurodesis and get medical advice regarding air travel.
- Gupta N, Kopras EJ, Henske EP, James LE, El-Chemaly S, Veeraraghavan S, Drake MG, & McCormack FX (2017). Spontaneous Pneumothoraces in Patients with Birt-Hogg-Dubé Syndrome. Annals of the American Thoracic Society PMID: 28248571