Pneumothorax can occur in patients with underlying lung diseases; it occurs most frequently in patients with COPD followed by those with interstitial pneumonia [10]. Pneumothorax that occurs in patients with chronic lung disease is reportedly associated with higher mortality and recurrence rates than primary spontaneous pneumothorax that occurs in patients without chronic lung disease [9, 10, 16]. Our study shows that pneumothorax in patients with IPF was difficult to treat successfully, shows a high recurrence rate, and has a relatively poor prognosis.
The British Thoracic Society recommends surgery for patients with a persistent air leak from the chest tube placed for drainage [19]. However, some patients with secondary spontaneous pneumothorax are not candidates for surgical intervention because of age, poor pulmonary function, or other comorbidities. In addition, acute exacerbation of IPF can occur after surgery [20]. Actually, only 2 patients during the first admission and 4 in all the admissions combined underwent surgery after chest tube drainage plus some additional treatments.
Chemical pleurodesis can be a nonsurgical option for patients with persistent air leakage from the chest tube [19]. Complete re-expansion of the lung is needed to achieve successful chemical pleurodesis. However, some IPF patients with pneumothorax do not obtain re-expansion of the lung because of the distinctive rigidity of the lung parenchyma in IPF [21]. Another concern with chemical pleurodesis is the risk of restrictive pulmonary dysfunction [22] and acute exacerbation of IPF after the procedure [23]. Probably for these reasons, chemical pleurodesis was not performed for any of the study patients. As another nonsurgical option, pleurodesis performed with an autologous-blood patch or fibrin glue has been reported to be effective [24, 25]. Although adequate pulmonary re-expansion is needed to achieve pleurodesis, the risks of restrictive pulmonary dysfunction and acute exacerbation of IPF after these procedures might be lower than they are after chemical pleurodesis. In our patient series, a respective 2 patients during the first admission and 3 patients during all the admissions combined underwent pleurodesis by fibrin glue or autologous blood patch for success rates of 50% and 66%.
An EWS is a silicone spigot used to occlude a bronchus [26]. The EWS has been reported to be effective for reducing air leakage in about 50% of patients [27]. In our study, the EWS showed relatively high success rates of 57.1% and 50.0% for the first and all the admissions combined, respectively. Given that the EWS has been found to be useful even in patients who have incomplete re-expansion of the lung, placement of an EWS might be suitable for patients with IPF and pneumothorax with persistent air leakage from the chest tube.
Hospital mortality rates of patients with secondary spontaneous pneumothorax have been reported to range from 4.5–17.9% [10, 17]. In these reports, the most frequent underlying disease was pulmonary emphysema. By contrast, a higher hospital mortality rate has been reported for pneumothorax in patients with IPF [6]. The hospital mortality rates in our study ranged from 24–28%, which were relatively high, although similar to the previous report [6]. The mortality of patients who required chest tube drainage was even higher in our study.
The recurrence rate of secondary spontaneous pneumothorax varies according to the published literature, ranging from 30–80% [17–19]. The recurrence rate of pneumothorax in patients with IPF is reportedly high (70.6%) [11]. In our study, 53.8% of patients with IPF developed recurrence after their first admission and subsequent discharge for pneumothorax. Furthermore, recurrence was observed within the first year after discharge. Given that recurrence of pneumothorax in a patient with IPF confers additional risk of death, preventative methods for recurrence should be developed.
This study has limitations. First, it was a single-center retrospective study of a relatively small number of patients. Second, the treatment for pneumothorax was not uniform because it was performed by individual physicians and based on their individual judgements. Third, the study might have included patients with PPFE [13.14]. Although major efforts were made to exclude patients with PPFE based on the chest HRCT, some patients with subclinical PPFE could have been included. Histological PPFE seen in the upper pulmonary lobes was reported to trigger pneumothorax in patients with IPF [15]. Further studies of pneumothorax in IPF patients should preferably base study enrollment on a histological evaluation of a lung specimen.
To the best of our knowledge, the study is the first to evaluate additional treatments in IPF patients with pneumothorax and persistent air leakage after placement of a chest drain. The efficacy of combined therapy, consisting of the treatments added to chest tube drainage should be improved.
In conclusion, pneumothorax in patients with IPF is difficult to treat successfully, and has a relatively poor prognosis and high recurrence rate.