Endobronchial one-way valves for treatment of persistent air leaks: a systematic review
Ding et al. Respiratory Research
Endobronchial one-way valves for treatment of persistent air leaks: a systematic review
Mei Ding 0 2
Ya-dong Gao 0 2
Xian-Tao Zeng 1
Yi Guo 1
Jiong Yang 0 2
0 Department of Respiratory Medicine, Zhongnan Hospital of Wuhan University , Donghu Road 169, Wuhan 430071 , People's Republic of China
1 Center for Evidence-based and Translational Medicine, Zhongnan Hospital of Wuhan University , Donghu Road 169, Wuhan 430071 , People's Republic of China
2 Department of Respiratory Medicine, Zhongnan Hospital of Wuhan University , Donghu Road 169, Wuhan 430071 , People's Republic of China
Persistent air leak (PAL) is associated with significant morbidity and mortality, prolonged hospitalization and increased health-care costs. It can arise from a number of conditions, including pneumothorax, necrotizing infection, trauma, malignancies, procedural interventions and complications after thoracic surgery. Numerous therapeutic options, including noninvasive and invasive techniques, are available to treat PALs. Recently, endobronchial one-way valves have been used to treat PAL. We conducted a systematic review based on studies retrieved from PubMed, EMbase and Cochrane library. We also did a hand-search in the bibliographies of relevant articles for additional studies. 34 case reports and 10 case series comprising 208 patients were included in our review. Only 4 patients were children, most of the patients were males. The most common underlying disease was COPD, emphysema and cancer. The most remarkable cause was pneumothorax. The upper lobes were the most frequent locations of air leaks. Complete resolution was gained within less than 24 h in majority of patients. Complications were migration or expectoration of valves, moderate oxygen desaturation and infection of related lung. No death related to endobronchial one-way valves implantation has been found. The use of endobronchial one-way valve adds to the armamentarium for non-invasive treatments of challenging PAL, especially those with difficulties of anesthesia, poor condition and high morbidity. Nevertheless, prospective randomized control trials with large sample should be needed to further evaluate the effects and safety of endobronchial one-way valve implantation in the treatment of PAL.
Persistent air leak; Bronchopleural fistulas; Alveolar-pleural fistulas; Endobronchial valve; Bronchoscopic intervention
Pulmonary air leak is a common clinical problem which
can be resulted from both bronchopleural fistulas (BPFs)
and alveolar-pleural fistulas (APFs). BPFs are abnormal
communications between the bronchial tree and the pleural
space, while APFs are pathologic communications between
the alveoli and pleural space [
]. Persistent air leak (PAL) is
defined as those lasting more than 5 to 7 days
postoperatively, without forced expiration or expulsion maneuvers
]. The presence of PAL is associated with
significant morbidity and mortality, prolonged hospitalization
and increased health-care costs .
Air leak, both BPF and APF, can arise from a number of
conditions, including, but not limited to, pneumothorax,
necrotizing infection, trauma, malignancies, procedural
interventions (biopsy, CPR, radiofrequency ablation of
lung tumors, etc) and complications after thoracic surgery
]. Primary spontaneous pneumothorax rarely results
in PAL; it is substantially more frequent (20%) in the
setting of underlying COPD [
]. Incidence of iatrogenic
pneumothorax is reported at 1.36% in hospitalized
patients due to invasive procedures or positive pressure
]. More commonly, lung resections carry
significant risks of PALs, with an incidence ranging from
8% after a sublobar resection to 45% after lung volume
reduction surgery (LVRS). The incidence of postoperative
air leak ranges from 28% to 60% immediately after
surgery, 26% to 48% on postoperative day 1, 22% to 24% on
day 2, and 8% on day 4 [
]. The National Emphysema
Treatment Trial suggests that postoperative air leak occur in
90% of patients undergoing bilateral LVRS procedures [
Numerous therapeutic options, including noninvasive
and invasive techniques, are available to treat PALs.
Noninvasive approaches rely on prolonged chest tube
drainage either on water seal or Heimlich valve system
or coupled with tailored ventilator strategies to
establish acceptable ventilation while reducing the flow
through the alveolar- or bronchopleural fistula. Invasive
therapies include pleurodesis either surgical or at
bedside through the indwelling chest tube, by instillation of
talc slurry or doxycycline, mechanical pleurodesis by
pleural abrasion, application of fibrin sealant, bronchial
stump stapling, muscle flap construction, omental flap
coverage, or pericardial fat pad flap to the bronchial
stump, and surgical lobectomy [
Recently, endobronchial one-way valves, initially
designed for bronchoscopic lung volume reduction (BLVR)
in emphysema, have been used to treat PAL. The
objective of this article was to summarize current clinical
evidence of the management of PAL with endobronchial
one-way valves to define the role of this bronchoscopic
Literature search strategy
A search was conducted on PubMed, EMbase and
Cochrane library for original studies published from 2005
to April 2017 on endobronchial one-way valves placement
for treating PAL, using the keywords as “valve” AND “air
leak” OR “bronchopleural fistula” OR “alveolar-pleural
fistula”. We also did a hand-search in the bibliographies of
relevant articles for additional studies.
Studies reporting data on endobronchial one-way valves
in the treatment of PAL were included in this review.
Abstracts, animal studies and studies published in
languages other than English and German were excluded
from this review.
Persistent air leak was defined as the presence of an air
leak lasting more than 5 days with postsurgical or
medical etiology. In studies where a different definition was
used, we adopted the definition specified by the authors
of the selected papers.
Description of included studies
One hundred and seventy- three full-length articles were
identified by our literature search. After being appraised,
129 were excluded due to the following reasons: articles
that referred to the use of endobronchial one-way valves
in COPD (n = 11), articles that referred to the valves
other than endobronchial one-way valves (n = 85),
animal studies (n = 3), reviews (n = 8), articles written in
the excluded languages (n = 2) and duplicated cases
(n = 11), meeting abstract (n = 9). The search strategy
was showed in Fig. 1.
Case reports of PAL treated with endobronchial one-way
Characteristics of included case reports are shown in
Table 1, data for 52 patients from 34 case reports are
]. Age of patients ranged from 18 to 93 years
with median age at 57 years. Most of the patients were
males (28/51, 54.9%). The most common underlying
diseases in patients were lung infection (11/52, 21.2%),
cancer (14/52, 26.9%) and lung related diseases (26/52, 50%)
which included bronchiectasis, COPD, cystic fibrosis,
bulla and lymphangioleiomyomatosis.
Clinical features of air leak: the most remarkable cause
was pneumothorax (tension pneumothorax comprised)
(35/52, 67.3%). Postoperative air leak and empyema were
Age (years), median (range)
Infections of other sites
Lung related diseases
Causes of air leak
Alveolar-pleural and trans-diaphragmatic fistula
Postoperative air leak
Duration of air leak before endobronchial oneway valve deployment (days),median (range)
Location of air leak
Right main bronchus
Left main bronchus
Spiration® IBV valves
Type of endobronchial one-way valve used
Number of endobronchial one-way valves (per patient),median (range) Duration of air leak after endobronchial one-way valve deployment
< 1 day
> 2 days
1 day≦ ≦2 days
Removal of endobronchial one-way valve
Migration of endobronchial one-way valve 1/50c
Expectoration of endobronchial one-way valve
Recurrence of air leak
Death not related to deployment
of endobronchial one-way valve
asex of patient in one case report not given
bduration of initial air leak not given in 2 case reports
c1 patient lost to follow-up and 1 patient without plan to valve removal
following significant causes of air leak with percentage at
23.1% and 17.3% respectively. The median duration of
air leak before EBV deployment was 15 days. Air leak
was most frequently located in upper lobes as 17/52,
32.7% for right upper lobe and 15/52, 28.8% for left
upper lobe. It was least located in main bronchi (2/52,
4%) and bronchus intermedius (1/52, 2%). The rest lobes
shared an average location of air leak.
Information of endobronchial one-way valves: the
median number of valves deployed in patients was 2. Three
commercial types of valves were used: Emphasys® (32/
122, 26.2%), Spiration® IBV valves (59/122, 48.4%) and
Zephyr® valves (31/122, 25.4%).
Outcome of endobronchial one-way valves
deployment: optimal decrease of air leak was gained posterior
valve deployment within less than 24 h in majority of
patients (31/50, 62%). Valves were removed after cessation
of air leak in 20/50 patients (40%). One case of valve
migration and another case of valve expectoration were
described. Recurrence of air leak was reported in 3
patients. Three patients died after valve deployment but
not related to the procedure. None of complication like
infection was noted.
Case series of PAL treated with endobronchial one-way
Characteristics of included case series are shown in
Table 2 and Table 3, data for 156 patients from 10 case
series were identified in which half were prospective
]. Four children patients were reported
while the rest were adults. Most of the patients were
males (96/143, 67.1%). The most common underlying
disease was COPD, emphysema and cancer. The largest
amount of endobronchial one-way valves were deployed
in the upper lobes with 28.4% (75/264) of overall at right
upper lobe and 26.5% (70/264) at left upper lobe.
Complete resolution was obviously noted in all case
series with rate ranging from 47.5% to 100%. Ninety
0 0 0
ob (n (L5 /4 /4 /4
nd se LL (1 (1 (1
e lv , , L L L
f a )0 ,) , ) L M U
o v 4 0 ) 0 R R L
iton yaw (/11 (/34 (/340 (/114 and and and
c e L L L L L L L
o n U M L U U L U
L o R R R L R R R
f m e
o ce 20 ilrt sy
n la : a a
ito p ian u d
v ed rteq 45
D v M In to
,) ,) ,) /
0 0 0 ( )
4 4 n 0
/4 / / 4
9 (1 (3 ito /1
3 c (
a ch se i
e l t
b f a re s
e u tu re p e d
s io ) ts ss d g ro
a v N e e o d u
c re / h lo lo e le
n P (n c E B w p
e a ) 5
it p F /1
o M 2
p . ( (
f o xe 0
o N s 4
ra lub yep rt d
a e tu
P t R s
C ,r ]
2 oh o , ]
t n e 9
;) ;) ;)1 LL
3 3 /3 d
4 6 (7 an
L L L L
U L U U
L L R L
:an ske tsh
d e n
e w o
M 2 m
ic r )
g u 7
r e /
s p (4
:8 6 1
an ,2 :
d an g
e e an
M M R
:6 5 8 8
n 7 :6 :2
d to an g
e 6 e an
M 4 M R
p y p y
s d s d
o u o u
r t r t
p s p s
] la ]
, 3 li 4
s [5 v [5
odb lave sed ;)
n v u (1 ; 8
fe ya se ve : 1
o w lav laV ian :e
ep -e v d ng
y n f V e a
T o o IB M R
e lv d
fo va iife
n y c
o a e
t w s
c e t
o n o
L o N
le t ;s ;s
r en y y
i a a
) fa m d d
d o ce 6 8
e n la .21 :1n
u io p :
itn ta ve an iad
n ru la e e
o D v M M
sa ivo )N tse
c re / h
n P (n C
ite fap )/F )/4
ap .o (M (10
f o xe 4
o N s 1
is n it
r io c
e t e
t a p
c ic s y
ra lPub tyep rto ud
a re ts
C ,r ]
2 tho no ]5
le au le ,e [5
c c 5
lllll-scaeunonngm iiiliffrtttssaeeund ,)(/411 lirtscyaveuoogm ,)(/411 ,()/414PCDO lii(t/ssssa11oohpm ,i()/a114euonnpm llryaeuunnoodpm iliitcaauhonoppdm ,)14 ,illi()r/sssa114eogp ,iiif()rt/ssscyc114ob ilittttsscaaeeeohommm ttssaeeuunonnoohppm )41 ,()rt/sscaa11e9ooOm ,()/991PCDO ,i()r/scaaa119oongm iiirrtzcycaenononggpg ,i()/a119euonnpm i(rrt/ccccaaaee119nnp iilliirtttsssaaeeeunngd ,()r/ccaLe511unng ,li()t/sae1e11hoomm ,()/611PCDO ,iii()/ssycccc111ooodm iilliirtttsssaaeeeunngd ,()rt/sscaa11e3ooOm ,()/731PCDO ,iI()rt/cae413nog ,i()rtt/savee213Poop ,i()r/scaa113oongAm i(rrt/ccccaaaee113nnp iiirrtzcycaeononnggpg i()/a113euonnpm
M M 8
(7 ; 6
ve : 2
l n :
aV ia e
V e a
IB M R
,)9 ro )
e p c
b l t
u ca ap
e em od
h h lo
C C B
iand :a6n 90
e e –8
M M 3
S ; 3
± 5 :
a ± ng
e 5 a
M 6 R
s -w )s
y e y aen ang
aD on (ad
1 (9 /
e ) e
p 3 o
/ / /
/ 3 (3 N /
(57.7%) patients received removal of endobronchial
oneway valves and the mean duration of endobronchial
oneway valve use was 23–138 days. Recurrence was observed
in 14/156 (9.0%) patients. Travaline et al. reported 6
patients with complications related to endobronchial
oneway valves in their case series in 2009: valve expectoration,
moderate oxygen desaturation, initial malposition of the
valve redeployment required, pneumonia,
methicillinresistant Staphylococcus aureus colonization and one
unspecified. Hance et al. reported 2 deaths after
endobronchial one-way valve deployment but not related to
the procedure. There was no other complication reported
in the rest 148/156 (94.9%) patients.
The common treatment for PAL is surgery. However,
for those patients with poor cardiopulmonary reserve,
the risks of general anesthesia and surgical intervention
pose a challenge [
]. Meanwhile, poor wound-healing
characteristics could contribute to failure of surgery for
PAL such as a low FEV1 percentage, and low maximum
voluntary ventilation percentage, steroid use, prior
radiochemotherapy, malnutrition, diabetes, etc. [
Previous nonsurgical treatments for PAL have had limited
success. Pleurodesis may indirectly impact air leak by
creating pleural symphysis and localized inflammatory
response, but data is lacking regarding its efficacy .
Likewise, autologous blood patch pleurodesis helps to seal
air leak with the blood components that can initiate and
support a fibrinous and inflammatory response, there is
no substantive evidence that it results in earlier resolution
of air leak [
There is a variety of bronchosopic management of air
leak. The first description of bronchoscopic closure of
PAL was reported by Hartmann and Rausch in 1977
using tissue glue [
]. Largest case series using glue
sealant was reported by Hollaus et al. Forty-five male PAL
patients were treated endoscopically for 13 years since
1983 using fibrin glue alone or combination with spongy
calf bone depending on size of defects. Air leak was
successfully sealed in 16/45 (36%) patients and 2/16 (12%
failure rate) recurred [
]. Another category to eliminate
air leaks endoscopically is sclerosants. Five patients with
visible, central BPF were successfully treated by 100%
ethanol injection without complication [
]. 23/35 (66%)
patients recovered completely after polidocanol injection
without major complication [
]. Different from
formers, thermal energy could also be used to treat air
leaks. Aynaci et al. reported a successful elimination of
air leak by using argon plasma coagulation (APC) which
cauterized the area around two BPFs of 1 and 3 mm
A variety of devices employed other than licensed
purposes consist of a large category of invasive broncoscopic
technique in treating PALs, including Watanabe spigot,
vascular occlusion coils, tracheobronchial stents, and
Amplatzer occlude devices [
]. Sasada et al. reported a
case series of 24 patients treated by Watanabe spigots.
Complete resolution of air leak was observed in 12/24
(50%) patients, and a reduction in 7/24 (29%). 5/24 (21%)
patients showed no improvement. Complications were as
following: migration of the spigot in 4/24(17%) patients;
fever, pneumonia, or lung abscess in 5/24 (21%) [
Endobronchial one-way valves (Fig. 2) are one of the
latest additions to the therapeutic armamentarium for
PAL. Since that the interventions using flexible
bronchoscopy is possible, it can be performed at the bedside in even
the sickest patients [
]. A major benefit of bronchoscopic
interventions lies in the fact that they are completely
removable. Moreover, endobronchial one-way valves have
its advantage for allowing expiration and clearance of
distal bronchial secretions, therefore probably reducing
the risk of post-obstructive pneumonia [
The endobronchial one-way valve system comprises a
delivery catheter, a loader system and the implantable
valves. Endobronchial one-way valve delivery could
depend on either larger lumen of the rigid bronchoscopes
or longer and thinner flexible bronchoscopes, the latter
becomes the most common choice as it could be easily
performed under moderate sedation and could help
navigate into more distal bronchi [
]. Former endobronchial
one-way valve, the Emphasys® (Emphasys Medical, Inc.,
Redwood City, CA) is no more commercially circulated.
Endobronchial one-way valves are only approved for use
in Europe under the name Zephyr® made by Pulmonx
while US FDA approved IBV under the name Spiration®
made by Olympus. The size of Spiration® IBVs comes to
5 mm, 6 mm, and 7 mm, which is smaller than Zephyr®
valves with up to 8.5 mm. It is not equal to compare the
number of valves used in the procedure between Zephyr®
valves and Spiration® IBV because it could be occurred
that instead of using a larger valve to occlude the
proximal bronchus, the smaller size would be chosen to be
deployed at segmental bronchi to achieve complete
Although methylene blue has been used for diagnosis
of fistulas for many years, it is not frequently used in the
treatment of PAL. Methylene blue could be seen within
the bronchial tree leading to the fistula following being
inserted via the chest tubes. The origin of the air leak
could then be identified. Zeller et al. emphasized the use
of methylene blue for guiding endobronchial one-way
valve deployment. They reported identification of one
bronchial segment leading to fistula by methylene blue
inserting via chest tube which has not previously been
identified by the common balloon method [
]. It could
be suggested that it may be also helpful in identification
of origin of the intermittent air leak which could not
detected by balloon occlusion test.
Another helpful technique in the endobronchial
oneway valve deployment procedure is the digital pleural
drainage system which is able to continuously monitor
and record the air leak in milliliter leakage per minute
(ml/min−1) providing an objective and reproducible
quantitative air leak assessment [
]. Pompili et al.
conducted a multicenter international randomized study
and showed that, compared with those managed with
traditional devices, patients managed with digital drainage
systems after lung resections experienced a shorter
duration of chest tube placement, shorter hospital stays, and
a higher satisfaction rate [
Chartis system is originally used to assess collateral
ventilation between target lobe and adjacent lobes in
endobronchial lung volume reduction. Interestingly,
Tian et al. reported a successful treatment of PAL with
Zephyr EBVs being placed in bronchus B1 after Chartis
system assessment which indicated a significant and
constant negative pressure following the catheter being
inserted into the bronchus B1 and the balloon sealing
the S1 segment [
It is believed that continuation of air leaks after
valve deployment was due to collateral ventilation
between the lobes [
]. Endobronchial lung volume
reduction studies have showed underestimated
existence of collateral ventilation, or even alveolar-alveolar
]. Absence of atelectasis after lobar
exclusion for PAL on chest x-ray is indicative of
collateral ventilation which depends on the presence of
incomplete fissures [
]. However, Rosell et al. reported
a previous reduction of air debit in one patient treated
with endobronchial one-way valves proceeding to
complete resolution of PAL without further
intervention. The simple reduction of the air debit may
transform an incontrollable air leak into a situation for
conservative management until it heals, and it should
not be initially considered a failure [
Safety of endobronchial one-way valve implantation
could be concluded according to complications listed
from the available literature as valve migration or
expectoration, moderate oxygen desaturation and infection of
related lung. No death related to endobronchial one-way
valve implantation has been found in our review. Since
that decreased FEV1 after endobronchial one-way valve
deployment is inevitable and even immediate respiratory
failure has been reported, the patient should be carefully
selected before treatment with endobronchial one-way
valves in PAL [
Endobronchial one-way valve implantation would
produce a financial benefit as it can minimize direct
hospital costs and eliminate the risks of potential
complications. Podgaetz et al. reported that the
average cost of the hospitalization before valve
implantation was $14,605 including all levels of care. Total
cost of procedure, valves, and hospital stay since valve
implantation was $13,900 [
]. Dooms and his
colleagues reported that in their study the median direct
cost related to valve management was €6970 per
]. Santini et al. reported that the mean cost of
valve was €4500 whereas the average cost day per day
in the intensive care unit in Italy was estimated to be
€1500. Thus, a modest reduction in the intensive care
unit would justify the use of endobronchial one-way
valves as a cost-effective procedure [
Although endobronchial one-way valve implantation
has now been performed in many countries, most of the
studies have limitations of small number of patients
included and lack of control. Prospective randomized
control studies should be needed to evaluate the effects
and safety of endobronchial one-way valve implantation.
PAL is a common clinical problem with significant
morbidity and mortality. It’s possible that traditional
treatments are not feasible in high-risk patients and
that air leak remains persistent in spite of traditional
treatments. The use of endobronchial one-way valve
adds to the armamentarium for non-invasive treatments
of challenging PAL, especially those with difficulties of
anesthesia, poor condition and high morbidity. With its
minimal complications, endobronchial one-way valve is a
considerable therapeutical option. Nevertheless,
prospective randomized controlled trials with large sample should
be needed to further evaluate the effects and safety of
endobronchial one-way valve implantation in the
treatment of PAL.
There is no funding received.
Availability of data and materials
The work presented here was carried out in collaboration between all
authors. GY and YJ defined the research theme. ZX and GY designed
database searching methods and data analysis; DM carried out the
database searching, analyzed the data, interpreted the results and wrote
the paper. All authors have contributed to, seen and approved the
Ethics approval and consent to participate
Consent for publication
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Submit your next manuscript to BioMed Central
and we will help you at every step:
1. Williams N , Lewis C . Bronchopleural fistula: a review of 86 cases . Br J Surg . 1976 ; 63 : 520 - 2 .
2. Cerfolio RJ , Tummala RP , Holman WL , et al. A prospective algorithm for the management of air leaks after pulmonary resection . Ann Thorac Surg . 1998 ; 66 : 1726 - 31 .
3. Brunelli A , Monteverdi M , Borri A , et al. Predictors of prolonged air leak after pulmonary lobectomy . Ann Thorac Surg . 2004 ; 77 : 1205 - 10 .
4. Lois M , Noppen M. Bronchopleural fistulas: an overview of the problem with special focus on endoscopic management . Chest . 2005 ; 128 : 3955 - 65 .
5. Mahajan AK , Doeing DC , Hogarth DK . Isolation of persistent air leaks and placement of intrabronchial valves . J Thorac Cardiovasc Surg . 2013 ; 145 ( 3 ): 626 - 30 .
6. Jones DR , Stiles BM , Denlinger CE , et al. Pulmonary segmentectomy: results and complications . Ann Thorac Surg . 2003 ; 76 : 343 - 8 .
7. Ciccone A , Meyers B , Guthrie T , et al. Long term outcome of bilateral lung volume reduction in 250 consecutive patients with emphysema . J Thorac Cardiovasc Surg . 2003 ; 125 : 513 - 25 .
8. Videm V , Pillgram-Larsen J , Oyvind E , et al. Spontaneous pneumothorax in COPD; complications, treatment and recurrences . Eur J Respir Dis . 1987 ; 71 : 365 - 71 .
9. Celik B. SahinE , NadirA, et al. iatrogenic pneumothorax: etiology, incidence and risk factors . Thorac Cardiovasc Surg . 2009 ; 57 ( 5 ): 286 - 90 .
10. Okereke I , Murthy SC , Alster JM , et al. Characterization and importance of air leak after lobectomy . Ann Thorac Surg . 2005 ; 79 ( 4 ): 1167 - 73 .
11. Okamoto J , Okamoto T , Fukuyama Y , et al. The use of a water seal to manage air leaks after a pulmonary lobectomy: a retrospective study . Ann Thorac Cardiovasc Surg . 2006 ; 12 ( 4 ): 242 - 4 .
12. Alphonso N , Tan C , Utley M , et al. A prospective randomized controlled trial of suction versus non-suction to the under-water seal drains following lung resection . Eur J Cardiothorac Surg . 2005 ; 27 ( 3 ): 391 - 4 .
13. DeCamp MM , Blackstone EH , Naunheim KS , et al. Patient and surgical factors influencing air leak after lung volume reduction surgery: lessons learned from the National Emphysema Treatment Trial . Ann Thorac Surg . 2006 ; 82 : 197 - 207 .
14. Podgaetz E , Zamora F , Gibson H , et al. Intrabronchial valve treatment for prolonged air leak: can we justify the cost? Can Respir J. 2016 ; 2867547 : 2016 .
15. El-Sameed Y , Waness A , Al Shamsi I , et al. Endobronchial valves in the management of broncho-pleural and alveolo-pleural fistulae . Lung . 2012 ; 190 ( 3 ): 347 - 51 .
16. Snell GI , Holsworth L , Fowler S , et al. Occlusion of a broncho-cutaneous fistula with endobronchial one-way valves . Ann Thorac Surg . 2005 ; 80 ( 5 ): 1930 - 2 .
17. Toma TP , Kon OM , Oldfield W , et al. Reduction of persistent air leak with endoscopic valve implants . Thorax . 2007 ; 62 ( 9 ): 830 - 3 .
18. Feller-Kopman D , Bechara R , Garland R , et al. Use of a removable endobronchial valve for the treatment of bronchopleural fistula . Chest . 2006 ; 130 ( 1 ): 273 - 5 .
19. Ferguson JS , Sprenger K , Van Natta T. Closure of a bronchopleural fistula using bronchoscopic placement of an endobronchial valve designed for the treatment of emphysema . Chest . 2006 ; 129 ( 2 ): 479 - 81 .
20. Mitchell KM , Boley TM , Hazelrigg SR . Endobronchial valves for treatment of bronchopleural fistula . Ann Thorac Surg . 2006 ; 81 ( 3 ): 1129 - 31 .
21. De Giacomo T , Venuta F , Diso D , et al. Successful treatment with one-way endobronchial valve of large air-leakage complicating narrow-bore enteral feeding tube malposition . Eur J Cardiothorac Surg . 2006 ; 30 ( 5 ): 811 - 2 .
22. Anile M , Venuta F , De Giacomo T , et al. Treatment of persistent air leakage with endobronchial one-way valves . J Thorac Cardiovasc Surg . 2006 ; 132 ( 3 ): 711 - 2 .
23. Fischer W , Feller-Kopman D , Shah A , et al. Endobronchial valve therapy for pneumothorax as a bridge to lung transplantation . J Heart Lung Transplant . 2012 ; 31 ( 3 ): 334 - 6 .
24. Mahajan AK , Verhoef P , Patel SB , et al. Intrabronchial valves: a case series describing a minimally invasive approach to bronchopleural fistulas in medical intensive care unit patients . J Bronchology Interv Pulmonol . 2012 ; 19 ( 2 ): 137 - 41 .
25. Abu-Hijleh M , Blundin M. Emergency use of an endobronchial one-way valve in the management of severe air leak and massive subcutaneous emphysema . Lung . 2010 ; 188 ( 3 ): 253 - 7 .
26. Schiavon M , Marulli G , Zuin A , et al. Endobronchial valve for secondary pneumothorax in a severe emphysema patient . Thorac Cardiovasc Surg . 2011 ; 59 ( 8 ): 509 - 10 .
27. Ambrosino N , Ribechini A , Allidi F , et al. Use of endobronchial valves in persistent air leaks: a case report and review of the literature . Expert Rev Respir Med . 2013 ; 7 ( 1 ): 85 - 90 .
28. Qi F , Tian Q , Chen L , et al. Use of endobronchial valve insertion to treat relapsing pneumothorax: a case report and literature review . Clin Respir J . 2015 : 10 .
29. Conforti S , Torre M , Fieschi S , et al. Successful treatment of persistent postoperative air leaks following the placement of an endobronchial oneway valve . Monaldi Arch Chest Dis . 2010 ; 73 ( 2 ): 88 - 91 .
30. Santini M , Fiorelli A , Vicidomini G , et al. Iatrogenic air leak successfully treated by bronchoscopic placement of unidirectional endobronchial valves . Ann Thorac Surg . 2010 ; 89 ( 6 ): 2007 - 2010 .
31. Schweigert M , Kraus D , Ficker JH , et al. Closure of persisting air leaks in patients with severe pleural empyema-use of endoscopic one-way endobronchial valve . Eur J Cardiothorac Surg . 2011 ; 39 ( 3 ): 401 - 3 .
32. Dooms CA , De Leyn PR , Yserbyt J , et al. Endobronchial valves for persistent postoperative pulmonary air leak: accurate monitoring and functional implications . Respiration . 2012 ; 84 ( 4 ): 329 - 33 .
33. WC Y , Yeung YC , Chang Y , et al. Use of endobronchial one-way valves reveals questions on etiology of spontaneous pneumothorax: report of three cases . J Cardiothorac Surg . 2009 ; 4 : 63 .
34. Rosell A , López-Lisbona R , Cubero N , et al. Endoscopic treatment of persistent alveolar-pleural air leaks with a unidirectional endobronchial valve . Arch Bronconeumol . 2011 ; 47 ( 7 ): 371 - 3 .
35. Alexander ES , Healey TT , Martin DW , et al. Use of endobronchial valves for the treatment of bronchopleural fistulas after thermal ablation of lung neoplasms . J Vasc Interv Radiol . 2012 ; 23 ( 9 ): 1236 - 40 .
36. Gudbjartsson T , Helgadottir S , Ek L. One-way endobronchial valve for bronchopleural fistula after necrotizing pneumonia . Asian Cardiovasc Thorac Ann . 2013 ; 21 ( 4 ): 498 - 9 .
37. Brichon PY , Poquet C , Arvieux C , et al. Successful treatment of a lifethreatening air leakage, complicating severe abdominal sepsis, with a one-way endobronchial valve . Interact Cardiovasc Thorac Surg . 2012 ; 15 ( 4 ): 779 - 80 .
38. van Zeller M , Bastos P , Fernandes G , et al. Clinical challenges of persistent pulmonary air-leaks-case report . Rev Port Pneumol . 2014 ; 20 ( 3 ): 162 - 6 .
39. Fielding DI , Bashirzadeh F , Deller D , et al. Life-saving closure of a pulmonary cavity by endobronchial valve placement . Am J Respir Crit Care Med . 2013 ; 187 ( 10 ): 1145 - 6 .
40. Jenkins M , Vaughan P , Place D , et al. Endobronchial valve migration . Eur J Cardiothorac Surg . 2011 ; 40 ( 5 ): 1258 - 60 .
41. Seyfried U , Firlinger I , Reiter M , et al. A leak in the lung: endobronchial oneway valve placement as treatment for a persistent bronchopleural fistula . Pneumologie . 2012 ; 66 ( 3 ): 188 - 91 .
42. Venkatappa N , Fadul R , Raymond D , et al. Endobronchial valves for treatment of bronchopleural fistula in granulomatous polyangitis: a longitudinal case report . J Bronchology Interv Pulmonol . 2013 ; 20 ( 2 ): 186 - 8 .
43. Tsim S , Paton L , Nicholson F , et al. Rescue therapy using an endobronchial valve and digital air leak monitoring in invasive pulmonary aspergillosis . Respir Med Case Rep . 2014 ; 14 : 27 - 9 .
44. Morrison M , Marshall A , Giavedonni S , et al. Case report: endobronchial valve placement for treatment of a persistent air leak . Breathe (Sheff) . 2016 ; 12 ( 1 ): 61 - 4 .
45. Hodges AM , Gillham MJ , Lewis CA . Bedside placement of an endobronchial valve to aid invasive ventilation and weaning from extracorporeal membrane oxygenation . Crit Care Resusc . 2015 ; 17 ( 3 ): 219 - 22 .
46. Kalatoudis H , Nikhil M , Zeid F , et al. Bronchopleural fistula resolution with endobronchial valve placement and liberation from mechanical ventilation in acute respiratory distress syndrome: a case series . Case Rep Crit Care . 2017 ; 3092457 : 2017 .
47. Ballay N , Soder B , Smith J , et al. Intrabronchial pneumonectomy for vanishing lung syndrome: first reported case . Ann Thorac Surg . 2017 ; 103 ( 3 ): e277 - 9 .
48. Spratt JR , Podgaetz E , Loor G , et al. Endobronchial valve therapy for a refractory air leak after lung transplantation in a patient with multiple connective tissue disorders . J Thorac Cardiovasc Surg . 2017 ; 153 ( 1 ): e17 - 8 .
49. Travaline JM , McKenna RJ Jr, De Giacomo T , et al. Treatment of persistent pulmonary air leaks using endobronchial valves . Chest 2009 ; 136 ( 2 ): 355 - 360 .
50. Gillespie CT , Sterman DH , Cerfolio RJ , et al. Endobronchial valve treatment for prolonged air leaks of the lung: a case series . Ann Thorac Surg . 2011 ; 91 ( 1 ): 270 - 3 .
51. Firlinger I , Stubenberger E , Müller MR , et al. Endoscopic one-way valve implantation in patients with prolonged air leak and the use of digital air leak monitoring . Ann Thorac Surg . 2013 ; 95 ( 4 ): 1243 - 9 .
52. Reed MF , Gilbert CR , Taylor MD , et al. Endobronchial valves for challenging air leaks . Ann Thorac Surg . 2015 ; 100 ( 4 ): 1181 - 6 .
53. Dooms CA , Decaluwe H , Yserbyt J , et al. Bronchial valve treatment for pulmonary air leak after anatomical lung resection for cancer . Eur Respir J . 2014 ; 43 ( 4 ): 1142 - 8 .
54. Cordovilla R , Torracchi AM , Novoa N , et al. Endobronchial valves in the treatment of persistent air leak, an alternative to surgery . Arch Bronconeumol . 2015 ; 51 ( 1 ): 10 - 5 .
55. Hance JM , Martin JT , Mullett TW . Endobronchial valves in the treatment of persistent air leaks . Ann Thorac Surg . 2015 ; 100 ( 5 ): 1780 - 5 .
56. Podgaetz E , Andrade RS , Zamora F , et al. Endobronchial treatment of bronchopleural fistulas by using Intrabronchial valve system: a case series . Semin Thorac Cardiovasc Surg . 2015 Summer; 27 ( 2 ): 218 - 22 .
57. Bakhos C , Doelken P , Pupovac S , et al. Management of Prolonged Pulmonary Air Leaks With Endobronchial Valve Placement . JSLS . 2016 ; 20 ( 3 )
58. Cerfolio RJ , Bass CS , Pask AH , et al. Predictors and treatment of persistent air leaks . Ann Thorac Surg . 2002 ; 73 : 1727 - 31 .
59. Wood DE , Cerfolio RJ , Gonzalez X , et al. Bronchoscopic management of prolonged air leak . Clin Chest Med . 2010 ; 31 ( 1 ): 127 - 33 .
60. Oliveira FH , Cataneo DC , Ruiz RL Jr, et al. Persistent pleuropulmonary air leak treated with autologous blood: results from a university hospital and review of literature . Respiration 2010 ; 79 ( 4 ): 302 - 306 .
61. Hartmann W , Rausch V . New therapeutic application of the fiberoptic bronchoscope . Chest . 1977 ; 71 ( 2 ): 237 .
62. Hollaus PH , Lax F , Janakiev D , et al. Endoscopic treatment of postoperative bronchopleural fistula: experience with 45 cases . Ann Thorac Surg. 1998 ; 66 ( 3 ): 923 - 7 .
63. Takaoka K , Inoue S , Ohira S. Central bronchopleural fistulas closed by bronchoscopic injection of absolute ethanol . Chest . 2002 ; 122 ( 1 ): 374 - 8 .
64. Varoli F , Roviaro G , Grignani F , et al. Endoscopic treatment of bronchopleural fistulas . Ann Thorac Surg . 1998 ; 65 ( 3 ): 807 - 9 .
65. Aynaci E , Kocatürk CI , Yildiz P , et al. Argon plasma coagulation as an alternative treatment for bronchopleural fistulas developed after sleeve pneumonectomy . Interact Cardiovasc Thorac Surg . 2012 ; 14 ( 6 ): 912 - 4 .
66. Slade M. Management of pneumothorax and prolonged air leak . Semin Respir Crit Care Med . 2014 ; 35 ( 6 ): 706 - 14 .
67. Sasada S , Tamura K , Chang YS , et al. Clinical evaluation of endoscopic bronchial occlusion with silicone spigots for the management of persistent pulmonary air leaks . Intern Med . 2011 ; 50 ( 11 ): 1169 - 73 .
68. Gkegkes ID , Mourtarakos S , Gakidis I. Endobronchial valves in treatment of persistent air leaks: a systematic review of clinical evidence . Med Sci Monit . 2015 ; 21 : 432 - 8 .
69. Pompili C , Detterbeck F , Papagiannopoulos K , et al. Multicenter international randomized comparison of objective and subjective outcomes between electronic and traditional chest drainage systems . Ann Thorac Surg . 2014 ; 98 : 490 - 7 .
70. Tian Q , Qi F , An Y , et al. Using the Chartis system to selectively target a lung segment with a persistent air leak . Eur Respir J . 2013 ; 41 ( 6 ): 1461 - 3 .
71. Fessler HE . Collateral ventilation, the bane of bronchoscopic volume reduction . Am J Respir Crit Care Med . 2005 ; 171 : 423 - 4 .