This is a 15-year old male with a history of severe 
chronic lung disease and bronchopulmonary dysplasia 
since birth.  He was premature, and since then has 
required multiple hospitalizations for acute 
exacerbations of his chronic lung disease.  He is well 
known to the children's hospital staff, but in the past few 
years, he has done well and has not required 
hospitalization.  He now presents to the emergency 
department in severe respiratory distress.
     Exam VS T38.4 (oral), P110, R40, BP 120/70.  
Oxygen saturation 75% in room air.  On oxygen by 
mask, his oxygen saturation increases to 90%.  He is in 
severe respiratory distress.  His color is pale and 
cyanotic.  Heart regular.  Lungs rhonchi, wheezing, and 
diminished aeration throughout.  Moderately severe 
retractions.  Perfusion good.  Capillary refill time 2 
seconds.
     Bronchodilator therapy is administered and a 
portable chest radiograph is obtained.

View portable CXR.

     There are extensive infiltrates in both lungs.  
However, the left upper lung and both lower lungs show 
hyperlucent areas.  This film image was difficult to 
accurately capture with the scanner since the important 
findings are not easy to see.  Thus, the findings 
described here could only be appreciated on the original 
film.  Upon closer inspection of the original film, lung 
markings are faintly visible in the left upper and left 
lower hyperlucent regions.  However, no lung markings 
are visible in the right lower hyperlucent region.  A 
pneumothorax is suspected.  Previous radiographs 
show large blebs in the hyperlucent regions.

Questions:
     Is this a pneumothorax ?
     If you aren't sure, should you put a chest tube in ?

     There is some concern that this air collection may 
be a loculated pneumothorax.  The density of the right 
upper lung may be due to acute infiltrates or 
compression of lung tissue from the pneumothorax.  
Evacuating the pneumothorax may result in better 
expansion of the right lung and improvement in the 
patient's condition.  However, if this is just a 
hyperexpanded intrapulmonary bleb, inserting a chest 
tube into the pleural space would not be beneficial and 
may also worsen the patient's condition by inducing a 
pneumothorax.  When such a patient is critically ill, this 
decision is extremely difficult.
     It is difficult to distinguish an intrapulmonary bleb 
from a loculated pneumothorax.  However, in our 
patient with a preexisting bleb in that location, the 
former is more likely.  It is crucial to compare the 
patient's current films with previous films to assist in this 
determination.
     There should be no doubt that this radiograph does 
NOT demonstrate a TENSION pneumothorax.  
Although a tension pneumothorax requires immediate 
intervention, the therapy for an intrapulmonary bleb 
versus a loculated pneumothorax can usually wait for 
more decision making before rushing into an invasive
procedure.
     A tension pneumothorax is associated with a 
mediastinal shift to the opposite side and compression 
of the contralateral lung.  Clinically, a tension 
pneumothorax is usually associated with cardiovascular 
compromise (hypotension and/or bradycardia) in 
addition to respiratory deterioration.  Since our patient 
does NOT have cardiovascular compromise, despite 
the severe degree of respiratory distress, a tension 
pneumothorax is unlikely.  If the patient's clinical 
condition is not deteriorating, it may be best to delay an 
evacuation procedure until consideration of all clinical 
factors can be carefully assessed.  A second opinion 
with an intensivist, a surgeon, or another emergency 
physician would be helpful.
     Although such a bleb may appear to be fragile, it is 
often surrounded by fibrous tissue.  This patient went 
on to require positive pressure ventilation for many days 
and the bleb did not rupture.  Placing a tube 
thoracostomy prophylactically anticipating a 
pneumothorax in such a patient with a large 
pneumatocele undergoing positive pressure ventilation 
may seem to be reasonably justified.  However, the 
tube thoracostomy itself may result in significant 
deterioration in such as patient as well.

References
     Templeton JM.  Thoracic Emergencies.  In:  Fleisher 
GR, Ludwig S (eds).  Textbook of Pediatric Emergency 
Medicine, third edition.  Baltimore, MD, Williams and 
Wilkins, 1993, pp. 1348-1349.