N. Lu1, C. Ursic1, H. Penney1,2, S. Steinemann1, S. Moran1 1University Of Hawaii,Department Of Surgery,Honolulu, HI, USA 2University Of Hawaii,Department Of Radiology,Honolulu, HI, USA
Introduction: With the widespread use of computed tomography (CT) imaging, the occult pneumothorax (PTX) has become a common finding. It has been shown that it is safe to monitor occult PTX in stable patients, even if they are on positive pressure ventilation. Observation of occult PTX without chest tube placement has been supported for those seen on CT to be <7mm measured perpendicular from lung to chest wall. However, patients transported by air are not optimally monitored and not in the care of practitioners skilled in thoracostomy tube placement.
Methods: We undertook a retrospective chart review of patients with traumatic PTX who were transported by air over the course of three years (2010-2012) to a level II trauma center that serves 1.3 million people. Occult PTX was defined as a pneumothorax that was not visible on chest radiograph (CXR), but was visible on CT imaging. Patients who did not have an overt PTX or a clinical reason for immediate chest tube placement were divided into two groups: those with PTX<7mm and those with PTX>7 mm.
Results: From 2010 to 2012, 66 patients were transferred with a total of 83 PTX. Eleven PTX in 8 patients were treated with chest tubes placed for clinical reasons such as CPR or needle decompression in the field. For 11 PTX, we have no information about pre-transport CXR or were unable to measure the PTX on CT. Eleven overt PTX were treated with thoracostomy tubes. Of the 10 large occult (>7mm) PTX, 8 were treated with thoracostomy tubes and two were treated with observation in transport. Of the 39 small (<7mm) PTX, 19 were treated with thoracostomy tubes (15 ventilated, 4 not ventilated); and 20 were observed during transportation (5 ventilated, 15 not ventilated). Of all patients without thoracostomy tubes prior to transport, 3 were placed on arrival. One was placed in a patient whose repeat CXR showed the PTX (no longer occult), though the patient was stable. One was placed in a patient whose follow up CT showed expansion to 8mm and who was to be intubated for an operation. One was placed in a patient with a pre-transfer PTX>7 mm and with copious subcutaneous emphysema which expanded en route. There were 15 total complications. Thirteen were malpositioned and two were related to empyema requiring thoracoscopic drainage.
Conclusion: Patients with small PTX can safely be transported by air without thoracostomy tubes. Only one of 20 patients sent without a chest tube required immediate chest tube placement and, in retrospect, it would have been recommended that a tube be placed prior to transport due to the size of the PTX and the amount of subcutaneous air. Mechanical ventilation prompted more thoracostomy tube placements. In addition, observation may reduce complications from chest tube placement (malposition, infection, increased number of CXR, increase in hospital length of stay, and delay in returning home). Further studies with large numbers of patients are warranted.