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Distension of extrapleural spaces with contrast medium or air: value in creating safe percutaneous access to the mediastinum in cadavers.

OBJECTIVE
We artificially widened the extrapleural space with contrast medium or air in 33 cadavers to create a safe extrapleural route to the anterior mediastinum and the posterior mediastinum for large-bore needle biopsies.


MATERIAL AND METHODS
Under CT guidance, 120 ml of diluted contrast medium (10%) or 300 ml of air was injected percutaneously into the right paravertebral (n = 23) and left retroaortic (n = 5) or ventral parasternal (n = 5) extrapleural spaces.


RESULTS
In six of 18 cases, the paravertebral space was found to be wide enough to advance a 14-gauge cannula to the extrapleural paraesophageal space. After injection of 120 ml of diluted contrast medium, the width of the right paravertebral space at the level of the posterior rim of the vertebral body was dilated from a mean of 0.62 cm to 1.06 cm, and the width of the anterior rim was dilated from a mean of 0.91 cm to 1.97 cm. In 17 of 18 cases, the paravertebral space was wide enough to accommodate a 14-gauge cannula. A large osteophyte blocked the access route in one case. Artificial widening regresses within 7 min by an average of 33% at the level of the posterior rim of the vertebral body and by an average of 18% at the level of the anterior rim. Dilatation was significantly more effective with diluted contrast medium than with air. When 120 ml of diluted contrast medium was injected into the left retroaortic extrapleural space, the distance between the aorta and the vertebral column was widened from a mean of 0.40 cm to 1.50 cm. Using a ventral approach for injecting 120 ml of solution, we widened the parasternal access route from a mean of 0.42 cm to 1.90 cm.


CONCLUSION
In this cadaver study, artificial dilatation of the mediastinum with diluted contrast medium allowed extrapleural access from right paravertebral, left retroaortic, and parasternal directions for large-bore needle biopsies.