Introduction: The treatment of recurrent pleural effusion or recurrent pneumothorax frequently involves the creation of a pleurodesis. Ultrasound is being used more frequently to assess the presence of pleural fluid or pneumothorax. With ultrasound, the gliding sign displays the gliding of the visceral pleura over the parietal pleura during respiration. The absence of a gliding sign is indicative of a pneumothorax.
Hypothesis: We hypothesized that the presence of pleurodesis would be indicated by the absence of a gliding sign on ultrasound.
Methods: To create a pleurodesis, a single intrapleural injection of transforming growth factor-beta2 at a dosage of 1.70 microg/kg or doxycycline at a dosage of 10 mg/kg in a volume of 2.0 mL was administered randomly to one side of a New Zealand White rabbit. Prior to death on day 14 after intrapleural injection, all rabbits underwent an ultrasonic examination at three marked sites on each side of the chest. At each site, three ultrasonic features (gliding sign, pleural thickening, and pleural effusion) were evaluated and graded. The gliding sign was graded as follows: 0 = gliding sign definitely present, 1 = gliding sign questionable, 2 = gliding sign absent.
Results: In a preliminary study for developing skill in assessing the gliding sign, the correlation between the gliding sign and the pleurodesis score in 16 rabbits was highly significant (r = 0.568, p = 0.02). In the subsequent main study with 18 additional rabbits, the correlation between the gliding sign score and the pleurodesis score was even better (r = 0.806, p = 0.00009). The gliding sign was definitely present on the noninjected side in all rabbits.
Conclusions: The presence of a pleurodesis is indicated by the absence of a pleural guiding sign on ultrasound.