Mesothelial cells on the visceral pleura were graded as either absent or present. Intrapleural adhesions and the visceral pleura were assessed for the degree of cellularity and neovascularity and graded as absent, mild, moderate, or severe (grades 0 to 3).
The thickness of the visceral pleura was measured at five randomly selected sites, taken perpendicular to the lung surface. The pathologist interpreting these slides (K.L.) was blinded to the mode of pleurodesis read more.
Histologic characteristics were compared before and after each of the pleurodesis regimens by one-way analysis of variance. Differences were considered significant when p<0.05.
Intrapleural injection was tolerated without labored breathing and with the rapid return of the rabbits to normal feeding and activities. Immediate complications (<24 h) were recognized in four rabbits and included pneumothorax in one animal (DOXY group, confirmed by radiograph) and acute pulmonary edema in an additional three rabbits. Each of these animals was immediately killed and their data were not included in the study. No late complications occurred.
Upon opening the thorax, marked abnormalities of the left (injected) pleural space were evident in all rabbits and were similar in both TCN- and DOXY-treated animals.
Hemorrhagic fluid filled the left pleural cavity in all animals of both groups and caused the diaphragm to bulge prominently into the abdomen. Adhesions extended from visceral to parietal pleura in all animals. In one rabbit from each group, these adhesions were thin and easily lysed with blunt dissection. In the majority (four of five), the bands were thick and completely obliterated the pleural space. The left lung was surrounded by this thick pleural peel whereas the right lung and pleural space appeared to be completely normal (Fig 1). Macroscopically, we found no difference in the number or thickness of pleural adhesions between TCN- and DOXY-treated animals.
Figure 1. Anterior view of lungs and tracheobronchial tree in rabbit treated with doxycycline in left pleural space. The left lung (LL) is seen to be entirely encased in a thick pleural peel whereas the right lung (RL) is completely normal in appearance. T= trachea.