We initiated this study to determine the efficacy of DOXY pleurodesis and to compare the results with TCN pleurodesis in rabbits. We analyzed the histologic changes of the pleura at high and moderate concentrations of DOXY and at acid and neutral pH. Our findings indicate that DOXY is as effective as TCN in sclerosing the pleural space, that this effect is independent of the acidity of the DOXY solution, and that moderate concentrations of DOXY (10 mg/kg) can produce excellent results online antibiotics.
The following protocol was approved and monitored by the Institutional Animal Care and Use Committee at SUNY Stony Brook. Twenty-five New Zealand White rabbits (weight approximately 3 kg) were anesthetized with an intramuscular mixture of ketamine (25 mg/kg) and xylazine (2 mg/kg). Three milliliters of a solution of either DOXY hyclate or TCN hydrochloride diluted in normal saline solution was injected intrapleurally through a 22-g angiocath that had been aseptically placed into the left pleural space.
Five rabbits (group 1) received TCN at a concentration of 35 mg/kg and at the unmodified pH=2.0. Four other groups of five rabbits each received DOXY as follows: 35 mg/kg, pH=2.0 (group 2); 35 mg/kg, pH 7.6 (group 3); 10 mg/kg, pH=2.0 (group 4); and 10 mg/kg, pH 7.6 (group 5). Animals were killed 14 days later by a lethal intravenous injection of sodium pentobarbital. At autopsy, the thorax was removed and immersed in 10 percent neutral buffered formalin. The central thoracic wall was removed and the pleural space was inspected for gross evidence of pleurodesis as follows: 0=normal, l+=a few thin adhesions, 2+ diffuse but individually distinct intrapleural bands, and 3+ complete obliteration of the pleural space. Sections of both lungs were taken in the anteroposterior plane in the midlung zone. Pleural tissue was stained with hematoxylin-eosin and Masson’s trichrome for accentuation of collagen deposition.