Autologous Blood Pleurodesis in Rats to Elucidate the Amounts of Blood Required for Reliable and Reproducible Results

BackgroundPleurodesis is used in the treatment of spontaneous pneumothorax or refractory pleural effusions of different etiologies. Several agents have been employed, but many questions remain unanswered about their effectiveness and toxicity. Use of autologous blood pleurodesis in clinical practice has been described in the literature without any clear consensus regarding its efficacy. Experimental studies using this technique are limited to a single study in rabbits. We performed a prospective, randomized, observer-blinded, controlled study to evaluate the safety and efficacy of increasing doses of autologous blood pleurodesis in a novel rat model.Materials and MethodsTwenty-eight albino Wistar rats were divided into four groups. Groups 1, 2, and 3 were the study groups and group 4 was the control group, with seven animals in each group. Groups 1, 2, and 3 were given autologous blood, 1mL/kg, 2mL/kg, 3mL/kg, respectively, and group 4 (control) was given only 2mL/kg saline intrapleurally. The rats were sacrificed on postoperative day 30. The surfaces were graded by macroscopic (visible adhesion formation) and microscopic (inflammation and fibrosis) examination.ResultsMacroscopically, group 2 and group 3 developed significantly more adhesions; 3mL/kg autologous blood produced the most significant pleurodesis with generalized adhesions seen between visceral, parietal, and mediastinal pleura. Microscopic examination showed that all study groups developed an inflammatory response at the site of blood injection. There were no pathologic changes in ipsilateral and contralateral lung parenchyma.ConclusionsAutologous blood at doses 2–3mL/kg were shown to be effective to produce adhesions in 30 d, and the results were highly reproducible in all rats. We propose that the occasional negative results obtained in humans may be related to an insufficient amount of injected blood, as observed in our rat model.