| OBJECTIVE: To establish the tetracycline-induced pleural effusion and adhesion model in rabbit ; Investigate the role of LMWH in preventing pleural adhesion.METHODS: Thirty New Zealand white rabbits were randomly divided into model group, therapy group and control group. All rabbits received light anesthesia with 1ml.kg-1 intravenous 3% pentobarbital before insertion of a chest tube between the spine and the tip of the scapula into the right pleural space. The model group and therapy group received 35 mg.kg-1 TCN in 2ml of 0.9%NaCl. The control group was given 2ml Normal saline intrapleurally via a chest tube. Thereafter, the therapy group animals received 55 U .kg-1 intrapleural LMWH in 2 ml of 0.9% NaCl ; the model group animals received an additional 2 ml of 0.9% NaCl given intrapleurally . Chest tube was aspirated at 24 hours intervals until their removal at 96 hours. One-stage recalcification assays were performed in normal pooled plasma to determine the ability of pleural fluid to initiate clotting. The recalcification time was shortening, indicating that procoagulant activity intensified in pleural fluid. PT and APTT were determined before and post-treatment 24h, 48h, 72h, 96h in the therapy group. Rabbits were sacrificed with intravenous pentobarbital on the fourteenth day, estimated the pleurodesis score and pleural thickness.RESULTS: 1. In model group , pleural effusion appeared in 2hours after TCN intrapleural and reached maximum amount within 48~-72 hours, the volume was 11.7±2.3ml, then became decrease. With LMWH treatment, pleural effusion decreased. At the 96 hours pleural effusion was entirely disappeared in the 4 of 10 rabbits in therapy group. The pleural effusion volume was 1.6±2.4 mlo No fluid was obtained by chest tube at any time in control group. There was significant difference among the groups (PO.05). 2. The pleural fluid leukocyte counts and total protein in model and therapy group accumulated and decreased significantly over time, no significant difference was found between two groups.3. Pleural fluid in model group were capable of shortening the recalcification times of normal pooled human plasma (184±46s), indicating the presence of procoagulant activity. The recalcification times in therapy group were markedly prolonged ( > 500s), indicating that procoagulant activity was reduced in these LMWH-treated animals. There was significant difference between the model and therapy group (PO.05).4. The pleurodesis score was 3.2±0.4 in the model group, one rabbit developed haemothorax effusion and its right pleural space was entirely adhesion and encapsulation. Pleural fibrous adhesion was attenuated in therapy group, no pleural adhesion was observed by the fourteenth day. The pleural space in control group was normal. 5. The model group showed marked pleural fibrous thickening in the visceral and parietal pleural; Rabbits from the therapy group showed minimal pleural fibrosis; The control rabbits had normal pleural spaces with glistening, non-wrinkled visceral and parietal pleural, absence of fibrous adhesion. Pleural thickness: the model group was 768±596 \irn-, the therapy group was 11l±90 u.m; the control group was 19±8 urn There were significant difference among the 3... |
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