Non-steroidal anti-inflammatory drugs decrease the quality of pleurodesis after mechanical pleural abrasion

Objective: Non-steroidal anti-inflammatory drugs (NSAIDs) are often applied for pain management after thoracic surgery. Since these drugs diminish collagen deposition through inhibition of the prostaglandin synthesis, we investigated their effects on adhesion formation after endoscopic mechanical pleural abrasion, which is often applied in the therapy of pneumothorax. Methods: Mechanical pleural abrasion was performed unilaterally by the use of video-assisted thoracoscopic surgery technique in an established pig model. Ten animals (41.3±3.4 kg) were divided into a treatment group and a control group. In the treatment group, animals received 100 mg diclofenac (2 mg/kg body weight) orally daily for 3 weeks after surgery. At 3 weeks, all animals were sacrificed and efficacy of pleurodesis was macroscopically assessed by three independent reviewers blinded to the treatment of animals using a five-point severity pleurodesis score (from 0, no adhesions to 4, complete symphisis) and obliteration grade rating the distribution of adhesions (from 0, no adhesions to 4, adhesions in the whole chest). Microscopic evaluation was performed by two pathologists blinded to the study groups as well. A four-point score assessed the amount of collagen deposition (from 1, a few collagen fibers to 4, scar). Results: Gross observation showed more dense adhesions in control animals with a median pleurodesis score of 3.67±1.0 in comparison to 2±2.2 in the treatment group (P=0.01*, Mann-Whitney non-parametric test). Distribution of adhesions was comparable in both groups with a median obliteration score of 3.67±1.3. Histopathologic examination showed a higher amount of collagen deposition in the control group, suggesting more dense adhesions, whereas in the treatment group there was loose granulation tissue (score of 4.0±0.8 vs. 2.3±1.0 in the treatment group, P=0.06). The degree of inflammatory reaction was comparable in the two groups. Conclusions: Our results demonstrate that perioperative