Chest
Volume 122, Issue 6, December 2002, Pages 2122-2126
Journal home page for Chest

Laboratory and Animal Investigations
Lung Damage in Experimental Pleurodesis Induced by Silver Nitrate or Talc: 1-Year Follow-up

https://doi.org/10.1378/chest.122.6.2122Get rights and content

Study objective

To compare the lung damage caused by intrapleural silver nitrate (SN) with that caused by talc over a 12-month period.

Design

One hundred forty rabbits received an intrapleural injection of 0.5% SN or 400 mg/kg talc slurry in 2 mL saline solution. Groups of 10 rabbits were killed after 1, 2, 4, 6, 8, 10, or 12 months. The macroscopic pleurodesis, microscopic lung changes (ie, collapse, hemorrhage, and edema), and cellular infiltrates (number and proportion of cells) were graded on a scale of 0 to 4.

Results

The mean (± SEM) adhesion score after SN injection (3.3 ± 0.1) was higher (p < 0.001) than that after talc injection (2.3 ± 0.1). The mean alveolar collapse score was greater (p < 0.001) 1 month after SN injection (2.2 ± 0.3) than after talc injection (0.2 ± 0.1) and was similar from the second month on. The degree of parenchymal hemorrhage, by alveolar collapse score, (SN injection, 0.2 ± 0.1; talc injection, 0.2 ± 0.0) and edema (SN injection, 0.4 ± 0.1; talc injection, 0.3 ± 0.1) was minimal in both groups (p > 0.05). One month after the injection, the total number of inflammatory cells was greater (p < 0.001) in rabbits that had received SN injections (2.7 ± 0.3) than in those that had received talc injections (1.2 ± 0.1). From the second month on, cellularity decreased and became similar in both groups. The cellular profile was different, with a predominantly neutrophilic reaction after talc injection and a predominantly eosinophilic reaction after SN injection.

Conclusions

Rabbits injected with intrapleural 0.5% SN had significantly higher scores for adhesions than did those that had received talc injections, with mild and reversible alveolar collapse and an eosinophilic responses, conditions showing a clear tendency to normalize with time.

Section snippets

Materials and Methods

This study was approved by the Ethics Committee of the Heart Institute (InCor) at the University of São Paulo Medical School, and the methods are similar to those previously described.6,7 New Zealand white rabbits (weight range, 2.0 to 2.5 kg) were anesthetized, and, under aseptic conditions, a 2-cm skin incision was made in the right hemithorax. The intercostal muscles were dissected, and, under direct vision, a 25-gauge needle was inserted into the pleural space and the sclerosant was

Results

The intrapleural administration either of SN or talc slurry did not cause distress in any of the animals. They rapidly regained normal feeding and returned to normal activities. None of the rabbits required any additional treatment. Deposits of talc in the pleural cavity were seen in rabbits from all groups.

The intrapleural instillation of SN resulted in a significantly greater degree of pleurodesis than did that with the talc slurry. The mean adhesion score after the administration of

Discussion

The present study demonstrates that in this rabbit model 0.5% SN produced more intrapleural adhesions than did talc (400 mg/kg). It also shows that 1 month after the intrapleural injection of SN, the lung architecture was mildly and reversibly affected with a discrete alveolar collapse and minimal signs of hemorrhage and edema. Two months after SN injection, the parenchymal changes were minimal and similar to those observed after talc injection. The local inflammatory responses were different

References (14)

There are more references available in the full text version of this article.

Cited by (0)

This study was supported by the Foundation to Support Research for the State of São Paulo (FAPESP) and the National Board of Scientific and Technologic Development (CNPq) of Brazil.

View full text