Low doses of silver nitrate induce pleurodesis with a limited systemic response.
OBJECTIVE
Both talc and 0.5% silver nitrate have been shown to induce effective pleurodesis. However, acute adverse systemic inflammatory effects have been described with both agents. The aim of this study was to assess in rabbits the systemic effects associated with a new technique of pleurodesis using repeated low doses of 0.1% silver nitrate.


METHODS
Rabbits were injected intrapleurally through a chest tube with 0.1% silver nitrate at 0, 24 and 48 h. Other groups received a single injection of 0.5% silver nitrate or 400 mg/kg of talc. Blood samples were collected at 24, 48 and 72 h, and at 7 days, and cytological and biochemical measurements were performed. After 28 days, the presence of macroscopic pleural adhesions and microscopic pleural fibrosis in the pleural cavity were evaluated.


RESULTS
Both talc and 0.5% silver nitrate caused significant increases in blood neutrophils, serum LDH, IL-8, transforming growth factor-beta and CRP in comparison with control at almost all time points, whereas sequential doses of 0.1% silver nitrate only increased LDH and CRP in the first 24 h and transforming growth factor-beta at all time points. All groups showed efficient pleurodesis, with no differences in pleural adhesions or fibrosis.


CONCLUSIONS
Sequential doses of 0.1% silver nitrate produced efficient pleurodesis in rabbits, with a low systemic inflammatory response in comparison with 400 mg/kg of talc or 0.5% silver nitrate.
Marchi
Evaldo
E
Pleura Laboratory, Pulmonary Division, Heart Institute (InCor), University of São Paulo Medical School, Sao Paulo, Brazil. evmarchi@uol.com.br
Vargas
Francisco S
FS
Acencio
Milena M P
MM
Antonangelo
Leila
L
Teixeira
Lisete R
LR
Light
Richard W
RW
D000818:Animals; D002097:C-Reactive Protein / Q000378:metabolism; D015505:Chest Tubes; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005355:Fibrosis; D007249:Inflammation / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology*; D016209:Interleukin-8 / Q000097:blood; D007770:L-Lactate Dehydrogenase / Q000097:blood; D007962:Leukocytes / Q000473:pathology; D008297:Male; D009504:Neutrophils / Q000473:pathology; D010994:Pleura / Q000473:pathology; D018700:Pleurodesis / Q000379:methods*; D011817:Rabbits; D012307:Risk Factors; D012835:Silver Nitrate / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use*; D013627:Talc / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D016212:Transforming Growth Factor beta / Q000097:blood
D016209:Interleukin-8; D016212:Transforming Growth Factor beta; D013627:Talc; D002097:C-Reactive Protein; D012835:Silver Nitrate; D007770:L-Lactate Dehydrogenase