Using urea dilution to standardise components of pleural and bronchoalveolar lavage fluids in the dog

Abstract

AIM: To develop a technique to estimate the volume of epithelial lining fluid (ELF) obtained during bronchoalveolar lavage (BAL) and pleural lavage (PL) in the dog, using the urea dilution method.

METHODS: BAL and PL fluids were obtained by saline lavage of pulmonary and pleural cavities of nine clinically healthy mixed-breed dogs immediately after euthanasia. Cell counts in the BAL and PL fluids were measured using standard techniques. The concentration of ELF in each lavage fluid was calculated from the relative concentration of urea in plasma and in each type of lavage fluid. Cell counts in ELF were then calculated.

RESULTS: There were substantially higher cell counts in ELF compared to BAL or PF fluid. However, nucleated cell counts in ELF could not be predicted from cell counts in BAL or PL fluid.

CONCLUSIONS AND CLINICAL RELEVANCE: These results suggest that accurate assessment of cellular or non-cellular components in lavage fluids should include a calculation of the proportion of ELF recovered, using a method such as urea dilution.

KEY WORDS:

• Dog
• bronchoalveolar lavage
• pleural lavage
• epithelial lining fluid

Acknowledgements

This work was financially supported by the John and Mary Kibble Trust. The authors would like to thank Brian Bynon for performing the biochemical and cytological analyses of pleural and bronchoalveolar lavage fluids.