A drop of hydrogen peroxide can differentiate exudative pleural effusion from transudate--development of a bedside...

There is no bedside test to classify pleural fluid as exudate or transudate. The aim of the present study is to develop such a test.

We analyzed the Light's criteria parameters from bloodless pleural fluid and classified the biofluid as exudate or transudate and also estimated some parameters of oxidative stress in the biofluid by established spectrophotometric procedure. Two hundred microliters of sample was taken and added with 10 microl of 30% hydrogen peroxide followed by inspection of the sample for appearance of bubbles.

All exudative fluids (n=52) have shown appearance of profuse bubbles within 1 min of addition of hydrogen peroxide along with significantly more catalase activity compared to transudate. All transudative fluids (n=32) have not shown bubble formation within 1 min after addition of hydrogen peroxide. The exudate does not show bubble formation if supplemented with catalase inhibitors. Blood mixed transudate have shown profuse bubble formation after addition of hydrogen peroxide.

In the case of blood uncontaminated pleural fluid, this newly developed protocol's sensitivity and specificity will be equivalent to Light's criteria probably with more advantage as by this procedure transport of the sample to the clinical laboratory is not required due to its inherent simplicity.