Extended Light's Criteria

This morning we discussed an approach to pleural effusion.

 

One concept we discussed was the possibility of transforming transudative pleural fluid in patients receiving diuretic therapy to an exudate.

In such cases we can use the “extended Light’s criteria”, which is to calculate the total protein gradient (serum minus pleural fluid). The fluid is a transudate if the total protein gradient is greater than 31g/L.

Here is a previous post about the Light’s criteria with a review article by Dr. Light himself!

Pleural Effusion and Ultrasound

At Gel Rounds today, we discussed pleural effusion. The image above is the ultrasound image of a small right sided effusion. The top of the image represents the probe resting on the chest wall, the dark area (e) is the effusion. The Bright band between (e) and the liver is the diaphragm (d). The lung is seen superior and deep to the effusion.

Now that you know how to identify pleural effusion with the ultrasound, use it in addition to your physical exam when doing a bedside thoracentesis.

Light's Criteria for Pleural Effusion

Today at morning report we discussed the Light's Criteria.

Light's criteria for exudative effusion are any of
protein level pleural:serum over 0.5
LDH pleural:serum of over 0.6
pleural LDH over 2/3 upper limit of normal for serum

The combination of the three criteria has a higher sensitivity, but a lower specificity, than each individual criterion. Light's criteria are sensitive for exudate; may have transudates falsely called exudates. If clinical appearance suggests transudate but Light's criteria says exudate, measure albumin in serum vs. pleural fluid. If serum albumin is over 12 greater than pleural fluid almost all have transudative.

Our case had a bloody effusion, which narrows Ddx somewhat to cancer, PE, trauma, infection (inc. pneumonia, TB)

Here is a review of Pleural Effusion by Dr. Light himself!

*A large left sided pleural effusion as seen on an upright chest X-ray.