Correspondence

Pleural Effusion

N Engl J Med 2002; 347:1286-1287October 17, 2002

Article

To the Editor:

The criteria discussed by Light in his Clinical Practice article on pleural effusion (June 20 issue)1 are stringent and highly sensitive in identifying an exudate. However, their specificity is low, particularly in patients with heart failure. Studies have shown that up to one third of pleural-fluid specimens from the subgroup of patients with the sole diagnosis of congestive heart failure fulfill at least one of Light's criteria for an exudate.2,3 We found that patients with congestive heart failure who had false positive results were more likely to meet only one of Light's criteria and to have received intravenous diuretics within 24 hours before the pleural tap. A possible explanation is that diuretics shift fluids from the pleural space, thereby changing biochemical transudates into exudates.4

A careful evaluation of the number of positive criteria and of whether a patient has recently received diuretic treatment could improve the specificity of Light's criteria in patients with congestive heart failure.

Zvi G. Fridlender, M.D.
Israel Gotsman, M.D.
Hadassah University Hospital, Jerusalem 91120, Israel
zvi_f@yahoo.com

4 References

1. 1

   Light RW. Pleural effusion. N Engl J Med 2002;346:1971-1977
   Full Text | Web of Science | Medline

2. 2

   Gotsman I, Fridlender Z, Meirovitz A, Dratva D, Muszkat M. The evaluation of pleural effusions in patients with heart failure. Am J Med 2001;111:375-378
   CrossRef | Web of Science | Medline

3. 3

   Vives M, Porcel JM, Vincente de Vera MC, Ribelles E, Rubio M. A study of Light's criteria and possible modifications for distinguishing exudative from transudative pleural effusions. Chest 1996;109:1503-1507
   CrossRef | Web of Science | Medline

4. 4

   Chakko SC, Caldwell SH, Sforza PP. Treatment of congestive heart failure: its effect on pleural fluid chemistry. Chest 1989;95:798-802
   CrossRef | Web of Science | Medline

Author/Editor Response

Dr. Light replies:

To the Editor: I agree with Drs. Fridlender and Gotsman that pleural-fluid samples from many patients with congestive heart failure fulfill at least one of Light's criteria for an exudate. I would add that laboratory values for patients with heart failure alone that fulfill Light's criteria for an exudate usually only barely do so. As I mentioned in the article, measuring the difference between the serum and the pleural-fluid albumin levels is useful in such patients since a difference greater than 1.2 g per deciliter is consistent with a transudative effusion, even though other criteria for an exudative effusion have been met.1

Richard W. Light, M.D.
Saint Thomas Hospital, Nashville, TN 37205
rlight98@yahoo.com

1 References

1. 1

   Burgess LJ, Maritz FJ, Taljaard JJ. Comparative analysis of the biochemical parameters used to distinguish between pleural transudates and exudates. Chest 1995;107:1604-1609
   CrossRef | Web of Science | Medline