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Old 09-23-2012
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Arrow Gyrus Daily Questions; Internal Medicine #20

A 52-year-old female presents with a communityacquired pneumonia complicated by pleural effusion. A thoracentesis is performed, with the following results:


Appearance Viscous, cloudy
pH 7.11
Protein 5.8 g/dL
LDH 285 IU/L
Glucose 66 mg/dL
WBC 3800/mm3
RBC 24,000/mm3
PMNs 93%
Gram stain Many PMNs; no organism seen


Bacterial cultures are sent, but the results are not currently available. Which characteristic of the pleural fluid is most suggestive that the patient will require tube thoracostomy?


A. Presence of more than 90% polymorphonucleocytes (PMNs)
B. Glucose less than 100 mg/dL
C. Presence of more than 1000 white blood cells
D. pH less than 7.20
E. Lactate dehydrogenase (LDH) more than two-thirds of the normal upper limit for serum
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I think E indicates an exudate which may need drainage.......
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The pH is extremely acidotic as well.. i would go for pH but E also looks nice because it is one of the criteria to differentiate exudate from transudate

Exudate have got to be drained if we want to avoid the development of empyema and pleural scarring.
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D. pH less than 7.20
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PH < 7.20 & Glucose < 60 are most suggestive of empyema and requires chest tube drainage (UW QID 4073)
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Quote:
Originally Posted by Novobiocin View Post
PH < 7.20 & Glucose < 60 are most suggestive of empyema and requires chest tube drainage (UW QID 4073)

Yes correct...

The answer is D.

Thoracentesis is indicated for any patient presenting with pneumonia and

a pleural effusion more than 10 mm thick on lateral decubitus imaging because a significant percentage of these patients will show evidence of bacterial invasion and require further intervention.

Other indications for thoracentesis for pleural effusions that complicate pneumonias include
loculation of the pleural fluid and evidence of thickened parietal pleura on chest CT.

All effusions complicating pneumonia should be exudative, meeting at least one of Light’s criteria:
(1) pleural fluid protein/serum protein over 0.5,
(2) pleural fluid LDH/serum LDH over 0.6, and
(3) pleural fluid LDH more than two-thirds of the normal upper limit for serum.

Factors that increase the likelihood that tube thoracostomy will have to be performed include loculated pleural fluid,

pH below 7.20, pleural fluid glucose below 60 mg/ dL, positive Gram stain or culture of pleural fluid, and presence of gross pus on aspiration

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Quote:
Originally Posted by Novobiocin View Post
PH < 7.20 & Glucose < 60 are most suggestive of empyema and requires chest tube drainage (UW QID 4073)

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This question prompted me to post the following from an article on "Pleural Empyema" by Richard E. Bryant and Christopher J. Salmon:

Laboratory clues of Pleural fluid Empyema

1. pH <7.10 (or >0.3 lower than serum pH)
2. Glucose <40mg/dl
3. LDH >1,000IU/L
4. Gram stain positivity
5. WBC >50,000 x 10^9/L
6. Cloudy, bloody, purulent
7. Viscous and fetid (~2/3 of anaerobic empyema)
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D. pH less than 7.20
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