Pleural Fluid Parameters Identifying Complicated Parapneumonic Effusions

Abstract

Background: Controversy exists regarding the clinical utility of pleural fluid parameters as prognosticators of complicated parapneumonic effusions that require drainage. Objectives: The purpose of this prospective study is to further assess the utility of these parameters in the management of a larger series of parapneumonic effusions and to determine appropriate binary decision thresholds. Methods: We studied 238 consecutive patients with parapneumonic effusions who underwent diagnostic thoracentesis. Results: We found that pleural fluid pH had the highest diagnostic accuracy (area under the curve, AUC: 0.928; 95% confidence interval, CI: 0.894–0.963) compared with pleural fluid glucose (AUC: 0.835; 95% CI: 0.773–0.897), LDH (AUC: 0.824; 95% CI: 0.761–0.887) or pleural fluid volume (AUC: 0.706; 95% CI: 0.634–0.777). The optimal binary decision threshold for pleural fluid pH identifying complicated effusions requiring drainage was 7.15. Binary, multilevel and continuous likelihood ratios (LRs) for pH were calculated to estimate the likelihood of complication of the pleural effusion. Values for the LRs were compared for each of the three strategies, and relative clinical and statistical significances were assessed. Binary LRs provided significantly less information than continuous strategies. Conclusion: The pH has the highest diagnostic accuracy for identifying complicated parapneumonic pleural effusions. The binary decision threshold determining the need for chest drainage is 7.15 in our patient series. We recommend continuous LRs to estimate the post-test probability of the complication as they provide the most information compared with binary LRs. Our results do not support the use of pleural fluid LDH as independent predictor of complicated parapneumonic effusions.

Sonographic Diagnosis and Follow-Up of Pneumonia: A Prospective Study

“…Most of the parapneumonic effusions are uncomplicated and will resolve with antibiotic therapy alone. However, 5–10% of the hospitalized patients with pneumonia follow a complicated course and require a pleural drainage for full recovery [13,14,15,16]. In the present study, typical complications associated with pneumonia were not discerned, probably due to the limited number of patients.…”

Prognostic value of C‐reactive protein in parapneumonic effusions

“…Although current guidelines suggest that pH <7.20 is the most accurate criterion for this purpose, a study by Jimenez et al . of 238 patients with PPE showed that some PPE with a pH of 7.20–7.37 required drainage, while 33% of the PPE with a pH of 7.00–7.20 resolved with antibiotic treatment alone 26 . In the present study, a pH <7.20 showed the best performance, giving 91% sensitivity and 93% specificity, with a NPV of 93%.…”

Residual Pleural Thickening Is Related to Vascular Endothelial Growth Factor Levels in Parapneumonic Pleural Effusions

“…pH is a major factor for the differentiation of parapneumonic pleural effusions into simple and complicated parapneumonic effusions [1], and has also been shown to have the highest diagnostic accuracy for identifying complicated parapneumonic pleural effusions [19]. Furthermore, pleural fluid pH has been shown to be an independent factor associated with residual pleural thickening in parapneumonic effusions [4].…”