Measurement of lactate in pleural fluid rapidly identify infection and guide therapy

Abstract

Background

Measurements of pleural fluid biomarkers for rapid identification of complicated parapneumonic effusion (CPPE) are crucial for optimal management. Previous studies for biomarker evaluation were however based on pleura culture, not modern DNA technique. Lactate has not been thoroughly studied earlier as a potential biomarker in this regard.

Objectives

To evaluate whether the routine biomarkers pH, glucose, lactate dehydrogenase (LDH) measured in pleural fluid in a microbiological well characterised cohort could differentiate simple parapneumonic effusion (SPPE) from CPPE and if pleural fluid lactate could be of additional use in this discrimination.

Methods

Pleural fluid prospectively collected from adult patients (n = 112) with PPE admitted to the Departments of Infectious Diseases (DIDs) at four Stockholm County hospitals were characterised microbiologically with bacterial culture and 16S rDNA sequencing, and biochemically with pH, glucose, LDH and lactate.

Results

Forty and seventy two patients were categorised as SPPE/CPPE. The median values between SPPE/CPPE differed significantly for all biomarkers with varying overlap. Receiver operating characteristics (ROC) curves showed the area under the curve (AUC) for pH 0.905 (CI 0.847–0.963), glucose 0.861 (CI 0.79–0.932), LDH 0.917 (CI 0.860–0.974) and lactate 0.927 (CI 0.877–0.977), corresponding to best cut-off levels and sensitivity/specificity for pH of 7.255, 0.819/0.9, glucose 5.35 mmol/L, 0.847/0.775, LDH 9.8 µcat/L, 0.905/0.825 and lactate 4.9 mmol/L, 0.875/0.85.

Conclusions

To distinguish between SPPE/CPPE, pH and LDH performed well, but optimal cut-off values differed from earlier established recommendations. Pleura lactate had the largest AUC of the investigated biomarkers and may be used in the analyses of PPE-staging.

Keywords:

• Parapneumonic effusion
• pleural biomarkers
• pleural lactate

Acknowledgements

The authors thank the staff at Danderyd Hospital and Södersjukhuset for sample collection of the patients with PPE admitted to their units.

Author contributions

Niclas Johansson contributed with data collection, data analyses and manuscript preparation, Karin Andersson Ydsten contributed with data collection, data analyses and manuscript preparation. Carolina Backman-Johansson contributed with data analyses and manuscript preparation. Martin Vondracek contributed with data collection and analyses, Jonas Hedlund contributed with data collection, data analyses and manuscript preparation.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by ALF Grants, Stockholm County [grant number 20110088].