The Use of a Novel Quantitative Marker of Echogenicity of Pleural Fluid in Parapneumonic Pleural Effusions.

Background: Thoracic ultrasound is an essential tool in the daily clinical care of pleural effusions and especially parapneumonic pleural effusions (PPEs), in terms of diagnosis, management, and follow-up. Hypoechogenicity index (HI) is a quantitative marker of pleural fluid echogenicity. We aimed to examine associations of HI with pleural inflammation in patients with PPE.

Methods: All patients included underwent a thoracic ultrasound with HI determination at the first day of their admission for a PPE. Thoracentesis was performed in all patients. Demographics, laboratory measurements, and clinical data were collected prospectively and recorded in all subjects.

Results: Twenty-four patients with PPE were included in the study. HI was statistically significantly correlated with intensity of inflammation as suggested by pleural fluid LDH ( < 0.001,  = -0.831), pleural fluid glucose (=0.022,  = 0.474), and pleural fluid pH ( < 0.001,  = 0.811). HI was correlated with ADA levels (=0.005,  = -0.552). We observed a statistically significant correlation of HI with pleural fluid total cell number ( < 0.001,  = -0.657) and polymorphonuclears percentage (=0.02,  = -0.590), as well as days to afebrile (=0.046,  = -0.411), duration of chest tube placement ( < 0.001,  = -0.806), and days of hospitalization (=0.013,  = -0.501). . HI presents a fast, easily applicable, objective, and quantitative marker of pleural inflammation that reliably reflects the intensity of pleural inflammation and could potentially guide therapeutic management of PPE.