Objective: To evaluate Light's criteria for drainage in children with parapneumonic pleural effusion. Methods: Prospective cross-sectional study on 85 children who were admitted to Hospital da Criança Santo Antônio, State of Rio Grande do Sul, Southern Brazil, presenting pneumonia with pleural effusion confirmed by chest X-ray and/or chest ultrasonography. The exclusion criteria were: previous drainage, pleural effusions associated with other disorders. The pH analysis was performed with a blood gas analyzer. Glucose and LDH were analyzed by spectrophotometry. The decision to perform pleural drainage was made by the attending physician without the participation of the researchers. Results: Pleural fluid in parapneumonic effusion with pH < 7.2 and glucose < 40 mg/dl presented higher drainage rate than LDH > 1,000 UI/l. The pH and glucose had high specificity (89% and 88%) and above the LDH (65%). The same results were observed when non-purulent fluids were analyzed (pH < 7.2 94%, glucose 88%, LDH 68%). In patients with pH < 7.2 LDH > 1,000 UI/l and glucose < 40 mg/dl predominated fluid with cloudy or purulent aspect. In more than 21% of patients who have indication of drainage by the classic criteria, was found limpid aspect. Conclusions: These data indicate that biochemical test support indication of drainage in children presenting with parapneumonic pleural effusion in non-purulent fluid. The specificity for drainage was 89% for pH and 88% for glucose and around 65% for LDH.
Pleural effusion; Pleural empyema; Postural drainage
