Paediatric empyema: are ultrasound characteristics at the time of
intervention predictive of treatment failure?
Background: Parapneumonic effusions and empyema are the most frequent
complication of paediatric pneumonia. Treatment options include chest
drain and fibrinolytics (CDF) or thoracoscopic surgery. CDF is
considered less invasive, more cost effective though with higher rates
of reintervention. Pleural fluid characteristics on ultrasound may
identify cases at increased risk of treatment failure with primary CDF.
Methods: A retrospective cohort 2011-2018 of complicated pneumonia
managed with primary CDF. Cases were reviewed using ultrasound criteria
to describe pleural fluid. We compared ultrasound findings and treatment
failure. Results: We report 137 cases with a median age 3.8 years and
43% female. Treatment failure occurred for 32/137 (23%) cases. The
interobserver reliability was substantial for the number of septations
(Kappa 0.72, 95% CI 0.6 to 0.8), moderate for the size of the largest
locule (Kappa 0.55, 95% CI 0.4 to 0.7) and fair for the level of
echogenicity (Kappa 0.22, 95%CI 0.1 to 0.3), pleural thickening (Kappa
0.28, 95% CI 0.2 to 0.4), maximum effusion depth (Kappa 0.37, 95%CI
0.2 to 0.5) and radiologist’s risk for reintervention (Kappa 0.32, 95%
CI 0.2 to 0.5). Hyperechoic pleural fluid was associated with treatment
failure, with cases nearly five times more likely than anechoic fluid to
have a reintervention (OR 4.9 95%CI 1.7 to 14.2, p=0.04). Treatment
failure was not associated with other variables. Conclusion: We did not
find an association between ultrasound characteristics and treatment
failure for complicated pneumonia managed with primary CDF.
Inter-observer agreement of ultrasound findings was difficult despite
more objective criteria.