Diagnosis of complicated parapneumonic effusion by pleural pH measurement is jeopardized by inadequate physician knowledge and guideline-discordant laboratory practice.

Pleural fluid pH is a crucial determinant of complicated parapneumonic effusion diagnosis and the need for drainage. It is best measured by blood gas analyzer. We examined whether physicians were aware of this, and whether their laboratories measured pleural pH according to their expectations. Only 53% of physicians understood the need for blood gas analyzer measurements, only 50% of laboratories used blood gas analyzers, and only 35% of physicians correctly identified the method performed in their laboratory. Diagnosis of complicated parapneumonic effusion is jeopardized by inadequate physician knowledge and guideline-discordant laboratory practice. We recommend cooperation between thoracic and biochemistry specialty societies to rectify this issue.