Shining a new light on pericardial fluid

In a healthy individual, there is 15–50 mL of fluid between the visceral and parietal layers of the fibroelastic pericardium. The normal composition of pericardial fluid is currently ill-defined. In the USA, pericardiocentesis is performed in patients with pericardial disease approximately 1000 times per month.1 2 During pericardiocentesis fluid is almost uniformly sent for laboratory analysis per guideline recommendations to quantify general chemistry and cellular composition.3 To date, there is no established methodology to assess pericardial fluid composition nor are there recognised reference values for the normal constituents of pericardial fluid. Interpretation of pericardial fluid composition is commonly performed by extending the Light’s criteria validated on pleural fluid analysis to pericardial fluid.3 4 The accuracy of this approach to establish if pericardial fluid is transudative or exudative is unknown. Available data regarding the biochemical and cellular composition of physiological pericardial fluid are sparse. In a study of 30 consecutive patients without pericardial disease undergoing coronary artery bypass grafting or valvular replacement that underwent pericardial fluid analysis, mean fluid lactate …