Objective: To identify diagnostic markers distinguishing between acute lung injury/acute respiratory distress syndrome (ALI/ARDS) due to fat embolism syndrome (FES) and that due to other causes, and to investigate whether phospholipase A2 and platelet-activating factor (PAF) play a role in the pathogenesis of ALI due to FES.
Design and setting: A prospective study in a 14-bed ICU.
Patients: We studied 13 patients with FES, 11 with ALI/ARDS from other causes (6 without trauma, ALI/ARDS group 1; 7 with trauma, ALI/ARDS group 2) and 5 without cardiopulmonary disease.
Measurements and results: We compared broncholveolar lavage (BAL) fluid alterations in the respective groups. Total BAL protein in FES group was significantly higher compared to in ALI/ARDS group 1 and controls but ALI/ARDS group 2. Higher total phospholipids were found than in other groups. The alterations in individual phospholipid classes were similar to those in ALI/ARDS patients. However, total cholesterol, lipid esters, and monoglycerides were significantly higher in FES than in other groups. The level of PAF in FES was significantly higher and there was an inverse correlation between PAF and PAF-acetylhydrolase. Phospholipase A2 activity was significantly higher in both FES and ALI/ARDS groups than in control.
Conclusions: The levels of neutral lipids and especially cholesterol and cholesterol esters in BAL can be used to distinguish patients with FES from ALI/ARDS due to other predisposing factors. Phospholipase A(2) may be involved in the development, and PAF-acetylhydrolase in the downregulation of inflammation in FES.