Evaluation of prostaglandin D2 as a CSF leak marker: implications in safe epidural anesthesia

BACKGROUND It is accepted that there is a severe risk of dural puncture in epidural anesthesia. Of major concern to anesthesiologists is unintentional spinal block. Reliable identification of cerebrospinal fluid (CSF) from the aspirate is crucial for safe epidural anesthesia. The aim of this study was to determine whether prostaglandin D2 could be clinically used as a marker for the detection of CSF traces. METHODS After obtaining Institutional Review Board approval and patient consent, CSF was obtained from patients undergoing spinal anesthesia, and blood, urine, and saliva were obtained from normal subjects and analyzed for prostaglandin D2 (PGD). CSF (n=5) samples were diluted with local anesthetic (bupivacaine), normal saline and blood in the ratios of 1:5 and 1:10. PGD levels in the CSF samples were analyzed with a PGD-Methoxime (MOX) EIA Kit (Cayman Chemicals, MI). This assay is based on the conversion of PGD to a stable derivative, which is analyzed with antiserum specific for PGD-MOX. RESULTS Different concentrations of pure PGD-MOX conjugate were analyzed by EIA and a standard curve was derived. PGD levels in CSF and CSF with diluents were determined and the values were extrapolated onto the standard curve. Our results show a well-defined correlation for the presence of PGD both in straight CSF samples and in diluted CSF (dilution factor of 1:5 and 1:10). CONCLUSION Prostaglandin D2 was reliably identified in CSF by enzyme-linked immunosorbent assay when diluted with local anesthetic, saline, and serum, and can be used as a marker to identify the presence of CSF in epidural aspirates.