1. In a patient with suspected meningitis, should you give dexamethasone?
2. In the same patient, how much time do you have after giving empiric antibiotics to perform your LP?
Studies have shown varying effects of dexamethasone given for meningitis. Most suggest that a dose of dexamethasone (.15mg/kg IV, usually 10mg) with or before the first dose of antibiotics and subsequent q6h dosing may reduce mortality in bacterial meningitis, specifically with strep pneumo. A recent 2013 Cochrane review suggested a reduction in hearing loss and neurologic sequelae with steroid administration but not mortality.
Given the fact that when we are treating meningitis in the emergency department and we rarely, if ever, know the bacterial agent right away, it is reasonable to give a dose of dexamethasone with your first round of antibiotics.
In some cases, an LP may be delayed due to imaging or limited resources in the emergency department, it is prudent to give your patients empiric antibiotic therapy. Studies suggest that CSF cytology may not be altered for 24-48 hours. However, there may be an approximate window of 4-10 hours to perform an LP after antibiotic administration before csf samples in strep pneumo infections are sterile, and for meningococcal infections , you may only have 1 hour. Of note, evidence for these time windows is limited, and based on small trials. Perform your LPs as soon as possible.
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