Abstract
We aimed to evaluate the diagnostic value of lumbar puncture in excluding nosocomial meningitis as the cause of mental status changes in medical intensive care unit patients. We retrospectively reviewed the records of all patients admitted to the medical intensive care unit at our institution over a four-year period who had a lumbar puncture performed during their stay. Patients with central nervous system devices were excluded.
During the study period 63 lumbar punctures were performed, 31 to exclude nosocomial meningitis. Of these 31 patients, 25 (80.6%) received antimicrobials during hospitalization before performance of lumbar puncture. In one patient with human immunodeficiency virus (HIV) infection, Gram stain demonstrated yeast; in the remainder, Gram stain was negative. Cultures were negative for pathogenic bacteria in all 30 of these patients (overall yield: 0%, 95% CI: 0-10.0%). Five patients (16.1%) had a cerebrospinal fluid leucocytosis (>10 leucocytes/mm3); of these, all had received prior antibiotics, two had positive cryptococcal antigen results, and three had central nervous system infection suspected clinically without an evident alternative diagnosis. In no non-HW subject did lumbar puncture alter management.
Lumbar puncture performed in the medical intensive care unit to exclude nosocomial meningitis as the cause of mental status changes has a low yield and rarely changes management. These findings should not be generalized to patients who have sustained head trauma, have undergone neurosurgical procedures, or may be immunosuppressed.