It is a common practice to perform lumbar puncture (LP) in critically ill patients with delirium and/or fever. The purpose of this review was to determine the diagnostic value of LPs in the MICU patients.
Retrospective chart review of all LPs performed in two MICUs in an urban university hospital from January 2000 to December 2001. we excluded all repeated LPs, or those done outside the MICU. A positive LP was defined by a proved infection by culture or appropriate stain. Aseptic meningitis was diagnosed when the cerebrospinal fluid (CSF) analysis revealed lymphatic pleocytosis and no pathogens. Suspected nosocomial meningitis was defined if the indication for LP arose > 48 hours following admission
155 LP were performed to rule out meningitis in critically ill patients with delirium and/or fever. 136 patients (88%) were considered negative. 19 patients (12%) were found to have positive CSF results. 68 patients ( 44%) were considered to be high risk (cancer, HIV positive, chronic renal failure). Out of the high risk group 14/68 patients (21%) were considered positive.Whereas, only 5 patients (5.7%) had positive CSF among those without any risk factors (P< 0.01). Out of the 19 patients with positive CSF 6 (30%) were suspected for nosocomial meningitis (2 due to cryptococcal, 1 bacterial, 3 aseptic), 13 (70%) for community acquired meningitis (2 due to cryptococcal, 1 tuberculous,2 bacterial, and 8 cases were considered to be aseptic). The only case of nosocomial meningitis due to bacterial etiology was due to iatrogenic meningitis.CONCLUSIONS: Bacterial etiology is a rare etiology of nosocomial meningitis in the absence of invasive intervention to CNS. However; in an appropriate setting, LP is still an important diagnostic procedure in ICU patients to rule out cryptococcal and tuberculous meningitis as the etiology for delirium and/or fever.CLINICAL IMPLICATION: It is appropriate to perform LP in MICU patients with high risk factors presenting with delirium and/or fever even in the absence of meningeal irritation signs.
M.M. Kannass, None.