From the Research
For obtaining CSF cultures from an external ventricular drain (EVD), draw 1-2 mL of CSF for routine cultures and sensitivity testing, as this volume is sufficient for standard microbiological analysis while minimizing unnecessary CSF removal 1. The procedure should be performed using strict aseptic technique to prevent contamination and introduction of pathogens. Before collecting the sample, discard the first 0.5-1 mL of CSF as this may contain contaminants from the catheter. The sample should be collected in sterile containers and transported promptly to the laboratory, ideally within 30 minutes of collection. If anaerobic organisms are suspected, additional CSF (1-2 mL) should be collected in appropriate anaerobic transport media. For suspected fungal or mycobacterial infections, consider collecting an additional 2-5 mL of CSF. Minimizing CSF removal is important to prevent rapid changes in intracranial pressure, which could lead to neurological deterioration, especially in patients with elevated intracranial pressure or small ventricles.
Some key points to consider when collecting CSF from an EVD include:
- The use of silver-bearing EVD catheters may reduce the risk of catheter-related infections 2
- The FilmArray Meningitis/Encephalitis Panel is a sensitive and specific test for detecting bacteria, viruses, and yeast in CSF specimens, and may aid in diagnosis and treatment of infectious meningitis and encephalitis 3
- CSF parameters, such as cell count, protein, lactate, and glucose, can be reliably assessed from the EVD collection bag 1
- Routine culture of CSF in patients with EVDs may not be necessary, and cultures should be performed based on clinical indicators such as new fever, peripheral leukocytosis, neurological deterioration, or a change in CSF appearance 4