Zero-Calibrating External Ventricular Drains: Exploring Practice

BACKGROUND: Guidelines call for the removal of the nonvented cap (NVC) on the flushless transducer applied to the external ventricular drain (EVD) to zero the device to atmospheric pressure. Some hospitals have abandoned this practice to prevent opening the system to air. No data exist to determine the safest, most effective method of EVD zero-calibration. METHODS: A multidisciplinary team was assembled to use reflective practice to evaluate current zero-calibration of EVD practice. RESULTS: Clinical Nursing Focus showed recommendations largely out of date without detailed rationale or a high level of evidence. Manufacturer recommendations were fragmented and did not address rationale for technique. Bedside trial showed equivalence when comparing intracranial pressure (ICP) tidal, ICP after EVD zero with NVC removal, and ICP after EVD zero without NVC removal. CONCLUSION: Institutional guidelines were changed to reflect zero-calibration of EVD without NVC removal in systems that are amendable to this procedure. Further study is needed to determine best practice.