Standardized Criteria to Initiate External Ventricular Drain (EVD) Weaning in a Neurological Intensive Care Unit to Increase the Safety of EVD Discontinuation and Reduce the Need for a Shunt.

Introduction Patients with subarachnoid hemorrhages (SAH) with external ventricular drains (EVD) can develop chronic hydrocephalus (HCP), requiring permanent cerebrospinal fluid (CSF) diversion via an external shunt. Two different strategies have been used to assess for dependence on EVD: 1) prompt closure, and 2) gradual weaning. Gradual weaning of EVDs is performed by increasing drainage resistance to outflow over days. However, when to start one strategy or the other is up to the physician. No uniform guidelines exist raising a question: Are standardized criteria necessary to initiate the EVD weaning process for SAH patients to increase the safety of EVD discontinuation and reduce the need for a shunt? This study shares criteria used to initiate EVD weaning that displayed increased safety of EVD discontinuation for patients with subarachnoid hemorrhage requiring EVD, particularly with regards to length of hospital stay (LOS), hospital-acquired infection rates, and ventriculoperitoneal shunt/endoscopic third ventriculostomy (VPS/ETV) placement. Methods One hundred and fifty-one SAH patients from January 2016 to January 2019 were analyzed. 60 aneurysmal SAH (aSAH) and 18 non-aneurysmal nontraumatic SAH (naSAH) patients required EVD placement. A gradual EVD weaning protocol was initiated if patients met the following criteria: 1. The reason for EVD placement has resolved or is resolving, 2. The quantity of CSF output is <250mL over 24 hours, 3. Quality of CSF is nonbloody, 4. Intracranial Pressure (ICP) must be within normal limits, and 5. The patient must be neurologically stable. It was acceptable to initiate the weaning process when the patient had mild cerebral vasospasm, but not moderate to severe cerebral vasospasm. EVD weaning was performed by increasing the drain (chamber) height by 5 millimeters of mercury every 24 hours if the criteria were met. Charts were reviewed for LOS, infection rates, and rate of VPS/ETV. Gender, age, race, wean failure incidence, Hunt-Hess scores, modified Fisher scores, and syndrome of inappropriate antidiuretic hormone/cerebral salt wasting (SIADH/CSW) rates were obtained. Results The average LOS for aSAH patients with EVD was 20.35 days. The incidence of VPS/ETV was 11%. A chi-square analysis revealed that aSAH patients had higher rates of VPS/ETV placement (p<0.001) and EVD wean failures (p<0.001) than naSAH patients. aSAH patients had a lower incidence of VPS/ETV placement of 11% compared to 21% nationally. Conclusions Standardized criteria to initiate EVD weaning provided a reduction in VPS/ETV placement among aSAH patients compared to national averages and provided a uniform approach to EVD management. Comparable infection rates and LOS for SAH patients requiring EVDs compared to national averages were found.