Quantitative Modeling for Prediction of Shunt Dependence in Subarachnoid Hemorrhage Derived from 10-Day Ventriculostomy Metrics

Background Acute hydrocephalus (HCP) is a common and serious complications of aneurysmal subarachnoid hemorrhage (SAH), frequently requiring emergent cerebrospinal fluid (CSF) diversion via external ventricular drain (EVD) placement. A substantial proportion of SAH patients with HCP ultimately require permanent CSF diversion, via ventriculoperitoneal shunt (VPS) placement; however, decision making with respect to patient selection and shunt timing is controversial, particularly given the parallel risks of morbidity attributable to undertreatment of chronic HCP, multiple failed attempts at EVD weaning, or placement of an unnecessary VPS. We sought to quantitatively study patients who underwent EVD placement for treatment of SAH-induced HCP, to identify potential predictors of eventual VPS dependence.

Methods A prospectively maintained SAH database was retrospectively reviewed for patients who underwent EVD placement within 24 hours of admission. Baseline characteristics and ventriculostomy metrics were assessed with respect to VPS placement. Statistical tests included Fisher’s exact/chi-square test, Mann–Whitney test, Pearson’s correlation, and multivariable logistic regression using odds ratios (ORs) and 95% confidence intervals (CIs).

Results A total of 218 SAH patients were treated with EVD for a median of 12 days (range: 1–54); 85 subsequently required VPS placement (39%). On univariate analysis, significant predictors of VPS placement included prolonged EVD duration (median: 10 vs. 15, p < 0.001), prolonged drainage at ≤5 mm Hg (median: 0 vs. 3 days, p < 0.001), greater average 10-day CSF output (median: 177 vs. 223 mL, p < 0.001), and 10-day total CSF drainage (median: 1,898 vs. 3,261 mL, p < 0.001). Patients presenting with modified Fisher’s grades 2 or 4 (i.e., intraventricular hemorrhage) were significantly more likely to require VPS placement than those with grades 1 or 3 (74 vs. 26%, p = 0.015). VPS placement was significantly associated ≥2 wean failures (6 vs. 33%, p < 0.001), or any clamp trial failure (11 vs. 32%, p < 0.001). On multivariate logistic regression, VPS placement remained significantly and independently associated with higher 10-day average daily drainage (log-transformed, OR = 3.58, CI = 1.62–7.91), ≥2 wean failures (OR = 5.55, CI = 2.08–14.8), clamp failure (OR = 2.61, CI = 1.16–5.85), and age >55 years (OR = 1.03, CI = 1.00–1.05). Average daily and overall CSF outputs were inversely correlated with age (ρ = −0.28, p < 0.001; ρ = −0.21, p = 0.002).

Conclusion HCP after SAH requires VPS in more than one-in-three patients. Predictors of VPS include duration of EVD drainage, particularly if prolonged drainage at lower pressure is required or persistently high daily drainage is observed. Intraventricular hemorrhage, serial wean failures, and any clamp failure are also associated with requiring EVD. Based on our findings, we recommend consideration for VPS placement in lieu of continued weaning trials after initial failure. Similarly, 10-day average daily drainage >200 mL, or the need for >3 days of drainage at ≥5 mm Hg, should prompt consideration for VPS placement—particularly when observed in combination.