Objective:

Determining the effect of intrathecal nicardipine on microvascular cerebral blood flow

Background:

A common complication of subarachnoid hemorrhage is cerebral vasospasm, which is associated with delayed cerebral ischemia (DCI), a predictor of poor functional outcome. Intrathecal administration of nicardipine (ITn) upon detection of vasospasm holds promise as a treatment that reduces the incidence of secondary stroke. Herein, we utilize a novel non-invasive optical measurement of regional microvascular perfusion to determine the effect of ITn on microvascular cerebral blood flow (CBF).

Design/Methods:

In this observational study, we prospectively studied 20 patients with non-traumatic subarachnoid hemorrhage who were treated with ITn as part of usual care for evolving cerebral vasospasm. Regional microvascular CBF in the frontal cortex was measured with diffuse correlation spectroscopy for up to 90 min after the first treatment dose, and for a subset of patients, on days 2 and 3 of treatment as well. Outcome was assessed as the presence of DCI on imaging. 

Results:

CBF increased significantly over the 90 min of monitoring after the first and subsequent doses (p<0.001) in the absence of systemic hemodynamic changes. In general, the CBF response was heterogeneous across subjects. Using data from the first dose, a latent class mixture model was used to classify 19/20 patients into two distinct classes of cerebral blood flow response: patients in class 1 (n=6) showed a decrease or no change in CBF, while patients in class 2 (n=13) showed a pronounced increase in CBF in response to nicardipine. The incidence of DCI was 5/6 in class 1 and 0/13 in class 2 (p<0.001). Similar significant differences in CBF response in patients with and without DCI were also observed on days 2 and 3 (both p<0.001).

Conclusions:

Microvascular CBF monitoring is feasible in critically ill subarachnoid hemorrhage patients. CBF response may provide a valuable biomarker for treatment responsiveness.