Cerebral Blood Flow Response to Fluid Challenge in Acute Ischemic Stroke
Keene S, Miller J, Price CL, Thompson R, Calo S, Levy P, and Lewandowski C. Cerebral blood flow response to fluid challenge in acute ischemic stroke. Acad Emerg Med 2017; 24:S193.
Acad Emerg Med
Background: Debate exists on the efficacy of intravenous fluids to improve cerebral blood flow in acute ischemic stroke (AIS).
Objective: We tested the hypothesis that bolus crystalloid therapy would improve cerebral blood flow velocity as measured using transcranial Doppler (TCD) in patients with AIS. Secondarily, we determined the modifying effect of key, non-invasive hemodynamic parameters on this relationship.
Methods: Prospective, quasi-experimental study of patients confirmed AIS and a NIHSS > 3. Exclusion criteria were: age < 18 years, time of onset > 12 hours, brain hemorrhage, inadequate temporal windows for TCD measurement, and contraindication to bolus fluids per treating team. We performed baseline noninvasive, continuous non-invasive hemodynamic monitoring using the Nexfin device, and we measured cerebral blood flow velocity with TCD insonation of the middle cerebral arteries (MCA) fixed to a headframe. Next, each patient received a 500 mL bolus of crystalloid, followed by repeat hemodynamic and TCD measurements. We performed univariate comparisons of the change in mean flow velocity (MFV) of the MCA on the affected side following confirmation of stroke location and multiple linear regression to test the modifying effect of hemodynamic variables such as systolic blood pressure (sBP), stroke volume index (SVI) and cardiac index (CI).
Results: We enrolled 30 patients with confirmed AIS. The mean age was 53 (± 13) years and 50% were female. The median NIHSS was 6 (IQR 4,7) and baseline sBP 155 mmHg. Following the fluid bolus, there was significant increase in sBP (+7, 95%CI 0.6-13 mmHg) and SVI (+2.2, 95%CI 0.3-4.1 mL/m2). The average change in MFV was not significant (0.3, 95%CI -3.7 to 4.3 cm/sec). In a model adjusting for NIHSS, BUN/Cr ratio, age, and baseline CI and sBP, increasing age and lower baseline CI were associated with an increase in MFV after a fluid bolus.
Conclusion: In this sample of AIS patients, a fluid bolus did not increase MFV overall. However, on adjusted subanalysis, older individuals with reduced baseline CI appeared to respond better suggesting the potential for targeted therapeutic intervention in such patients.