Introduction: Intravenous infusion of 0.9% normal saline (NS) is used routinely after acute ischemic stroke (AIS). Since cerebral autoregulation is impaired after AIS, volume expansion due to NS infusion holds potential to increase cerebral blood flow (CBF). Here, we use transcranial optics to quantify the CBF response to a NS bolus.
Hypothesis: An increase in CBF during a 500cc bolus of NS will be detectable using transcranial optics.
Methods: Adults ≥ 18 years with unilateral supratentorial AIS were enrolled within 96 hours of onset. Relative CBF was noninvasively monitored bifrontally using diffuse correlation spectroscopy with a 15 minute baseline, followed by a 500cc bolus of NS administered over 30 minutes, and a 15 minute post-bolus period. Repeated measures ANOVA and piecewise linear regression were used to quantify the effects of NS bolus on CBF.
Results: Data from 36 subjects was analyzed (mean age: 64.7±13.5; median NIHSS: 4.5 (IQR 2-9)) at a mean of 66 ± 18 hours after symptom onset. Mean arterial pressure increased during the NS bolus (mean 3.4±9.0 mm Hg). Mean CBF during NS was 22±17% higher than baseline in the ipsilateral hemisphere (p<0.001), and 21±17% higher in the contralateral hemisphere, (p<0.001). Piecewise linear regression estimated an average rate of CBF increase during NS of 0.71%/min in the ipsi and 0.68%/min in the contralateral hemispheres. An average rate of CBF increase of 0.44%/min and 0.48%/min was also observed during the baseline period in the ipsi/contralateral hemispheres.
Conclusion: NS infusion was associated with a significant increase in CBF from baseline in both hemispheres in patients with subacute stroke. CBF responses to NS infusion were heterogeneous across subjects, suggesting the potential of bedside CBF monitoring for personalized CBF management in patients with AIS.