We piloted long-term diffuse correlation spectroscopy (DCS) monitoring of cerebral blood flow in a patient with an aneurysmal subarachnoid hemorrhage. Measurements were conducted for 18 days. We also recorded blood pressure, ECG, and other clinical monitors as available. The blood flow index from 5, 25, and 30 mm separation channels showed a variety of responses depending on the patient condition and treatment. As an example, repeated doses of nimodipine were given for treatment purposes, resulting in level or increased cerebral blood flow despite a decrease in mean arterial blood pressure. There was correlation between the short-distance channel and heart rate.
Transcatheter aortic valve replacement (TAVR) surgery has a risk of cognitive impairment and neurological injury. Currently, there are few options for non-invasively monitoring brain activity and perfusion, with electroencephalography, transcranial Doppler, and near-infrared spectroscopy (NIRS) all having significant drawbacks. By combining NIRS with diffuse correlation spectroscopy (DCS) we can obtain a more complete picture of cerebral hemodynamics during TAVR procedures and examine the link to neurological outcomes. We show examples of post-valve replacement hemodynamic changes that correspond with worse/better patient outcomes
Cerebral autoregulation (CA), the brain’s ability to regulate perfusion independently of blood pressure, can be assessed by evaluating the degree of correlation between cerebral blood flow (CBF) and mean arterial pressure. Non-invasive, optical measurements of brain hemodynamics using DCS/NIRS can be used to assess CA and show agreement with invasive metrics (laser doppler perfusion and intracranial pressure) in a pediatric swine model of cardiac arrest. Wavelet based coherence methods of assessing autoregulation are a useful alternative to correlation based methods.
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