Real-Time Non-invasive Assessment of Cerebral Hemodynamics With Diffuse Optical Spectroscopies in a Neuro Intensive Care Unit: An Observational Case Study

Abstract

Prevention of secondary damage is an important goal in the treatment of severe neurological conditions, such as major head trauma or stroke. However, there is currently a lack of non-invasive methods for monitoring cerebral physiology. Diffuse optical methods have been proposed as an inexpensive, non-invasive bedside monitor capable of providing neurophysiology information in neurocritical patients. However, the reliability of the technique to provide accurate longitudinal measurement during the clinical evolution of a patient remains largely unaddressed. Here, we report on the translation of a hybrid diffuse optical system combining frequency domain diffuse optical spectroscopy (FD-DOS) and diffuse correlation spectroscopy (DCS) for real-time monitoring of cerebral physiology in a neuro intensive care unit (neuro-ICU). More specifically, we present a case study of a patient admitted with a high-grade aneurysmal subarachnoid hemorrhage, who was monitored throughout hospitalization. We show that the neurophysiological parameters measured by diffuse optics at the bedside are consistent with the clinical evolution of the patient at all the different stages following its brain lesion. These data provide support for clinical translation of DOS/DCS as a useful biomarker of neurophysiology in the neuro-ICU, particularly in locations where other clinical resources are limited.

Keywords: aneurysmal subarachnoid hemorrhage; cerebral blood flow (CBF); diffuse correlation spectroscopy (DCS); diffuse optical spectroscopy (DOS); neuro intensive care unit.

Figure 1

Evolution of the brain lesion in a 62 years old female patient following a high-grade aneurysmal subarachnoid hemorrhage (aSAH). (A) Neurophysiological parameters measured with the diffuse optical system, as well as the systemic mean arterial pressure (MAP). (B) Computed tomography (CT) images at different days during hospitalization (marked as vertical lines in the left panel). The patient died 9 days after hospitalization. The red areas in the CT images represent the optical sensitivity region. The error bars of each point represent the standard deviation of each parameter across the monitoring time-window. For some days, the standard deviation was too small to be shown. CBF, cerebral blood flow; OEF, oxygen extraction fraction; CMRO₂, cerebral metabolic rate of oxygen; HbT, total hemoglobin concentration.