Assessment of cerebral autoregulation and cerebral perfusion in patients with sickle cell disease using frequency-domain near-infrared spectroscopy

Cerebral small vessel disease is a neurological complication of sickle cell disease (SCD) associated with cerebral hypoperfusion and cognitive dysfunction. Early and prompt detection is important for prevention and treatment, preferably with a noninvasive, inexpensive point-of-care test. Impaired cerebral autoregulation (CA) is a marker of cerebral small vessel disease, so we evaluated whether imaging hemodynamic changes in the microvasculature can assess abnormal CA in patients with SCD. We instructed patients (<i>n</i> = 13) and healthy controls (<i>n</i> = 14) to breathe at three different rates using a metronome whereas frequency-domain near-infrared spectroscopy (FDNIRS), a noninvasive optical imaging method, measured the phase delay and amplitude ratios between oxygenated and deoxygenated hemoglobin concentration changes. These measurements served as a surrogate measure of CA efficiency. We applied a mathematical hemodynamic model to calculate blood transit times and CA efficiency. We found that patients with SCD had significantly lower phase difference between oxyhemoglobin and deoxyhemoglobin oscillations (-320° to -340°) than controls (-200° to -240°), indicating differences in CA and blood transit time between the groups. Cerebral tissue oxygen saturation was reduced in patients with SCD (63.1 ± 7.8%) compared with controls (66.1 ± 4.7%). The hemodynamic model further found a significant difference in the capillary transit time and autoregulation cutoff frequency between SCD (1.88 ± 0.14 s; 0.016 ± 0.0033 Hz) and controls (0.71 ± 0.24 s, <i>P</i> < 0.05; 0.02 ± 0.0052 Hz, <i>P</i> < 0.05). Herein, we present preliminary evidence of the utility of NIRS to monitor CA in SCD; NIRS may represent a new screening method for cerebral small vessel disease in SCD.<b>NEW & NOTEWORTHY</b> This study explored near-infrared spectroscopy (NIRS) for monitoring cerebral autoregulation (CA) in patients with sickle cell disease (SCD). Cerebral small vessel disease, a complication of SCD, is associated with cerebral hypoperfusion and cognitive dysfunction. The results revealed that SCD exhibited impaired CA, longer blood transit times, and decreased tissue oxygen saturation compared with healthy controls. NIRS shows promise as a tool for screening cerebral small vessel disease in SCD, providing preliminary evidence of its utility.