Characterization of the microvascular cerebral blood flow response to obstructive apneic events during night sleep

Abstract

Abstract.Obstructive apnea causes periodic changes in cerebral and systemic hemodynamics, which may contribute to the increased risk of cerebrovascular disease of patients with obstructive sleep apnea (OSA) syndrome. The improved understanding of the consequences of an apneic event on the brain perfusion may improve our knowledge of these consequences and then allow for the development of preventive strategies. Our aim was to characterize the typical microvascular, cortical cerebral blood flow (CBF) changes in an OSA population during an apneic event. Sixteen patients (age 58±8 years, 75% male) with a high risk of severe OSA were measured with a polysomnography device and with diffuse correlation spectroscopy (DCS) during one night of sleep with 1365 obstructive apneic events detected. All patients were later confirmed to suffer from severe OSA syndrome with a mean of 83±15 apneas and hypopneas per hour. DCS has been shown to be able to characterize the microvascular CBF response to each event with a sufficient contrast-to-noise ratio to reveal its dynamics. It has also revealed that an apnea causes a peak increase of microvascular CBF (30±17%) at the end of the event followed by a drop (−20±12%) similar to what was observed in macrovascular CBF velocity of the middle cerebral artery. This study paves the way for the utilization of DCS for further studies on these populations.

Microvascular cerebral blood flow fluctuations in association with apneas and hypopneas in acute ischemic stroke

“…This increase is similar to the CBF increase of 30% AE 17% and the decrease of −20% AE 12% described previously by us using DCS in obstructive sleep apneic events. 42 It is also consistent with the CBFVof 22% to 42% increase found by Alex et al 23 and also to the 14.6% AE 14% increase right after the apnea end by Bålfors and Franklin. 20 However, other authors have found larger CBFV increases.…”

“…20,41 These analysis methods have previously been verified in nocturnal measurements of chronic obstructive sleep apnea patients. 42 Averages and standard deviations have been performed considering all apneic and hypopneic events for each patient and also for the population. The Wilcoxon signed-rank test was used to assess the difference between ipsilesional and contralesional ΔrCBF responses.…”

Influence of probe pressure on the pulsatile diffuse correlation spectroscopy blood flow signal on the forearm and forehead regions

“…11,19 Accordingly, DCS is well-suited for continuous prolonged monitoring. [20][21][22]45 Herein, we investigated the effects of pressure on the DCS blood flow pulsatility signal These data were obtained on the right foreheads of 11 healthy adult volunteers at multiple probe pressures for each subject (i.e., N ¼ 60 probe pressures total; 1-min of DCS data acquired for each pressure, 2.1-cm source-detector separation). hBFIi o , P o , and PI o denote the subject's mean steady-state BFI, probe pressure, and PI measured at the baseline (initial) probe pressure.…”

Continuous non-invasive optical monitoring of cerebral blood flow and oxidative metabolism after acute brain injury

“…Physiological monitoring in the intensive care unit (ICU) presents unique challenges due to the presence of numerous other monitors that can interfere with measurement fidelity, as well as artifacts caused by patient agitation, nursing care, bedside procedures, and transport to and from other diagnostic/imaging studies. As demonstrated by our group and others, 36,38,45,77,78,79 – 87 diffuse optics is well-suited for continuous, long-term monitoring of patients. Accordingly, we were able to perform continuous stretches of optical monitoring for several hours/day in all our patients.…”