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

Figures

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  Fig. 1. (a) Visualization of the averaging of the different apneas grouped by their duration. These apneas from the same duration range will be averaged for obtaining a canonical apnea shape. (b) Characterization of individual apneas, where the apnea end is considered as a pivot point. The light gray region indicates the apneic event. The dark gray region indicates the time window used to find the first extremum value. The first and second extrema are labeled.

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  Fig. 2. (a) Nasal airflow, (b) heart rate, (c) arterial oxygen saturation, and (d) cerebral blood flow index dynamics during 3 min of night sleep for one representative subject. The gray regions between two vertical lines indicate the obstructive apneic events.

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  Fig. 3. Mean relative cerebral blood flow changes (ΔrCBF) during obstructive apneic events for apnea durations of: (a) 10 to 15 s; (b) 15 to 30 s; (c) 30 to 45 s; and (d) 45 to 60 s. The gray regions between two vertical lines indicate the start of the events up-to the end of the longest events in each group. The total number of averaged apneas for each subfigure is included at the top right. The peaks and drops representative for the mean apnea hemodynamics response to obstructive apneic events for each group are labeled. See Fig. 1(a) for the visualization of the different apneas grouped by their duration before averaging.

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  Fig. 4. (a) Mean change of arterial oxygen saturation (ΔSpO2), (b) of relative heart rate (ΔrHR), and (c) of relative cerebral blood flow (ΔrCBF), for apnea durations from 15 up-to 30 s. The gray regions between two vertical lines indicate the start of the events up-to the end of the longest events of 30 s. The total number of averaged apneas for each subfigure is included at the top right. The peaks and drops representative for the mean ΔSpO2, ΔrHR, and ΔrCBF response to obstructive apneic events are labeled. See Fig. 1(a) for the visualization of the different apneas grouped by their duration before averaging.

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  Fig. 5. (a) Relative cerebral blood flow changes (ΔrCBF), (b) relative heart rate changes (ΔrHR), and (c) arterial oxygen saturation changes (ΔSpO2) peaks and/or drops are shown, divided in different apnea group durations and for all apneas. These are also summarized in Table 2. (*) indicates that the group is statistically different from zero with p<0.001. (†) indicates that the group is statistically different from zero with p<0.05.

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  Fig. 6. Mean relative cerebral blood flow changes (ΔrCBF) of apneas longer than 15 and up-to 30 s. (a) Average of all obstructive events, (b) those with no previous event 20 s before, (c) 30 s before, (d) 40 s before, and (e) 50 s before. The gray regions between two vertical lines indicates the start of the events up-to the end of the longest event of 30 s. The total number of averaged apneas for each panel is included at the top right.