Time course of the maximum (Δ) and minimum (▼) values of arterial oxygen saturation (SpO
) and brain tissue O
partial pressure (PtO
) recorded during each obstructive apnea. A schematic representation of the corresponding dips in both variables is superimposed for the purpose of clarity. Baseline value is represented by an open circle. Maximum and minimum values of PtO2 experienced a time-dependent increase (both, p < 0.001). In contrast, no changes were found in SpO2 maximum and minimum values. Results are shown as mean ± SE (n = 16). The time dependence of arterial SpO2 and brain tissue PtO2 was assessed with Friedman repeated measures ANOVA by comparing sample points at the first apnea and during the apneas at minute 10 and every 10 min up to 1 h with respect to baseline for maximum values or first event for minimum values. Comparisons were undertaken by means of the Student-Newman-Keuls method. * p < 0.05 respect to baseline ✟ p < 0.05 respect to the first apneic event.