Example of oxygen arterial saturation (SpO
) and brain tissue O
partial pressure (PtO
) signals recorded during the first ten minutes from a rat subjected to recurrent obstructive apneas. The SpO2 dips, mimicking those observed in OSA patients, were paralleled by similar dips in PtO2. However, while maximum and minimum values in SpO2 showed a stable pattern (top), PtO2 exhibited a progressive tendency to increase (bottom).