Cerebrovascular response to arousal from NREM and REM sleep.

Study Objective: To determine the effect of arousal from sleep on cerebral blood flow velocity (CBFV) in relation to associated ventilatory and systemic hemodynamic changes.

Participants: Eleven healthy individuals (6 men, 5 women).

Measurements: Pulsed Doppler ultrasonography was used to measure CBFV in the middle cerebral artery with simultaneous measurements of sleep state (EEG, EOG, and EMG), ventilation (inductance plethysmography), heart rate (ECG), and arterial pressure (finger plethysmography).

Mechanisms of the cerebrovascular response to apnoea in humans.

We measured ventilation, arterial O2 saturation, end-tidal CO2 (PET,CO2), blood pressure (intra-arterial catheter or photoelectric plethysmograph), and flow velocity in the middle cerebral artery (CFV) (pulsed Doppler ultrasound) in 17 healthy awake subjects while they performed 20 s breath holds under control conditions and during ganglionic blockade (intravenous trimethaphan, 4.4 +/- 1.1 mg min-1 (mean +/- S.