Physiologic algorithmic approach to the reversal of decreases in cerebral oxygen saturation. Step 1: Verify head position and position of vascular catheters. Step 2: Adjust blood pressure to within 20% of baseline values. Step 3: Increase inspired oxygen fraction to correct low oxygen saturation values. Step 4: Adjust ventilator parameters to increase arterial end tidal carbon dioxide levels within normal ranges (35 to 45 mmHg). Step 5: Consider giving blood transfusions to patients with low hemoglobin level when steps 1 to 4 have not increased cerebral oxygen saturation within 20% of baseline values. Step 6: Consider improving ventricular function in the presence of low output state. Step 7: Rule out hypothermia, seizures, and light anesthesia. Step 8: Consider cerebral edema and increased intracranial pressure. CT Scan = computed tomography scan; Hb = hemoglobin; ICHT = IntraCranial HyperTension; MAP = mean arterial pressure; MRI = magnetic resonance imaging; PaCO₂ = arterial carbon dioxide tension; SaO₂ = arterial oxygen saturation; SvO₂ = mixed venous oxygen saturation.