Electroconvulsive therapy (ECT) is an effective treatment for medication-resistant forms of depression, including major depressive disorder and mania. Therapeutic success of ECT is related to the duration and quality of Electroencephalogram (EEG) and motor seizures. Previous studies have demonstrated that deliberate hyperventilation augments seizure duration in anesthetized subjects. It has also been shown that seizure activity significantly increases cerebral metabolic rate, predisposing the patient to potentially severe cerebral desaturation events. These desaturation events are predicted to be exacerbated by pre-emptive hyperventilation which has a potent cerebral vasoconstrictive effect. Despite the widespread use of ECT, little is known about the effect of hyperventilation on cerebral metabolism in this setting. Ketamine has recently been demonstrated to have anti-depressant properties in patients with major depressive disorder, suggesting that patients treated with ketamine anesthesia and then ECT, may benefit clinically from the additive effects of both treatment modalities, compared to ECT alone.