Ketamine is a direct-acting anesthetic that is widely used in pediatric practice because of its dissociative properties and perceived beneficial cardiovascular effects. It is frequently used in the emergency department setting for minor procedures and is used in other areas for induction of anesthesia. Most other sedative and anesthetic agents result in some degree of cardiovascular depression in the form of hypotension, bradycardia, or direct negative inotropic effects. Ketamine, in contrast, typically causes an increase in heart rate, systemic blood pressure, and systemic vascular resistance. These effects result partially from inhibition of catecholamine reuptake, but also from direct sympathetic stimulation, resulting in increased release of catecholamines. Various studies have shown that ketamine can have either a negative or positive inotropic effect on cardiac function, with the overall effect being dosage dependent but generally negative. Because of these somewhat unpredictable cardiovascular effects, ketamine must be used with caution in certain situations, especially when patients are catecholamine depleted.