Mechanical ventilation of pediatric patients in the operating room is challenging. Infants require significantly smaller tidal volumes than adults and changes in delivered volume that would be clinically insignificant for an adult patient, can produce unintended hyper- or hypoventilation in children. The consequences of these unintended ventilation changes can produce hypoxemia, hypercarbia, or barotrauma. This article discusses unique aspects of pediatric ventilation in the operating room, limitations of traditional anesthesia machine technology, the features of modern anesthesia ventilators that circumvent these limitations, and presents several comparison studies.