A system for controlling patient sedation and spontaneous breathing intensity includes a ventilator system that delivers ventilation to the patient. The system further includes a spontaneous breathing control module configured to determine a first spontaneous breathing intensity at a first sedative status of the patient, and a second spontaneous breathing intensity at a second sedative status of the patient. A sedation/breathing relationship is then defined between spontaneous breathing intensity and sedative status for the patient based on the first and second sedative statuses and the first and second spontaneous breathing intensities. The spontaneous breathing control module then receives a desired spontaneous breathing intensity for the patient and determines a desired sedative status that achieves that desired spontaneous breathing intensity based on the sedation/breathing relationship.