inverse I:E ratio, an inspiratory/expiratory ratio in mechanical ventilation in which the duration of inspiration is prolonged relative to that of expiration. This condition is sometimes instituted to improve oxygenation, as in the care of infants with idiopathic respiratory distress syndrome and of adults in whom conventional ventilator techniques fail. I:E ratios in such cases may be approximately 2:1 or 3:1. Also called reversed I:E ratio. See also I:E ratio.
