The Univent tube was designed as an alternative to double lumen endotracheal tubes. It is a conventional single lumen tube with an additional small channel within the concave anterior wall portion that houses a movable bronchial blocker used for lung isolation. A thin lumen in the blocker itself allows lung deflation and various ventilatory patterns (oxygen inflow, CPAP, jet-ventilation) in the blocked lung. Main indications for the Univent tube include difficult intubation, risk of aspiration and planned postoperative ventilation. The "blind" insertion of the bronchial balloon carries a high risk of primary malpositioning or secondary displacement that may cause a loss of the lung isolation or even tracheal obstruction. Initial insertion with fiberoptic bronchoscope is therefore required and this device must also be available during the whole period of one lung ventilation. High pressures generated by the bronchial cuff and higher cost than that of double lumen endotracheal tubes are two other factors that limit the use of the Univent tube.