A respiratory treatment device comprising: a hosing enclosing a plurality of chambers; a first opening in the housing configured to transmit air exhaled into and air inhaled from the housing; a second opening in the housing configured to permit air exhaled into the first opening to exit the housing; a third opening in the housing configured to permit air outside the housing to enter the housing upon inhalation at the first opening; an exhalation flow path defined between the first opening and the second opening, and an inhalation flow path defined between the third opening and the first opening; a restrictor member positioned in the exhalation flow path and the inhalation flow path, such that the restrictor member is movable between a closed position, where a flow of air along the exhalation flow path or the inhalation flow path is restricted, and an open position, where the flow of exhaled air along the exhalation flow path or the inhalation flow path is less restricted; and, a vane in fluid communication with the exhalation flow path and the inhalation flow path, the vane being operatively connected to the restrictor member and configured to repeatedly reciprocate between a first position and a second position in response to the flow of air along the exhalation flow path or the inhalation flow path; a fourth opening in the housing configured to permit the flow of air along the exhalation flow path to exit the housing prior to the position of the restrictor member in the exhalation flow path; a fifth opening in the housing configured to permit air outside the housing to enter the inhalation flow path upon inhalation at the first opening subsequent to the position of the restrictor member in the inhalation flow path; and, a switch positioned relative to the fourth opening and the fifth opening such that one or both of the fourth opening and the fifth opening may be closed by the switch; thereby the device being capable of delivering oscillating pressure therapy upon both inhalation and exhalation.. a hosing enclosing a plurality of chambers; a first opening in the housing configured to transmit air exhaled into and air inhaled from the housing; a second opening in the housing configured to permit air exhaled into the first opening to exit the housing; a third opening in the housing configured to permit air outside the housing to enter the housing upon inhalation at the first opening; an exhalation flow path defined between the first opening and the second opening, and an inhalation flow path defined between the third opening and the first opening; a restrictor member positioned in the exhalation flow path and the inhalation flow path, such that the restrictor member is movable between a closed position, where a flow of air along the exhalation flow path or the inhalation flow path is restricted, and an open position, where the flow of exhaled air along the exhalation flow path or the inhalation flow path is less restricted; and, a vane in fluid communication with the exhalation flow path and the inhalation flow path, the vane being operatively connected to the restrictor member and configured to repeatedly reciprocate between a first position and a second position in response to the flow of air along the exhalation flow path or the inhalation flow path; a fourth opening in the housing configured to permit the flow of air along the exhalation flow path to exit the housing prior to the position of the restrictor member in the exhalation flow path; a fifth opening in the housing configured to permit air outside the housing to enter the inhalation flow path upon inhalation at the first opening subsequent to the position of the restrictor member in the inhalation flow path; and, a switch positioned relative to the fourth opening and the fifth opening such that one or both of the fourth opening and the fifth opening may be closed by the switch; thereby the device being capable of delivering oscillating pressure therapy upon both inhalation and exhalation..